summaryrefslogtreecommitdiff
path: root/drivers/ide/ide-tape.c
blob: c6eec0413a6c5f323bf67798554a6a794747773e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
/*
 * linux/drivers/ide/ide-tape.c		Version 1.19	Nov, 2003
 *
 * Copyright (C) 1995 - 1999 Gadi Oxman <gadio@netvision.net.il>
 *
 * $Header$
 *
 * This driver was constructed as a student project in the software laboratory
 * of the faculty of electrical engineering in the Technion - Israel's
 * Institute Of Technology, with the guide of Avner Lottem and Dr. Ilana David.
 *
 * It is hereby placed under the terms of the GNU general public license.
 * (See linux/COPYING).
 */
 
/*
 * IDE ATAPI streaming tape driver.
 *
 * This driver is a part of the Linux ide driver and works in co-operation
 * with linux/drivers/block/ide.c.
 *
 * The driver, in co-operation with ide.c, basically traverses the 
 * request-list for the block device interface. The character device
 * interface, on the other hand, creates new requests, adds them
 * to the request-list of the block device, and waits for their completion.
 *
 * Pipelined operation mode is now supported on both reads and writes.
 *
 * The block device major and minor numbers are determined from the
 * tape's relative position in the ide interfaces, as explained in ide.c.
 *
 * The character device interface consists of the following devices:
 *
 * ht0		major 37, minor 0	first  IDE tape, rewind on close.
 * ht1		major 37, minor 1	second IDE tape, rewind on close.
 * ...
 * nht0		major 37, minor 128	first  IDE tape, no rewind on close.
 * nht1		major 37, minor 129	second IDE tape, no rewind on close.
 * ...
 *
 * Run linux/scripts/MAKEDEV.ide to create the above entries.
 *
 * The general magnetic tape commands compatible interface, as defined by
 * include/linux/mtio.h, is accessible through the character device.
 *
 * General ide driver configuration options, such as the interrupt-unmask
 * flag, can be configured by issuing an ioctl to the block device interface,
 * as any other ide device.
 *
 * Our own ide-tape ioctl's can be issued to either the block device or
 * the character device interface.
 *
 * Maximal throughput with minimal bus load will usually be achieved in the
 * following scenario:
 *
 *	1.	ide-tape is operating in the pipelined operation mode.
 *	2.	No buffering is performed by the user backup program.
 *
 * Testing was done with a 2 GB CONNER CTMA 4000 IDE ATAPI Streaming Tape Drive.
 * 
 * Ver 0.1   Nov  1 95   Pre-working code :-)
 * Ver 0.2   Nov 23 95   A short backup (few megabytes) and restore procedure
 *                        was successful ! (Using tar cvf ... on the block
 *                        device interface).
 *                       A longer backup resulted in major swapping, bad
 *                        overall Linux performance and eventually failed as
 *                        we received non serial read-ahead requests from the
 *                        buffer cache.
 * Ver 0.3   Nov 28 95   Long backups are now possible, thanks to the
 *                        character device interface. Linux's responsiveness
 *                        and performance doesn't seem to be much affected
 *                        from the background backup procedure.
 *                       Some general mtio.h magnetic tape operations are
 *                        now supported by our character device. As a result,
 *                        popular tape utilities are starting to work with
 *                        ide tapes :-)
 *                       The following configurations were tested:
 *                       	1. An IDE ATAPI TAPE shares the same interface
 *                       	   and irq with an IDE ATAPI CDROM.
 *                        	2. An IDE ATAPI TAPE shares the same interface
 *                          	   and irq with a normal IDE disk.
 *                        Both configurations seemed to work just fine !
 *                        However, to be on the safe side, it is meanwhile
 *                        recommended to give the IDE TAPE its own interface
 *                        and irq.
 *                       The one thing which needs to be done here is to
 *                        add a "request postpone" feature to ide.c,
 *                        so that we won't have to wait for the tape to finish
 *                        performing a long media access (DSC) request (such
 *                        as a rewind) before we can access the other device
 *                        on the same interface. This effect doesn't disturb
 *                        normal operation most of the time because read/write
 *                        requests are relatively fast, and once we are
 *                        performing one tape r/w request, a lot of requests
 *                        from the other device can be queued and ide.c will
 *			  service all of them after this single tape request.
 * Ver 1.0   Dec 11 95   Integrated into Linux 1.3.46 development tree.
 *                       On each read / write request, we now ask the drive
 *                        if we can transfer a constant number of bytes
 *                        (a parameter of the drive) only to its buffers,
 *                        without causing actual media access. If we can't,
 *                        we just wait until we can by polling the DSC bit.
 *                        This ensures that while we are not transferring
 *                        more bytes than the constant referred to above, the
 *                        interrupt latency will not become too high and
 *                        we won't cause an interrupt timeout, as happened
 *                        occasionally in the previous version.
 *                       While polling for DSC, the current request is
 *                        postponed and ide.c is free to handle requests from
 *                        the other device. This is handled transparently to
 *                        ide.c. The hwgroup locking method which was used
 *                        in the previous version was removed.
 *                       Use of new general features which are provided by
 *                        ide.c for use with atapi devices.
 *                        (Programming done by Mark Lord)
 *                       Few potential bug fixes (Again, suggested by Mark)
 *                       Single character device data transfers are now
 *                        not limited in size, as they were before.
 *                       We are asking the tape about its recommended
 *                        transfer unit and send a larger data transfer
 *                        as several transfers of the above size.
 *                        For best results, use an integral number of this
 *                        basic unit (which is shown during driver
 *                        initialization). I will soon add an ioctl to get
 *                        this important parameter.
 *                       Our data transfer buffer is allocated on startup,
 *                        rather than before each data transfer. This should
 *                        ensure that we will indeed have a data buffer.
 * Ver 1.1   Dec 14 95   Fixed random problems which occurred when the tape
 *                        shared an interface with another device.
 *                        (poll_for_dsc was a complete mess).
 *                       Removed some old (non-active) code which had
 *                        to do with supporting buffer cache originated
 *                        requests.
 *                       The block device interface can now be opened, so
 *                        that general ide driver features like the unmask
 *                        interrupts flag can be selected with an ioctl.
 *                        This is the only use of the block device interface.
 *                       New fast pipelined operation mode (currently only on
 *                        writes). When using the pipelined mode, the
 *                        throughput can potentially reach the maximum
 *                        tape supported throughput, regardless of the
 *                        user backup program. On my tape drive, it sometimes
 *                        boosted performance by a factor of 2. Pipelined
 *                        mode is enabled by default, but since it has a few
 *                        downfalls as well, you may want to disable it.
 *                        A short explanation of the pipelined operation mode
 *                        is available below.
 * Ver 1.2   Jan  1 96   Eliminated pipelined mode race condition.
 *                       Added pipeline read mode. As a result, restores
 *                        are now as fast as backups.
 *                       Optimized shared interface behavior. The new behavior
 *                        typically results in better IDE bus efficiency and
 *                        higher tape throughput.
 *                       Pre-calculation of the expected read/write request
 *                        service time, based on the tape's parameters. In
 *                        the pipelined operation mode, this allows us to
 *                        adjust our polling frequency to a much lower value,
 *                        and thus to dramatically reduce our load on Linux,
 *                        without any decrease in performance.
 *                       Implemented additional mtio.h operations.
 *                       The recommended user block size is returned by
 *                        the MTIOCGET ioctl.
 *                       Additional minor changes.
 * Ver 1.3   Feb  9 96   Fixed pipelined read mode bug which prevented the
 *                        use of some block sizes during a restore procedure.
 *                       The character device interface will now present a
 *                        continuous view of the media - any mix of block sizes
 *                        during a backup/restore procedure is supported. The
 *                        driver will buffer the requests internally and
 *                        convert them to the tape's recommended transfer
 *                        unit, making performance almost independent of the
 *                        chosen user block size.
 *                       Some improvements in error recovery.
 *                       By cooperating with ide-dma.c, bus mastering DMA can
 *                        now sometimes be used with IDE tape drives as well.
 *                        Bus mastering DMA has the potential to dramatically
 *                        reduce the CPU's overhead when accessing the device,
 *                        and can be enabled by using hdparm -d1 on the tape's
 *                        block device interface. For more info, read the
 *                        comments in ide-dma.c.
 * Ver 1.4   Mar 13 96   Fixed serialize support.
 * Ver 1.5   Apr 12 96   Fixed shared interface operation, broken in 1.3.85.
 *                       Fixed pipelined read mode inefficiency.
 *                       Fixed nasty null dereferencing bug.
 * Ver 1.6   Aug 16 96   Fixed FPU usage in the driver.
 *                       Fixed end of media bug.
 * Ver 1.7   Sep 10 96   Minor changes for the CONNER CTT8000-A model.
 * Ver 1.8   Sep 26 96   Attempt to find a better balance between good
 *                        interactive response and high system throughput.
 * Ver 1.9   Nov  5 96   Automatically cross encountered filemarks rather
 *                        than requiring an explicit FSF command.
 *                       Abort pending requests at end of media.
 *                       MTTELL was sometimes returning incorrect results.
 *                       Return the real block size in the MTIOCGET ioctl.
 *                       Some error recovery bug fixes.
 * Ver 1.10  Nov  5 96   Major reorganization.
 *                       Reduced CPU overhead a bit by eliminating internal
 *                        bounce buffers.
 *                       Added module support.
 *                       Added multiple tape drives support.
 *                       Added partition support.
 *                       Rewrote DSC handling.
 *                       Some portability fixes.
 *                       Removed ide-tape.h.
 *                       Additional minor changes.
 * Ver 1.11  Dec  2 96   Bug fix in previous DSC timeout handling.
 *                       Use ide_stall_queue() for DSC overlap.
 *                       Use the maximum speed rather than the current speed
 *                        to compute the request service time.
 * Ver 1.12  Dec  7 97   Fix random memory overwriting and/or last block data
 *                        corruption, which could occur if the total number
 *                        of bytes written to the tape was not an integral
 *                        number of tape blocks.
 *                       Add support for INTERRUPT DRQ devices.
 * Ver 1.13  Jan  2 98   Add "speed == 0" work-around for HP COLORADO 5GB
 * Ver 1.14  Dec 30 98   Partial fixes for the Sony/AIWA tape drives.
 *                       Replace cli()/sti() with hwgroup spinlocks.
 * Ver 1.15  Mar 25 99   Fix SMP race condition by replacing hwgroup
 *                        spinlock with private per-tape spinlock.
 * Ver 1.16  Sep  1 99   Add OnStream tape support.
 *                       Abort read pipeline on EOD.
 *                       Wait for the tape to become ready in case it returns
 *                        "in the process of becoming ready" on open().
 *                       Fix zero padding of the last written block in
 *                        case the tape block size is larger than PAGE_SIZE.
 *                       Decrease the default disconnection time to tn.
 * Ver 1.16e Oct  3 99   Minor fixes.
 * Ver 1.16e1 Oct 13 99  Patches by Arnold Niessen,
 *                          niessen@iae.nl / arnold.niessen@philips.com
 *                   GO-1)  Undefined code in idetape_read_position
 *				according to Gadi's email
 *                   AJN-1) Minor fix asc == 11 should be asc == 0x11
 *                               in idetape_issue_packet_command (did effect
 *                               debugging output only)
 *                   AJN-2) Added more debugging output, and
 *                              added ide-tape: where missing. I would also
 *				like to add tape->name where possible
 *                   AJN-3) Added different debug_level's 
 *                              via /proc/ide/hdc/settings
 * 				"debug_level" determines amount of debugging output;
 * 				can be changed using /proc/ide/hdx/settings
 * 				0 : almost no debugging output
 * 				1 : 0+output errors only
 * 				2 : 1+output all sensekey/asc
 * 				3 : 2+follow all chrdev related procedures
 * 				4 : 3+follow all procedures
 * 				5 : 4+include pc_stack rq_stack info
 * 				6 : 5+USE_COUNT updates
 *                   AJN-4) Fixed timeout for retension in idetape_queue_pc_tail
 *				from 5 to 10 minutes
 *                   AJN-5) Changed maximum number of blocks to skip when
 *                              reading tapes with multiple consecutive write
 *                              errors from 100 to 1000 in idetape_get_logical_blk
 *                   Proposed changes to code:
 *                   1) output "logical_blk_num" via /proc
 *                   2) output "current_operation" via /proc
 *                   3) Either solve or document the fact that `mt rewind' is
 *                      required after reading from /dev/nhtx to be
 *			able to rmmod the idetape module;
 *			Also, sometimes an application finishes but the
 *			device remains `busy' for some time. Same cause ?
 *                   Proposed changes to release-notes:
 *		     4) write a simple `quickstart' section in the
 *                      release notes; I volunteer if you don't want to
 * 		     5) include a pointer to video4linux in the doc
 *                      to stimulate video applications
 *                   6) release notes lines 331 and 362: explain what happens
 *			if the application data rate is higher than 1100 KB/s; 
 *			similar approach to lower-than-500 kB/s ?
 *		     7) 6.6 Comparison; wouldn't it be better to allow different 
 *			strategies for read and write ?
 *			Wouldn't it be better to control the tape buffer
 *			contents instead of the bandwidth ?
 *		     8) line 536: replace will by would (if I understand
 *			this section correctly, a hypothetical and unwanted situation
 *			 is being described)
 * Ver 1.16f Dec 15 99   Change place of the secondary OnStream header frames.
 * Ver 1.17  Nov 2000 / Jan 2001  Marcel Mol, marcel@mesa.nl
 *			- Add idetape_onstream_mode_sense_tape_parameter_page
 *			  function to get tape capacity in frames: tape->capacity.
 *			- Add support for DI-50 drives( or any DI- drive).
 *			- 'workaround' for read error/blank block around block 3000.
 *			- Implement Early warning for end of media for Onstream.
 *			- Cosmetic code changes for readability.
 *			- Idetape_position_tape should not use SKIP bit during
 *			  Onstream read recovery.
 *			- Add capacity, logical_blk_num and first/last_frame_position
 *			  to /proc/ide/hd?/settings.
 *			- Module use count was gone in the Linux 2.4 driver.
 * Ver 1.17a Apr 2001 Willem Riede osst@riede.org
 * 			- Get drive's actual block size from mode sense block descriptor
 * 			- Limit size of pipeline
 * Ver 1.17b Oct 2002   Alan Stern <stern@rowland.harvard.edu>
 *			Changed IDETAPE_MIN_PIPELINE_STAGES to 1 and actually used
 *			 it in the code!
 *			Actually removed aborted stages in idetape_abort_pipeline
 *			 instead of just changing the command code.
 *			Made the transfer byte count for Request Sense equal to the
 *			 actual length of the data transfer.
 *			Changed handling of partial data transfers: they do not
 *			 cause DMA errors.
 *			Moved initiation of DMA transfers to the correct place.
 *			Removed reference to unallocated memory.
 *			Made __idetape_discard_read_pipeline return the number of
 *			 sectors skipped, not the number of stages.
 *			Replaced errant kfree() calls with __idetape_kfree_stage().
 *			Fixed off-by-one error in testing the pipeline length.
 *			Fixed handling of filemarks in the read pipeline.
 *			Small code optimization for MTBSF and MTBSFM ioctls.
 *			Don't try to unlock the door during device close if is
 *			 already unlocked!
 *			Cosmetic fixes to miscellaneous debugging output messages.
 *			Set the minimum /proc/ide/hd?/settings values for "pipeline",
 *			 "pipeline_min", and "pipeline_max" to 1.
 *
 * Here are some words from the first releases of hd.c, which are quoted
 * in ide.c and apply here as well:
 *
 * | Special care is recommended.  Have Fun!
 *
 */

/*
 * An overview of the pipelined operation mode.
 *
 * In the pipelined write mode, we will usually just add requests to our
 * pipeline and return immediately, before we even start to service them. The
 * user program will then have enough time to prepare the next request while
 * we are still busy servicing previous requests. In the pipelined read mode,
 * the situation is similar - we add read-ahead requests into the pipeline,
 * before the user even requested them.
 *
 * The pipeline can be viewed as a "safety net" which will be activated when
 * the system load is high and prevents the user backup program from keeping up
 * with the current tape speed. At this point, the pipeline will get
 * shorter and shorter but the tape will still be streaming at the same speed.
 * Assuming we have enough pipeline stages, the system load will hopefully
 * decrease before the pipeline is completely empty, and the backup program
 * will be able to "catch up" and refill the pipeline again.
 * 
 * When using the pipelined mode, it would be best to disable any type of
 * buffering done by the user program, as ide-tape already provides all the
 * benefits in the kernel, where it can be done in a more efficient way.
 * As we will usually not block the user program on a request, the most
 * efficient user code will then be a simple read-write-read-... cycle.
 * Any additional logic will usually just slow down the backup process.
 *
 * Using the pipelined mode, I get a constant over 400 KBps throughput,
 * which seems to be the maximum throughput supported by my tape.
 *
 * However, there are some downfalls:
 *
 *	1.	We use memory (for data buffers) in proportional to the number
 *		of pipeline stages (each stage is about 26 KB with my tape).
 *	2.	In the pipelined write mode, we cheat and postpone error codes
 *		to the user task. In read mode, the actual tape position
 *		will be a bit further than the last requested block.
 *
 * Concerning (1):
 *
 *	1.	We allocate stages dynamically only when we need them. When
 *		we don't need them, we don't consume additional memory. In
 *		case we can't allocate stages, we just manage without them
 *		(at the expense of decreased throughput) so when Linux is
 *		tight in memory, we will not pose additional difficulties.
 *
 *	2.	The maximum number of stages (which is, in fact, the maximum
 *		amount of memory) which we allocate is limited by the compile
 *		time parameter IDETAPE_MAX_PIPELINE_STAGES.
 *
 *	3.	The maximum number of stages is a controlled parameter - We
 *		don't start from the user defined maximum number of stages
 *		but from the lower IDETAPE_MIN_PIPELINE_STAGES (again, we
 *		will not even allocate this amount of stages if the user
 *		program can't handle the speed). We then implement a feedback
 *		loop which checks if the pipeline is empty, and if it is, we
 *		increase the maximum number of stages as necessary until we
 *		reach the optimum value which just manages to keep the tape
 *		busy with minimum allocated memory or until we reach
 *		IDETAPE_MAX_PIPELINE_STAGES.
 *
 * Concerning (2):
 *
 *	In pipelined write mode, ide-tape can not return accurate error codes
 *	to the user program since we usually just add the request to the
 *      pipeline without waiting for it to be serviced. In case an error
 *      occurs, I will report it on the next user request.
 *
 *	In the pipelined read mode, subsequent read requests or forward
 *	filemark spacing will perform correctly, as we preserve all blocks
 *	and filemarks which we encountered during our excess read-ahead.
 * 
 *	For accurate tape positioning and error reporting, disabling
 *	pipelined mode might be the best option.
 *
 * You can enable/disable/tune the pipelined operation mode by adjusting
 * the compile time parameters below.
 */

/*
 *	Possible improvements.
 *
 *	1.	Support for the ATAPI overlap protocol.
 *
 *		In order to maximize bus throughput, we currently use the DSC
 *		overlap method which enables ide.c to service requests from the
 *		other device while the tape is busy executing a command. The
 *		DSC overlap method involves polling the tape's status register
 *		for the DSC bit, and servicing the other device while the tape
 *		isn't ready.
 *
 *		In the current QIC development standard (December 1995),
 *		it is recommended that new tape drives will *in addition* 
 *		implement the ATAPI overlap protocol, which is used for the
 *		same purpose - efficient use of the IDE bus, but is interrupt
 *		driven and thus has much less CPU overhead.
 *
 *		ATAPI overlap is likely to be supported in most new ATAPI
 *		devices, including new ATAPI cdroms, and thus provides us
 *		a method by which we can achieve higher throughput when
 *		sharing a (fast) ATA-2 disk with any (slow) new ATAPI device.
 */

#define IDETAPE_VERSION "1.19"

#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/timer.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/major.h>
#include <linux/errno.h>
#include <linux/genhd.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include <linux/ide.h>
#include <linux/smp_lock.h>
#include <linux/completion.h>
#include <linux/bitops.h>
#include <linux/mutex.h>

#include <asm/byteorder.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/unaligned.h>

/*
 * partition
 */
typedef struct os_partition_s {
	__u8	partition_num;
	__u8	par_desc_ver;
	__u16	wrt_pass_cntr;
	__u32	first_frame_addr;
	__u32	last_frame_addr;
	__u32	eod_frame_addr;
} os_partition_t;

/*
 * DAT entry
 */
typedef struct os_dat_entry_s {
	__u32	blk_sz;
	__u16	blk_cnt;
	__u8	flags;
	__u8	reserved;
} os_dat_entry_t;

/*
 * DAT
 */
#define OS_DAT_FLAGS_DATA	(0xc)
#define OS_DAT_FLAGS_MARK	(0x1)

typedef struct os_dat_s {
	__u8		dat_sz;
	__u8		reserved1;
	__u8		entry_cnt;
	__u8		reserved3;
	os_dat_entry_t	dat_list[16];
} os_dat_t;

#include <linux/mtio.h>

/**************************** Tunable parameters *****************************/


/*
 *	Pipelined mode parameters.
 *
 *	We try to use the minimum number of stages which is enough to
 *	keep the tape constantly streaming. To accomplish that, we implement
 *	a feedback loop around the maximum number of stages:
 *
 *	We start from MIN maximum stages (we will not even use MIN stages
 *      if we don't need them), increment it by RATE*(MAX-MIN)
 *	whenever we sense that the pipeline is empty, until we reach
 *	the optimum value or until we reach MAX.
 *
 *	Setting the following parameter to 0 is illegal: the pipelined mode
 *	cannot be disabled (calculate_speeds() divides by tape->max_stages.)
 */
#define IDETAPE_MIN_PIPELINE_STAGES	  1
#define IDETAPE_MAX_PIPELINE_STAGES	400
#define IDETAPE_INCREASE_STAGES_RATE	 20

/*
 *	The following are used to debug the driver:
 *
 *	Setting IDETAPE_DEBUG_INFO to 1 will report device capabilities.
 *	Setting IDETAPE_DEBUG_LOG to 1 will log driver flow control.
 *	Setting IDETAPE_DEBUG_BUGS to 1 will enable self-sanity checks in
 *	some places.
 *
 *	Setting them to 0 will restore normal operation mode:
 *
 *		1.	Disable logging normal successful operations.
 *		2.	Disable self-sanity checks.
 *		3.	Errors will still be logged, of course.
 *
 *	All the #if DEBUG code will be removed some day, when the driver
 *	is verified to be stable enough. This will make it much more
 *	esthetic.
 */
#define IDETAPE_DEBUG_INFO		0
#define IDETAPE_DEBUG_LOG		0
#define IDETAPE_DEBUG_BUGS		1

/*
 *	After each failed packet command we issue a request sense command
 *	and retry the packet command IDETAPE_MAX_PC_RETRIES times.
 *
 *	Setting IDETAPE_MAX_PC_RETRIES to 0 will disable retries.
 */
#define IDETAPE_MAX_PC_RETRIES		3

/*
 *	With each packet command, we allocate a buffer of
 *	IDETAPE_PC_BUFFER_SIZE bytes. This is used for several packet
 *	commands (Not for READ/WRITE commands).
 */
#define IDETAPE_PC_BUFFER_SIZE		256

/*
 *	In various places in the driver, we need to allocate storage
 *	for packet commands and requests, which will remain valid while
 *	we leave the driver to wait for an interrupt or a timeout event.
 */
#define IDETAPE_PC_STACK		(10 + IDETAPE_MAX_PC_RETRIES)

