summaryrefslogtreecommitdiff
path: root/drivers/tty/hvc/hvc_iucv.c
blob: 2af1e5751bd6302463a397cedd68bdccb23d8313 (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
// SPDX-License-Identifier: GPL-2.0
/*
 * z/VM IUCV hypervisor console (HVC) device driver
 *
 * This HVC device driver provides terminal access using
 * z/VM IUCV communication paths.
 *
 * Copyright IBM Corp. 2008, 2013
 *
 * Author(s):	Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
 */
#define KMSG_COMPONENT		"hvc_iucv"
#define pr_fmt(fmt)		KMSG_COMPONENT ": " fmt

#include <linux/types.h>
#include <linux/slab.h>
#include <asm/ebcdic.h>
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/mempool.h>
#include <linux/moduleparam.h>
#include <linux/tty.h>
#include <linux/wait.h>
#include <net/iucv/iucv.h>

#include "hvc_console.h"


/* General device driver settings */
#define HVC_IUCV_MAGIC		0xc9e4c3e5
#define MAX_HVC_IUCV_LINES	HVC_ALLOC_TTY_ADAPTERS
#define MEMPOOL_MIN_NR		(PAGE_SIZE / sizeof(struct iucv_tty_buffer)/4)

/* IUCV TTY message  */
#define MSG_VERSION		0x02	/* Message version */
#define MSG_TYPE_ERROR		0x01	/* Error message */
#define MSG_TYPE_TERMENV	0x02	/* Terminal environment variable */
#define MSG_TYPE_TERMIOS	0x04	/* Terminal IO struct update */
#define MSG_TYPE_WINSIZE	0x08	/* Terminal window size update */
#define MSG_TYPE_DATA		0x10	/* Terminal data */

struct iucv_tty_msg {
	u8	version;		/* Message version */
	u8	type;			/* Message type */
#define MSG_MAX_DATALEN		((u16)(~0))
	u16	datalen;		/* Payload length */
	u8	data[];			/* Payload buffer */
} __attribute__((packed));
#define MSG_SIZE(s)		((s) + offsetof(struct iucv_tty_msg, data))

enum iucv_state_t {
	IUCV_DISCONN	= 0,
	IUCV_CONNECTED	= 1,
	IUCV_SEVERED	= 2,
};

enum tty_state_t {
	TTY_CLOSED	= 0,
	TTY_OPENED	= 1,
};

struct hvc_iucv_private {
	struct hvc_struct	*hvc;		/* HVC struct reference */
	u8			srv_name[8];	/* IUCV service name (ebcdic) */
	unsigned char		is_console;	/* Linux console usage flag */
	enum iucv_state_t	iucv_state;	/* IUCV connection status */
	enum tty_state_t	tty_state;	/* TTY status */
	struct iucv_path	*path;		/* IUCV path pointer */
	spinlock_t		lock;		/* hvc_iucv_private lock */
#define SNDBUF_SIZE		(PAGE_SIZE)	/* must be < MSG_MAX_DATALEN */
	void			*sndbuf;	/* send buffer		  */
	size_t			sndbuf_len;	/* length of send buffer  */
#define QUEUE_SNDBUF_DELAY	(HZ / 25)
	struct delayed_work	sndbuf_work;	/* work: send iucv msg(s) */
	wait_queue_head_t	sndbuf_waitq;	/* wait for send completion */
	struct list_head	tty_outqueue;	/* outgoing IUCV messages */
	struct list_head	tty_inqueue;	/* incoming IUCV messages */
	struct device		*dev;		/* device structure */
	u8			info_path[16];	/* IUCV path info (dev attr) */
};

struct iucv_tty_buffer {
	struct list_head	list;	/* list pointer */
	struct iucv_message	msg;	/* store an IUCV message */
	size_t			offset;	/* data buffer offset */
	struct iucv_tty_msg	*mbuf;	/* buffer to store input/output data */
};

/* IUCV callback handler */
static	int hvc_iucv_path_pending(struct iucv_path *, u8 *, u8 *);
static void hvc_iucv_path_severed(struct iucv_path *, u8 *);
static void hvc_iucv_msg_pending(struct iucv_path *, struct iucv_message *);
static void hvc_iucv_msg_complete(struct iucv_path *, struct iucv_message *);


/* Kernel module parameter: use one terminal device as default */
static unsigned long hvc_iucv_devices = 1;

/* Array of allocated hvc iucv tty lines... */
static struct hvc_iucv_private *hvc_iucv_table[MAX_HVC_IUCV_LINES];
#define IUCV_HVC_CON_IDX	(0)
/* List of z/VM user ID filter entries (struct iucv_vmid_filter) */
#define MAX_VMID_FILTER		(500)
#define FILTER_WILDCARD_CHAR	'*'
static size_t hvc_iucv_filter_size;
static void *hvc_iucv_filter;
static const char *hvc_iucv_filter_string;
static DEFINE_RWLOCK(hvc_iucv_filter_lock);

/* Kmem cache and mempool for iucv_tty_buffer elements */
static struct kmem_cache *hvc_iucv_buffer_cache;
static mempool_t *hvc_iucv_mempool;

/* IUCV handler callback functions */
static struct iucv_handler hvc_iucv_handler = {
	.path_pending  = hvc_iucv_path_pending,
	.path_severed  = hvc_iucv_path_severed,
	.message_complete = hvc_iucv_msg_complete,
	.message_pending  = hvc_iucv_msg_pending,
};


/**
 * hvc_iucv_get_private() - Return a struct hvc_iucv_private instance.
 * @num:	The HVC virtual terminal number (vtermno)
 *
 * This function returns the struct hvc_iucv_private instance that corresponds
 * to the HVC virtual terminal number specified as parameter @num.
 */
static struct hvc_iucv_private *hvc_iucv_get_private(uint32_t num)
{
	if ((num < HVC_IUCV_MAGIC) || (num - HVC_IUCV_MAGIC > hvc_iucv_devices))
		return NULL;
	return hvc_iucv_table[num - HVC_IUCV_MAGIC];
}