/*
 * Some drives (for example, Seagate STT3401A Travan) require a very long
 * timeout, because they don't return an interrupt or clear their busy bit
 * until after the command completes (even retension commands).
 */
#define IDETAPE_WAIT_CMD		(900*HZ)

/*
 *	The following parameter is used to select the point in the internal
 *	tape fifo in which we will start to refill the buffer. Decreasing
 *	the following parameter will improve the system's latency and
 *	interactive response, while using a high value might improve sytem
 *	throughput.
 */
#define IDETAPE_FIFO_THRESHOLD 		2

/*
 *	DSC polling parameters.
 *
 *	Polling for DSC (a single bit in the status register) is a very
 *	important function in ide-tape. There are two cases in which we
 *	poll for DSC:
 *
 *	1.	Before a read/write packet command, to ensure that we
 *		can transfer data from/to the tape's data buffers, without
 *		causing an actual media access. In case the tape is not
 *		ready yet, we take out our request from the device
 *		request queue, so that ide.c will service requests from
 *		the other device on the same interface meanwhile.
 *
 *	2.	After the successful initialization of a "media access
 *		packet command", which is a command which can take a long
 *		time to complete (it can be several seconds or even an hour).
 *
 *		Again, we postpone our request in the middle to free the bus
 *		for the other device. The polling frequency here should be
 *		lower than the read/write frequency since those media access
 *		commands are slow. We start from a "fast" frequency -
 *		IDETAPE_DSC_MA_FAST (one second), and if we don't receive DSC
 *		after IDETAPE_DSC_MA_THRESHOLD (5 minutes), we switch it to a
 *		lower frequency - IDETAPE_DSC_MA_SLOW (1 minute).
 *
 *	We also set a timeout for the timer, in case something goes wrong.
 *	The timeout should be longer then the maximum execution time of a
 *	tape operation.
 */
 
/*
 *	DSC timings.
 */
#define IDETAPE_DSC_RW_MIN		5*HZ/100	/* 50 msec */
#define IDETAPE_DSC_RW_MAX		40*HZ/100	/* 400 msec */
#define IDETAPE_DSC_RW_TIMEOUT		2*60*HZ		/* 2 minutes */
#define IDETAPE_DSC_MA_FAST		2*HZ		/* 2 seconds */
#define IDETAPE_DSC_MA_THRESHOLD	5*60*HZ		/* 5 minutes */
#define IDETAPE_DSC_MA_SLOW		30*HZ		/* 30 seconds */
#define IDETAPE_DSC_MA_TIMEOUT		2*60*60*HZ	/* 2 hours */

/*************************** End of tunable parameters ***********************/

/*
 *	Debugging/Performance analysis
 *
 *	I/O trace support
 */
#define USE_IOTRACE	0
#if USE_IOTRACE
#include <linux/io_trace.h>
#define IO_IDETAPE_FIFO	500
#endif

/*
 *	Read/Write error simulation
 */
#define SIMULATE_ERRORS			0

/*
 *	For general magnetic tape device compatibility.
 */
typedef enum {
	idetape_direction_none,
	idetape_direction_read,
	idetape_direction_write
} idetape_chrdev_direction_t;

struct idetape_bh {
	unsigned short b_size;
	atomic_t b_count;
	struct idetape_bh *b_reqnext;
	char *b_data;
};

/*
 *	Our view of a packet command.
 */
typedef struct idetape_packet_command_s {
	u8 c[12];				/* Actual packet bytes */
	int retries;				/* On each retry, we increment retries */
	int error;				/* Error code */
	int request_transfer;			/* Bytes to transfer */
	int actually_transferred;		/* Bytes actually transferred */
	int buffer_size;			/* Size of our data buffer */
	struct idetape_bh *bh;
	char *b_data;
	int b_count;
	u8 *buffer;				/* Data buffer */
	u8 *current_position;			/* Pointer into the above buffer */
	ide_startstop_t (*callback) (ide_drive_t *);	/* Called when this packet command is completed */
	u8 pc_buffer[IDETAPE_PC_BUFFER_SIZE];	/* Temporary buffer */
	unsigned long flags;			/* Status/Action bit flags: long for set_bit */
} idetape_pc_t;

/*
 *	Packet command flag bits.
 */
/* Set when an error is considered normal - We won't retry */
#define	PC_ABORT			0
/* 1 When polling for DSC on a media access command */
#define PC_WAIT_FOR_DSC			1
/* 1 when we prefer to use DMA if possible */
#define PC_DMA_RECOMMENDED		2
/* 1 while DMA in progress */
#define	PC_DMA_IN_PROGRESS		3
/* 1 when encountered problem during DMA */
#define	PC_DMA_ERROR			4
/* Data direction */
#define	PC_WRITING			5

/*
 *	Capabilities and Mechanical Status Page
 */
typedef struct {
	unsigned	page_code	:6;	/* Page code - Should be 0x2a */
	__u8		reserved0_6	:1;
	__u8		ps		:1;	/* parameters saveable */
	__u8		page_length;		/* Page Length - Should be 0x12 */
	__u8		reserved2, reserved3;
	unsigned	ro		:1;	/* Read Only Mode */
	unsigned	reserved4_1234	:4;
	unsigned	sprev		:1;	/* Supports SPACE in the reverse direction */
	unsigned	reserved4_67	:2;
	unsigned	reserved5_012	:3;
	unsigned	efmt		:1;	/* Supports ERASE command initiated formatting */
	unsigned	reserved5_4	:1;
	unsigned	qfa		:1;	/* Supports the QFA two partition formats */
	unsigned	reserved5_67	:2;
	unsigned	lock		:1;	/* Supports locking the volume */
	unsigned	locked		:1;	/* The volume is locked */
	unsigned	prevent		:1;	/* The device defaults in the prevent state after power up */	
	unsigned	eject		:1;	/* The device can eject the volume */
	__u8		disconnect	:1;	/* The device can break request > ctl */	
	__u8		reserved6_5	:1;
	unsigned	ecc		:1;	/* Supports error correction */
	unsigned	cmprs		:1;	/* Supports data compression */
	unsigned	reserved7_0	:1;
	unsigned	blk512		:1;	/* Supports 512 bytes block size */
	unsigned	blk1024		:1;	/* Supports 1024 bytes block size */
	unsigned	reserved7_3_6	:4;
	unsigned	blk32768	:1;	/* slowb - the device restricts the byte count for PIO */
						/* transfers for slow buffer memory ??? */
						/* Also 32768 block size in some cases */
	__u16		max_speed;		/* Maximum speed supported in KBps */
	__u8		reserved10, reserved11;
	__u16		ctl;			/* Continuous Transfer Limit in blocks */
	__u16		speed;			/* Current Speed, in KBps */
	__u16		buffer_size;		/* Buffer Size, in 512 bytes */
	__u8		reserved18, reserved19;
} idetape_capabilities_page_t;

/*
 *	Block Size Page
 */
typedef struct {
	unsigned	page_code	:6;	/* Page code - Should be 0x30 */
	unsigned	reserved1_6	:1;
	unsigned	ps		:1;
	__u8		page_length;		/* Page Length - Should be 2 */
	__u8		reserved2;
	unsigned	play32		:1;
	unsigned	play32_5	:1;
	unsigned	reserved2_23	:2;
	unsigned	record32	:1;
	unsigned	record32_5	:1;
	unsigned	reserved2_6	:1;
	unsigned	one		:1;
} idetape_block_size_page_t;

/*
 *	A pipeline stage.
 */
typedef struct idetape_stage_s {
	struct request rq;			/* The corresponding request */
	struct idetape_bh *bh;			/* The data buffers */
	struct idetape_stage_s *next;		/* Pointer to the next stage */
} idetape_stage_t;

/*
 *	REQUEST SENSE packet command result - Data Format.
 */
typedef struct {
	unsigned	error_code	:7;	/* Current of deferred errors */
	unsigned	valid		:1;	/* The information field conforms to QIC-157C */
	__u8		reserved1	:8;	/* Segment Number - Reserved */
	unsigned	sense_key	:4;	/* Sense Key */
	unsigned	reserved2_4	:1;	/* Reserved */
	unsigned	ili		:1;	/* Incorrect Length Indicator */
	unsigned	eom		:1;	/* End Of Medium */
	unsigned	filemark 	:1;	/* Filemark */
	__u32		information __attribute__ ((packed));
	__u8		asl;			/* Additional sense length (n-7) */
	__u32		command_specific;	/* Additional command specific information */
	__u8		asc;			/* Additional Sense Code */
	__u8		ascq;			/* Additional Sense Code Qualifier */
	__u8		replaceable_unit_code;	/* Field Replaceable Unit Code */
	unsigned	sk_specific1 	:7;	/* Sense Key Specific */
	unsigned	sksv		:1;	/* Sense Key Specific information is valid */
	__u8		sk_specific2;		/* Sense Key Specific */
	__u8		sk_specific3;		/* Sense Key Specific */
	__u8		pad[2];			/* Padding to 20 bytes */
} idetape_request_sense_result_t;


/*
 *	Most of our global data which we need to save even as we leave the
 *	driver due to an interrupt or a timer event is stored in a variable
 *	of type idetape_tape_t, defined below.
 */
typedef struct ide_tape_obj {
	ide_drive_t	*drive;
	ide_driver_t	*driver;
	struct gendisk	*disk;
	struct kref	kref;

	/*
	 *	Since a typical character device operation requires more
	 *	than one packet command, we provide here enough memory
	 *	for the maximum of interconnected packet commands.
	 *	The packet commands are stored in the circular array pc_stack.
	 *	pc_stack_index points to the last used entry, and warps around
	 *	to the start when we get to the last array entry.
	 *
	 *	pc points to the current processed packet command.
	 *
	 *	failed_pc points to the last failed packet command, or contains
	 *	NULL if we do not need to retry any packet command. This is
	 *	required since an additional packet command is needed before the
	 *	retry, to get detailed information on what went wrong.
	 */
	/* Current packet command */
	idetape_pc_t *pc;
	/* Last failed packet command */
	idetape_pc_t *failed_pc;
	/* Packet command stack */
	idetape_pc_t pc_stack[IDETAPE_PC_STACK];
	/* Next free packet command storage space */
	int pc_stack_index;
	struct request rq_stack[IDETAPE_PC_STACK];
	/* We implement a circular array */
	int rq_stack_index;

	/*
	 *	DSC polling variables.
	 *
	 *	While polling for DSC we use postponed_rq to postpone the
	 *	current request so that ide.c will be able to service
	 *	pending requests on the other device. Note that at most
	 *	we will have only one DSC (usually data transfer) request
	 *	in the device request queue. Additional requests can be
	 *	queued in our internal pipeline, but they will be visible
	 *	to ide.c only one at a time.
	 */
	struct request *postponed_rq;
	/* The time in which we started polling for DSC */
	unsigned long dsc_polling_start;
	/* Timer used to poll for dsc */
	struct timer_list dsc_timer;
	/* Read/Write dsc polling frequency */
	unsigned long best_dsc_rw_frequency;
	/* The current polling frequency */
	unsigned long dsc_polling_frequency;
	/* Maximum waiting time */
	unsigned long dsc_timeout;

	/*
	 *	Read position information
	 */
	u8 partition;
	/* Current block */
	unsigned int first_frame_position;
	unsigned int last_frame_position;
	unsigned int blocks_in_buffer;

	/*
	 *	Last error information
	 */
	u8 sense_key, asc, ascq;

	/*
	 *	Character device operation
	 */
	unsigned int minor;
	/* device name */
	char name[4];
	/* Current character device data transfer direction */
	idetape_chrdev_direction_t chrdev_direction;

	/*
	 *	Device information
	 */
	/* Usually 512 or 1024 bytes */
	unsigned short tape_block_size;
	int user_bs_factor;
	/* Copy of the tape's Capabilities and Mechanical Page */
	idetape_capabilities_page_t capabilities;

	/*
	 *	Active data transfer request parameters.
	 *
	 *	At most, there is only one ide-tape originated data transfer
	 *	request in the device request queue. This allows ide.c to
	 *	easily service requests from the other device when we
	 *	postpone our active request. In the pipelined operation
	 *	mode, we use our internal pipeline structure to hold
	 *	more data requests.
	 *
	 *	The data buffer size is chosen based on the tape's
	 *	recommendation.
	 */
	/* Pointer to the request which is waiting in the device request queue */
	struct request *active_data_request;
	/* Data buffer size (chosen based on the tape's recommendation */
	int stage_size;
	idetape_stage_t *merge_stage;
	int merge_stage_size;
	struct idetape_bh *bh;
	char *b_data;
	int b_count;
	
	/*
	 *	Pipeline parameters.
	 *
	 *	To accomplish non-pipelined mode, we simply set the following
	 *	variables to zero (or NULL, where appropriate).
	 */
	/* Number of currently used stages */
	int nr_stages;
	/* Number of pending stages */
	int nr_pending_stages;
	/* We will not allocate more than this number of stages */
	int max_stages, min_pipeline, max_pipeline;
	/* The first stage which will be removed from the pipeline */
	idetape_stage_t *first_stage;
	/* The currently active stage */
	idetape_stage_t *active_stage;
	/* Will be serviced after the currently active request */
	idetape_stage_t *next_stage;
	/* New requests will be added to the pipeline here */
	idetape_stage_t *last_stage;
	/* Optional free stage which we can use */
	idetape_stage_t *cache_stage;
	int pages_per_stage;
	/* Wasted space in each stage */
	int excess_bh_size;

	/* Status/Action flags: long for set_bit */
	unsigned long flags;
	/* protects the ide-tape queue */
	spinlock_t spinlock;

	/*
	 * Measures average tape speed
	 */
	unsigned long avg_time;
	int avg_size;
	int avg_speed;

	/* last sense information */
	idetape_request_sense_result_t sense;

	char vendor_id[10];
	char product_id[18];
	char firmware_revision[6];
	int firmware_revision_num;

	/* the door is currently locked */
	int door_locked;
	/* the tape hardware is write protected */
	char drv_write_prot;
	/* the tape is write protected (hardware or opened as read-only) */
	char write_prot;

	/*
	 * Limit the number of times a request can
	 * be postponed, to avoid an infinite postpone
	 * deadlock.
	 */
	/* request postpone count limit */
	int postpone_cnt;

	/*
	 * Measures number of frames:
	 *
	 * 1. written/read to/from the driver pipeline (pipeline_head).
	 * 2. written/read to/from the tape buffers (idetape_bh).
	 * 3. written/read by the tape to/from the media (tape_head).
	 */
	int pipeline_head;
	int buffer_head;
	int tape_head;
	int last_tape_head;

	/*
	 * Speed control at the tape buffers input/output
	 */
	unsigned long insert_time;
	int insert_size;
	int insert_speed;
	int max_insert_speed;
	int measure_insert_time;

	/*
	 * Measure tape still time, in milliseconds
	 */
	unsigned long tape_still_time_begin;
	int tape_still_time;

	/*
	 * Speed regulation negative feedback loop
	 */
	int speed_control;
	int pipeline_head_speed;
	int controlled_pipeline_head_speed;
	int uncontrolled_pipeline_head_speed;
	int controlled_last_pipeline_head;
	int uncontrolled_last_pipeline_head;
	unsigned long uncontrolled_pipeline_head_time;
	unsigned long controlled_pipeline_head_time;
	int controlled_previous_pipeline_head;
	int uncontrolled_previous_pipeline_head;
	unsigned long controlled_previous_head_time;
	unsigned long uncontrolled_previous_head_time;
	int restart_speed_control_req;

        /*
         * Debug_level determines amount of debugging output;
         * can be changed using /proc/ide/hdx/settings
         * 0 : almost no debugging output
         * 1 : 0+output errors only
         * 2 : 1+output all sensekey/asc
         * 3 : 2+follow all chrdev related procedures
         * 4 : 3+follow all procedures
         * 5 : 4+include pc_stack rq_stack info
         * 6 : 5+USE_COUNT updates
         */
         int debug_level; 
} idetape_tape_t;

static DEFINE_MUTEX(idetape_ref_mutex);

static struct class *idetape_sysfs_class;

#define to_ide_tape(obj) container_of(obj, struct ide_tape_obj, kref)

#define ide_tape_g(disk) \
	container_of((disk)->private_data, struct ide_tape_obj, driver)

static struct ide_tape_obj *ide_tape_get(struct gendisk *disk)
{
	struct ide_tape_obj *tape = NULL;

	mutex_lock(&idetape_ref_mutex);
	tape = ide_tape_g(disk);
	if (tape)
		kref_get(&tape->kref);
	mutex_unlock(&idetape_ref_mutex);
	return tape;
}

static void ide_tape_release(struct kref *);

static void ide_tape_put(struct ide_tape_obj *tape)
{
	mutex_lock(&idetape_ref_mutex);
	kref_put(&tape->kref, ide_tape_release);
	mutex_unlock(&idetape_ref_mutex);
}

/*
 *	Tape door status
 */
#define DOOR_UNLOCKED			0
#define DOOR_LOCKED			1
#define DOOR_EXPLICITLY_LOCKED		2

/*
 *	Tape flag bits values.
 */
#define IDETAPE_IGNORE_DSC		0
#define IDETAPE_ADDRESS_VALID		1	/* 0 When the tape position is unknown */
#define IDETAPE_BUSY			2	/* Device already opened */
#define IDETAPE_PIPELINE_ERROR		3	/* Error detected in a pipeline stage */
#define IDETAPE_DETECT_BS		4	/* Attempt to auto-detect the current user block size */
#define IDETAPE_FILEMARK		5	/* Currently on a filemark */
#define IDETAPE_DRQ_INTERRUPT		6	/* DRQ interrupt device */
#define IDETAPE_READ_ERROR		7
#define IDETAPE_PIPELINE_ACTIVE		8	/* pipeline active */
/* 0 = no tape is loaded, so we don't rewind after ejecting */
#define IDETAPE_MEDIUM_PRESENT		9

/*
 *	Supported ATAPI tape drives packet commands
 */
#define IDETAPE_TEST_UNIT_READY_CMD	0x00
#define IDETAPE_REWIND_CMD		0x01
#define IDETAPE_REQUEST_SENSE_CMD	0x03
#define IDETAPE_READ_CMD		0x08
#define IDETAPE_WRITE_CMD		0x0a
#define IDETAPE_WRITE_FILEMARK_CMD	0x10
#define IDETAPE_SPACE_CMD		0x11
#define IDETAPE_INQUIRY_CMD		0x12
#define IDETAPE_ERASE_CMD		0x19
#define IDETAPE_MODE_SENSE_CMD		0x1a
#define IDETAPE_MODE_SELECT_CMD		0x15
#define IDETAPE_LOAD_UNLOAD_CMD		0x1b
#define IDETAPE_PREVENT_CMD		0x1e
#define IDETAPE_LOCATE_CMD		0x2b
#define IDETAPE_READ_POSITION_CMD	0x34
#define IDETAPE_READ_BUFFER_CMD		0x3c
#define IDETAPE_SET_SPEED_CMD		0xbb

/*
 *	Some defines for the READ BUFFER command
 */
#define IDETAPE_RETRIEVE_FAULTY_BLOCK	6

/*
 *	Some defines for the SPACE command
 */
#define IDETAPE_SPACE_OVER_FILEMARK	1
#define IDETAPE_SPACE_TO_EOD		3

/*
 *	Some defines for the LOAD UNLOAD command
 */
#define IDETAPE_LU_LOAD_MASK		1
#define IDETAPE_LU_RETENSION_MASK	2
#define IDETAPE_LU_EOT_MASK		4

/*
 *	Special requests for our block device strategy routine.
 *
 *	In order to service a character device command, we add special
 *	requests to the tail of our block device request queue and wait
 *	for their completion.
 */

enum {
	REQ_IDETAPE_PC1		= (1 << 0), /* packet command (first stage) */
	REQ_IDETAPE_PC2		= (1 << 1), /* packet command (second stage) */
	REQ_IDETAPE_READ	= (1 << 2),
	REQ_IDETAPE_WRITE	= (1 << 3),
	REQ_IDETAPE_READ_BUFFER	= (1 << 4),
};

/*
 *	Error codes which are returned in rq->errors to the higher part
 *	of the driver.
 */
#define	IDETAPE_ERROR_GENERAL		101
#define	IDETAPE_ERROR_FILEMARK		102
#define	IDETAPE_ERROR_EOD		103

/*
 *	The following is used to format the general configuration word of
 *	the ATAPI IDENTIFY DEVICE command.
 */
struct idetape_id_gcw {	
	unsigned packet_size		:2;	/* Packet Size */
	unsigned reserved234		:3;	/* Reserved */
	unsigned drq_type		:2;	/* Command packet DRQ type */
	unsigned removable		:1;	/* Removable media */
	unsigned device_type		:5;	/* Device type */
	unsigned reserved13		:1;	/* Reserved */
	unsigned protocol		:2;	/* Protocol type */
};

/*
 *	INQUIRY packet command - Data Format (From Table 6-8 of QIC-157C)
 */
typedef struct {
	unsigned	device_type	:5;	/* Peripheral Device Type */
	unsigned	reserved0_765	:3;	/* Peripheral Qualifier - Reserved */
	unsigned	reserved1_6t0	:7;	/* Reserved */
	unsigned	rmb		:1;	/* Removable Medium Bit */
	unsigned	ansi_version	:3;	/* ANSI Version */
	unsigned	ecma_version	:3;	/* ECMA Version */
	unsigned	iso_version	:2;	/* ISO Version */
	unsigned	response_format :4;	/* Response Data Format */
	unsigned	reserved3_45	:2;	/* Reserved */
	unsigned	reserved3_6	:1;	/* TrmIOP - Reserved */
	unsigned	reserved3_7	:1;	/* AENC - Reserved */
	__u8		additional_length;	/* Additional Length (total_length-4) */
	__u8		rsv5, rsv6, rsv7;	/* Reserved */
	__u8		vendor_id[8];		/* Vendor Identification */
	__u8		product_id[16];		/* Product Identification */
	__u8		revision_level[4];	/* Revision Level */
	__u8		vendor_specific[20];	/* Vendor Specific - Optional */
	__u8		reserved56t95[40];	/* Reserved - Optional */
						/* Additional information may be returned */
} idetape_inquiry_result_t;

/*
 *	READ POSITION packet command - Data Format (From Table 6-57)
 */
typedef struct {
	unsigned	reserved0_10	:2;	/* Reserved */
	unsigned	bpu		:1;	/* Block Position Unknown */	
	unsigned	reserved0_543	:3;	/* Reserved */
	unsigned	eop		:1;	/* End Of Partition */
	unsigned	bop		:1;	/* Beginning Of Partition */
	u8		partition;		/* Partition Number */
	u8		reserved2, reserved3;	/* Reserved */
	u32		first_block;		/* First Block Location */
	u32		last_block;		/* Last Block Location (Optional) */
	u8		reserved12;		/* Reserved */
	u8		blocks_in_buffer[3];	/* Blocks In Buffer - (Optional) */
	u32		bytes_in_buffer;	/* Bytes In Buffer (Optional) */
} idetape_read_position_result_t;

/*
 *	Follows structures which are related to the SELECT SENSE / MODE SENSE
 *	packet commands. Those packet commands are still not supported
 *	by ide-tape.
 */
#define IDETAPE_BLOCK_DESCRIPTOR	0
#define	IDETAPE_CAPABILITIES_PAGE	0x2a
#define IDETAPE_PARAMTR_PAGE		0x2b   /* Onstream DI-x0 only */
#define IDETAPE_BLOCK_SIZE_PAGE		0x30
#define IDETAPE_BUFFER_FILLING_PAGE	0x33

/*
 *	Mode Parameter Header for the MODE SENSE packet command
 */
typedef struct {
	__u8	mode_data_length;	/* Length of the following data transfer */
	__u8	medium_type;		/* Medium Type */
	__u8	dsp;			/* Device Specific Parameter */
	__u8	bdl;			/* Block Descriptor Length */
#if 0
	/* data transfer page */
	__u8	page_code	:6;
	__u8	reserved0_6	:1;
	__u8	ps		:1;	/* parameters saveable */
	__u8	page_length;		/* page Length == 0x02 */
	__u8	reserved2;
	__u8	read32k		:1;	/* 32k blk size (data only) */
	__u8	read32k5	:1;	/* 32.5k blk size (data&AUX) */
	__u8	reserved3_23	:2;
	__u8	write32k	:1;	/* 32k blk size (data only) */
	__u8	write32k5	:1;	/* 32.5k blk size (data&AUX) */
	__u8	reserved3_6	:1;
	__u8	streaming	:1;	/* streaming mode enable */
#endif
} idetape_mode_parameter_header_t;

/*
 *	Mode Parameter Block Descriptor the MODE SENSE packet command
 *
 *	Support for block descriptors is optional.
 */
typedef struct {
	__u8		density_code;		/* Medium density code */
	__u8		blocks[3];		/* Number of blocks */
	__u8		reserved4;		/* Reserved */
	__u8		length[3];		/* Block Length */
} idetape_parameter_block_descriptor_t;

/*
 *	The Data Compression Page, as returned by the MODE SENSE packet command.
 */
typedef struct {
	unsigned	page_code	:6;	/* Page Code - Should be 0xf */
	unsigned	reserved0	:1;	/* Reserved */
	unsigned	ps		:1;
	__u8		page_length;		/* Page Length - Should be 14 */
	unsigned	reserved2	:6;	/* Reserved */
	unsigned	dcc		:1;	/* Data Compression Capable */
	unsigned	dce		:1;	/* Data Compression Enable */
	unsigned	reserved3	:5;	/* Reserved */
	unsigned	red		:2;	/* Report Exception on Decompression */
	unsigned	dde		:1;	/* Data Decompression Enable */
	__u32		ca;			/* Compression Algorithm */
	__u32		da;			/* Decompression Algorithm */
	__u8		reserved[4];		/* Reserved */
} idetape_data_compression_page_t;

/*
 *	The Medium Partition Page, as returned by the MODE SENSE packet command.
 */
typedef struct {
	unsigned	page_code	:6;	/* Page Code - Should be 0x11 */
	unsigned	reserved1_6	:1;	/* Reserved */
	unsigned	ps		:1;
	__u8		page_length;		/* Page Length - Should be 6 */
	__u8		map;			/* Maximum Additional Partitions - Should be 0 */
	__u8		apd;			/* Additional Partitions Defined - Should be 0 */
	unsigned	reserved4_012	:3;	/* Reserved */
	unsigned	psum		:2;	/* Should be 0 */
	unsigned	idp		:1;	/* Should be 0 */
	unsigned	sdp		:1;	/* Should be 0 */
	unsigned	fdp		:1;	/* Fixed Data Partitions */
	__u8		mfr;			/* Medium Format Recognition */
	__u8		reserved[2];		/* Reserved */
} idetape_medium_partition_page_t;

/*
 *	Run time configurable parameters.
 */
typedef struct {
	int	dsc_rw_frequency;
	int	dsc_media_access_frequency;
	int	nr_stages;
} idetape_config_t;

/*
 *	The variables below are used for the character device interface.
 *	Additional state variables are defined in our ide_drive_t structure.
 */
static struct ide_tape_obj * idetape_devs[MAX_HWIFS * MAX_DRIVES];

#define ide_tape_f(file) ((file)->private_data)

static struct ide_tape_obj *ide_tape_chrdev_get(unsigned int i)
{
	struct ide_tape_obj *tape = NULL;

	mutex_lock(&idetape_ref_mutex);
	tape = idetape_devs[i];
	if (tape)
		kref_get(&tape->kref);
	mutex_unlock(&idetape_ref_mutex);
	return tape;
}

/*
 *      Function declarations
 *
 */
static int idetape_chrdev_release (struct inode *inode, struct file *filp);
static void idetape_write_release (ide_drive_t *drive, unsigned int minor);

/*
 * Too bad. The drive wants to send us data which we are not ready to accept.
 * Just throw it away.
 */
static void idetape_discard_data (ide_drive_t *drive, unsigned int bcount)
{
	while (bcount--)
		(void) HWIF(drive)->INB(IDE_DATA_REG);
}

static void idetape_input_buffers (ide_drive_t *drive, idetape_pc_t *pc, unsigned int bcount)
{
	struct idetape_bh *bh = pc->bh;
	int count;

	while (bcount) {
#if IDETAPE_DEBUG_BUGS
		if (bh == NULL) {
			printk(KERN_ERR "ide-tape: bh == NULL in "
				"idetape_input_buffers\n");
			idetape_discard_data(drive, bcount);
			return;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		count = min((unsigned int)(bh->b_size - atomic_read(&bh->b_count)), bcount);
		HWIF(drive)->atapi_input_bytes(drive, bh->b_data + atomic_read(&bh->b_count), count);
		bcount -= count;
		atomic_add(count, &bh->b_count);
		if (atomic_read(&bh->b_count) == bh->b_size) {
			bh = bh->b_reqnext;
			if (bh)
				atomic_set(&bh->b_count, 0);
		}
	}
	pc->bh = bh;
}

static void idetape_output_buffers (ide_drive_t *drive, idetape_pc_t *pc, unsigned int bcount)
{
	struct idetape_bh *bh = pc->bh;
	int count;

	while (bcount) {
#if IDETAPE_DEBUG_BUGS
		if (bh == NULL) {
			printk(KERN_ERR "ide-tape: bh == NULL in "
				"idetape_output_buffers\n");
			return;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		count = min((unsigned int)pc->b_count, (unsigned int)bcount);
		HWIF(drive)->atapi_output_bytes(drive, pc->b_data, count);
		bcount -= count;
		pc->b_data += count;
		pc->b_count -= count;
		if (!pc->b_count) {
			pc->bh = bh = bh->b_reqnext;
			if (bh) {
				pc->b_data = bh->b_data;
				pc->b_count = atomic_read(&bh->b_count);
			}
		}
	}
}

static void idetape_update_buffers (idetape_pc_t *pc)
{
	struct idetape_bh *bh = pc->bh;
	int count;
	unsigned int bcount = pc->actually_transferred;

	if (test_bit(PC_WRITING, &pc->flags))
		return;
	while (bcount) {
#if IDETAPE_DEBUG_BUGS
		if (bh == NULL) {
			printk(KERN_ERR "ide-tape: bh == NULL in "
				"idetape_update_buffers\n");
			return;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		count = min((unsigned int)bh->b_size, (unsigned int)bcount);
		atomic_set(&bh->b_count, count);
		if (atomic_read(&bh->b_count) == bh->b_size)
			bh = bh->b_reqnext;
		bcount -= count;
	}
	pc->bh = bh;
}

/*
 *	idetape_next_pc_storage returns a pointer to a place in which we can
 *	safely store a packet command, even though we intend to leave the
 *	driver. A storage space for a maximum of IDETAPE_PC_STACK packet
 *	commands is allocated at initialization time.
 */
static idetape_pc_t *idetape_next_pc_storage (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 5)
		printk(KERN_INFO "ide-tape: pc_stack_index=%d\n",
			tape->pc_stack_index);
#endif /* IDETAPE_DEBUG_LOG */
	if (tape->pc_stack_index == IDETAPE_PC_STACK)
		tape->pc_stack_index=0;
	return (&tape->pc_stack[tape->pc_stack_index++]);
}

/*
 *	idetape_next_rq_storage is used along with idetape_next_pc_storage.
 *	Since we queue packet commands in the request queue, we need to
 *	allocate a request, along with the allocation of a packet command.
 */
 
/**************************************************************
 *                                                            *
 *  This should get fixed to use kmalloc(.., GFP_ATOMIC)      *
 *  followed later on by kfree().   -ml                       *
 *                                                            *
 **************************************************************/
 
static struct request *idetape_next_rq_storage (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 5)
		printk(KERN_INFO "ide-tape: rq_stack_index=%d\n",
			tape->rq_stack_index);
#endif /* IDETAPE_DEBUG_LOG */
	if (tape->rq_stack_index == IDETAPE_PC_STACK)
		tape->rq_stack_index=0;
	return (&tape->rq_stack[tape->rq_stack_index++]);
}

/*
 *	idetape_init_pc initializes a packet command.
 */
static void idetape_init_pc (idetape_pc_t *pc)
{
	memset(pc->c, 0, 12);
	pc->retries = 0;
	pc->flags = 0;
	pc->request_transfer = 0;
	pc->buffer = pc->pc_buffer;
	pc->buffer_size = IDETAPE_PC_BUFFER_SIZE;
	pc->bh = NULL;
	pc->b_data = NULL;
}

/*
 *	idetape_analyze_error is called on each failed packet command retry
 *	to analyze the request sense. We currently do not utilize this
 *	information.
 */
static void idetape_analyze_error (ide_drive_t *drive, idetape_request_sense_result_t *result)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t *pc = tape->failed_pc;

	tape->sense     = *result;
	tape->sense_key = result->sense_key;
	tape->asc       = result->asc;
	tape->ascq      = result->ascq;
#if IDETAPE_DEBUG_LOG
	/*
	 *	Without debugging, we only log an error if we decided to
	 *	give up retrying.
	 */
	if (tape->debug_level >= 1)
		printk(KERN_INFO "ide-tape: pc = %x, sense key = %x, "
			"asc = %x, ascq = %x\n",
			pc->c[0], result->sense_key,
			result->asc, result->ascq);
#endif /* IDETAPE_DEBUG_LOG */

	/*
	 *	Correct pc->actually_transferred by asking the tape.
	 */
	if (test_bit(PC_DMA_ERROR, &pc->flags)) {
		pc->actually_transferred = pc->request_transfer - tape->tape_block_size * ntohl(get_unaligned(&result->information));
		idetape_update_buffers(pc);
	}

	/*
	 * If error was the result of a zero-length read or write command,
	 * with sense key=5, asc=0x22, ascq=0, let it slide.  Some drives
	 * (i.e. Seagate STT3401A Travan) don't support 0-length read/writes.
	 */
	if ((pc->c[0] == IDETAPE_READ_CMD || pc->c[0] == IDETAPE_WRITE_CMD)
	    && pc->c[4] == 0 && pc->c[3] == 0 && pc->c[2] == 0) { /* length==0 */
		if (result->sense_key == 5) {
			/* don't report an error, everything's ok */
			pc->error = 0;
			/* don't retry read/write */
			set_bit(PC_ABORT, &pc->flags);
		}
	}
	if (pc->c[0] == IDETAPE_READ_CMD && result->filemark) {
		pc->error = IDETAPE_ERROR_FILEMARK;
		set_bit(PC_ABORT, &pc->flags);
	}
	if (pc->c[0] == IDETAPE_WRITE_CMD) {
		if (result->eom ||
		    (result->sense_key == 0xd && result->asc == 0x0 &&
		     result->ascq == 0x2)) {
			pc->error = IDETAPE_ERROR_EOD;
			set_bit(PC_ABORT, &pc->flags);
		}
	}
	if (pc->c[0] == IDETAPE_READ_CMD || pc->c[0] == IDETAPE_WRITE_CMD) {
		if (result->sense_key == 8) {
			pc->error = IDETAPE_ERROR_EOD;
			set_bit(PC_ABORT, &pc->flags);
		}
		if (!test_bit(PC_ABORT, &pc->flags) &&
		    pc->actually_transferred)
			pc->retries = IDETAPE_MAX_PC_RETRIES + 1;
	}
}

/*
 * idetape_active_next_stage will declare the next stage as "active".
 */
static void idetape_active_next_stage (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *stage = tape->next_stage;
	struct request *rq = &stage->rq;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_active_next_stage\n");
#endif /* IDETAPE_DEBUG_LOG */
#if IDETAPE_DEBUG_BUGS
	if (stage == NULL) {
		printk(KERN_ERR "ide-tape: bug: Trying to activate a non existing stage\n");
		return;
	}
#endif /* IDETAPE_DEBUG_BUGS */	

	rq->rq_disk = tape->disk;
	rq->buffer = NULL;
	rq->special = (void *)stage->bh;
	tape->active_data_request = rq;
	tape->active_stage = stage;
	tape->next_stage = stage->next;
}

/*
 *	idetape_increase_max_pipeline_stages is a part of the feedback
 *	loop which tries to find the optimum number of stages. In the
 *	feedback loop, we are starting from a minimum maximum number of
 *	stages, and if we sense that the pipeline is empty, we try to
 *	increase it, until we reach the user compile time memory limit.
 */
static void idetape_increase_max_pipeline_stages (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	int increase = (tape->max_pipeline - tape->min_pipeline) / 10;
	
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk (KERN_INFO "ide-tape: Reached idetape_increase_max_pipeline_stages\n");
#endif /* IDETAPE_DEBUG_LOG */

	tape->max_stages += max(increase, 1);
	tape->max_stages = max(tape->max_stages, tape->min_pipeline);
	tape->max_stages = min(tape->max_stages, tape->max_pipeline);
}

/*
 *	idetape_kfree_stage calls kfree to completely free a stage, along with
 *	its related buffers.
 */
static void __idetape_kfree_stage (idetape_stage_t *stage)
{
	struct idetape_bh *prev_bh, *bh = stage->bh;
	int size;

	while (bh != NULL) {
		if (bh->b_data != NULL) {
			size = (int) bh->b_size;
			while (size > 0) {
				free_page((unsigned long) bh->b_data);
				size -= PAGE_SIZE;
				bh->b_data += PAGE_SIZE;
			}
		}
		prev_bh = bh;
		bh = bh->b_reqnext;
		kfree(prev_bh);
	}
	kfree(stage);
}

static void idetape_kfree_stage (idetape_tape_t *tape, idetape_stage_t *stage)
{
	__idetape_kfree_stage(stage);
}

/*
 *	idetape_remove_stage_head removes tape->first_stage from the pipeline.
 *	The caller should avoid race conditions.
 */
static void idetape_remove_stage_head (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *stage;
	
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_remove_stage_head\n");
#endif /* IDETAPE_DEBUG_LOG */
#if IDETAPE_DEBUG_BUGS
	if (tape->first_stage == NULL) {
		printk(KERN_ERR "ide-tape: bug: tape->first_stage is NULL\n");
		return;		
	}
	if (tape->active_stage == tape->first_stage) {
		printk(KERN_ERR "ide-tape: bug: Trying to free our active pipeline stage\n");
		return;
	}
#endif /* IDETAPE_DEBUG_BUGS */
	stage = tape->first_stage;
	tape->first_stage = stage->next;
	idetape_kfree_stage(tape, stage);
	tape->nr_stages--;
	if (tape->first_stage == NULL) {
		tape->last_stage = NULL;
#if IDETAPE_DEBUG_BUGS
		if (tape->next_stage != NULL)
			printk(KERN_ERR "ide-tape: bug: tape->next_stage != NULL\n");
		if (tape->nr_stages)
			printk(KERN_ERR "ide-tape: bug: nr_stages should be 0 now\n");
#endif /* IDETAPE_DEBUG_BUGS */
	}
}

/*
 * This will free all the pipeline stages starting from new_last_stage->next
 * to the end of the list, and point tape->last_stage to new_last_stage.
 */
static void idetape_abort_pipeline(ide_drive_t *drive,
				   idetape_stage_t *new_last_stage)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *stage = new_last_stage->next;
	idetape_stage_t *nstage;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: %s: idetape_abort_pipeline called\n", tape->name);
#endif
	while (stage) {
		nstage = stage->next;
		idetape_kfree_stage(tape, stage);
		--tape->nr_stages;
		--tape->nr_pending_stages;
		stage = nstage;
	}
	if (new_last_stage)
		new_last_stage->next = NULL;
	tape->last_stage = new_last_stage;
	tape->next_stage = NULL;
}

/*
 *	idetape_end_request is used to finish servicing a request, and to
 *	insert a pending pipeline request into the main device queue.
 */
static int idetape_end_request(ide_drive_t *drive, int uptodate, int nr_sects)
{
	struct request *rq = HWGROUP(drive)->rq;
	idetape_tape_t *tape = drive->driver_data;
	unsigned long flags;
	int error;
	int remove_stage = 0;
	idetape_stage_t *active_stage;

#if IDETAPE_DEBUG_LOG
        if (tape->debug_level >= 4)
	printk(KERN_INFO "ide-tape: Reached idetape_end_request\n");
#endif /* IDETAPE_DEBUG_LOG */

	switch (uptodate) {
		case 0:	error = IDETAPE_ERROR_GENERAL; break;
		case 1: error = 0; break;
		default: error = uptodate;
	}
	rq->errors = error;
	if (error)
		tape->failed_pc = NULL;

	spin_lock_irqsave(&tape->spinlock, flags);

	/* The request was a pipelined data transfer request */
	if (tape->active_data_request == rq) {
		active_stage = tape->active_stage;
		tape->active_stage = NULL;
		tape->active_data_request = NULL;
		tape->nr_pending_stages--;
		if (rq->cmd[0] & REQ_IDETAPE_WRITE) {
			remove_stage = 1;
			if (error) {
				set_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);
				if (error == IDETAPE_ERROR_EOD)
					idetape_abort_pipeline(drive, active_stage);
			}
		} else if (rq->cmd[0] & REQ_IDETAPE_READ) {
			if (error == IDETAPE_ERROR_EOD) {
				set_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);
				idetape_abort_pipeline(drive, active_stage);
			}
		}
		if (tape->next_stage != NULL) {
			idetape_active_next_stage(drive);

			/*
			 * Insert the next request into the request queue.
			 */
			(void) ide_do_drive_cmd(drive, tape->active_data_request, ide_end);
		} else if (!error) {
				idetape_increase_max_pipeline_stages(drive);
		}
	}
	ide_end_drive_cmd(drive, 0, 0);
//	blkdev_dequeue_request(rq);
//	drive->rq = NULL;
//	end_that_request_last(rq);

	if (remove_stage)
		idetape_remove_stage_head(drive);
	if (tape->active_data_request == NULL)
		clear_bit(IDETAPE_PIPELINE_ACTIVE, &tape->flags);
	spin_unlock_irqrestore(&tape->spinlock, flags);
	return 0;
}

static ide_startstop_t idetape_request_sense_callback (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_request_sense_callback\n");
#endif /* IDETAPE_DEBUG_LOG */
	if (!tape->pc->error) {
		idetape_analyze_error(drive, (idetape_request_sense_result_t *) tape->pc->buffer);
		idetape_end_request(drive, 1, 0);
	} else {
		printk(KERN_ERR "ide-tape: Error in REQUEST SENSE itself - Aborting request!\n");
		idetape_end_request(drive, 0, 0);
	}
	return ide_stopped;
}

static void idetape_create_request_sense_cmd (idetape_pc_t *pc)
{
	idetape_init_pc(pc);	
	pc->c[0] = IDETAPE_REQUEST_SENSE_CMD;
	pc->c[4] = 20;
	pc->request_transfer = 20;
	pc->callback = &idetape_request_sense_callback;
}

static void idetape_init_rq(struct request *rq, u8 cmd)
{
	memset(rq, 0, sizeof(*rq));
	rq->cmd_type = REQ_TYPE_SPECIAL;
	rq->cmd[0] = cmd;
}

/*
 *	idetape_queue_pc_head generates a new packet command request in front
 *	of the request queue, before the current request, so that it will be
 *	processed immediately, on the next pass through the driver.
 *
 *	idetape_queue_pc_head is called from the request handling part of
 *	the driver (the "bottom" part). Safe storage for the request should
 *	be allocated with idetape_next_pc_storage and idetape_next_rq_storage
 *	before calling idetape_queue_pc_head.
 *
 *	Memory for those requests is pre-allocated at initialization time, and
 *	is limited to IDETAPE_PC_STACK requests. We assume that we have enough
 *	space for the maximum possible number of inter-dependent packet commands.
 *
 *	The higher level of the driver - The ioctl handler and the character
 *	device handling functions should queue request to the lower level part
 *	and wait for their completion using idetape_queue_pc_tail or
 *	idetape_queue_rw_tail.
 */
static void idetape_queue_pc_head (ide_drive_t *drive, idetape_pc_t *pc,struct request *rq)
{
	struct ide_tape_obj *tape = drive->driver_data;

	idetape_init_rq(rq, REQ_IDETAPE_PC1);
	rq->buffer = (char *) pc;
	rq->rq_disk = tape->disk;
	(void) ide_do_drive_cmd(drive, rq, ide_preempt);
}

/*
 *	idetape_retry_pc is called when an error was detected during the
 *	last packet command. We queue a request sense packet command in
 *	the head of the request list.
 */
static ide_startstop_t idetape_retry_pc (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t *pc;
	struct request *rq;
	atapi_error_t error;

	error.all = HWIF(drive)->INB(IDE_ERROR_REG);
	pc = idetape_next_pc_storage(drive);
	rq = idetape_next_rq_storage(drive);
	idetape_create_request_sense_cmd(pc);
	set_bit(IDETAPE_IGNORE_DSC, &tape->flags);
	idetape_queue_pc_head(drive, pc, rq);
	return ide_stopped;
}

/*
 *	idetape_postpone_request postpones the current request so that
 *	ide.c will be able to service requests from another device on
 *	the same hwgroup while we are polling for DSC.
 */
static void idetape_postpone_request (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: idetape_postpone_request\n");
#endif
	tape->postponed_rq = HWGROUP(drive)->rq;
	ide_stall_queue(drive, tape->dsc_polling_frequency);
}

/*
 *	idetape_pc_intr is the usual interrupt handler which will be called
 *	during a packet command. We will transfer some of the data (as
 *	requested by the drive) and will re-point interrupt handler to us.
 *	When data transfer is finished, we will act according to the
 *	algorithm described before idetape_issue_packet_command.
 *
 */
static ide_startstop_t idetape_pc_intr (ide_drive_t *drive)
{
	ide_hwif_t *hwif = drive->hwif;
	idetape_tape_t *tape = drive->driver_data;
	atapi_status_t status;
	atapi_bcount_t bcount;
	atapi_ireason_t ireason;
	idetape_pc_t *pc = tape->pc;

	unsigned int temp;
#if SIMULATE_ERRORS
	static int error_sim_count = 0;
#endif

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_pc_intr "
				"interrupt handler\n");
#endif /* IDETAPE_DEBUG_LOG */	

	/* Clear the interrupt */
	status.all = HWIF(drive)->INB(IDE_STATUS_REG);

	if (test_bit(PC_DMA_IN_PROGRESS, &pc->flags)) {
		if (HWIF(drive)->ide_dma_end(drive) || status.b.check) {
			/*
			 * A DMA error is sometimes expected. For example,
			 * if the tape is crossing a filemark during a
			 * READ command, it will issue an irq and position
			 * itself before the filemark, so that only a partial
			 * data transfer will occur (which causes the DMA
			 * error). In that case, we will later ask the tape
			 * how much bytes of the original request were
			 * actually transferred (we can't receive that
			 * information from the DMA engine on most chipsets).
			 */