/**
 * alloc_tty_buffer() - Return a new struct iucv_tty_buffer element.
 * @size:	Size of the internal buffer used to store data.
 * @flags:	Memory allocation flags passed to mempool.
 *
 * This function allocates a new struct iucv_tty_buffer element and, optionally,
 * allocates an internal data buffer with the specified size @size.
 * The internal data buffer is always allocated with GFP_DMA which is
 * required for receiving and sending data with IUCV.
 * Note: The total message size arises from the internal buffer size and the
 *	 members of the iucv_tty_msg structure.
 * The function returns NULL if memory allocation has failed.
 */
static struct iucv_tty_buffer *alloc_tty_buffer(size_t size, gfp_t flags)
{
	struct iucv_tty_buffer *bufp;

	bufp = mempool_alloc(hvc_iucv_mempool, flags);
	if (!bufp)
		return NULL;
	memset(bufp, 0, sizeof(*bufp));

	if (size > 0) {
		bufp->msg.length = MSG_SIZE(size);
		bufp->mbuf = kmalloc(bufp->msg.length, flags | GFP_DMA);
		if (!bufp->mbuf) {
			mempool_free(bufp, hvc_iucv_mempool);
			return NULL;
		}
		bufp->mbuf->version = MSG_VERSION;
		bufp->mbuf->type    = MSG_TYPE_DATA;
		bufp->mbuf->datalen = (u16) size;
	}
	return bufp;
}

/**
 * destroy_tty_buffer() - destroy struct iucv_tty_buffer element.
 * @bufp:	Pointer to a struct iucv_tty_buffer element, SHALL NOT be NULL.
 */
static void destroy_tty_buffer(struct iucv_tty_buffer *bufp)
{
	kfree(bufp->mbuf);
	mempool_free(bufp, hvc_iucv_mempool);
}

/**
 * destroy_tty_buffer_list() - call destroy_tty_buffer() for each list element.
 * @list:	List containing struct iucv_tty_buffer elements.
 */
static void destroy_tty_buffer_list(struct list_head *list)
{
	struct iucv_tty_buffer *ent, *next;

	list_for_each_entry_safe(ent, next, list, list) {
		list_del(&ent->list);
		destroy_tty_buffer(ent);
	}
}

/**
 * hvc_iucv_write() - Receive IUCV message & write data to HVC buffer.
 * @priv:		Pointer to struct hvc_iucv_private
 * @buf:		HVC buffer for writing received terminal data.
 * @count:		HVC buffer size.
 * @has_more_data:	Pointer to an int variable.
 *
 * The function picks up pending messages from the input queue and receives
 * the message data that is then written to the specified buffer @buf.
 * If the buffer size @count is less than the data message size, the
 * message is kept on the input queue and @has_more_data is set to 1.
 * If all message data has been written, the message is removed from
 * the input queue.
 *
 * The function returns the number of bytes written to the terminal, zero if
 * there are no pending data messages available or if there is no established
 * IUCV path.
 * If the IUCV path has been severed, then -EPIPE is returned to cause a
 * hang up (that is issued by the HVC layer).
 */
static int hvc_iucv_write(struct hvc_iucv_private *priv,
			  char *buf, int count, int *has_more_data)
{
	struct iucv_tty_buffer *rb;
	int written;
	int rc;

	/* immediately return if there is no IUCV connection */
	if (priv->iucv_state == IUCV_DISCONN)
		return 0;

	/* if the IUCV path has been severed, return -EPIPE to inform the
	 * HVC layer to hang up the tty device. */
	if (priv->iucv_state == IUCV_SEVERED)
		return -EPIPE;

	/* check if there are pending messages */
	if (list_empty(&priv->tty_inqueue))
		return 0;

	/* receive an iucv message and flip data to the tty (ldisc) */
	rb = list_first_entry(&priv->tty_inqueue, struct iucv_tty_buffer, list);

	written = 0;
	if (!rb->mbuf) { /* message not yet received ... */
		/* allocate mem to store msg data; if no memory is available
		 * then leave the buffer on the list and re-try later */
		rb->mbuf = kmalloc(rb->msg.length, GFP_ATOMIC | GFP_DMA);
		if (!rb->mbuf)
			return -ENOMEM;

		rc = __iucv_message_receive(priv->path, &rb->msg, 0,
					    rb->mbuf, rb->msg.length, NULL);
		switch (rc) {
		case 0: /* Successful	    */
			break;
		case 2:	/* No message found */
		case 9: /* Message purged   */
			break;
		default:
			written = -EIO;
		}
		/* remove buffer if an error has occurred or received data
		 * is not correct */
		if (rc || (rb->mbuf->version != MSG_VERSION) ||
			  (rb->msg.length    != MSG_SIZE(rb->mbuf->datalen)))
			goto out_remove_buffer;
	}

	switch (rb->mbuf->type) {
	case MSG_TYPE_DATA:
		written = min_t(int, rb->mbuf->datalen - rb->offset, count);
		memcpy(buf, rb->mbuf->data + rb->offset, written);
		if (written < (rb->mbuf->datalen - rb->offset)) {
			rb->offset += written;
			*has_more_data = 1;
			goto out_written;
		}
		break;

	case MSG_TYPE_WINSIZE:
		if (rb->mbuf->datalen != sizeof(struct winsize))
			break;
		/* The caller must ensure that the hvc is locked, which
		 * is the case when called from hvc_iucv_get_chars() */
		__hvc_resize(priv->hvc, *((struct winsize *) rb->mbuf->data));
		break;

	case MSG_TYPE_ERROR:	/* ignored ... */
	case MSG_TYPE_TERMENV:	/* ignored ... */
	case MSG_TYPE_TERMIOS:	/* ignored ... */
		break;
	}

out_remove_buffer:
	list_del(&rb->list);
	destroy_tty_buffer(rb);
	*has_more_data = !list_empty(&priv->tty_inqueue);

out_written:
	return written;
}

/**
 * hvc_iucv_get_chars() - HVC get_chars operation.
 * @vtermno:	HVC virtual terminal number.
 * @buf:	Pointer to a buffer to store data
 * @count:	Size of buffer available for writing
 *
 * The HVC thread calls this method to read characters from the back-end.
 * If an IUCV communication path has been established, pending IUCV messages
 * are received and data is copied into buffer @buf up to @count bytes.
 *
 * Locking:	The routine gets called under an irqsave() spinlock; and
 *		the routine locks the struct hvc_iucv_private->lock to call
 *		helper functions.
 */
static int hvc_iucv_get_chars(uint32_t vtermno, char *buf, int count)
{
	struct hvc_iucv_private *priv = hvc_iucv_get_private(vtermno);
	int written;
	int has_more_data;

	if (count <= 0)
		return 0;

	if (!priv)
		return -ENODEV;

	spin_lock(&priv->lock);
	has_more_data = 0;
	written = hvc_iucv_write(priv, buf, count, &has_more_data);
	spin_unlock(&priv->lock);