			/*
			 * On the contrary, a DMA error is never expected;
			 * it usually indicates a hardware error or abort.
			 * If the tape crosses a filemark during a READ
			 * command, it will issue an irq and position itself
			 * after the filemark (not before). Only a partial
			 * data transfer will occur, but no DMA error.
			 * (AS, 19 Apr 2001)
			 */
			set_bit(PC_DMA_ERROR, &pc->flags);
		} else {
			pc->actually_transferred = pc->request_transfer;
			idetape_update_buffers(pc);
		}
#if IDETAPE_DEBUG_LOG
		if (tape->debug_level >= 4)
			printk(KERN_INFO "ide-tape: DMA finished\n");
#endif /* IDETAPE_DEBUG_LOG */
	}

	/* No more interrupts */
	if (!status.b.drq) {
#if IDETAPE_DEBUG_LOG
		if (tape->debug_level >= 2)
			printk(KERN_INFO "ide-tape: Packet command completed, %d bytes transferred\n", pc->actually_transferred);
#endif /* IDETAPE_DEBUG_LOG */
		clear_bit(PC_DMA_IN_PROGRESS, &pc->flags);

		local_irq_enable();

#if SIMULATE_ERRORS
		if ((pc->c[0] == IDETAPE_WRITE_CMD ||
		     pc->c[0] == IDETAPE_READ_CMD) &&
		    (++error_sim_count % 100) == 0) {
			printk(KERN_INFO "ide-tape: %s: simulating error\n",
				tape->name);
			status.b.check = 1;
		}
#endif
		if (status.b.check && pc->c[0] == IDETAPE_REQUEST_SENSE_CMD)
			status.b.check = 0;
		if (status.b.check || test_bit(PC_DMA_ERROR, &pc->flags)) {	/* Error detected */
#if IDETAPE_DEBUG_LOG
			if (tape->debug_level >= 1)
				printk(KERN_INFO "ide-tape: %s: I/O error\n",
					tape->name);
#endif /* IDETAPE_DEBUG_LOG */
			if (pc->c[0] == IDETAPE_REQUEST_SENSE_CMD) {
				printk(KERN_ERR "ide-tape: I/O error in request sense command\n");
				return ide_do_reset(drive);
			}
#if IDETAPE_DEBUG_LOG
			if (tape->debug_level >= 1)
				printk(KERN_INFO "ide-tape: [cmd %x]: check condition\n", pc->c[0]);
#endif
			/* Retry operation */
			return idetape_retry_pc(drive);
		}
		pc->error = 0;
		if (test_bit(PC_WAIT_FOR_DSC, &pc->flags) &&
		    !status.b.dsc) {
			/* Media access command */
			tape->dsc_polling_start = jiffies;
			tape->dsc_polling_frequency = IDETAPE_DSC_MA_FAST;
			tape->dsc_timeout = jiffies + IDETAPE_DSC_MA_TIMEOUT;
			/* Allow ide.c to handle other requests */
			idetape_postpone_request(drive);
			return ide_stopped;
		}
		if (tape->failed_pc == pc)
			tape->failed_pc = NULL;
		/* Command finished - Call the callback function */
		return pc->callback(drive);
	}
	if (test_and_clear_bit(PC_DMA_IN_PROGRESS, &pc->flags)) {
		printk(KERN_ERR "ide-tape: The tape wants to issue more "
				"interrupts in DMA mode\n");
		printk(KERN_ERR "ide-tape: DMA disabled, reverting to PIO\n");
		(void)__ide_dma_off(drive);
		return ide_do_reset(drive);
	}
	/* Get the number of bytes to transfer on this interrupt. */
	bcount.b.high = hwif->INB(IDE_BCOUNTH_REG);
	bcount.b.low = hwif->INB(IDE_BCOUNTL_REG);

	ireason.all = hwif->INB(IDE_IREASON_REG);

	if (ireason.b.cod) {
		printk(KERN_ERR "ide-tape: CoD != 0 in idetape_pc_intr\n");
		return ide_do_reset(drive);
	}
	if (ireason.b.io == test_bit(PC_WRITING, &pc->flags)) {
		/* Hopefully, we will never get here */
		printk(KERN_ERR "ide-tape: We wanted to %s, ",
			ireason.b.io ? "Write":"Read");
		printk(KERN_ERR "ide-tape: but the tape wants us to %s !\n",
			ireason.b.io ? "Read":"Write");
		return ide_do_reset(drive);
	}
	if (!test_bit(PC_WRITING, &pc->flags)) {
		/* Reading - Check that we have enough space */
		temp = pc->actually_transferred + bcount.all;
		if (temp > pc->request_transfer) {
			if (temp > pc->buffer_size) {
				printk(KERN_ERR "ide-tape: The tape wants to send us more data than expected - discarding data\n");
				idetape_discard_data(drive, bcount.all);
				ide_set_handler(drive, &idetape_pc_intr, IDETAPE_WAIT_CMD, NULL);
				return ide_started;
			}
#if IDETAPE_DEBUG_LOG
			if (tape->debug_level >= 2)
				printk(KERN_NOTICE "ide-tape: The tape wants to send us more data than expected - allowing transfer\n");
#endif /* IDETAPE_DEBUG_LOG */
		}
	}
	if (test_bit(PC_WRITING, &pc->flags)) {
		if (pc->bh != NULL)
			idetape_output_buffers(drive, pc, bcount.all);
		else
			/* Write the current buffer */
			HWIF(drive)->atapi_output_bytes(drive, pc->current_position, bcount.all);
	} else {
		if (pc->bh != NULL)
			idetape_input_buffers(drive, pc, bcount.all);
		else
			/* Read the current buffer */
			HWIF(drive)->atapi_input_bytes(drive, pc->current_position, bcount.all);
	}
	/* Update the current position */
	pc->actually_transferred += bcount.all;
	pc->current_position += bcount.all;
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 2)
		printk(KERN_INFO "ide-tape: [cmd %x] transferred %d bytes on that interrupt\n", pc->c[0], bcount.all);
#endif
	/* And set the interrupt handler again */
	ide_set_handler(drive, &idetape_pc_intr, IDETAPE_WAIT_CMD, NULL);
	return ide_started;
}

/*
 *	Packet Command Interface
 *
 *	The current Packet Command is available in tape->pc, and will not
 *	change until we finish handling it. Each packet command is associated
 *	with a callback function that will be called when the command is
 *	finished.
 *
 *	The handling will be done in three stages:
 *
 *	1.	idetape_issue_packet_command will send the packet command to the
 *		drive, and will set the interrupt handler to idetape_pc_intr.
 *
 *	2.	On each interrupt, idetape_pc_intr will be called. This step
 *		will be repeated until the device signals us that no more
 *		interrupts will be issued.
 *
 *	3.	ATAPI Tape media access commands have immediate status with a
 *		delayed process. In case of a successful initiation of a
 *		media access packet command, the DSC bit will be set when the
 *		actual execution of the command is finished. 
 *		Since the tape drive will not issue an interrupt, we have to
 *		poll for this event. In this case, we define the request as
 *		"low priority request" by setting rq_status to
 *		IDETAPE_RQ_POSTPONED, 	set a timer to poll for DSC and exit
 *		the driver.
 *
 *		ide.c will then give higher priority to requests which
 *		originate from the other device, until will change rq_status
 *		to RQ_ACTIVE.
 *
 *	4.	When the packet command is finished, it will be checked for errors.
 *
 *	5.	In case an error was found, we queue a request sense packet
 *		command in front of the request queue and retry the operation
 *		up to IDETAPE_MAX_PC_RETRIES times.
 *
 *	6.	In case no error was found, or we decided to give up and not
 *		to retry again, the callback function will be called and then
 *		we will handle the next request.
 *
 */
static ide_startstop_t idetape_transfer_pc(ide_drive_t *drive)
{
	ide_hwif_t *hwif = drive->hwif;
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t *pc = tape->pc;
	atapi_ireason_t ireason;
	int retries = 100;
	ide_startstop_t startstop;

	if (ide_wait_stat(&startstop,drive,DRQ_STAT,BUSY_STAT,WAIT_READY)) {
		printk(KERN_ERR "ide-tape: Strange, packet command initiated yet DRQ isn't asserted\n");
		return startstop;
	}
	ireason.all = hwif->INB(IDE_IREASON_REG);
	while (retries-- && (!ireason.b.cod || ireason.b.io)) {
		printk(KERN_ERR "ide-tape: (IO,CoD != (0,1) while issuing "
				"a packet command, retrying\n");
		udelay(100);
		ireason.all = hwif->INB(IDE_IREASON_REG);
		if (retries == 0) {
			printk(KERN_ERR "ide-tape: (IO,CoD != (0,1) while "
					"issuing a packet command, ignoring\n");
			ireason.b.cod = 1;
			ireason.b.io = 0;
		}
	}
	if (!ireason.b.cod || ireason.b.io) {
		printk(KERN_ERR "ide-tape: (IO,CoD) != (0,1) while issuing "
				"a packet command\n");
		return ide_do_reset(drive);
	}
	/* Set the interrupt routine */
	ide_set_handler(drive, &idetape_pc_intr, IDETAPE_WAIT_CMD, NULL);
#ifdef CONFIG_BLK_DEV_IDEDMA
	/* Begin DMA, if necessary */
	if (test_bit(PC_DMA_IN_PROGRESS, &pc->flags))
		hwif->dma_start(drive);
#endif
	/* Send the actual packet */
	HWIF(drive)->atapi_output_bytes(drive, pc->c, 12);
	return ide_started;
}

static ide_startstop_t idetape_issue_packet_command (ide_drive_t *drive, idetape_pc_t *pc)
{
	ide_hwif_t *hwif = drive->hwif;
	idetape_tape_t *tape = drive->driver_data;
	atapi_bcount_t bcount;
	int dma_ok = 0;

#if IDETAPE_DEBUG_BUGS
	if (tape->pc->c[0] == IDETAPE_REQUEST_SENSE_CMD &&
	    pc->c[0] == IDETAPE_REQUEST_SENSE_CMD) {
		printk(KERN_ERR "ide-tape: possible ide-tape.c bug - "
			"Two request sense in serial were issued\n");
	}
#endif /* IDETAPE_DEBUG_BUGS */

	if (tape->failed_pc == NULL && pc->c[0] != IDETAPE_REQUEST_SENSE_CMD)
		tape->failed_pc = pc;
	/* Set the current packet command */
	tape->pc = pc;

	if (pc->retries > IDETAPE_MAX_PC_RETRIES ||
	    test_bit(PC_ABORT, &pc->flags)) {
		/*
		 *	We will "abort" retrying a packet command in case
		 *	a legitimate error code was received (crossing a
		 *	filemark, or end of the media, for example).
		 */
		if (!test_bit(PC_ABORT, &pc->flags)) {
			if (!(pc->c[0] == IDETAPE_TEST_UNIT_READY_CMD &&
			      tape->sense_key == 2 && tape->asc == 4 &&
			     (tape->ascq == 1 || tape->ascq == 8))) {
				printk(KERN_ERR "ide-tape: %s: I/O error, "
						"pc = %2x, key = %2x, "
						"asc = %2x, ascq = %2x\n",
						tape->name, pc->c[0],
						tape->sense_key, tape->asc,
						tape->ascq);
			}
			/* Giving up */
			pc->error = IDETAPE_ERROR_GENERAL;
		}
		tape->failed_pc = NULL;
		return pc->callback(drive);
	}
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 2)
		printk(KERN_INFO "ide-tape: Retry number - %d, cmd = %02X\n", pc->retries, pc->c[0]);
#endif /* IDETAPE_DEBUG_LOG */

	pc->retries++;
	/* We haven't transferred any data yet */
	pc->actually_transferred = 0;
	pc->current_position = pc->buffer;
	/* Request to transfer the entire buffer at once */
	bcount.all = pc->request_transfer;

	if (test_and_clear_bit(PC_DMA_ERROR, &pc->flags)) {
		printk(KERN_WARNING "ide-tape: DMA disabled, "
				"reverting to PIO\n");
		(void)__ide_dma_off(drive);
	}
	if (test_bit(PC_DMA_RECOMMENDED, &pc->flags) && drive->using_dma)
		dma_ok = !hwif->dma_setup(drive);

	if (IDE_CONTROL_REG)
		hwif->OUTB(drive->ctl, IDE_CONTROL_REG);
	hwif->OUTB(dma_ok ? 1 : 0, IDE_FEATURE_REG);	/* Use PIO/DMA */
	hwif->OUTB(bcount.b.high, IDE_BCOUNTH_REG);
	hwif->OUTB(bcount.b.low, IDE_BCOUNTL_REG);
	hwif->OUTB(drive->select.all, IDE_SELECT_REG);
	if (dma_ok)			/* Will begin DMA later */
		set_bit(PC_DMA_IN_PROGRESS, &pc->flags);
	if (test_bit(IDETAPE_DRQ_INTERRUPT, &tape->flags)) {
		ide_set_handler(drive, &idetape_transfer_pc, IDETAPE_WAIT_CMD, NULL);
		hwif->OUTB(WIN_PACKETCMD, IDE_COMMAND_REG);
		return ide_started;
	} else {
		hwif->OUTB(WIN_PACKETCMD, IDE_COMMAND_REG);
		return idetape_transfer_pc(drive);
	}
}

/*
 *	General packet command callback function.
 */
static ide_startstop_t idetape_pc_callback (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_pc_callback\n");
#endif /* IDETAPE_DEBUG_LOG */

	idetape_end_request(drive, tape->pc->error ? 0 : 1, 0);
	return ide_stopped;
}

/*
 *	A mode sense command is used to "sense" tape parameters.
 */
static void idetape_create_mode_sense_cmd (idetape_pc_t *pc, u8 page_code)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_MODE_SENSE_CMD;
	if (page_code != IDETAPE_BLOCK_DESCRIPTOR)
		pc->c[1] = 8;	/* DBD = 1 - Don't return block descriptors */
	pc->c[2] = page_code;
	/*
	 * Changed pc->c[3] to 0 (255 will at best return unused info).
	 *
	 * For SCSI this byte is defined as subpage instead of high byte
	 * of length and some IDE drives seem to interpret it this way
	 * and return an error when 255 is used.
	 */
	pc->c[3] = 0;
	pc->c[4] = 255;		/* (We will just discard data in that case) */
	if (page_code == IDETAPE_BLOCK_DESCRIPTOR)
		pc->request_transfer = 12;
	else if (page_code == IDETAPE_CAPABILITIES_PAGE)
		pc->request_transfer = 24;
	else
		pc->request_transfer = 50;
	pc->callback = &idetape_pc_callback;
}

static void calculate_speeds(ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	int full = 125, empty = 75;

	if (time_after(jiffies, tape->controlled_pipeline_head_time + 120 * HZ)) {
		tape->controlled_previous_pipeline_head = tape->controlled_last_pipeline_head;
		tape->controlled_previous_head_time = tape->controlled_pipeline_head_time;
		tape->controlled_last_pipeline_head = tape->pipeline_head;
		tape->controlled_pipeline_head_time = jiffies;
	}
	if (time_after(jiffies, tape->controlled_pipeline_head_time + 60 * HZ))
		tape->controlled_pipeline_head_speed = (tape->pipeline_head - tape->controlled_last_pipeline_head) * 32 * HZ / (jiffies - tape->controlled_pipeline_head_time);
	else if (time_after(jiffies, tape->controlled_previous_head_time))
		tape->controlled_pipeline_head_speed = (tape->pipeline_head - tape->controlled_previous_pipeline_head) * 32 * HZ / (jiffies - tape->controlled_previous_head_time);

	if (tape->nr_pending_stages < tape->max_stages /*- 1 */) {
		/* -1 for read mode error recovery */
		if (time_after(jiffies, tape->uncontrolled_previous_head_time + 10 * HZ)) {
			tape->uncontrolled_pipeline_head_time = jiffies;
			tape->uncontrolled_pipeline_head_speed = (tape->pipeline_head - tape->uncontrolled_previous_pipeline_head) * 32 * HZ / (jiffies - tape->uncontrolled_previous_head_time);
		}
	} else {
		tape->uncontrolled_previous_head_time = jiffies;
		tape->uncontrolled_previous_pipeline_head = tape->pipeline_head;
		if (time_after(jiffies, tape->uncontrolled_pipeline_head_time + 30 * HZ)) {
			tape->uncontrolled_pipeline_head_time = jiffies;
		}
	}
	tape->pipeline_head_speed = max(tape->uncontrolled_pipeline_head_speed, tape->controlled_pipeline_head_speed);
	if (tape->speed_control == 0) {
		tape->max_insert_speed = 5000;
	} else if (tape->speed_control == 1) {
		if (tape->nr_pending_stages >= tape->max_stages / 2)
			tape->max_insert_speed = tape->pipeline_head_speed +
				(1100 - tape->pipeline_head_speed) * 2 * (tape->nr_pending_stages - tape->max_stages / 2) / tape->max_stages;
		else
			tape->max_insert_speed = 500 +
				(tape->pipeline_head_speed - 500) * 2 * tape->nr_pending_stages / tape->max_stages;
		if (tape->nr_pending_stages >= tape->max_stages * 99 / 100)
			tape->max_insert_speed = 5000;
	} else if (tape->speed_control == 2) {
		tape->max_insert_speed = tape->pipeline_head_speed * empty / 100 +
			(tape->pipeline_head_speed * full / 100 - tape->pipeline_head_speed * empty / 100) * tape->nr_pending_stages / tape->max_stages;
	} else
		tape->max_insert_speed = tape->speed_control;
	tape->max_insert_speed = max(tape->max_insert_speed, 500);
}

static ide_startstop_t idetape_media_access_finished (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t *pc = tape->pc;
	atapi_status_t status;

	status.all = HWIF(drive)->INB(IDE_STATUS_REG);
	if (status.b.dsc) {
		if (status.b.check) {
			/* Error detected */
			if (pc->c[0] != IDETAPE_TEST_UNIT_READY_CMD)
				printk(KERN_ERR "ide-tape: %s: I/O error, ",
						tape->name);
			/* Retry operation */
			return idetape_retry_pc(drive);
		}
		pc->error = 0;
		if (tape->failed_pc == pc)
			tape->failed_pc = NULL;
	} else {
		pc->error = IDETAPE_ERROR_GENERAL;
		tape->failed_pc = NULL;
	}
	return pc->callback(drive);
}

static ide_startstop_t idetape_rw_callback (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	struct request *rq = HWGROUP(drive)->rq;
	int blocks = tape->pc->actually_transferred / tape->tape_block_size;

	tape->avg_size += blocks * tape->tape_block_size;
	tape->insert_size += blocks * tape->tape_block_size;
	if (tape->insert_size > 1024 * 1024)
		tape->measure_insert_time = 1;
	if (tape->measure_insert_time) {
		tape->measure_insert_time = 0;
		tape->insert_time = jiffies;
		tape->insert_size = 0;
	}
	if (time_after(jiffies, tape->insert_time))
		tape->insert_speed = tape->insert_size / 1024 * HZ / (jiffies - tape->insert_time);
	if (time_after_eq(jiffies, tape->avg_time + HZ)) {
		tape->avg_speed = tape->avg_size * HZ / (jiffies - tape->avg_time) / 1024;
		tape->avg_size = 0;
		tape->avg_time = jiffies;
	}

#if IDETAPE_DEBUG_LOG	
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_rw_callback\n");
#endif /* IDETAPE_DEBUG_LOG */

	tape->first_frame_position += blocks;
	rq->current_nr_sectors -= blocks;

	if (!tape->pc->error)
		idetape_end_request(drive, 1, 0);
	else
		idetape_end_request(drive, tape->pc->error, 0);
	return ide_stopped;
}

static void idetape_create_read_cmd(idetape_tape_t *tape, idetape_pc_t *pc, unsigned int length, struct idetape_bh *bh)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_READ_CMD;
	put_unaligned(htonl(length), (unsigned int *) &pc->c[1]);
	pc->c[1] = 1;
	pc->callback = &idetape_rw_callback;
	pc->bh = bh;
	atomic_set(&bh->b_count, 0);
	pc->buffer = NULL;
	pc->request_transfer = pc->buffer_size = length * tape->tape_block_size;
	if (pc->request_transfer == tape->stage_size)
		set_bit(PC_DMA_RECOMMENDED, &pc->flags);
}

static void idetape_create_read_buffer_cmd(idetape_tape_t *tape, idetape_pc_t *pc, unsigned int length, struct idetape_bh *bh)
{
	int size = 32768;
	struct idetape_bh *p = bh;

	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_READ_BUFFER_CMD;
	pc->c[1] = IDETAPE_RETRIEVE_FAULTY_BLOCK;
	pc->c[7] = size >> 8;
	pc->c[8] = size & 0xff;
	pc->callback = &idetape_pc_callback;
	pc->bh = bh;
	atomic_set(&bh->b_count, 0);
	pc->buffer = NULL;
	while (p) {
		atomic_set(&p->b_count, 0);
		p = p->b_reqnext;
	}
	pc->request_transfer = pc->buffer_size = size;
}

static void idetape_create_write_cmd(idetape_tape_t *tape, idetape_pc_t *pc, unsigned int length, struct idetape_bh *bh)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_WRITE_CMD;
	put_unaligned(htonl(length), (unsigned int *) &pc->c[1]);
	pc->c[1] = 1;
	pc->callback = &idetape_rw_callback;
	set_bit(PC_WRITING, &pc->flags);
	pc->bh = bh;
	pc->b_data = bh->b_data;
	pc->b_count = atomic_read(&bh->b_count);
	pc->buffer = NULL;
	pc->request_transfer = pc->buffer_size = length * tape->tape_block_size;
	if (pc->request_transfer == tape->stage_size)
		set_bit(PC_DMA_RECOMMENDED, &pc->flags);
}

/*
 * idetape_do_request is our request handling function.	
 */
static ide_startstop_t idetape_do_request(ide_drive_t *drive,
					  struct request *rq, sector_t block)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t *pc = NULL;
	struct request *postponed_rq = tape->postponed_rq;
	atapi_status_t status;

#if IDETAPE_DEBUG_LOG
#if 0
	if (tape->debug_level >= 5)
		printk(KERN_INFO "ide-tape:  %d, "
			"dev: %s, cmd: %ld, errors: %d\n",
			 rq->rq_disk->disk_name, rq->cmd[0], rq->errors);
#endif
	if (tape->debug_level >= 2)
		printk(KERN_INFO "ide-tape: sector: %ld, "
			"nr_sectors: %ld, current_nr_sectors: %d\n",
			rq->sector, rq->nr_sectors, rq->current_nr_sectors);
#endif /* IDETAPE_DEBUG_LOG */

	if (!blk_special_request(rq)) {
		/*
		 * We do not support buffer cache originated requests.
		 */
		printk(KERN_NOTICE "ide-tape: %s: Unsupported request in "
			"request queue (%d)\n", drive->name, rq->cmd_type);
		ide_end_request(drive, 0, 0);
		return ide_stopped;
	}

	/*
	 *	Retry a failed packet command
	 */
	if (tape->failed_pc != NULL &&
	    tape->pc->c[0] == IDETAPE_REQUEST_SENSE_CMD) {
		return idetape_issue_packet_command(drive, tape->failed_pc);
	}
#if IDETAPE_DEBUG_BUGS
	if (postponed_rq != NULL)
		if (rq != postponed_rq) {
			printk(KERN_ERR "ide-tape: ide-tape.c bug - "
					"Two DSC requests were queued\n");
			idetape_end_request(drive, 0, 0);
			return ide_stopped;
		}
#endif /* IDETAPE_DEBUG_BUGS */

	tape->postponed_rq = NULL;