	/* if there are still messages on the queue... schedule another run */
	if (has_more_data)
		hvc_kick();

	return written;
}

/**
 * hvc_iucv_queue() - Buffer terminal data for sending.
 * @priv:	Pointer to struct hvc_iucv_private instance.
 * @buf:	Buffer containing data to send.
 * @count:	Size of buffer and amount of data to send.
 *
 * The function queues data for sending. To actually send the buffered data,
 * a work queue function is scheduled (with QUEUE_SNDBUF_DELAY).
 * The function returns the number of data bytes that has been buffered.
 *
 * If the device is not connected, data is ignored and the function returns
 * @count.
 * If the buffer is full, the function returns 0.
 * If an existing IUCV communicaton path has been severed, -EPIPE is returned
 * (that can be passed to HVC layer to cause a tty hangup).
 */
static int hvc_iucv_queue(struct hvc_iucv_private *priv, const char *buf,
			  int count)
{
	size_t len;

	if (priv->iucv_state == IUCV_DISCONN)
		return count;			/* ignore data */

	if (priv->iucv_state == IUCV_SEVERED)
		return -EPIPE;

	len = min_t(size_t, count, SNDBUF_SIZE - priv->sndbuf_len);
	if (!len)
		return 0;

	memcpy(priv->sndbuf + priv->sndbuf_len, buf, len);
	priv->sndbuf_len += len;

	if (priv->iucv_state == IUCV_CONNECTED)
		schedule_delayed_work(&priv->sndbuf_work, QUEUE_SNDBUF_DELAY);

	return len;
}

/**
 * hvc_iucv_send() - Send an IUCV message containing terminal data.
 * @priv:	Pointer to struct hvc_iucv_private instance.
 *
 * If an IUCV communication path has been established, the buffered output data
 * is sent via an IUCV message and the number of bytes sent is returned.
 * Returns 0 if there is no established IUCV communication path or
 * -EPIPE if an existing IUCV communicaton path has been severed.
 */
static int hvc_iucv_send(struct hvc_iucv_private *priv)
{
	struct iucv_tty_buffer *sb;
	int rc, len;

	if (priv->iucv_state == IUCV_SEVERED)
		return -EPIPE;

	if (priv->iucv_state == IUCV_DISCONN)
		return -EIO;

	if (!priv->sndbuf_len)
		return 0;

	/* allocate internal buffer to store msg data and also compute total
	 * message length */
	sb = alloc_tty_buffer(priv->sndbuf_len, GFP_ATOMIC);
	if (!sb)
		return -ENOMEM;

	memcpy(sb->mbuf->data, priv->sndbuf, priv->sndbuf_len);
	sb->mbuf->datalen = (u16) priv->sndbuf_len;
	sb->msg.length = MSG_SIZE(sb->mbuf->datalen);

	list_add_tail(&sb->list, &priv->tty_outqueue);

	rc = __iucv_message_send(priv->path, &sb->msg, 0, 0,
				 (void *) sb->mbuf, sb->msg.length);
	if (rc) {
		/* drop the message here; however we might want to handle
		 * 0x03 (msg limit reached) by trying again... */
		list_del(&sb->list);
		destroy_tty_buffer(sb);
	}
	len = priv->sndbuf_len;
	priv->sndbuf_len = 0;

	return len;
}

/**
 * hvc_iucv_sndbuf_work() - Send buffered data over IUCV
 * @work:	Work structure.
 *
 * This work queue function sends buffered output data over IUCV and,
 * if not all buffered data could be sent, reschedules itself.
 */
static void hvc_iucv_sndbuf_work(struct work_struct *work)
{
	struct hvc_iucv_private *priv;

	priv = container_of(work, struct hvc_iucv_private, sndbuf_work.work);
	if (!priv)
		return;

	spin_lock_bh(&priv->lock);
	hvc_iucv_send(priv);
	spin_unlock_bh(&priv->lock);
}

/**
 * hvc_iucv_put_chars() - HVC put_chars operation.
 * @vtermno:	HVC virtual terminal number.
 * @buf:	Pointer to an buffer to read data from
 * @count:	Size of buffer available for reading
 *
 * The HVC thread calls this method to write characters to the back-end.
 * The function calls hvc_iucv_queue() to queue terminal data for sending.
 *
 * Locking:	The method gets called under an irqsave() spinlock; and
 *		locks struct hvc_iucv_private->lock.
 */
static int hvc_iucv_put_chars(uint32_t vtermno, const char *buf, int count)
{
	struct hvc_iucv_private *priv = hvc_iucv_get_private(vtermno);
	int queued;

	if (count <= 0)
		return 0;

	if (!priv)
		return -ENODEV;

	spin_lock(&priv->lock);
	queued = hvc_iucv_queue(priv, buf, count);
	spin_unlock(&priv->lock);

	return queued;
}

/**
 * hvc_iucv_notifier_add() - HVC notifier for opening a TTY for the first time.
 * @hp:	Pointer to the HVC device (struct hvc_struct)
 * @id:	Additional data (originally passed to hvc_alloc): the index of an struct
 *	hvc_iucv_private instance.
 *
 * The function sets the tty state to TTY_OPENED for the struct hvc_iucv_private
 * instance that is derived from @id. Always returns 0.
 *
 * Locking:	struct hvc_iucv_private->lock, spin_lock_bh
 */
static int hvc_iucv_notifier_add(struct hvc_struct *hp, int id)
{
	struct hvc_iucv_private *priv;

	priv = hvc_iucv_get_private(id);
	if (!priv)
		return 0;

	spin_lock_bh(&priv->lock);
	priv->tty_state = TTY_OPENED;
	spin_unlock_bh(&priv->lock);

	return 0;
}

/**
 * hvc_iucv_cleanup() - Clean up and reset a z/VM IUCV HVC instance.
 * @priv:	Pointer to the struct hvc_iucv_private instance.
 */
static void hvc_iucv_cleanup(struct hvc_iucv_private *priv)
{
	destroy_tty_buffer_list(&priv->tty_outqueue);
	destroy_tty_buffer_list(&priv->tty_inqueue);

	priv->tty_state = TTY_CLOSED;
	priv->iucv_state = IUCV_DISCONN;

	priv->sndbuf_len = 0;
}

/**
 * tty_outqueue_empty() - Test if the tty outq is empty
 * @priv:	Pointer to struct hvc_iucv_private instance.
 */
static inline int tty_outqueue_empty(struct hvc_iucv_private *priv)
{
	int rc;

	spin_lock_bh(&priv->lock);
	rc = list_empty(&priv->tty_outqueue);
	spin_unlock_bh(&priv->lock);

	return rc;
}

/**
 * flush_sndbuf_sync() - Flush send buffer and wait for completion
 * @priv:	Pointer to struct hvc_iucv_private instance.
 *
 * The routine cancels a pending sndbuf work, calls hvc_iucv_send()
 * to flush any buffered terminal output data and waits for completion.
 */
static void flush_sndbuf_sync(struct hvc_iucv_private *priv)
{
	int sync_wait;

	cancel_delayed_work_sync(&priv->sndbuf_work);

	spin_lock_bh(&priv->lock);
	hvc_iucv_send(priv);		/* force sending buffered data */
	sync_wait = !list_empty(&priv->tty_outqueue); /* anything queued ? */
	spin_unlock_bh(&priv->lock);

	if (sync_wait)
		wait_event_timeout(priv->sndbuf_waitq,
				   tty_outqueue_empty(priv), HZ/10);
}

/**
 * hvc_iucv_hangup() - Sever IUCV path and schedule hvc tty hang up
 * @priv:	Pointer to hvc_iucv_private structure
 *
 * This routine severs an existing IUCV communication path and hangs
 * up the underlying HVC terminal device.
 * The hang-up occurs only if an IUCV communication path is established;
 * otherwise there is no need to hang up the terminal device.
 *
 * The IUCV HVC hang-up is separated into two steps:
 * 1. After the IUCV path has been severed, the iucv_state is set to
 *    IUCV_SEVERED.
 * 2. Later, when the HVC thread calls hvc_iucv_get_chars(), the
 *    IUCV_SEVERED state causes the tty hang-up in the HVC layer.
 *
 * If the tty has not yet been opened, clean up the hvc_iucv_private
 * structure to allow re-connects.
 * If the tty has been opened, let get_chars() return -EPIPE to signal
 * the HVC layer to hang up the tty and, if so, wake up the HVC thread
 * to call get_chars()...
 *
 * Special notes on hanging up a HVC terminal instantiated as console:
 * Hang-up:	1. do_tty_hangup() replaces file ops (= hung_up_tty_fops)
 *		2. do_tty_hangup() calls tty->ops->close() for console_filp
 *			=> no hangup notifier is called by HVC (default)
 *		2. hvc_close() returns because of tty_hung_up_p(filp)
 *			=> no delete notifier is called!
 * Finally, the back-end is not being notified, thus, the tty session is
 * kept active (TTY_OPEN) to be ready for re-connects.
 *
 * Locking:	spin_lock(&priv->lock) w/o disabling bh
 */
static void hvc_iucv_hangup(struct hvc_iucv_private *priv)
{
	struct iucv_path *path;

	path = NULL;
	spin_lock(&priv->lock);
	if (priv->iucv_state == IUCV_CONNECTED) {
		path = priv->path;
		priv->path = NULL;
		priv->iucv_state = IUCV_SEVERED;
		if (priv->tty_state == TTY_CLOSED)
			hvc_iucv_cleanup(priv);
		else
			/* console is special (see above) */
			if (priv->is_console) {
				hvc_iucv_cleanup(priv);
				priv->tty_state = TTY_OPENED;
			} else
				hvc_kick();
	}
	spin_unlock(&priv->lock);

	/* finally sever path (outside of priv->lock due to lock ordering) */
	if (path) {
		iucv_path_sever(path, NULL);
		iucv_path_free(path);
	}
}

/**
 * hvc_iucv_notifier_hangup() - HVC notifier for TTY hangups.
 * @hp:		Pointer to the HVC device (struct hvc_struct)
 * @id:		Additional data (originally passed to hvc_alloc):
 *		the index of an struct hvc_iucv_private instance.
 *
 * This routine notifies the HVC back-end that a tty hangup (carrier loss,
 * virtual or otherwise) has occurred.
 * The z/VM IUCV HVC device driver ignores virtual hangups (vhangup())
 * to keep an existing IUCV communication path established.
 * (Background: vhangup() is called from user space (by getty or login) to
 *		disable writing to the tty by other applications).
 * If the tty has been opened and an established IUCV path has been severed
 * (we caused the tty hangup), the function calls hvc_iucv_cleanup().
 *
 * Locking:	struct hvc_iucv_private->lock
 */
static void hvc_iucv_notifier_hangup(struct hvc_struct *hp, int id)
{
	struct hvc_iucv_private *priv;

	priv = hvc_iucv_get_private(id);
	if (!priv)
		return;

	flush_sndbuf_sync(priv);

	spin_lock_bh(&priv->lock);
	/* NOTE: If the hangup was scheduled by ourself (from the iucv
	 *	 path_servered callback [IUCV_SEVERED]), we have to clean up
	 *	 our structure and to set state to TTY_CLOSED.
	 *	 If the tty was hung up otherwise (e.g. vhangup()), then we
	 *	 ignore this hangup and keep an established IUCV path open...
	 *	 (...the reason is that we are not able to connect back to the
	 *	 client if we disconnect on hang up) */
	priv->tty_state = TTY_CLOSED;

	if (priv->iucv_state == IUCV_SEVERED)
		hvc_iucv_cleanup(priv);
	spin_unlock_bh(&priv->lock);
}

/**
 * hvc_iucv_dtr_rts() - HVC notifier for handling DTR/RTS
 * @hp:		Pointer the HVC device (struct hvc_struct)
 * @raise:	Non-zero to raise or zero to lower DTR/RTS lines
 *
 * This routine notifies the HVC back-end to raise or lower DTR/RTS
 * lines.  Raising DTR/RTS is ignored.  Lowering DTR/RTS indicates to
 * drop the IUCV connection (similar to hang up the modem).
 */
static void hvc_iucv_dtr_rts(struct hvc_struct *hp, int raise)
{
	struct hvc_iucv_private *priv;
	struct iucv_path        *path;

	/* Raising the DTR/RTS is ignored as IUCV connections can be
	 * established at any times.
	 */
	if (raise)
		return;

	priv = hvc_iucv_get_private(hp->vtermno);
	if (!priv)
		return;

	/* Lowering the DTR/RTS lines disconnects an established IUCV
	 * connection.
	 */
	flush_sndbuf_sync(priv);

	spin_lock_bh(&priv->lock);
	path = priv->path;		/* save reference to IUCV path */
	priv->path = NULL;
	priv->iucv_state = IUCV_DISCONN;
	spin_unlock_bh(&priv->lock);

	/* Sever IUCV path outside of priv->lock due to lock ordering of:
	 * priv->lock <--> iucv_table_lock */
	if (path) {
		iucv_path_sever(path, NULL);
		iucv_path_free(path);
	}
}