	/*
	 * If the tape is still busy, postpone our request and service
	 * the other device meanwhile.
	 */
	status.all = HWIF(drive)->INB(IDE_STATUS_REG);

	if (!drive->dsc_overlap && !(rq->cmd[0] & REQ_IDETAPE_PC2))
		set_bit(IDETAPE_IGNORE_DSC, &tape->flags);

	if (drive->post_reset == 1) {
		set_bit(IDETAPE_IGNORE_DSC, &tape->flags);
		drive->post_reset = 0;
	}

	if (tape->tape_still_time > 100 && tape->tape_still_time < 200)
		tape->measure_insert_time = 1;
	if (time_after(jiffies, tape->insert_time))
		tape->insert_speed = tape->insert_size / 1024 * HZ / (jiffies - tape->insert_time);
	calculate_speeds(drive);
	if (!test_and_clear_bit(IDETAPE_IGNORE_DSC, &tape->flags) &&
	    !status.b.dsc) {
		if (postponed_rq == NULL) {
			tape->dsc_polling_start = jiffies;
			tape->dsc_polling_frequency = tape->best_dsc_rw_frequency;
			tape->dsc_timeout = jiffies + IDETAPE_DSC_RW_TIMEOUT;
		} else if (time_after(jiffies, tape->dsc_timeout)) {
			printk(KERN_ERR "ide-tape: %s: DSC timeout\n",
				tape->name);
			if (rq->cmd[0] & REQ_IDETAPE_PC2) {
				idetape_media_access_finished(drive);
				return ide_stopped;
			} else {
				return ide_do_reset(drive);
			}
		} else if (time_after(jiffies, tape->dsc_polling_start + IDETAPE_DSC_MA_THRESHOLD))
			tape->dsc_polling_frequency = IDETAPE_DSC_MA_SLOW;
		idetape_postpone_request(drive);
		return ide_stopped;
	}
	if (rq->cmd[0] & REQ_IDETAPE_READ) {
		tape->buffer_head++;
#if USE_IOTRACE
		IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
#endif
		tape->postpone_cnt = 0;
		pc = idetape_next_pc_storage(drive);
		idetape_create_read_cmd(tape, pc, rq->current_nr_sectors, (struct idetape_bh *)rq->special);
		goto out;
	}
	if (rq->cmd[0] & REQ_IDETAPE_WRITE) {
		tape->buffer_head++;
#if USE_IOTRACE
		IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
#endif
		tape->postpone_cnt = 0;
		pc = idetape_next_pc_storage(drive);
		idetape_create_write_cmd(tape, pc, rq->current_nr_sectors, (struct idetape_bh *)rq->special);
		goto out;
	}
	if (rq->cmd[0] & REQ_IDETAPE_READ_BUFFER) {
		tape->postpone_cnt = 0;
		pc = idetape_next_pc_storage(drive);
		idetape_create_read_buffer_cmd(tape, pc, rq->current_nr_sectors, (struct idetape_bh *)rq->special);
		goto out;
	}
	if (rq->cmd[0] & REQ_IDETAPE_PC1) {
		pc = (idetape_pc_t *) rq->buffer;
		rq->cmd[0] &= ~(REQ_IDETAPE_PC1);
		rq->cmd[0] |= REQ_IDETAPE_PC2;
		goto out;
	}
	if (rq->cmd[0] & REQ_IDETAPE_PC2) {
		idetape_media_access_finished(drive);
		return ide_stopped;
	}
	BUG();
out:
	return idetape_issue_packet_command(drive, pc);
}

/*
 *	Pipeline related functions
 */
static inline int idetape_pipeline_active (idetape_tape_t *tape)
{
	int rc1, rc2;

	rc1 = test_bit(IDETAPE_PIPELINE_ACTIVE, &tape->flags);
	rc2 = (tape->active_data_request != NULL);
	return rc1;
}

/*
 *	idetape_kmalloc_stage uses __get_free_page to allocate a pipeline
 *	stage, along with all the necessary small buffers which together make
 *	a buffer of size tape->stage_size (or a bit more). We attempt to
 *	combine sequential pages as much as possible.
 *
 *	Returns a pointer to the new allocated stage, or NULL if we
 *	can't (or don't want to) allocate a stage.
 *
 *	Pipeline stages are optional and are used to increase performance.
 *	If we can't allocate them, we'll manage without them.
 */
static idetape_stage_t *__idetape_kmalloc_stage (idetape_tape_t *tape, int full, int clear)
{
	idetape_stage_t *stage;
	struct idetape_bh *prev_bh, *bh;
	int pages = tape->pages_per_stage;
	char *b_data = NULL;

	if ((stage = kmalloc(sizeof (idetape_stage_t),GFP_KERNEL)) == NULL)
		return NULL;
	stage->next = NULL;

	bh = stage->bh = kmalloc(sizeof(struct idetape_bh), GFP_KERNEL);
	if (bh == NULL)
		goto abort;
	bh->b_reqnext = NULL;
	if ((bh->b_data = (char *) __get_free_page (GFP_KERNEL)) == NULL)
		goto abort;
	if (clear)
		memset(bh->b_data, 0, PAGE_SIZE);
	bh->b_size = PAGE_SIZE;
	atomic_set(&bh->b_count, full ? bh->b_size : 0);

	while (--pages) {
		if ((b_data = (char *) __get_free_page (GFP_KERNEL)) == NULL)
			goto abort;
		if (clear)
			memset(b_data, 0, PAGE_SIZE);
		if (bh->b_data == b_data + PAGE_SIZE) {
			bh->b_size += PAGE_SIZE;
			bh->b_data -= PAGE_SIZE;
			if (full)
				atomic_add(PAGE_SIZE, &bh->b_count);
			continue;
		}
		if (b_data == bh->b_data + bh->b_size) {
			bh->b_size += PAGE_SIZE;
			if (full)
				atomic_add(PAGE_SIZE, &bh->b_count);
			continue;
		}
		prev_bh = bh;
		if ((bh = kmalloc(sizeof(struct idetape_bh), GFP_KERNEL)) == NULL) {
			free_page((unsigned long) b_data);
			goto abort;
		}
		bh->b_reqnext = NULL;
		bh->b_data = b_data;
		bh->b_size = PAGE_SIZE;
		atomic_set(&bh->b_count, full ? bh->b_size : 0);
		prev_bh->b_reqnext = bh;
	}
	bh->b_size -= tape->excess_bh_size;
	if (full)
		atomic_sub(tape->excess_bh_size, &bh->b_count);
	return stage;
abort:
	__idetape_kfree_stage(stage);
	return NULL;
}

static idetape_stage_t *idetape_kmalloc_stage (idetape_tape_t *tape)
{
	idetape_stage_t *cache_stage = tape->cache_stage;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_kmalloc_stage\n");
#endif /* IDETAPE_DEBUG_LOG */

	if (tape->nr_stages >= tape->max_stages)
		return NULL;
	if (cache_stage != NULL) {
		tape->cache_stage = NULL;
		return cache_stage;
	}
	return __idetape_kmalloc_stage(tape, 0, 0);
}

static int idetape_copy_stage_from_user (idetape_tape_t *tape, idetape_stage_t *stage, const char __user *buf, int n)
{
	struct idetape_bh *bh = tape->bh;
	int count;
	int ret = 0;

	while (n) {
#if IDETAPE_DEBUG_BUGS
		if (bh == NULL) {
			printk(KERN_ERR "ide-tape: bh == NULL in "
				"idetape_copy_stage_from_user\n");
			return 1;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		count = min((unsigned int)(bh->b_size - atomic_read(&bh->b_count)), (unsigned int)n);
		if (copy_from_user(bh->b_data + atomic_read(&bh->b_count), buf, count))
			ret = 1;
		n -= count;
		atomic_add(count, &bh->b_count);
		buf += count;
		if (atomic_read(&bh->b_count) == bh->b_size) {
			bh = bh->b_reqnext;
			if (bh)
				atomic_set(&bh->b_count, 0);
		}
	}
	tape->bh = bh;
	return ret;
}

static int idetape_copy_stage_to_user (idetape_tape_t *tape, char __user *buf, idetape_stage_t *stage, int n)
{
	struct idetape_bh *bh = tape->bh;
	int count;
	int ret = 0;

	while (n) {
#if IDETAPE_DEBUG_BUGS
		if (bh == NULL) {
			printk(KERN_ERR "ide-tape: bh == NULL in "
				"idetape_copy_stage_to_user\n");
			return 1;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		count = min(tape->b_count, n);
		if  (copy_to_user(buf, tape->b_data, count))
			ret = 1;
		n -= count;
		tape->b_data += count;
		tape->b_count -= count;
		buf += count;
		if (!tape->b_count) {
			tape->bh = bh = bh->b_reqnext;
			if (bh) {
				tape->b_data = bh->b_data;
				tape->b_count = atomic_read(&bh->b_count);
			}
		}
	}
	return ret;
}

static void idetape_init_merge_stage (idetape_tape_t *tape)
{
	struct idetape_bh *bh = tape->merge_stage->bh;
	
	tape->bh = bh;
	if (tape->chrdev_direction == idetape_direction_write)
		atomic_set(&bh->b_count, 0);
	else {
		tape->b_data = bh->b_data;
		tape->b_count = atomic_read(&bh->b_count);
	}
}

static void idetape_switch_buffers (idetape_tape_t *tape, idetape_stage_t *stage)
{
	struct idetape_bh *tmp;

	tmp = stage->bh;
	stage->bh = tape->merge_stage->bh;
	tape->merge_stage->bh = tmp;
	idetape_init_merge_stage(tape);
}

/*
 *	idetape_add_stage_tail adds a new stage at the end of the pipeline.
 */
static void idetape_add_stage_tail (ide_drive_t *drive,idetape_stage_t *stage)
{
	idetape_tape_t *tape = drive->driver_data;
	unsigned long flags;
	
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk (KERN_INFO "ide-tape: Reached idetape_add_stage_tail\n");
#endif /* IDETAPE_DEBUG_LOG */
	spin_lock_irqsave(&tape->spinlock, flags);
	stage->next = NULL;
	if (tape->last_stage != NULL)
		tape->last_stage->next=stage;
	else
		tape->first_stage = tape->next_stage=stage;
	tape->last_stage = stage;
	if (tape->next_stage == NULL)
		tape->next_stage = tape->last_stage;
	tape->nr_stages++;
	tape->nr_pending_stages++;
	spin_unlock_irqrestore(&tape->spinlock, flags);
}

/*
 *	idetape_wait_for_request installs a completion in a pending request
 *	and sleeps until it is serviced.
 *
 *	The caller should ensure that the request will not be serviced
 *	before we install the completion (usually by disabling interrupts).
 */
static void idetape_wait_for_request (ide_drive_t *drive, struct request *rq)
{
	DECLARE_COMPLETION_ONSTACK(wait);
	idetape_tape_t *tape = drive->driver_data;

#if IDETAPE_DEBUG_BUGS
	if (rq == NULL || !blk_special_request(rq)) {
		printk (KERN_ERR "ide-tape: bug: Trying to sleep on non-valid request\n");
		return;
	}
#endif /* IDETAPE_DEBUG_BUGS */
	rq->end_io_data = &wait;
	rq->end_io = blk_end_sync_rq;
	spin_unlock_irq(&tape->spinlock);
	wait_for_completion(&wait);
	/* The stage and its struct request have been deallocated */
	spin_lock_irq(&tape->spinlock);
}

static ide_startstop_t idetape_read_position_callback (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_read_position_result_t *result;
	
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_read_position_callback\n");
#endif /* IDETAPE_DEBUG_LOG */

	if (!tape->pc->error) {
		result = (idetape_read_position_result_t *) tape->pc->buffer;
#if IDETAPE_DEBUG_LOG
		if (tape->debug_level >= 2)
			printk(KERN_INFO "ide-tape: BOP - %s\n",result->bop ? "Yes":"No");
		if (tape->debug_level >= 2)
			printk(KERN_INFO "ide-tape: EOP - %s\n",result->eop ? "Yes":"No");
#endif /* IDETAPE_DEBUG_LOG */
		if (result->bpu) {
			printk(KERN_INFO "ide-tape: Block location is unknown to the tape\n");
			clear_bit(IDETAPE_ADDRESS_VALID, &tape->flags);
			idetape_end_request(drive, 0, 0);
		} else {
#if IDETAPE_DEBUG_LOG
			if (tape->debug_level >= 2)
				printk(KERN_INFO "ide-tape: Block Location - %u\n", ntohl(result->first_block));
#endif /* IDETAPE_DEBUG_LOG */
			tape->partition = result->partition;
			tape->first_frame_position = ntohl(result->first_block);
			tape->last_frame_position = ntohl(result->last_block);
			tape->blocks_in_buffer = result->blocks_in_buffer[2];
			set_bit(IDETAPE_ADDRESS_VALID, &tape->flags);
			idetape_end_request(drive, 1, 0);
		}
	} else {
		idetape_end_request(drive, 0, 0);
	}
	return ide_stopped;
}

/*
 *	idetape_create_write_filemark_cmd will:
 *
 *		1.	Write a filemark if write_filemark=1.
 *		2.	Flush the device buffers without writing a filemark
 *			if write_filemark=0.
 *
 */
static void idetape_create_write_filemark_cmd (ide_drive_t *drive, idetape_pc_t *pc,int write_filemark)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_WRITE_FILEMARK_CMD;
	pc->c[4] = write_filemark;
	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
	pc->callback = &idetape_pc_callback;
}

static void idetape_create_test_unit_ready_cmd(idetape_pc_t *pc)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_TEST_UNIT_READY_CMD;
	pc->callback = &idetape_pc_callback;
}

/*
 *	idetape_queue_pc_tail is based on the following functions:
 *
 *	ide_do_drive_cmd from ide.c
 *	cdrom_queue_request and cdrom_queue_packet_command from ide-cd.c
 *
 *	We add a special packet command request to the tail of the request
 *	queue, and wait for it to be serviced.
 *
 *	This is not to be called from within the request handling part
 *	of the driver ! We allocate here data in the stack, and it is valid
 *	until the request is finished. This is not the case for the bottom
 *	part of the driver, where we are always leaving the functions to wait
 *	for an interrupt or a timer event.
 *
 *	From the bottom part of the driver, we should allocate safe memory
 *	using idetape_next_pc_storage and idetape_next_rq_storage, and add
 *	the request to the request list without waiting for it to be serviced !
 *	In that case, we usually use idetape_queue_pc_head.
 */
static int __idetape_queue_pc_tail (ide_drive_t *drive, idetape_pc_t *pc)
{
	struct ide_tape_obj *tape = drive->driver_data;
	struct request rq;

	idetape_init_rq(&rq, REQ_IDETAPE_PC1);
	rq.buffer = (char *) pc;
	rq.rq_disk = tape->disk;
	return ide_do_drive_cmd(drive, &rq, ide_wait);
}

static void idetape_create_load_unload_cmd (ide_drive_t *drive, idetape_pc_t *pc,int cmd)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_LOAD_UNLOAD_CMD;
	pc->c[4] = cmd;
	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
	pc->callback = &idetape_pc_callback;
}

static int idetape_wait_ready(ide_drive_t *drive, unsigned long timeout)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t pc;
	int load_attempted = 0;

	/*
	 * Wait for the tape to become ready
	 */
	set_bit(IDETAPE_MEDIUM_PRESENT, &tape->flags);
	timeout += jiffies;
	while (time_before(jiffies, timeout)) {
		idetape_create_test_unit_ready_cmd(&pc);
		if (!__idetape_queue_pc_tail(drive, &pc))
			return 0;
		if ((tape->sense_key == 2 && tape->asc == 4 && tape->ascq == 2)
		    || (tape->asc == 0x3A)) {	/* no media */
			if (load_attempted)
				return -ENOMEDIUM;
			idetape_create_load_unload_cmd(drive, &pc, IDETAPE_LU_LOAD_MASK);
			__idetape_queue_pc_tail(drive, &pc);
			load_attempted = 1;
		/* not about to be ready */
		} else if (!(tape->sense_key == 2 && tape->asc == 4 &&
			     (tape->ascq == 1 || tape->ascq == 8)))
			return -EIO;
		msleep(100);
	}
	return -EIO;
}

static int idetape_queue_pc_tail (ide_drive_t *drive,idetape_pc_t *pc)
{
	return __idetape_queue_pc_tail(drive, pc);
}

static int idetape_flush_tape_buffers (ide_drive_t *drive)
{
	idetape_pc_t pc;
	int rc;

	idetape_create_write_filemark_cmd(drive, &pc, 0);
	if ((rc = idetape_queue_pc_tail(drive, &pc)))
		return rc;
	idetape_wait_ready(drive, 60 * 5 * HZ);
	return 0;
}

static void idetape_create_read_position_cmd (idetape_pc_t *pc)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_READ_POSITION_CMD;
	pc->request_transfer = 20;
	pc->callback = &idetape_read_position_callback;
}

static int idetape_read_position (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t pc;
	int position;

#if IDETAPE_DEBUG_LOG
        if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_read_position\n");
#endif /* IDETAPE_DEBUG_LOG */

	idetape_create_read_position_cmd(&pc);
	if (idetape_queue_pc_tail(drive, &pc))
		return -1;
	position = tape->first_frame_position;
	return position;
}

static void idetape_create_locate_cmd (ide_drive_t *drive, idetape_pc_t *pc, unsigned int block, u8 partition, int skip)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_LOCATE_CMD;
	pc->c[1] = 2;
	put_unaligned(htonl(block), (unsigned int *) &pc->c[3]);
	pc->c[8] = partition;
	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
	pc->callback = &idetape_pc_callback;
}

static int idetape_create_prevent_cmd (ide_drive_t *drive, idetape_pc_t *pc, int prevent)
{
	idetape_tape_t *tape = drive->driver_data;

	if (!tape->capabilities.lock)
		return 0;

	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_PREVENT_CMD;
	pc->c[4] = prevent;
	pc->callback = &idetape_pc_callback;
	return 1;
}

static int __idetape_discard_read_pipeline (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	unsigned long flags;
	int cnt;

	if (tape->chrdev_direction != idetape_direction_read)
		return 0;

	/* Remove merge stage. */
	cnt = tape->merge_stage_size / tape->tape_block_size;
	if (test_and_clear_bit(IDETAPE_FILEMARK, &tape->flags))
		++cnt;		/* Filemarks count as 1 sector */
	tape->merge_stage_size = 0;
	if (tape->merge_stage != NULL) {
		__idetape_kfree_stage(tape->merge_stage);
		tape->merge_stage = NULL;
	}

	/* Clear pipeline flags. */
	clear_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);
	tape->chrdev_direction = idetape_direction_none;

	/* Remove pipeline stages. */
	if (tape->first_stage == NULL)
		return 0;

	spin_lock_irqsave(&tape->spinlock, flags);
	tape->next_stage = NULL;
	if (idetape_pipeline_active(tape))
		idetape_wait_for_request(drive, tape->active_data_request);
	spin_unlock_irqrestore(&tape->spinlock, flags);

	while (tape->first_stage != NULL) {
		struct request *rq_ptr = &tape->first_stage->rq;

		cnt += rq_ptr->nr_sectors - rq_ptr->current_nr_sectors; 
		if (rq_ptr->errors == IDETAPE_ERROR_FILEMARK)
			++cnt;
		idetape_remove_stage_head(drive);
	}
	tape->nr_pending_stages = 0;
	tape->max_stages = tape->min_pipeline;
	return cnt;
}

/*
 *	idetape_position_tape positions the tape to the requested block
 *	using the LOCATE packet command. A READ POSITION command is then
 *	issued to check where we are positioned.
 *
 *	Like all higher level operations, we queue the commands at the tail
 *	of the request queue and wait for their completion.
 *	
 */
static int idetape_position_tape (ide_drive_t *drive, unsigned int block, u8 partition, int skip)
{
	idetape_tape_t *tape = drive->driver_data;
	int retval;
	idetape_pc_t pc;

	if (tape->chrdev_direction == idetape_direction_read)
		__idetape_discard_read_pipeline(drive);
	idetape_wait_ready(drive, 60 * 5 * HZ);
	idetape_create_locate_cmd(drive, &pc, block, partition, skip);
	retval = idetape_queue_pc_tail(drive, &pc);
	if (retval)
		return (retval);

	idetape_create_read_position_cmd(&pc);
	return (idetape_queue_pc_tail(drive, &pc));
}

static void idetape_discard_read_pipeline (ide_drive_t *drive, int restore_position)
{
	idetape_tape_t *tape = drive->driver_data;
	int cnt;
	int seek, position;

	cnt = __idetape_discard_read_pipeline(drive);
	if (restore_position) {
		position = idetape_read_position(drive);
		seek = position > cnt ? position - cnt : 0;
		if (idetape_position_tape(drive, seek, 0, 0)) {
			printk(KERN_INFO "ide-tape: %s: position_tape failed in discard_pipeline()\n", tape->name);
			return;
		}
	}
}

/*
 * idetape_queue_rw_tail generates a read/write request for the block
 * device interface and wait for it to be serviced.
 */
static int idetape_queue_rw_tail(ide_drive_t *drive, int cmd, int blocks, struct idetape_bh *bh)
{
	idetape_tape_t *tape = drive->driver_data;
	struct request rq;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 2)
		printk(KERN_INFO "ide-tape: idetape_queue_rw_tail: cmd=%d\n",cmd);
#endif /* IDETAPE_DEBUG_LOG */
#if IDETAPE_DEBUG_BUGS
	if (idetape_pipeline_active(tape)) {
		printk(KERN_ERR "ide-tape: bug: the pipeline is active in idetape_queue_rw_tail\n");
		return (0);
	}
#endif /* IDETAPE_DEBUG_BUGS */	

	idetape_init_rq(&rq, cmd);
	rq.rq_disk = tape->disk;
	rq.special = (void *)bh;
	rq.sector = tape->first_frame_position;
	rq.nr_sectors = rq.current_nr_sectors = blocks;
	(void) ide_do_drive_cmd(drive, &rq, ide_wait);

	if ((cmd & (REQ_IDETAPE_READ | REQ_IDETAPE_WRITE)) == 0)
		return 0;

	if (tape->merge_stage)
		idetape_init_merge_stage(tape);
	if (rq.errors == IDETAPE_ERROR_GENERAL)
		return -EIO;
	return (tape->tape_block_size * (blocks-rq.current_nr_sectors));
}

/*
 *	idetape_insert_pipeline_into_queue is used to start servicing the
 *	pipeline stages, starting from tape->next_stage.
 */
static void idetape_insert_pipeline_into_queue (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

	if (tape->next_stage == NULL)
		return;
	if (!idetape_pipeline_active(tape)) {
		set_bit(IDETAPE_PIPELINE_ACTIVE, &tape->flags);
		idetape_active_next_stage(drive);
		(void) ide_do_drive_cmd(drive, tape->active_data_request, ide_end);
	}
}

static void idetape_create_inquiry_cmd (idetape_pc_t *pc)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_INQUIRY_CMD;
	pc->c[4] = pc->request_transfer = 254;
	pc->callback = &idetape_pc_callback;
}

static void idetape_create_rewind_cmd (ide_drive_t *drive, idetape_pc_t *pc)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_REWIND_CMD;
	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
	pc->callback = &idetape_pc_callback;
}

#if 0
static void idetape_create_mode_select_cmd (idetape_pc_t *pc, int length)
{
	idetape_init_pc(pc);
	set_bit(PC_WRITING, &pc->flags);
	pc->c[0] = IDETAPE_MODE_SELECT_CMD;
	pc->c[1] = 0x10;
	put_unaligned(htons(length), (unsigned short *) &pc->c[3]);
	pc->request_transfer = 255;
	pc->callback = &idetape_pc_callback;
}
#endif

static void idetape_create_erase_cmd (idetape_pc_t *pc)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_ERASE_CMD;
	pc->c[1] = 1;
	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
	pc->callback = &idetape_pc_callback;
}

static void idetape_create_space_cmd (idetape_pc_t *pc,int count, u8 cmd)
{
	idetape_init_pc(pc);
	pc->c[0] = IDETAPE_SPACE_CMD;
	put_unaligned(htonl(count), (unsigned int *) &pc->c[1]);
	pc->c[1] = cmd;
	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
	pc->callback = &idetape_pc_callback;
}

static void idetape_wait_first_stage (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	unsigned long flags;

	if (tape->first_stage == NULL)
		return;
	spin_lock_irqsave(&tape->spinlock, flags);
	if (tape->active_stage == tape->first_stage)
		idetape_wait_for_request(drive, tape->active_data_request);
	spin_unlock_irqrestore(&tape->spinlock, flags);
}

/*
 *	idetape_add_chrdev_write_request tries to add a character device
 *	originated write request to our pipeline. In case we don't succeed,
 *	we revert to non-pipelined operation mode for this request.
 *
 *	1.	Try to allocate a new pipeline stage.
 *	2.	If we can't, wait for more and more requests to be serviced
 *		and try again each time.
 *	3.	If we still can't allocate a stage, fallback to
 *		non-pipelined operation mode for this request.
 */
static int idetape_add_chrdev_write_request (ide_drive_t *drive, int blocks)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *new_stage;
	unsigned long flags;
	struct request *rq;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 3)
		printk(KERN_INFO "ide-tape: Reached idetape_add_chrdev_write_request\n");
#endif /* IDETAPE_DEBUG_LOG */

     	/*
     	 *	Attempt to allocate a new stage.
	 *	Pay special attention to possible race conditions.
	 */
	while ((new_stage = idetape_kmalloc_stage(tape)) == NULL) {
		spin_lock_irqsave(&tape->spinlock, flags);
		if (idetape_pipeline_active(tape)) {
			idetape_wait_for_request(drive, tape->active_data_request);
			spin_unlock_irqrestore(&tape->spinlock, flags);
		} else {
			spin_unlock_irqrestore(&tape->spinlock, flags);
			idetape_insert_pipeline_into_queue(drive);
			if (idetape_pipeline_active(tape))
				continue;
			/*
			 *	Linux is short on memory. Fallback to
			 *	non-pipelined operation mode for this request.
			 */
			return idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, blocks, tape->merge_stage->bh);
		}
	}
	rq = &new_stage->rq;
	idetape_init_rq(rq, REQ_IDETAPE_WRITE);
	/* Doesn't actually matter - We always assume sequential access */
	rq->sector = tape->first_frame_position;
	rq->nr_sectors = rq->current_nr_sectors = blocks;

	idetape_switch_buffers(tape, new_stage);
	idetape_add_stage_tail(drive, new_stage);
	tape->pipeline_head++;
#if USE_IOTRACE
	IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
#endif
	calculate_speeds(drive);

	/*
	 *	Estimate whether the tape has stopped writing by checking
	 *	if our write pipeline is currently empty. If we are not
	 *	writing anymore, wait for the pipeline to be full enough
	 *	(90%) before starting to service requests, so that we will
	 *	be able to keep up with the higher speeds of the tape.
	 */
	if (!idetape_pipeline_active(tape)) {
		if (tape->nr_stages >= tape->max_stages * 9 / 10 ||
		    tape->nr_stages >= tape->max_stages - tape->uncontrolled_pipeline_head_speed * 3 * 1024 / tape->tape_block_size) {
			tape->measure_insert_time = 1;
			tape->insert_time = jiffies;
			tape->insert_size = 0;
			tape->insert_speed = 0;
			idetape_insert_pipeline_into_queue(drive);
		}
	}
	if (test_and_clear_bit(IDETAPE_PIPELINE_ERROR, &tape->flags))
		/* Return a deferred error */
		return -EIO;
	return blocks;
}

/*
 *	idetape_wait_for_pipeline will wait until all pending pipeline
 *	requests are serviced. Typically called on device close.
 */
static void idetape_wait_for_pipeline (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	unsigned long flags;

	while (tape->next_stage || idetape_pipeline_active(tape)) {
		idetape_insert_pipeline_into_queue(drive);
		spin_lock_irqsave(&tape->spinlock, flags);
		if (idetape_pipeline_active(tape))
			idetape_wait_for_request(drive, tape->active_data_request);
		spin_unlock_irqrestore(&tape->spinlock, flags);
	}
}

static void idetape_empty_write_pipeline (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	int blocks, min;
	struct idetape_bh *bh;
	
#if IDETAPE_DEBUG_BUGS
	if (tape->chrdev_direction != idetape_direction_write) {
		printk(KERN_ERR "ide-tape: bug: Trying to empty write pipeline, but we are not writing.\n");
		return;
	}
	if (tape->merge_stage_size > tape->stage_size) {
		printk(KERN_ERR "ide-tape: bug: merge_buffer too big\n");
		tape->merge_stage_size = tape->stage_size;
	}
#endif /* IDETAPE_DEBUG_BUGS */
	if (tape->merge_stage_size) {
		blocks = tape->merge_stage_size / tape->tape_block_size;
		if (tape->merge_stage_size % tape->tape_block_size) {
			unsigned int i;

			blocks++;
			i = tape->tape_block_size - tape->merge_stage_size % tape->tape_block_size;
			bh = tape->bh->b_reqnext;
			while (bh) {
				atomic_set(&bh->b_count, 0);
				bh = bh->b_reqnext;
			}
			bh = tape->bh;
			while (i) {
				if (bh == NULL) {

					printk(KERN_INFO "ide-tape: bug, bh NULL\n");
					break;
				}
				min = min(i, (unsigned int)(bh->b_size - atomic_read(&bh->b_count)));
				memset(bh->b_data + atomic_read(&bh->b_count), 0, min);
				atomic_add(min, &bh->b_count);
				i -= min;
				bh = bh->b_reqnext;
			}
		}
		(void) idetape_add_chrdev_write_request(drive, blocks);
		tape->merge_stage_size = 0;
	}
	idetape_wait_for_pipeline(drive);
	if (tape->merge_stage != NULL) {
		__idetape_kfree_stage(tape->merge_stage);
		tape->merge_stage = NULL;
	}
	clear_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);
	tape->chrdev_direction = idetape_direction_none;

	/*
	 *	On the next backup, perform the feedback loop again.
	 *	(I don't want to keep sense information between backups,
	 *	 as some systems are constantly on, and the system load
	 *	 can be totally different on the next backup).
	 */
	tape->max_stages = tape->min_pipeline;
#if IDETAPE_DEBUG_BUGS
	if (tape->first_stage != NULL ||
	    tape->next_stage != NULL ||
	    tape->last_stage != NULL ||
	    tape->nr_stages != 0) {
		printk(KERN_ERR "ide-tape: ide-tape pipeline bug, "
			"first_stage %p, next_stage %p, "
			"last_stage %p, nr_stages %d\n",
			tape->first_stage, tape->next_stage,
			tape->last_stage, tape->nr_stages);
	}
#endif /* IDETAPE_DEBUG_BUGS */
}

static void idetape_restart_speed_control (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

	tape->restart_speed_control_req = 0;
	tape->pipeline_head = 0;
	tape->controlled_last_pipeline_head = tape->uncontrolled_last_pipeline_head = 0;
	tape->controlled_previous_pipeline_head = tape->uncontrolled_previous_pipeline_head = 0;
	tape->pipeline_head_speed = tape->controlled_pipeline_head_speed = 5000;
	tape->uncontrolled_pipeline_head_speed = 0;
	tape->controlled_pipeline_head_time = tape->uncontrolled_pipeline_head_time = jiffies;
	tape->controlled_previous_head_time = tape->uncontrolled_previous_head_time = jiffies;
}

static int idetape_initiate_read (ide_drive_t *drive, int max_stages)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *new_stage;
	struct request rq;
	int bytes_read;
	int blocks = tape->capabilities.ctl;

	/* Initialize read operation */
	if (tape->chrdev_direction != idetape_direction_read) {
		if (tape->chrdev_direction == idetape_direction_write) {
			idetape_empty_write_pipeline(drive);
			idetape_flush_tape_buffers(drive);
		}
#if IDETAPE_DEBUG_BUGS
		if (tape->merge_stage || tape->merge_stage_size) {
			printk (KERN_ERR "ide-tape: merge_stage_size should be 0 now\n");
			tape->merge_stage_size = 0;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		if ((tape->merge_stage = __idetape_kmalloc_stage(tape, 0, 0)) == NULL)
			return -ENOMEM;
		tape->chrdev_direction = idetape_direction_read;

		/*
		 *	Issue a read 0 command to ensure that DSC handshake
		 *	is switched from completion mode to buffer available
		 *	mode.
		 *	No point in issuing this if DSC overlap isn't supported,
		 *	some drives (Seagate STT3401A) will return an error.
		 */
		if (drive->dsc_overlap) {
			bytes_read = idetape_queue_rw_tail(drive, REQ_IDETAPE_READ, 0, tape->merge_stage->bh);
			if (bytes_read < 0) {
				__idetape_kfree_stage(tape->merge_stage);
				tape->merge_stage = NULL;
				tape->chrdev_direction = idetape_direction_none;
				return bytes_read;
			}
		}
	}
	if (tape->restart_speed_control_req)
		idetape_restart_speed_control(drive);
	idetape_init_rq(&rq, REQ_IDETAPE_READ);
	rq.sector = tape->first_frame_position;
	rq.nr_sectors = rq.current_nr_sectors = blocks;
	if (!test_bit(IDETAPE_PIPELINE_ERROR, &tape->flags) &&
	    tape->nr_stages < max_stages) {
		new_stage = idetape_kmalloc_stage(tape);
		while (new_stage != NULL) {
			new_stage->rq = rq;
			idetape_add_stage_tail(drive, new_stage);
			if (tape->nr_stages >= max_stages)
				break;
			new_stage = idetape_kmalloc_stage(tape);
		}
	}
	if (!idetape_pipeline_active(tape)) {
		if (tape->nr_pending_stages >= 3 * max_stages / 4) {
			tape->measure_insert_time = 1;
			tape->insert_time = jiffies;
			tape->insert_size = 0;
			tape->insert_speed = 0;
			idetape_insert_pipeline_into_queue(drive);
		}
	}
	return 0;
}

/*
 *	idetape_add_chrdev_read_request is called from idetape_chrdev_read
 *	to service a character device read request and add read-ahead
 *	requests to our pipeline.
 */
static int idetape_add_chrdev_read_request (ide_drive_t *drive,int blocks)
{
	idetape_tape_t *tape = drive->driver_data;
	unsigned long flags;
	struct request *rq_ptr;
	int bytes_read;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_add_chrdev_read_request, %d blocks\n", blocks);
#endif /* IDETAPE_DEBUG_LOG */

	/*
	 * If we are at a filemark, return a read length of 0
	 */
	if (test_bit(IDETAPE_FILEMARK, &tape->flags))
		return 0;

	/*
	 * Wait for the next block to be available at the head
	 * of the pipeline
	 */
	idetape_initiate_read(drive, tape->max_stages);
	if (tape->first_stage == NULL) {
		if (test_bit(IDETAPE_PIPELINE_ERROR, &tape->flags))
			return 0;
		return idetape_queue_rw_tail(drive, REQ_IDETAPE_READ, blocks, tape->merge_stage->bh);
	}
	idetape_wait_first_stage(drive);
	rq_ptr = &tape->first_stage->rq;
	bytes_read = tape->tape_block_size * (rq_ptr->nr_sectors - rq_ptr->current_nr_sectors);
	rq_ptr->nr_sectors = rq_ptr->current_nr_sectors = 0;


	if (rq_ptr->errors == IDETAPE_ERROR_EOD)
		return 0;
	else {
		idetape_switch_buffers(tape, tape->first_stage);
		if (rq_ptr->errors == IDETAPE_ERROR_FILEMARK)
			set_bit(IDETAPE_FILEMARK, &tape->flags);
		spin_lock_irqsave(&tape->spinlock, flags);
		idetape_remove_stage_head(drive);
		spin_unlock_irqrestore(&tape->spinlock, flags);
		tape->pipeline_head++;
#if USE_IOTRACE
		IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
#endif
		calculate_speeds(drive);
	}
#if IDETAPE_DEBUG_BUGS
	if (bytes_read > blocks * tape->tape_block_size) {
		printk(KERN_ERR "ide-tape: bug: trying to return more bytes than requested\n");
		bytes_read = blocks * tape->tape_block_size;
	}
#endif /* IDETAPE_DEBUG_BUGS */
	return (bytes_read);
}

static void idetape_pad_zeros (ide_drive_t *drive, int bcount)
{
	idetape_tape_t *tape = drive->driver_data;
	struct idetape_bh *bh;
	int blocks;
	
	while (bcount) {
		unsigned int count;

		bh = tape->merge_stage->bh;
		count = min(tape->stage_size, bcount);
		bcount -= count;
		blocks = count / tape->tape_block_size;
		while (count) {
			atomic_set(&bh->b_count, min(count, (unsigned int)bh->b_size));
			memset(bh->b_data, 0, atomic_read(&bh->b_count));
			count -= atomic_read(&bh->b_count);
			bh = bh->b_reqnext;
		}
		idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, blocks, tape->merge_stage->bh);
	}
}

static int idetape_pipeline_size (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_stage_t *stage;
	struct request *rq;
	int size = 0;

	idetape_wait_for_pipeline(drive);
	stage = tape->first_stage;
	while (stage != NULL) {
		rq = &stage->rq;
		size += tape->tape_block_size * (rq->nr_sectors-rq->current_nr_sectors);
		if (rq->errors == IDETAPE_ERROR_FILEMARK)
			size += tape->tape_block_size;
		stage = stage->next;
	}
	size += tape->merge_stage_size;
	return size;
}

/*
 *	Rewinds the tape to the Beginning Of the current Partition (BOP).
 *
 *	We currently support only one partition.
 */ 
static int idetape_rewind_tape (ide_drive_t *drive)
{
	int retval;
	idetape_pc_t pc;
#if IDETAPE_DEBUG_LOG
	idetape_tape_t *tape = drive->driver_data;
	if (tape->debug_level >= 2)
		printk(KERN_INFO "ide-tape: Reached idetape_rewind_tape\n");
#endif /* IDETAPE_DEBUG_LOG */	
	
	idetape_create_rewind_cmd(drive, &pc);
	retval = idetape_queue_pc_tail(drive, &pc);
	if (retval)
		return retval;

	idetape_create_read_position_cmd(&pc);
	retval = idetape_queue_pc_tail(drive, &pc);
	if (retval)
		return retval;
	return 0;
}

/*
 *	Our special ide-tape ioctl's.
 *
 *	Currently there aren't any ioctl's.
 *	mtio.h compatible commands should be issued to the character device
 *	interface.
 */
static int idetape_blkdev_ioctl(ide_drive_t *drive, unsigned int cmd, unsigned long arg)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_config_t config;
	void __user *argp = (void __user *)arg;

#if IDETAPE_DEBUG_LOG	
	if (tape->debug_level >= 4)
		printk(KERN_INFO "ide-tape: Reached idetape_blkdev_ioctl\n");
#endif /* IDETAPE_DEBUG_LOG */
	switch (cmd) {
		case 0x0340:
			if (copy_from_user(&config, argp, sizeof (idetape_config_t)))
				return -EFAULT;
			tape->best_dsc_rw_frequency = config.dsc_rw_frequency;
			tape->max_stages = config.nr_stages;
			break;
		case 0x0350:
			config.dsc_rw_frequency = (int) tape->best_dsc_rw_frequency;
			config.nr_stages = tape->max_stages; 
			if (copy_to_user(argp, &config, sizeof (idetape_config_t)))
				return -EFAULT;
			break;
		default:
			return -EIO;
	}
	return 0;
}

/*
 *	idetape_space_over_filemarks is now a bit more complicated than just
 *	passing the command to the tape since we may have crossed some
 *	filemarks during our pipelined read-ahead mode.
 *
 *	As a minor side effect, the pipeline enables us to support MTFSFM when
 *	the filemark is in our internal pipeline even if the tape doesn't
 *	support spacing over filemarks in the reverse direction.
 */
static int idetape_space_over_filemarks (ide_drive_t *drive,short mt_op,int mt_count)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t pc;
	unsigned long flags;
	int retval,count=0;

	if (mt_count == 0)
		return 0;
	if (MTBSF == mt_op || MTBSFM == mt_op) {
		if (!tape->capabilities.sprev)
			return -EIO;
		mt_count = - mt_count;
	}

	if (tape->chrdev_direction == idetape_direction_read) {
		/*
		 *	We have a read-ahead buffer. Scan it for crossed
		 *	filemarks.
		 */
		tape->merge_stage_size = 0;
		if (test_and_clear_bit(IDETAPE_FILEMARK, &tape->flags))
			++count;
		while (tape->first_stage != NULL) {
			if (count == mt_count) {
				if (mt_op == MTFSFM)
					set_bit(IDETAPE_FILEMARK, &tape->flags);
				return 0;
			}
			spin_lock_irqsave(&tape->spinlock, flags);
			if (tape->first_stage == tape->active_stage) {
				/*
				 *	We have reached the active stage in the read pipeline.
				 *	There is no point in allowing the drive to continue
				 *	reading any farther, so we stop the pipeline.
				 *
				 *	This section should be moved to a separate subroutine,
				 *	because a similar function is performed in
				 *	__idetape_discard_read_pipeline(), for example.
				 */
				tape->next_stage = NULL;
				spin_unlock_irqrestore(&tape->spinlock, flags);
				idetape_wait_first_stage(drive);
				tape->next_stage = tape->first_stage->next;
			} else
				spin_unlock_irqrestore(&tape->spinlock, flags);
			if (tape->first_stage->rq.errors == IDETAPE_ERROR_FILEMARK)
				++count;
			idetape_remove_stage_head(drive);
		}
		idetape_discard_read_pipeline(drive, 0);
	}

	/*
	 *	The filemark was not found in our internal pipeline.
	 *	Now we can issue the space command.
	 */
	switch (mt_op) {
		case MTFSF:
		case MTBSF:
			idetape_create_space_cmd(&pc,mt_count-count,IDETAPE_SPACE_OVER_FILEMARK);
			return (idetape_queue_pc_tail(drive, &pc));
		case MTFSFM:
		case MTBSFM:
			if (!tape->capabilities.sprev)
				return (-EIO);
			retval = idetape_space_over_filemarks(drive, MTFSF, mt_count-count);
			if (retval) return (retval);
			count = (MTBSFM == mt_op ? 1 : -1);
			return (idetape_space_over_filemarks(drive, MTFSF, count));
		default:
			printk(KERN_ERR "ide-tape: MTIO operation %d not supported\n",mt_op);
			return (-EIO);
	}
}


/*
 *	Our character device read / write functions.
 *
 *	The tape is optimized to maximize throughput when it is transferring
 *	an integral number of the "continuous transfer limit", which is
 *	a parameter of the specific tape (26 KB on my particular tape).
 *      (32 kB for Onstream)
 *
 *	As of version 1.3 of the driver, the character device provides an
 *	abstract continuous view of the media - any mix of block sizes (even 1
 *	byte) on the same backup/restore procedure is supported. The driver
 *	will internally convert the requests to the recommended transfer unit,
 *	so that an unmatch between the user's block size to the recommended
 *	size will only result in a (slightly) increased driver overhead, but
 *	will no longer hit performance.
 *      This is not applicable to Onstream.
 */
static ssize_t idetape_chrdev_read (struct file *file, char __user *buf,
				    size_t count, loff_t *ppos)
{
	struct ide_tape_obj *tape = ide_tape_f(file);
	ide_drive_t *drive = tape->drive;
	ssize_t bytes_read,temp, actually_read = 0, rc;
	ssize_t ret = 0;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 3)
		printk(KERN_INFO "ide-tape: Reached idetape_chrdev_read, count %Zd\n", count);
#endif /* IDETAPE_DEBUG_LOG */

	if (tape->chrdev_direction != idetape_direction_read) {
		if (test_bit(IDETAPE_DETECT_BS, &tape->flags))
			if (count > tape->tape_block_size &&
			    (count % tape->tape_block_size) == 0)
				tape->user_bs_factor = count / tape->tape_block_size;
	}
	if ((rc = idetape_initiate_read(drive, tape->max_stages)) < 0)
		return rc;
	if (count == 0)
		return (0);
	if (tape->merge_stage_size) {
		actually_read = min((unsigned int)(tape->merge_stage_size), (unsigned int)count);
		if (idetape_copy_stage_to_user(tape, buf, tape->merge_stage, actually_read))
			ret = -EFAULT;
		buf += actually_read;
		tape->merge_stage_size -= actually_read;
		count -= actually_read;
	}
	while (count >= tape->stage_size) {
		bytes_read = idetape_add_chrdev_read_request(drive, tape->capabilities.ctl);
		if (bytes_read <= 0)
			goto finish;
		if (idetape_copy_stage_to_user(tape, buf, tape->merge_stage, bytes_read))
			ret = -EFAULT;
		buf += bytes_read;
		count -= bytes_read;
		actually_read += bytes_read;
	}
	if (count) {
		bytes_read = idetape_add_chrdev_read_request(drive, tape->capabilities.ctl);
		if (bytes_read <= 0)
			goto finish;
		temp = min((unsigned long)count, (unsigned long)bytes_read);
		if (idetape_copy_stage_to_user(tape, buf, tape->merge_stage, temp))
			ret = -EFAULT;
		actually_read += temp;
		tape->merge_stage_size = bytes_read-temp;
	}
finish:
	if (!actually_read && test_bit(IDETAPE_FILEMARK, &tape->flags)) {
#if IDETAPE_DEBUG_LOG
		if (tape->debug_level >= 2)
			printk(KERN_INFO "ide-tape: %s: spacing over filemark\n", tape->name);
#endif
		idetape_space_over_filemarks(drive, MTFSF, 1);
		return 0;
	}

	return (ret) ? ret : actually_read;
}

static ssize_t idetape_chrdev_write (struct file *file, const char __user *buf,
				     size_t count, loff_t *ppos)
{
	struct ide_tape_obj *tape = ide_tape_f(file);
	ide_drive_t *drive = tape->drive;
	ssize_t actually_written = 0;
	ssize_t ret = 0;

	/* The drive is write protected. */
	if (tape->write_prot)
		return -EACCES;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 3)
		printk(KERN_INFO "ide-tape: Reached idetape_chrdev_write, "
			"count %Zd\n", count);
#endif /* IDETAPE_DEBUG_LOG */

	/* Initialize write operation */
	if (tape->chrdev_direction != idetape_direction_write) {
		if (tape->chrdev_direction == idetape_direction_read)
			idetape_discard_read_pipeline(drive, 1);
#if IDETAPE_DEBUG_BUGS
		if (tape->merge_stage || tape->merge_stage_size) {
			printk(KERN_ERR "ide-tape: merge_stage_size "
				"should be 0 now\n");
			tape->merge_stage_size = 0;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		if ((tape->merge_stage = __idetape_kmalloc_stage(tape, 0, 0)) == NULL)
			return -ENOMEM;
		tape->chrdev_direction = idetape_direction_write;
		idetape_init_merge_stage(tape);