/**
 * hvc_iucv_notifier_del() - HVC notifier for closing a TTY for the last time.
 * @hp:		Pointer to the HVC device (struct hvc_struct)
 * @id:		Additional data (originally passed to hvc_alloc):
 *		the index of an struct hvc_iucv_private instance.
 *
 * This routine notifies the HVC back-end that the last tty device fd has been
 * closed.  The function cleans up tty resources.  The clean-up of the IUCV
 * connection is done in hvc_iucv_dtr_rts() and depends on the HUPCL termios
 * control setting.
 *
 * Locking:	struct hvc_iucv_private->lock
 */
static void hvc_iucv_notifier_del(struct hvc_struct *hp, int id)
{
	struct hvc_iucv_private *priv;

	priv = hvc_iucv_get_private(id);
	if (!priv)
		return;

	flush_sndbuf_sync(priv);

	spin_lock_bh(&priv->lock);
	destroy_tty_buffer_list(&priv->tty_outqueue);
	destroy_tty_buffer_list(&priv->tty_inqueue);
	priv->tty_state = TTY_CLOSED;
	priv->sndbuf_len = 0;
	spin_unlock_bh(&priv->lock);
}

/**
 * hvc_iucv_filter_connreq() - Filter connection request based on z/VM user ID
 * @ipvmid:	Originating z/VM user ID (right padded with blanks)
 *
 * Returns 0 if the z/VM user ID that is specified with @ipvmid is permitted to
 * connect, otherwise non-zero.
 */
static int hvc_iucv_filter_connreq(u8 ipvmid[8])
{
	const char *wildcard, *filter_entry;
	size_t i, len;

	/* Note: default policy is ACCEPT if no filter is set */
	if (!hvc_iucv_filter_size)
		return 0;

	for (i = 0; i < hvc_iucv_filter_size; i++) {
		filter_entry = hvc_iucv_filter + (8 * i);

		/* If a filter entry contains the filter wildcard character,
		 * reduce the length to match the leading portion of the user
		 * ID only (wildcard match).  Characters following the wildcard
		 * are ignored.
		 */
		wildcard = strnchr(filter_entry, 8, FILTER_WILDCARD_CHAR);
		len = (wildcard) ? wildcard - filter_entry : 8;
		if (0 == memcmp(ipvmid, filter_entry, len))
			return 0;
	}
	return 1;
}

/**
 * hvc_iucv_path_pending() - IUCV handler to process a connection request.
 * @path:	Pending path (struct iucv_path)
 * @ipvmid:	z/VM system identifier of originator
 * @ipuser:	User specified data for this path
 *		(AF_IUCV: port/service name and originator port)
 *
 * The function uses the @ipuser data to determine if the pending path belongs
 * to a terminal managed by this device driver.
 * If the path belongs to this driver, ensure that the terminal is not accessed
 * multiple times (only one connection to a terminal is allowed).
 * If the terminal is not yet connected, the pending path is accepted and is
 * associated to the appropriate struct hvc_iucv_private instance.
 *
 * Returns 0 if @path belongs to a terminal managed by the this device driver;
 * otherwise returns -ENODEV in order to dispatch this path to other handlers.
 *
 * Locking:	struct hvc_iucv_private->lock
 */
static	int hvc_iucv_path_pending(struct iucv_path *path, u8 *ipvmid,
				  u8 *ipuser)
{
	struct hvc_iucv_private *priv, *tmp;
	u8 wildcard[9] = "lnxhvc  ";
	int i, rc, find_unused;
	u8 nuser_data[16];
	u8 vm_user_id[9];

	ASCEBC(wildcard, sizeof(wildcard));
	find_unused = !memcmp(wildcard, ipuser, 8);

	/* First, check if the pending path request is managed by this
	 * IUCV handler:
	 * - find a disconnected device if ipuser contains the wildcard
	 * - find the device that matches the terminal ID in ipuser
	 */
	priv = NULL;
	for (i = 0; i < hvc_iucv_devices; i++) {
		tmp = hvc_iucv_table[i];
		if (!tmp)
			continue;

		if (find_unused) {
			spin_lock(&tmp->lock);
			if (tmp->iucv_state == IUCV_DISCONN)
				priv = tmp;
			spin_unlock(&tmp->lock);

		} else if (!memcmp(tmp->srv_name, ipuser, 8))
				priv = tmp;
		if (priv)
			break;
	}
	if (!priv)
		return -ENODEV;

	/* Enforce that ipvmid is allowed to connect to us */
	read_lock(&hvc_iucv_filter_lock);
	rc = hvc_iucv_filter_connreq(ipvmid);
	read_unlock(&hvc_iucv_filter_lock);
	if (rc) {
		iucv_path_sever(path, ipuser);
		iucv_path_free(path);
		memcpy(vm_user_id, ipvmid, 8);
		vm_user_id[8] = 0;
		pr_info("A connection request from z/VM user ID %s "
			"was refused\n", vm_user_id);
		return 0;
	}

	spin_lock(&priv->lock);

	/* If the terminal is already connected or being severed, then sever
	 * this path to enforce that there is only ONE established communication
	 * path per terminal. */
	if (priv->iucv_state != IUCV_DISCONN) {
		iucv_path_sever(path, ipuser);
		iucv_path_free(path);
		goto out_path_handled;
	}

	/* accept path */
	memcpy(nuser_data, ipuser + 8, 8);  /* remote service (for af_iucv) */
	memcpy(nuser_data + 8, ipuser, 8);  /* local service  (for af_iucv) */
	path->msglim = 0xffff;		    /* IUCV MSGLIMIT */
	path->flags &= ~IUCV_IPRMDATA;	    /* TODO: use IUCV_IPRMDATA */
	rc = iucv_path_accept(path, &hvc_iucv_handler, nuser_data, priv);
	if (rc) {
		iucv_path_sever(path, ipuser);
		iucv_path_free(path);
		goto out_path_handled;
	}
	priv->path = path;
	priv->iucv_state = IUCV_CONNECTED;

	/* store path information */
	memcpy(priv->info_path, ipvmid, 8);
	memcpy(priv->info_path + 8, ipuser + 8, 8);