		/*
		 *	Issue a write 0 command to ensure that DSC handshake
		 *	is switched from completion mode to buffer available
		 *	mode.
		 *	No point in issuing this if DSC overlap isn't supported,
		 *	some drives (Seagate STT3401A) will return an error.
		 */
		if (drive->dsc_overlap) {
			ssize_t retval = idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, 0, tape->merge_stage->bh);
			if (retval < 0) {
				__idetape_kfree_stage(tape->merge_stage);
				tape->merge_stage = NULL;
				tape->chrdev_direction = idetape_direction_none;
				return retval;
			}
		}
	}
	if (count == 0)
		return (0);
	if (tape->restart_speed_control_req)
		idetape_restart_speed_control(drive);
	if (tape->merge_stage_size) {
#if IDETAPE_DEBUG_BUGS
		if (tape->merge_stage_size >= tape->stage_size) {
			printk(KERN_ERR "ide-tape: bug: merge buffer too big\n");
			tape->merge_stage_size = 0;
		}
#endif /* IDETAPE_DEBUG_BUGS */
		actually_written = min((unsigned int)(tape->stage_size - tape->merge_stage_size), (unsigned int)count);
		if (idetape_copy_stage_from_user(tape, tape->merge_stage, buf, actually_written))
				ret = -EFAULT;
		buf += actually_written;
		tape->merge_stage_size += actually_written;
		count -= actually_written;

		if (tape->merge_stage_size == tape->stage_size) {
			ssize_t retval;
			tape->merge_stage_size = 0;
			retval = idetape_add_chrdev_write_request(drive, tape->capabilities.ctl);
			if (retval <= 0)
				return (retval);
		}
	}
	while (count >= tape->stage_size) {
		ssize_t retval;
		if (idetape_copy_stage_from_user(tape, tape->merge_stage, buf, tape->stage_size))
			ret = -EFAULT;
		buf += tape->stage_size;
		count -= tape->stage_size;
		retval = idetape_add_chrdev_write_request(drive, tape->capabilities.ctl);
		actually_written += tape->stage_size;
		if (retval <= 0)
			return (retval);
	}
	if (count) {
		actually_written += count;
		if (idetape_copy_stage_from_user(tape, tape->merge_stage, buf, count))
			ret = -EFAULT;
		tape->merge_stage_size += count;
	}
	return (ret) ? ret : actually_written;
}

static int idetape_write_filemark (ide_drive_t *drive)
{
	idetape_pc_t pc;

	/* Write a filemark */
	idetape_create_write_filemark_cmd(drive, &pc, 1);
	if (idetape_queue_pc_tail(drive, &pc)) {
		printk(KERN_ERR "ide-tape: Couldn't write a filemark\n");
		return -EIO;
	}
	return 0;
}

/*
 *	idetape_mtioctop is called from idetape_chrdev_ioctl when
 *	the general mtio MTIOCTOP ioctl is requested.
 *
 *	We currently support the following mtio.h operations:
 *
 *	MTFSF	-	Space over mt_count filemarks in the positive direction.
 *			The tape is positioned after the last spaced filemark.
 *
 *	MTFSFM	-	Same as MTFSF, but the tape is positioned before the
 *			last filemark.
 *
 *	MTBSF	-	Steps background over mt_count filemarks, tape is
 *			positioned before the last filemark.
 *
 *	MTBSFM	-	Like MTBSF, only tape is positioned after the last filemark.
 *
 *	Note:
 *
 *		MTBSF and MTBSFM are not supported when the tape doesn't
 *		support spacing over filemarks in the reverse direction.
 *		In this case, MTFSFM is also usually not supported (it is
 *		supported in the rare case in which we crossed the filemark
 *		during our read-ahead pipelined operation mode).
 *		
 *	MTWEOF	-	Writes mt_count filemarks. Tape is positioned after
 *			the last written filemark.
 *
 *	MTREW	-	Rewinds tape.
 *
 *	MTLOAD	-	Loads the tape.
 *
 *	MTOFFL	-	Puts the tape drive "Offline": Rewinds the tape and
 *	MTUNLOAD	prevents further access until the media is replaced.
 *
 *	MTNOP	-	Flushes tape buffers.
 *
 *	MTRETEN	-	Retension media. This typically consists of one end
 *			to end pass on the media.
 *
 *	MTEOM	-	Moves to the end of recorded data.
 *
 *	MTERASE	-	Erases tape.
 *
 *	MTSETBLK - 	Sets the user block size to mt_count bytes. If
 *			mt_count is 0, we will attempt to autodetect
 *			the block size.
 *
 *	MTSEEK	-	Positions the tape in a specific block number, where
 *			each block is assumed to contain which user_block_size
 *			bytes.
 *
 *	MTSETPART - 	Switches to another tape partition.
 *
 *	MTLOCK - 	Locks the tape door.
 *
 *	MTUNLOCK - 	Unlocks the tape door.
 *
 *	The following commands are currently not supported:
 *
 *	MTFSS, MTBSS, MTWSM, MTSETDENSITY,
 *	MTSETDRVBUFFER, MT_ST_BOOLEANS, MT_ST_WRITE_THRESHOLD.
 */
static int idetape_mtioctop (ide_drive_t *drive,short mt_op,int mt_count)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t pc;
	int i,retval;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 1)
		printk(KERN_INFO "ide-tape: Handling MTIOCTOP ioctl: "
			"mt_op=%d, mt_count=%d\n", mt_op, mt_count);
#endif /* IDETAPE_DEBUG_LOG */
	/*
	 *	Commands which need our pipelined read-ahead stages.
	 */
	switch (mt_op) {
		case MTFSF:
		case MTFSFM:
		case MTBSF:
		case MTBSFM:
			if (!mt_count)
				return (0);
			return (idetape_space_over_filemarks(drive,mt_op,mt_count));
		default:
			break;
	}
	switch (mt_op) {
		case MTWEOF:
			if (tape->write_prot)
				return -EACCES;
			idetape_discard_read_pipeline(drive, 1);
			for (i = 0; i < mt_count; i++) {
				retval = idetape_write_filemark(drive);
				if (retval)
					return retval;
			}
			return (0);
		case MTREW:
			idetape_discard_read_pipeline(drive, 0);
			if (idetape_rewind_tape(drive))
				return -EIO;
			return 0;
		case MTLOAD:
			idetape_discard_read_pipeline(drive, 0);
			idetape_create_load_unload_cmd(drive, &pc, IDETAPE_LU_LOAD_MASK);
			return (idetape_queue_pc_tail(drive, &pc));
		case MTUNLOAD:
		case MTOFFL:
			/*
			 * If door is locked, attempt to unlock before
			 * attempting to eject.
			 */
			if (tape->door_locked) {
				if (idetape_create_prevent_cmd(drive, &pc, 0))
					if (!idetape_queue_pc_tail(drive, &pc))
						tape->door_locked = DOOR_UNLOCKED;
			}
			idetape_discard_read_pipeline(drive, 0);
			idetape_create_load_unload_cmd(drive, &pc,!IDETAPE_LU_LOAD_MASK);
			retval = idetape_queue_pc_tail(drive, &pc);
			if (!retval)
				clear_bit(IDETAPE_MEDIUM_PRESENT, &tape->flags);
			return retval;
		case MTNOP:
			idetape_discard_read_pipeline(drive, 0);
			return (idetape_flush_tape_buffers(drive));
		case MTRETEN:
			idetape_discard_read_pipeline(drive, 0);
			idetape_create_load_unload_cmd(drive, &pc,IDETAPE_LU_RETENSION_MASK | IDETAPE_LU_LOAD_MASK);
			return (idetape_queue_pc_tail(drive, &pc));
		case MTEOM:
			idetape_create_space_cmd(&pc, 0, IDETAPE_SPACE_TO_EOD);
			return (idetape_queue_pc_tail(drive, &pc));
		case MTERASE:
			(void) idetape_rewind_tape(drive);
			idetape_create_erase_cmd(&pc);
			return (idetape_queue_pc_tail(drive, &pc));
		case MTSETBLK:
			if (mt_count) {
				if (mt_count < tape->tape_block_size || mt_count % tape->tape_block_size)
					return -EIO;
				tape->user_bs_factor = mt_count / tape->tape_block_size;
				clear_bit(IDETAPE_DETECT_BS, &tape->flags);
			} else
				set_bit(IDETAPE_DETECT_BS, &tape->flags);
			return 0;
		case MTSEEK:
			idetape_discard_read_pipeline(drive, 0);
			return idetape_position_tape(drive, mt_count * tape->user_bs_factor, tape->partition, 0);
		case MTSETPART:
			idetape_discard_read_pipeline(drive, 0);
			return (idetape_position_tape(drive, 0, mt_count, 0));
		case MTFSR:
		case MTBSR:
		case MTLOCK:
			if (!idetape_create_prevent_cmd(drive, &pc, 1))
				return 0;
			retval = idetape_queue_pc_tail(drive, &pc);
			if (retval) return retval;
			tape->door_locked = DOOR_EXPLICITLY_LOCKED;
			return 0;
		case MTUNLOCK:
			if (!idetape_create_prevent_cmd(drive, &pc, 0))
				return 0;
			retval = idetape_queue_pc_tail(drive, &pc);
			if (retval) return retval;
			tape->door_locked = DOOR_UNLOCKED;
			return 0;
		default:
			printk(KERN_ERR "ide-tape: MTIO operation %d not "
				"supported\n", mt_op);
			return (-EIO);
	}
}

/*
 *	Our character device ioctls.
 *
 *	General mtio.h magnetic io commands are supported here, and not in
 *	the corresponding block interface.
 *
 *	The following ioctls are supported:
 *
 *	MTIOCTOP -	Refer to idetape_mtioctop for detailed description.
 *
 *	MTIOCGET - 	The mt_dsreg field in the returned mtget structure
 *			will be set to (user block size in bytes <<
 *			MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK.
 *
 *			The mt_blkno is set to the current user block number.
 *			The other mtget fields are not supported.
 *
 *	MTIOCPOS -	The current tape "block position" is returned. We
 *			assume that each block contains user_block_size
 *			bytes.
 *
 *	Our own ide-tape ioctls are supported on both interfaces.
 */
static int idetape_chrdev_ioctl (struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
	struct ide_tape_obj *tape = ide_tape_f(file);
	ide_drive_t *drive = tape->drive;
	struct mtop mtop;
	struct mtget mtget;
	struct mtpos mtpos;
	int block_offset = 0, position = tape->first_frame_position;
	void __user *argp = (void __user *)arg;

#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 3)
		printk(KERN_INFO "ide-tape: Reached idetape_chrdev_ioctl, "
			"cmd=%u\n", cmd);
#endif /* IDETAPE_DEBUG_LOG */

	tape->restart_speed_control_req = 1;
	if (tape->chrdev_direction == idetape_direction_write) {
		idetape_empty_write_pipeline(drive);
		idetape_flush_tape_buffers(drive);
	}
	if (cmd == MTIOCGET || cmd == MTIOCPOS) {
		block_offset = idetape_pipeline_size(drive) / (tape->tape_block_size * tape->user_bs_factor);
		if ((position = idetape_read_position(drive)) < 0)
			return -EIO;
	}
	switch (cmd) {
		case MTIOCTOP:
			if (copy_from_user(&mtop, argp, sizeof (struct mtop)))
				return -EFAULT;
			return (idetape_mtioctop(drive,mtop.mt_op,mtop.mt_count));
		case MTIOCGET:
			memset(&mtget, 0, sizeof (struct mtget));
			mtget.mt_type = MT_ISSCSI2;
			mtget.mt_blkno = position / tape->user_bs_factor - block_offset;
			mtget.mt_dsreg = ((tape->tape_block_size * tape->user_bs_factor) << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK;
			if (tape->drv_write_prot) {
				mtget.mt_gstat |= GMT_WR_PROT(0xffffffff);
			}
			if (copy_to_user(argp, &mtget, sizeof(struct mtget)))
				return -EFAULT;
			return 0;
		case MTIOCPOS:
			mtpos.mt_blkno = position / tape->user_bs_factor - block_offset;
			if (copy_to_user(argp, &mtpos, sizeof(struct mtpos)))
				return -EFAULT;
			return 0;
		default:
			if (tape->chrdev_direction == idetape_direction_read)
				idetape_discard_read_pipeline(drive, 1);
			return idetape_blkdev_ioctl(drive, cmd, arg);
	}
}

static void idetape_get_blocksize_from_block_descriptor(ide_drive_t *drive);

/*
 *	Our character device open function.
 */
static int idetape_chrdev_open (struct inode *inode, struct file *filp)
{
	unsigned int minor = iminor(inode), i = minor & ~0xc0;
	ide_drive_t *drive;
	idetape_tape_t *tape;
	idetape_pc_t pc;
	int retval;

	/*
	 * We really want to do nonseekable_open(inode, filp); here, but some
	 * versions of tar incorrectly call lseek on tapes and bail out if that
	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
	 */
	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);

#if IDETAPE_DEBUG_LOG
	printk(KERN_INFO "ide-tape: Reached idetape_chrdev_open\n");
#endif /* IDETAPE_DEBUG_LOG */
	
	if (i >= MAX_HWIFS * MAX_DRIVES)
		return -ENXIO;

	if (!(tape = ide_tape_chrdev_get(i)))
		return -ENXIO;

	drive = tape->drive;

	filp->private_data = tape;

	if (test_and_set_bit(IDETAPE_BUSY, &tape->flags)) {
		retval = -EBUSY;
		goto out_put_tape;
	}

	retval = idetape_wait_ready(drive, 60 * HZ);
	if (retval) {
		clear_bit(IDETAPE_BUSY, &tape->flags);
		printk(KERN_ERR "ide-tape: %s: drive not ready\n", tape->name);
		goto out_put_tape;
	}

	idetape_read_position(drive);
	if (!test_bit(IDETAPE_ADDRESS_VALID, &tape->flags))
		(void)idetape_rewind_tape(drive);

	if (tape->chrdev_direction != idetape_direction_read)
		clear_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);

	/* Read block size and write protect status from drive. */
	idetape_get_blocksize_from_block_descriptor(drive);

	/* Set write protect flag if device is opened as read-only. */
	if ((filp->f_flags & O_ACCMODE) == O_RDONLY)
		tape->write_prot = 1;
	else
		tape->write_prot = tape->drv_write_prot;

	/* Make sure drive isn't write protected if user wants to write. */
	if (tape->write_prot) {
		if ((filp->f_flags & O_ACCMODE) == O_WRONLY ||
		    (filp->f_flags & O_ACCMODE) == O_RDWR) {
			clear_bit(IDETAPE_BUSY, &tape->flags);
			retval = -EROFS;
			goto out_put_tape;
		}
	}

	/*
	 * Lock the tape drive door so user can't eject.
	 */
	if (tape->chrdev_direction == idetape_direction_none) {
		if (idetape_create_prevent_cmd(drive, &pc, 1)) {
			if (!idetape_queue_pc_tail(drive, &pc)) {
				if (tape->door_locked != DOOR_EXPLICITLY_LOCKED)
					tape->door_locked = DOOR_LOCKED;
			}
		}
	}
	idetape_restart_speed_control(drive);
	tape->restart_speed_control_req = 0;
	return 0;

out_put_tape:
	ide_tape_put(tape);
	return retval;
}

static void idetape_write_release (ide_drive_t *drive, unsigned int minor)
{
	idetape_tape_t *tape = drive->driver_data;

	idetape_empty_write_pipeline(drive);
	tape->merge_stage = __idetape_kmalloc_stage(tape, 1, 0);
	if (tape->merge_stage != NULL) {
		idetape_pad_zeros(drive, tape->tape_block_size * (tape->user_bs_factor - 1));
		__idetape_kfree_stage(tape->merge_stage);
		tape->merge_stage = NULL;
	}
	idetape_write_filemark(drive);
	idetape_flush_tape_buffers(drive);
	idetape_flush_tape_buffers(drive);
}

/*
 *	Our character device release function.
 */
static int idetape_chrdev_release (struct inode *inode, struct file *filp)
{
	struct ide_tape_obj *tape = ide_tape_f(filp);
	ide_drive_t *drive = tape->drive;
	idetape_pc_t pc;
	unsigned int minor = iminor(inode);

	lock_kernel();
	tape = drive->driver_data;
#if IDETAPE_DEBUG_LOG
	if (tape->debug_level >= 3)
		printk(KERN_INFO "ide-tape: Reached idetape_chrdev_release\n");
#endif /* IDETAPE_DEBUG_LOG */

	if (tape->chrdev_direction == idetape_direction_write)
		idetape_write_release(drive, minor);
	if (tape->chrdev_direction == idetape_direction_read) {
		if (minor < 128)
			idetape_discard_read_pipeline(drive, 1);
		else
			idetape_wait_for_pipeline(drive);
	}
	if (tape->cache_stage != NULL) {
		__idetape_kfree_stage(tape->cache_stage);
		tape->cache_stage = NULL;
	}
	if (minor < 128 && test_bit(IDETAPE_MEDIUM_PRESENT, &tape->flags))
		(void) idetape_rewind_tape(drive);
	if (tape->chrdev_direction == idetape_direction_none) {
		if (tape->door_locked == DOOR_LOCKED) {
			if (idetape_create_prevent_cmd(drive, &pc, 0)) {
				if (!idetape_queue_pc_tail(drive, &pc))
					tape->door_locked = DOOR_UNLOCKED;
			}
		}
	}
	clear_bit(IDETAPE_BUSY, &tape->flags);
	ide_tape_put(tape);
	unlock_kernel();
	return 0;
}

/*
 *	idetape_identify_device is called to check the contents of the
 *	ATAPI IDENTIFY command results. We return:
 *
 *	1	If the tape can be supported by us, based on the information
 *		we have so far.
 *
 *	0 	If this tape driver is not currently supported by us.
 */
static int idetape_identify_device (ide_drive_t *drive)
{
	struct idetape_id_gcw gcw;
	struct hd_driveid *id = drive->id;
#if IDETAPE_DEBUG_INFO
	unsigned short mask,i;
#endif /* IDETAPE_DEBUG_INFO */

	if (drive->id_read == 0)
		return 1;

	*((unsigned short *) &gcw) = id->config;

#if IDETAPE_DEBUG_INFO
	printk(KERN_INFO "ide-tape: Dumping ATAPI Identify Device tape parameters\n");
	printk(KERN_INFO "ide-tape: Protocol Type: ");
	switch (gcw.protocol) {
		case 0: case 1: printk("ATA\n");break;
		case 2:	printk("ATAPI\n");break;
		case 3: printk("Reserved (Unknown to ide-tape)\n");break;
	}
	printk(KERN_INFO "ide-tape: Device Type: %x - ",gcw.device_type);	
	switch (gcw.device_type) {
		case 0: printk("Direct-access Device\n");break;
		case 1: printk("Streaming Tape Device\n");break;
		case 2: case 3: case 4: printk("Reserved\n");break;
		case 5: printk("CD-ROM Device\n");break;
		case 6: printk("Reserved\n");
		case 7: printk("Optical memory Device\n");break;
		case 0x1f: printk("Unknown or no Device type\n");break;
		default: printk("Reserved\n");
	}
	printk(KERN_INFO "ide-tape: Removable: %s",gcw.removable ? "Yes\n":"No\n");	
	printk(KERN_INFO "ide-tape: Command Packet DRQ Type: ");
	switch (gcw.drq_type) {
		case 0: printk("Microprocessor DRQ\n");break;
		case 1: printk("Interrupt DRQ\n");break;
		case 2: printk("Accelerated DRQ\n");break;
		case 3: printk("Reserved\n");break;
	}
	printk(KERN_INFO "ide-tape: Command Packet Size: ");
	switch (gcw.packet_size) {
		case 0: printk("12 bytes\n");break;
		case 1: printk("16 bytes\n");break;
		default: printk("Reserved\n");break;
	}
	printk(KERN_INFO "ide-tape: Model: %.40s\n",id->model);
	printk(KERN_INFO "ide-tape: Firmware Revision: %.8s\n",id->fw_rev);
	printk(KERN_INFO "ide-tape: Serial Number: %.20s\n",id->serial_no);
	printk(KERN_INFO "ide-tape: Write buffer size: %d bytes\n",id->buf_size*512);
	printk(KERN_INFO "ide-tape: DMA: %s",id->capability & 0x01 ? "Yes\n":"No\n");
	printk(KERN_INFO "ide-tape: LBA: %s",id->capability & 0x02 ? "Yes\n":"No\n");
	printk(KERN_INFO "ide-tape: IORDY can be disabled: %s",id->capability & 0x04 ? "Yes\n":"No\n");
	printk(KERN_INFO "ide-tape: IORDY supported: %s",id->capability & 0x08 ? "Yes\n":"Unknown\n");
	printk(KERN_INFO "ide-tape: ATAPI overlap supported: %s",id->capability & 0x20 ? "Yes\n":"No\n");
	printk(KERN_INFO "ide-tape: PIO Cycle Timing Category: %d\n",id->tPIO);
	printk(KERN_INFO "ide-tape: DMA Cycle Timing Category: %d\n",id->tDMA);
	printk(KERN_INFO "ide-tape: Single Word DMA supported modes: ");
	for (i=0,mask=1;i<8;i++,mask=mask << 1) {
		if (id->dma_1word & mask)
			printk("%d ",i);
		if (id->dma_1word & (mask << 8))
			printk("(active) ");
	}
	printk("\n");
	printk(KERN_INFO "ide-tape: Multi Word DMA supported modes: ");
	for (i=0,mask=1;i<8;i++,mask=mask << 1) {
		if (id->dma_mword & mask)
			printk("%d ",i);
		if (id->dma_mword & (mask << 8))
			printk("(active) ");
	}
	printk("\n");
	if (id->field_valid & 0x0002) {
		printk(KERN_INFO "ide-tape: Enhanced PIO Modes: %s\n",
			id->eide_pio_modes & 1 ? "Mode 3":"None");
		printk(KERN_INFO "ide-tape: Minimum Multi-word DMA cycle per word: ");
		if (id->eide_dma_min == 0)
			printk("Not supported\n");
		else
			printk("%d ns\n",id->eide_dma_min);

		printk(KERN_INFO "ide-tape: Manufacturer\'s Recommended Multi-word cycle: ");
		if (id->eide_dma_time == 0)
			printk("Not supported\n");
		else
			printk("%d ns\n",id->eide_dma_time);

		printk(KERN_INFO "ide-tape: Minimum PIO cycle without IORDY: ");
		if (id->eide_pio == 0)
			printk("Not supported\n");
		else
			printk("%d ns\n",id->eide_pio);

		printk(KERN_INFO "ide-tape: Minimum PIO cycle with IORDY: ");
		if (id->eide_pio_iordy == 0)
			printk("Not supported\n");
		else
			printk("%d ns\n",id->eide_pio_iordy);
		
	} else
		printk(KERN_INFO "ide-tape: According to the device, fields 64-70 are not valid.\n");
#endif /* IDETAPE_DEBUG_INFO */

	/* Check that we can support this device */

	if (gcw.protocol !=2 )
		printk(KERN_ERR "ide-tape: Protocol is not ATAPI\n");
	else if (gcw.device_type != 1)
		printk(KERN_ERR "ide-tape: Device type is not set to tape\n");
	else if (!gcw.removable)
		printk(KERN_ERR "ide-tape: The removable flag is not set\n");
	else if (gcw.packet_size != 0) {
		printk(KERN_ERR "ide-tape: Packet size is not 12 bytes long\n");
		if (gcw.packet_size == 1)
			printk(KERN_ERR "ide-tape: Sorry, padding to 16 bytes is still not supported\n");
	} else
		return 1;
	return 0;
}