	/* flush buffered output data... */
	schedule_delayed_work(&priv->sndbuf_work, 5);

out_path_handled:
	spin_unlock(&priv->lock);
	return 0;
}

/**
 * hvc_iucv_path_severed() - IUCV handler to process a path sever.
 * @path:	Pending path (struct iucv_path)
 * @ipuser:	User specified data for this path
 *		(AF_IUCV: port/service name and originator port)
 *
 * This function calls the hvc_iucv_hangup() function for the
 * respective IUCV HVC terminal.
 *
 * Locking:	struct hvc_iucv_private->lock
 */
static void hvc_iucv_path_severed(struct iucv_path *path, u8 *ipuser)
{
	struct hvc_iucv_private *priv = path->private;

	hvc_iucv_hangup(priv);
}

/**
 * hvc_iucv_msg_pending() - IUCV handler to process an incoming IUCV message.
 * @path:	Pending path (struct iucv_path)
 * @msg:	Pointer to the IUCV message
 *
 * The function puts an incoming message on the input queue for later
 * processing (by hvc_iucv_get_chars() / hvc_iucv_write()).
 * If the tty has not yet been opened, the message is rejected.
 *
 * Locking:	struct hvc_iucv_private->lock
 */
static void hvc_iucv_msg_pending(struct iucv_path *path,
				 struct iucv_message *msg)
{
	struct hvc_iucv_private *priv = path->private;
	struct iucv_tty_buffer *rb;

	/* reject messages that exceed max size of iucv_tty_msg->datalen */
	if (msg->length > MSG_SIZE(MSG_MAX_DATALEN)) {
		iucv_message_reject(path, msg);
		return;
	}

	spin_lock(&priv->lock);

	/* reject messages if tty has not yet been opened */
	if (priv->tty_state == TTY_CLOSED) {
		iucv_message_reject(path, msg);
		goto unlock_return;
	}

	/* allocate tty buffer to save iucv msg only */
	rb = alloc_tty_buffer(0, GFP_ATOMIC);
	if (!rb) {
		iucv_message_reject(path, msg);
		goto unlock_return;	/* -ENOMEM */
	}
	rb->msg = *msg;

	list_add_tail(&rb->list, &priv->tty_inqueue);

	hvc_kick();	/* wake up hvc thread */

unlock_return:
	spin_unlock(&priv->lock);
}

/**
 * hvc_iucv_msg_complete() - IUCV handler to process message completion
 * @path:	Pending path (struct iucv_path)
 * @msg:	Pointer to the IUCV message
 *
 * The function is called upon completion of message delivery to remove the
 * message from the outqueue. Additional delivery information can be found
 * msg->audit: rejected messages (0x040000 (IPADRJCT)), and
 *	       purged messages	 (0x010000 (IPADPGNR)).
 *
 * Locking:	struct hvc_iucv_private->lock
 */
static void hvc_iucv_msg_complete(struct iucv_path *path,
				  struct iucv_message *msg)
{
	struct hvc_iucv_private *priv = path->private;
	struct iucv_tty_buffer	*ent, *next;
	LIST_HEAD(list_remove);

	spin_lock(&priv->lock);
	list_for_each_entry_safe(ent, next, &priv->tty_outqueue, list)
		if (ent->msg.id == msg->id) {
			list_move(&ent->list, &list_remove);
			break;
		}
	wake_up(&priv->sndbuf_waitq);
	spin_unlock(&priv->lock);
	destroy_tty_buffer_list(&list_remove);
}

/**
 * hvc_iucv_pm_freeze() - Freeze PM callback
 * @dev:	IUVC HVC terminal device
 *
 * Sever an established IUCV communication path and
 * trigger a hang-up of the underlying HVC terminal.
 */
static int hvc_iucv_pm_freeze(struct device *dev)
{
	struct hvc_iucv_private *priv = dev_get_drvdata(dev);

	local_bh_disable();
	hvc_iucv_hangup(priv);
	local_bh_enable();

	return 0;
}

/**
 * hvc_iucv_pm_restore_thaw() - Thaw and restore PM callback
 * @dev:	IUVC HVC terminal device
 *
 * Wake up the HVC thread to trigger hang-up and respective
 * HVC back-end notifier invocations.
 */
static int hvc_iucv_pm_restore_thaw(struct device *dev)
{
	hvc_kick();
	return 0;
}

static ssize_t hvc_iucv_dev_termid_show(struct device *dev,
					struct device_attribute *attr,
					char *buf)
{
	struct hvc_iucv_private *priv = dev_get_drvdata(dev);
	size_t len;

	len = sizeof(priv->srv_name);
	memcpy(buf, priv->srv_name, len);
	EBCASC(buf, len);
	buf[len++] = '\n';
	return len;
}

static ssize_t hvc_iucv_dev_state_show(struct device *dev,
					struct device_attribute *attr,
					char *buf)
{
	struct hvc_iucv_private *priv = dev_get_drvdata(dev);
	return sprintf(buf, "%u:%u\n", priv->iucv_state, priv->tty_state);
}

static ssize_t hvc_iucv_dev_peer_show(struct device *dev,
				      struct device_attribute *attr,
				      char *buf)
{
	struct hvc_iucv_private *priv = dev_get_drvdata(dev);
	char vmid[9], ipuser[9];

	memset(vmid, 0, sizeof(vmid));
	memset(ipuser, 0, sizeof(ipuser));

	spin_lock_bh(&priv->lock);
	if (priv->iucv_state == IUCV_CONNECTED) {
		memcpy(vmid, priv->info_path, 8);
		memcpy(ipuser, priv->info_path + 8, 8);
	}
	spin_unlock_bh(&priv->lock);
	EBCASC(ipuser, 8);

	return sprintf(buf, "%s:%s\n", vmid, ipuser);
}


/* HVC operations */
static const struct hv_ops hvc_iucv_ops = {
	.get_chars = hvc_iucv_get_chars,
	.put_chars = hvc_iucv_put_chars,
	.notifier_add = hvc_iucv_notifier_add,
	.notifier_del = hvc_iucv_notifier_del,
	.notifier_hangup = hvc_iucv_notifier_hangup,
	.dtr_rts = hvc_iucv_dtr_rts,
};

/* Suspend / resume device operations */
static const struct dev_pm_ops hvc_iucv_pm_ops = {
	.freeze	  = hvc_iucv_pm_freeze,
	.thaw	  = hvc_iucv_pm_restore_thaw,
	.restore  = hvc_iucv_pm_restore_thaw,
};

/* IUCV HVC device driver */
static struct device_driver hvc_iucv_driver = {
	.name = KMSG_COMPONENT,
	.bus  = &iucv_bus,
	.pm   = &hvc_iucv_pm_ops,
};

/* IUCV HVC device attributes */
static DEVICE_ATTR(termid, 0640, hvc_iucv_dev_termid_show, NULL);
static DEVICE_ATTR(state, 0640, hvc_iucv_dev_state_show, NULL);
static DEVICE_ATTR(peer, 0640, hvc_iucv_dev_peer_show, NULL);
static struct attribute *hvc_iucv_dev_attrs[] = {
	&dev_attr_termid.attr,
	&dev_attr_state.attr,
	&dev_attr_peer.attr,
	NULL,
};
static struct attribute_group hvc_iucv_dev_attr_group = {
	.attrs = hvc_iucv_dev_attrs,
};
static const struct attribute_group *hvc_iucv_dev_attr_groups[] = {
	&hvc_iucv_dev_attr_group,
	NULL,
};


/**
 * hvc_iucv_alloc() - Allocates a new struct hvc_iucv_private instance
 * @id:			hvc_iucv_table index
 * @is_console:		Flag if the instance is used as Linux console
 *
 * This function allocates a new hvc_iucv_private structure and stores
 * the instance in hvc_iucv_table at index @id.
 * Returns 0 on success; otherwise non-zero.
 */
static int __init hvc_iucv_alloc(int id, unsigned int is_console)
{
	struct hvc_iucv_private *priv;
	char name[9];
	int rc;

	priv = kzalloc(sizeof(struct hvc_iucv_private), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	spin_lock_init(&priv->lock);
	INIT_LIST_HEAD(&priv->tty_outqueue);
	INIT_LIST_HEAD(&priv->tty_inqueue);
	INIT_DELAYED_WORK(&priv->sndbuf_work, hvc_iucv_sndbuf_work);
	init_waitqueue_head(&priv->sndbuf_waitq);

	priv->sndbuf = (void *) get_zeroed_page(GFP_KERNEL);
	if (!priv->sndbuf) {
		kfree(priv);
		return -ENOMEM;
	}

	/* set console flag */
	priv->is_console = is_console;

	/* allocate hvc device */
	priv->hvc = hvc_alloc(HVC_IUCV_MAGIC + id, /*		  PAGE_SIZE */
			      HVC_IUCV_MAGIC + id, &hvc_iucv_ops, 256);
	if (IS_ERR(priv->hvc)) {
		rc = PTR_ERR(priv->hvc);
		goto out_error_hvc;
	}

	/* notify HVC thread instead of using polling */
	priv->hvc->irq_requested = 1;

	/* setup iucv related information */
	snprintf(name, 9, "lnxhvc%-2d", id);
	memcpy(priv->srv_name, name, 8);
	ASCEBC(priv->srv_name, 8);

	/* create and setup device */
	priv->dev = kzalloc(sizeof(*priv->dev), GFP_KERNEL);
	if (!priv->dev) {
		rc = -ENOMEM;
		goto out_error_dev;
	}
	dev_set_name(priv->dev, "hvc_iucv%d", id);
	dev_set_drvdata(priv->dev, priv);
	priv->dev->bus = &iucv_bus;
	priv->dev->parent = iucv_root;
	priv->dev->driver = &hvc_iucv_driver;
	priv->dev->groups = hvc_iucv_dev_attr_groups;
	priv->dev->release = (void (*)(struct device *)) kfree;
	rc = device_register(priv->dev);
	if (rc) {
		put_device(priv->dev);
		goto out_error_dev;
	}

	hvc_iucv_table[id] = priv;
	return 0;

out_error_dev:
	hvc_remove(priv->hvc);
out_error_hvc:
	free_page((unsigned long) priv->sndbuf);
	kfree(priv);

	return rc;
}

/**
 * hvc_iucv_destroy() - Destroy and free hvc_iucv_private instances
 */
static void __init hvc_iucv_destroy(struct hvc_iucv_private *priv)
{
	hvc_remove(priv->hvc);
	device_unregister(priv->dev);
	free_page((unsigned long) priv->sndbuf);
	kfree(priv);
}

/**
 * hvc_iucv_parse_filter() - Parse filter for a single z/VM user ID
 * @filter:	String containing a comma-separated list of z/VM user IDs
 * @dest:	Location where to store the parsed z/VM user ID
 */
static const char *hvc_iucv_parse_filter(const char *filter, char *dest)
{
	const char *nextdelim, *residual;
	size_t len;

	nextdelim = strchr(filter, ',');
	if (nextdelim) {
		len = nextdelim - filter;
		residual = nextdelim + 1;
	} else {
		len = strlen(filter);
		residual = filter + len;
	}

	if (len == 0)
		return ERR_PTR(-EINVAL);

	/* check for '\n' (if called from sysfs) */
	if (filter[len - 1] == '\n')
		len--;

	/* prohibit filter entries containing the wildcard character only */
	if (len == 1 && *filter == FILTER_WILDCARD_CHAR)
		return ERR_PTR(-EINVAL);

	if (len > 8)
		return ERR_PTR(-EINVAL);

	/* pad with blanks and save upper case version of user ID */
	memset(dest, ' ', 8);
	while (len--)
		dest[len] = toupper(filter[len]);
	return residual;
}

/**
 * hvc_iucv_setup_filter() - Set up z/VM user ID filter
 * @filter:	String consisting of a comma-separated list of z/VM user IDs
 *
 * The function parses the @filter string and creates an array containing
 * the list of z/VM user ID filter entries.
 * Return code 0 means success, -EINVAL if the filter is syntactically
 * incorrect, -ENOMEM if there was not enough memory to allocate the
 * filter list array, or -ENOSPC if too many z/VM user IDs have been specified.
 */
static int hvc_iucv_setup_filter(const char *val)
{
	const char *residual;
	int err;
	size_t size, count;
	void *array, *old_filter;

	count = strlen(val);
	if (count == 0 || (count == 1 && val[0] == '\n')) {
		size  = 0;
		array = NULL;
		goto out_replace_filter;	/* clear filter */
	}

	/* count user IDs in order to allocate sufficient memory */
	size = 1;
	residual = val;
	while ((residual = strchr(residual, ',')) != NULL) {
		residual++;
		size++;
	}

	/* check if the specified list exceeds the filter limit */
	if (size > MAX_VMID_FILTER)
		return -ENOSPC;

	array = kcalloc(size, 8, GFP_KERNEL);
	if (!array)
		return -ENOMEM;

	count = size;
	residual = val;
	while (*residual && count) {
		residual = hvc_iucv_parse_filter(residual,
						 array + ((size - count) * 8));
		if (IS_ERR(residual)) {
			err = PTR_ERR(residual);
			kfree(array);
			goto out_err;
		}
		count--;
	}

out_replace_filter:
	write_lock_bh(&hvc_iucv_filter_lock);
	old_filter = hvc_iucv_filter;
	hvc_iucv_filter_size = size;
	hvc_iucv_filter = array;
	write_unlock_bh(&hvc_iucv_filter_lock);
	kfree(old_filter);

	err = 0;
out_err:
	return err;
}

/**
 * param_set_vmidfilter() - Set z/VM user ID filter parameter
 * @val:	String consisting of a comma-separated list of z/VM user IDs
 * @kp:		Kernel parameter pointing to hvc_iucv_filter array
 *
 * The function sets up the z/VM user ID filter specified as comma-separated
 * list of user IDs in @val.
 * Note: If it is called early in the boot process, @val is stored and
 *	 parsed later in hvc_iucv_init().
 */
static int param_set_vmidfilter(const char *val, const struct kernel_param *kp)
{
	int rc;

	if (!MACHINE_IS_VM || !hvc_iucv_devices)
		return -ENODEV;

	if (!val)
		return -EINVAL;

	rc = 0;
	if (slab_is_available())
		rc = hvc_iucv_setup_filter(val);
	else
		hvc_iucv_filter_string = val;	/* defer... */
	return rc;
}