/*
 * Use INQUIRY to get the firmware revision
 */
static void idetape_get_inquiry_results (ide_drive_t *drive)
{
	char *r;
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t pc;
	idetape_inquiry_result_t *inquiry;
	
	idetape_create_inquiry_cmd(&pc);
	if (idetape_queue_pc_tail(drive, &pc)) {
		printk(KERN_ERR "ide-tape: %s: can't get INQUIRY results\n", tape->name);
		return;
	}
	inquiry = (idetape_inquiry_result_t *) pc.buffer;
	memcpy(tape->vendor_id, inquiry->vendor_id, 8);
	memcpy(tape->product_id, inquiry->product_id, 16);
	memcpy(tape->firmware_revision, inquiry->revision_level, 4);
	ide_fixstring(tape->vendor_id, 10, 0);
	ide_fixstring(tape->product_id, 18, 0);
	ide_fixstring(tape->firmware_revision, 6, 0);
	r = tape->firmware_revision;
	if (*(r + 1) == '.')
		tape->firmware_revision_num = (*r - '0') * 100 + (*(r + 2) - '0') * 10 + *(r + 3) - '0';
	printk(KERN_INFO "ide-tape: %s <-> %s: %s %s rev %s\n", drive->name, tape->name, tape->vendor_id, tape->product_id, tape->firmware_revision);
}

/*
 *	idetape_get_mode_sense_results asks the tape about its various
 *	parameters. In particular, we will adjust our data transfer buffer
 *	size to the recommended value as returned by the tape.
 */
static void idetape_get_mode_sense_results (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t pc;
	idetape_mode_parameter_header_t *header;
	idetape_capabilities_page_t *capabilities;
	
	idetape_create_mode_sense_cmd(&pc, IDETAPE_CAPABILITIES_PAGE);
	if (idetape_queue_pc_tail(drive, &pc)) {
		printk(KERN_ERR "ide-tape: Can't get tape parameters - assuming some default values\n");
		tape->tape_block_size = 512;
		tape->capabilities.ctl = 52;
		tape->capabilities.speed = 450;
		tape->capabilities.buffer_size = 6 * 52;
		return;
	}
	header = (idetape_mode_parameter_header_t *) pc.buffer;
	capabilities = (idetape_capabilities_page_t *) (pc.buffer + sizeof(idetape_mode_parameter_header_t) + header->bdl);

	capabilities->max_speed = ntohs(capabilities->max_speed);
	capabilities->ctl = ntohs(capabilities->ctl);
	capabilities->speed = ntohs(capabilities->speed);
	capabilities->buffer_size = ntohs(capabilities->buffer_size);

	if (!capabilities->speed) {
		printk(KERN_INFO "ide-tape: %s: overriding capabilities->speed (assuming 650KB/sec)\n", drive->name);
		capabilities->speed = 650;
	}
	if (!capabilities->max_speed) {
		printk(KERN_INFO "ide-tape: %s: overriding capabilities->max_speed (assuming 650KB/sec)\n", drive->name);
		capabilities->max_speed = 650;
	}

	tape->capabilities = *capabilities;		/* Save us a copy */
	if (capabilities->blk512)
		tape->tape_block_size = 512;
	else if (capabilities->blk1024)
		tape->tape_block_size = 1024;

#if IDETAPE_DEBUG_INFO
	printk(KERN_INFO "ide-tape: Dumping the results of the MODE SENSE packet command\n");
	printk(KERN_INFO "ide-tape: Mode Parameter Header:\n");
	printk(KERN_INFO "ide-tape: Mode Data Length - %d\n",header->mode_data_length);
	printk(KERN_INFO "ide-tape: Medium Type - %d\n",header->medium_type);
	printk(KERN_INFO "ide-tape: Device Specific Parameter - %d\n",header->dsp);
	printk(KERN_INFO "ide-tape: Block Descriptor Length - %d\n",header->bdl);
	
	printk(KERN_INFO "ide-tape: Capabilities and Mechanical Status Page:\n");
	printk(KERN_INFO "ide-tape: Page code - %d\n",capabilities->page_code);
	printk(KERN_INFO "ide-tape: Page length - %d\n",capabilities->page_length);
	printk(KERN_INFO "ide-tape: Read only - %s\n",capabilities->ro ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports reverse space - %s\n",capabilities->sprev ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports erase initiated formatting - %s\n",capabilities->efmt ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports QFA two Partition format - %s\n",capabilities->qfa ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports locking the medium - %s\n",capabilities->lock ? "Yes":"No");
	printk(KERN_INFO "ide-tape: The volume is currently locked - %s\n",capabilities->locked ? "Yes":"No");
	printk(KERN_INFO "ide-tape: The device defaults in the prevent state - %s\n",capabilities->prevent ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports ejecting the medium - %s\n",capabilities->eject ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports error correction - %s\n",capabilities->ecc ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports data compression - %s\n",capabilities->cmprs ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports 512 bytes block size - %s\n",capabilities->blk512 ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports 1024 bytes block size - %s\n",capabilities->blk1024 ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Supports 32768 bytes block size / Restricted byte count for PIO transfers - %s\n",capabilities->blk32768 ? "Yes":"No");
	printk(KERN_INFO "ide-tape: Maximum supported speed in KBps - %d\n",capabilities->max_speed);
	printk(KERN_INFO "ide-tape: Continuous transfer limits in blocks - %d\n",capabilities->ctl);
	printk(KERN_INFO "ide-tape: Current speed in KBps - %d\n",capabilities->speed);	
	printk(KERN_INFO "ide-tape: Buffer size - %d\n",capabilities->buffer_size*512);
#endif /* IDETAPE_DEBUG_INFO */
}

/*
 *	ide_get_blocksize_from_block_descriptor does a mode sense page 0 with block descriptor
 *	and if it succeeds sets the tape block size with the reported value
 */
static void idetape_get_blocksize_from_block_descriptor(ide_drive_t *drive)
{

	idetape_tape_t *tape = drive->driver_data;
	idetape_pc_t pc;
	idetape_mode_parameter_header_t *header;
	idetape_parameter_block_descriptor_t *block_descrp;
	
	idetape_create_mode_sense_cmd(&pc, IDETAPE_BLOCK_DESCRIPTOR);
	if (idetape_queue_pc_tail(drive, &pc)) {
		printk(KERN_ERR "ide-tape: Can't get block descriptor\n");
		if (tape->tape_block_size == 0) {
			printk(KERN_WARNING "ide-tape: Cannot deal with zero block size, assume 32k\n");
			tape->tape_block_size =  32768;
		}
		return;
	}
	header = (idetape_mode_parameter_header_t *) pc.buffer;
	block_descrp = (idetape_parameter_block_descriptor_t *) (pc.buffer + sizeof(idetape_mode_parameter_header_t));
	tape->tape_block_size =( block_descrp->length[0]<<16) + (block_descrp->length[1]<<8) + block_descrp->length[2];
	tape->drv_write_prot = (header->dsp & 0x80) >> 7;

#if IDETAPE_DEBUG_INFO
	printk(KERN_INFO "ide-tape: Adjusted block size - %d\n", tape->tape_block_size);
#endif /* IDETAPE_DEBUG_INFO */
}
static void idetape_add_settings (ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

/*
 *			drive	setting name	read/write	ioctl	ioctl		data type	min			max			mul_factor			div_factor			data pointer				set function
 */
	ide_add_setting(drive,	"buffer",	SETTING_READ,	-1,	-1,		TYPE_SHORT,	0,			0xffff,			1,				2,				&tape->capabilities.buffer_size,	NULL);
	ide_add_setting(drive,	"pipeline_min",	SETTING_RW,	-1,	-1,		TYPE_INT,	1,			0xffff,			tape->stage_size / 1024,	1,				&tape->min_pipeline,			NULL);
	ide_add_setting(drive,	"pipeline",	SETTING_RW,	-1,	-1,		TYPE_INT,	1,			0xffff,			tape->stage_size / 1024,	1,				&tape->max_stages,			NULL);
	ide_add_setting(drive,	"pipeline_max",	SETTING_RW,	-1,	-1,		TYPE_INT,	1,			0xffff,			tape->stage_size / 1024,	1,				&tape->max_pipeline,			NULL);
	ide_add_setting(drive,	"pipeline_used",SETTING_READ,	-1,	-1,		TYPE_INT,	0,			0xffff,			tape->stage_size / 1024,	1,				&tape->nr_stages,			NULL);
	ide_add_setting(drive,	"pipeline_pending",SETTING_READ,-1,	-1,		TYPE_INT,	0,			0xffff,			tape->stage_size / 1024,	1,				&tape->nr_pending_stages,		NULL);
	ide_add_setting(drive,	"speed",	SETTING_READ,	-1,	-1,		TYPE_SHORT,	0,			0xffff,			1,				1,				&tape->capabilities.speed,		NULL);
	ide_add_setting(drive,	"stage",	SETTING_READ,	-1,	-1,		TYPE_INT,	0,			0xffff,			1,				1024,				&tape->stage_size,			NULL);
	ide_add_setting(drive,	"tdsc",		SETTING_RW,	-1,	-1,		TYPE_INT,	IDETAPE_DSC_RW_MIN,	IDETAPE_DSC_RW_MAX,	1000,				HZ,				&tape->best_dsc_rw_frequency,		NULL);
	ide_add_setting(drive,	"dsc_overlap",	SETTING_RW,	-1,	-1,		TYPE_BYTE,	0,			1,			1,				1,				&drive->dsc_overlap,			NULL);
	ide_add_setting(drive,	"pipeline_head_speed_c",SETTING_READ,	-1,	-1,	TYPE_INT,	0,			0xffff,			1,				1,				&tape->controlled_pipeline_head_speed,	NULL);
	ide_add_setting(drive,	"pipeline_head_speed_u",SETTING_READ,	-1,	-1,	TYPE_INT,	0,			0xffff,			1,				1,				&tape->uncontrolled_pipeline_head_speed,	NULL);
	ide_add_setting(drive,	"avg_speed",	SETTING_READ,	-1,	-1,		TYPE_INT,	0,			0xffff,			1,				1,				&tape->avg_speed,		NULL);
	ide_add_setting(drive,	"debug_level",SETTING_RW,	-1,	-1,		TYPE_INT,	0,			0xffff,			1,				1,				&tape->debug_level,		NULL);
}

/*
 *	ide_setup is called to:
 *
 *		1.	Initialize our various state variables.
 *		2.	Ask the tape for its capabilities.
 *		3.	Allocate a buffer which will be used for data
 *			transfer. The buffer size is chosen based on
 *			the recommendation which we received in step (2).
 *
 *	Note that at this point ide.c already assigned us an irq, so that
 *	we can queue requests here and wait for their completion.
 */
static void idetape_setup (ide_drive_t *drive, idetape_tape_t *tape, int minor)
{
	unsigned long t1, tmid, tn, t;
	int speed;
	struct idetape_id_gcw gcw;
	int stage_size;
	struct sysinfo si;

	spin_lock_init(&tape->spinlock);
	drive->dsc_overlap = 1;
#ifdef CONFIG_BLK_DEV_IDEPCI
	if (HWIF(drive)->pci_dev != NULL) {
		/*
		 * These two ide-pci host adapters appear to need DSC overlap disabled.
		 * This probably needs further analysis.
		 */
		if ((HWIF(drive)->pci_dev->device == PCI_DEVICE_ID_ARTOP_ATP850UF) ||
		    (HWIF(drive)->pci_dev->device == PCI_DEVICE_ID_TTI_HPT343)) {
			printk(KERN_INFO "ide-tape: %s: disabling DSC overlap\n", tape->name);
		    	drive->dsc_overlap = 0;
		}
	}
#endif /* CONFIG_BLK_DEV_IDEPCI */
	/* Seagate Travan drives do not support DSC overlap. */
	if (strstr(drive->id->model, "Seagate STT3401"))
		drive->dsc_overlap = 0;
	tape->minor = minor;
	tape->name[0] = 'h';
	tape->name[1] = 't';
	tape->name[2] = '0' + minor;
	tape->chrdev_direction = idetape_direction_none;
	tape->pc = tape->pc_stack;
	tape->max_insert_speed = 10000;
	tape->speed_control = 1;
	*((unsigned short *) &gcw) = drive->id->config;
	if (gcw.drq_type == 1)
		set_bit(IDETAPE_DRQ_INTERRUPT, &tape->flags);

	tape->min_pipeline = tape->max_pipeline = tape->max_stages = 10;
	
	idetape_get_inquiry_results(drive);
	idetape_get_mode_sense_results(drive);
	idetape_get_blocksize_from_block_descriptor(drive);
	tape->user_bs_factor = 1;
	tape->stage_size = tape->capabilities.ctl * tape->tape_block_size;
	while (tape->stage_size > 0xffff) {
		printk(KERN_NOTICE "ide-tape: decreasing stage size\n");
		tape->capabilities.ctl /= 2;
		tape->stage_size = tape->capabilities.ctl * tape->tape_block_size;
	}
	stage_size = tape->stage_size;
	tape->pages_per_stage = stage_size / PAGE_SIZE;
	if (stage_size % PAGE_SIZE) {
		tape->pages_per_stage++;
		tape->excess_bh_size = PAGE_SIZE - stage_size % PAGE_SIZE;
	}

	/*
	 *	Select the "best" DSC read/write polling frequency
	 *	and pipeline size.
	 */
	speed = max(tape->capabilities.speed, tape->capabilities.max_speed);

	tape->max_stages = speed * 1000 * 10 / tape->stage_size;

	/*
	 * 	Limit memory use for pipeline to 10% of physical memory
	 */
	si_meminfo(&si);
	if (tape->max_stages * tape->stage_size > si.totalram * si.mem_unit / 10)
		tape->max_stages = si.totalram * si.mem_unit / (10 * tape->stage_size);
	tape->max_stages   = min(tape->max_stages, IDETAPE_MAX_PIPELINE_STAGES);
	tape->min_pipeline = min(tape->max_stages, IDETAPE_MIN_PIPELINE_STAGES);
	tape->max_pipeline = min(tape->max_stages * 2, IDETAPE_MAX_PIPELINE_STAGES);
	if (tape->max_stages == 0)
		tape->max_stages = tape->min_pipeline = tape->max_pipeline = 1;

	t1 = (tape->stage_size * HZ) / (speed * 1000);
	tmid = (tape->capabilities.buffer_size * 32 * HZ) / (speed * 125);
	tn = (IDETAPE_FIFO_THRESHOLD * tape->stage_size * HZ) / (speed * 1000);

	if (tape->max_stages)
		t = tn;
	else
		t = t1;

	/*
	 *	Ensure that the number we got makes sense; limit
	 *	it within IDETAPE_DSC_RW_MIN and IDETAPE_DSC_RW_MAX.
	 */
	tape->best_dsc_rw_frequency = max_t(unsigned long, min_t(unsigned long, t, IDETAPE_DSC_RW_MAX), IDETAPE_DSC_RW_MIN);
	printk(KERN_INFO "ide-tape: %s <-> %s: %dKBps, %d*%dkB buffer, "
		"%dkB pipeline, %lums tDSC%s\n",
		drive->name, tape->name, tape->capabilities.speed,
		(tape->capabilities.buffer_size * 512) / tape->stage_size,
		tape->stage_size / 1024,
		tape->max_stages * tape->stage_size / 1024,
		tape->best_dsc_rw_frequency * 1000 / HZ,
		drive->using_dma ? ", DMA":"");

	idetape_add_settings(drive);
}

static void ide_tape_remove(ide_drive_t *drive)
{
	idetape_tape_t *tape = drive->driver_data;

	ide_unregister_subdriver(drive, tape->driver);

	ide_unregister_region(tape->disk);

	ide_tape_put(tape);
}

static void ide_tape_release(struct kref *kref)
{
	struct ide_tape_obj *tape = to_ide_tape(kref);
	ide_drive_t *drive = tape->drive;
	struct gendisk *g = tape->disk;

	BUG_ON(tape->first_stage != NULL || tape->merge_stage_size);

	drive->dsc_overlap = 0;
	drive->driver_data = NULL;
	class_device_destroy(idetape_sysfs_class,
			MKDEV(IDETAPE_MAJOR, tape->minor));
	class_device_destroy(idetape_sysfs_class,
			MKDEV(IDETAPE_MAJOR, tape->minor + 128));
	idetape_devs[tape->minor] = NULL;
	g->private_data = NULL;
	put_disk(g);
	kfree(tape);
}

#ifdef CONFIG_PROC_FS

static int proc_idetape_read_name
	(char *page, char **start, off_t off, int count, int *eof, void *data)
{
	ide_drive_t	*drive = (ide_drive_t *) data;
	idetape_tape_t	*tape = drive->driver_data;
	char		*out = page;
	int		len;

	len = sprintf(out, "%s\n", tape->name);
	PROC_IDE_READ_RETURN(page, start, off, count, eof, len);
}

static ide_proc_entry_t idetape_proc[] = {
	{ "capacity",	S_IFREG|S_IRUGO,	proc_ide_read_capacity, NULL },
	{ "name",	S_IFREG|S_IRUGO,	proc_idetape_read_name,	NULL },
	{ NULL, 0, NULL, NULL }
};

#else

#define	idetape_proc	NULL

#endif

static int ide_tape_probe(ide_drive_t *);

static ide_driver_t idetape_driver = {
	.gen_driver = {
		.owner		= THIS_MODULE,
		.name		= "ide-tape",
		.bus		= &ide_bus_type,
	},
	.probe			= ide_tape_probe,
	.remove			= ide_tape_remove,
	.version		= IDETAPE_VERSION,
	.media			= ide_tape,
	.supports_dsc_overlap 	= 1,
	.do_request		= idetape_do_request,
	.end_request		= idetape_end_request,
	.error			= __ide_error,
	.abort			= __ide_abort,
	.proc			= idetape_proc,
};

/*
 *	Our character device supporting functions, passed to register_chrdev.
 */
static const struct file_operations idetape_fops = {
	.owner		= THIS_MODULE,
	.read		= idetape_chrdev_read,
	.write		= idetape_chrdev_write,
	.ioctl		= idetape_chrdev_ioctl,
	.open		= idetape_chrdev_open,
	.release	= idetape_chrdev_release,
};

static int idetape_open(struct inode *inode, struct file *filp)
{
	struct gendisk *disk = inode->i_bdev->bd_disk;
	struct ide_tape_obj *tape;
	ide_drive_t *drive;

	if (!(tape = ide_tape_get(disk)))
		return -ENXIO;

	drive = tape->drive;

	drive->usage++;

	return 0;
}

static int idetape_release(struct inode *inode, struct file *filp)
{
	struct gendisk *disk = inode->i_bdev->bd_disk;
	struct ide_tape_obj *tape = ide_tape_g(disk);
	ide_drive_t *drive = tape->drive;

	drive->usage--;

	ide_tape_put(tape);

	return 0;
}

static int idetape_ioctl(struct inode *inode, struct file *file,
			unsigned int cmd, unsigned long arg)
{
	struct block_device *bdev = inode->i_bdev;
	struct ide_tape_obj *tape = ide_tape_g(bdev->bd_disk);
	ide_drive_t *drive = tape->drive;
	int err = generic_ide_ioctl(drive, file, bdev, cmd, arg);
	if (err == -EINVAL)
		err = idetape_blkdev_ioctl(drive, cmd, arg);
	return err;
}

static struct block_device_operations idetape_block_ops = {
	.owner		= THIS_MODULE,
	.open		= idetape_open,
	.release	= idetape_release,
	.ioctl		= idetape_ioctl,
};

static int ide_tape_probe(ide_drive_t *drive)
{
	idetape_tape_t *tape;
	struct gendisk *g;
	int minor;

	if (!strstr("ide-tape", drive->driver_req))
		goto failed;
	if (!drive->present)
		goto failed;
	if (drive->media != ide_tape)
		goto failed;
	if (!idetape_identify_device (drive)) {
		printk(KERN_ERR "ide-tape: %s: not supported by this version of ide-tape\n", drive->name);
		goto failed;
	}
	if (drive->scsi) {
		printk("ide-tape: passing drive %s to ide-scsi emulation.\n", drive->name);
		goto failed;
	}
	if (strstr(drive->id->model, "OnStream DI-")) {
		printk(KERN_WARNING "ide-tape: Use drive %s with ide-scsi emulation and osst.\n", drive->name);
		printk(KERN_WARNING "ide-tape: OnStream support will be removed soon from ide-tape!\n");
	}
	tape = kzalloc(sizeof (idetape_tape_t), GFP_KERNEL);
	if (tape == NULL) {
		printk(KERN_ERR "ide-tape: %s: Can't allocate a tape structure\n", drive->name);
		goto failed;
	}

	g = alloc_disk(1 << PARTN_BITS);
	if (!g)
		goto out_free_tape;

	ide_init_disk(g, drive);

	ide_register_subdriver(drive, &idetape_driver);

	kref_init(&tape->kref);

	tape->drive = drive;
	tape->driver = &idetape_driver;
	tape->disk = g;

	g->private_data = &tape->driver;

	drive->driver_data = tape;

	mutex_lock(&idetape_ref_mutex);
	for (minor = 0; idetape_devs[minor]; minor++)
		;
	idetape_devs[minor] = tape;
	mutex_unlock(&idetape_ref_mutex);

	idetape_setup(drive, tape, minor);

	class_device_create(idetape_sysfs_class, NULL,
			MKDEV(IDETAPE_MAJOR, minor), &drive->gendev, "%s", tape->name);
	class_device_create(idetape_sysfs_class, NULL,
			MKDEV(IDETAPE_MAJOR, minor + 128), &drive->gendev, "n%s", tape->name);

	g->fops = &idetape_block_ops;
	ide_register_region(g);

	return 0;

out_free_tape:
	kfree(tape);
failed:
	return -ENODEV;
}

MODULE_DESCRIPTION("ATAPI Streaming TAPE Driver");
MODULE_LICENSE("GPL");

static void __exit idetape_exit (void)
{
	driver_unregister(&idetape_driver.gen_driver);
	class_destroy(idetape_sysfs_class);
	unregister_chrdev(IDETAPE_MAJOR, "ht");
}

static int __init idetape_init(void)
{
	int error = 1;
	idetape_sysfs_class = class_create(THIS_MODULE, "ide_tape");
	if (IS_ERR(idetape_sysfs_class)) {
		idetape_sysfs_class = NULL;
		printk(KERN_ERR "Unable to create sysfs class for ide tapes\n");
		error = -EBUSY;
		goto out;
	}

	if (register_chrdev(IDETAPE_MAJOR, "ht", &idetape_fops)) {
		printk(KERN_ERR "ide-tape: Failed to register character device interface\n");
		error = -EBUSY;
		goto out_free_class;
	}

	error = driver_register(&idetape_driver.gen_driver);
	if (error)
		goto out_free_driver;

	return 0;

out_free_driver:
	driver_unregister(&idetape_driver.gen_driver);
out_free_class:
	class_destroy(idetape_sysfs_class);
out:
	return error;
}

MODULE_ALIAS("ide:*m-tape*");
module_init(idetape_init);
module_exit(idetape_exit);
MODULE_ALIAS_CHARDEV_MAJOR(IDETAPE_MAJOR);