/**
 * param_get_vmidfilter() - Get z/VM user ID filter
 * @buffer:	Buffer to store z/VM user ID filter,
 *		(buffer size assumption PAGE_SIZE)
 * @kp:		Kernel parameter pointing to the hvc_iucv_filter array
 *
 * The function stores the filter as a comma-separated list of z/VM user IDs
 * in @buffer. Typically, sysfs routines call this function for attr show.
 */
static int param_get_vmidfilter(char *buffer, const struct kernel_param *kp)
{
	int rc;
	size_t index, len;
	void *start, *end;

	if (!MACHINE_IS_VM || !hvc_iucv_devices)
		return -ENODEV;

	rc = 0;
	read_lock_bh(&hvc_iucv_filter_lock);
	for (index = 0; index < hvc_iucv_filter_size; index++) {
		start = hvc_iucv_filter + (8 * index);
		end   = memchr(start, ' ', 8);
		len   = (end) ? end - start : 8;
		memcpy(buffer + rc, start, len);
		rc += len;
		buffer[rc++] = ',';
	}
	read_unlock_bh(&hvc_iucv_filter_lock);
	if (rc)
		buffer[--rc] = '\0';	/* replace last comma and update rc */
	return rc;
}

#define param_check_vmidfilter(name, p) __param_check(name, p, void)

static const struct kernel_param_ops param_ops_vmidfilter = {
	.set = param_set_vmidfilter,
	.get = param_get_vmidfilter,
};

/**
 * hvc_iucv_init() - z/VM IUCV HVC device driver initialization
 */
static int __init hvc_iucv_init(void)
{
	int rc;
	unsigned int i;

	if (!hvc_iucv_devices)
		return -ENODEV;

	if (!MACHINE_IS_VM) {
		pr_notice("The z/VM IUCV HVC device driver cannot "
			   "be used without z/VM\n");
		rc = -ENODEV;
		goto out_error;
	}

	if (hvc_iucv_devices > MAX_HVC_IUCV_LINES) {
		pr_err("%lu is not a valid value for the hvc_iucv= "
			"kernel parameter\n", hvc_iucv_devices);
		rc = -EINVAL;
		goto out_error;
	}

	/* register IUCV HVC device driver */
	rc = driver_register(&hvc_iucv_driver);
	if (rc)
		goto out_error;

	/* parse hvc_iucv_allow string and create z/VM user ID filter list */
	if (hvc_iucv_filter_string) {
		rc = hvc_iucv_setup_filter(hvc_iucv_filter_string);
		switch (rc) {
		case 0:
			break;
		case -ENOMEM:
			pr_err("Allocating memory failed with "
				"reason code=%d\n", 3);
			goto out_error;
		case -EINVAL:
			pr_err("hvc_iucv_allow= does not specify a valid "
				"z/VM user ID list\n");
			goto out_error;
		case -ENOSPC:
			pr_err("hvc_iucv_allow= specifies too many "
				"z/VM user IDs\n");
			goto out_error;
		default:
			goto out_error;
		}
	}

	hvc_iucv_buffer_cache = kmem_cache_create(KMSG_COMPONENT,
					   sizeof(struct iucv_tty_buffer),
					   0, 0, NULL);
	if (!hvc_iucv_buffer_cache) {
		pr_err("Allocating memory failed with reason code=%d\n", 1);
		rc = -ENOMEM;
		goto out_error;
	}

	hvc_iucv_mempool = mempool_create_slab_pool(MEMPOOL_MIN_NR,
						    hvc_iucv_buffer_cache);
	if (!hvc_iucv_mempool) {
		pr_err("Allocating memory failed with reason code=%d\n", 2);
		kmem_cache_destroy(hvc_iucv_buffer_cache);
		rc = -ENOMEM;
		goto out_error;
	}

	/* register the first terminal device as console
	 * (must be done before allocating hvc terminal devices) */
	rc = hvc_instantiate(HVC_IUCV_MAGIC, IUCV_HVC_CON_IDX, &hvc_iucv_ops);
	if (rc) {
		pr_err("Registering HVC terminal device as "
		       "Linux console failed\n");
		goto out_error_memory;
	}

	/* allocate hvc_iucv_private structs */
	for (i = 0; i < hvc_iucv_devices; i++) {
		rc = hvc_iucv_alloc(i, (i == IUCV_HVC_CON_IDX) ? 1 : 0);
		if (rc) {
			pr_err("Creating a new HVC terminal device "
				"failed with error code=%d\n", rc);
			goto out_error_hvc;
		}
	}

	/* register IUCV callback handler */
	rc = iucv_register(&hvc_iucv_handler, 0);
	if (rc) {
		pr_err("Registering IUCV handlers failed with error code=%d\n",
			rc);
		goto out_error_hvc;
	}

	return 0;

out_error_hvc:
	for (i = 0; i < hvc_iucv_devices; i++)
		if (hvc_iucv_table[i])
			hvc_iucv_destroy(hvc_iucv_table[i]);
out_error_memory:
	mempool_destroy(hvc_iucv_mempool);
	kmem_cache_destroy(hvc_iucv_buffer_cache);
out_error:
	kfree(hvc_iucv_filter);
	hvc_iucv_devices = 0; /* ensure that we do not provide any device */
	return rc;
}

/**
 * hvc_iucv_config() - Parsing of hvc_iucv=  kernel command line parameter
 * @val:	Parameter value (numeric)
 */
static	int __init hvc_iucv_config(char *val)
{
	 return kstrtoul(val, 10, &hvc_iucv_devices);
}


device_initcall(hvc_iucv_init);
__setup("hvc_iucv=", hvc_iucv_config);
core_param(hvc_iucv_allow, hvc_iucv_filter, vmidfilter, 0640);