summaryrefslogtreecommitdiff
path: root/include/linux/uwb.h
blob: 0cd35937e1203c3f146dd3f86ce6f8c7628e5a27 (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
/*
 * Ultra Wide Band
 * UWB API
 *
 * Copyright (C) 2005-2006 Intel Corporation
 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version
 * 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 *
 * FIXME: doc: overview of the API, different parts and pointers
 */

#ifndef __LINUX__UWB_H__
#define __LINUX__UWB_H__

#include <linux/limits.h>
#include <linux/device.h>
#include <linux/mutex.h>
#include <linux/timer.h>
#include <linux/workqueue.h>
#include <linux/uwb/spec.h>

struct uwb_dev;
struct uwb_beca_e;
struct uwb_rc;
struct uwb_rsv;
struct uwb_dbg;

/**
 * struct uwb_dev - a UWB Device
 * @rc: UWB Radio Controller that discovered the device (kind of its
 *     parent).
 * @bce: a beacon cache entry for this device; or NULL if the device
 *     is a local radio controller.
 * @mac_addr: the EUI-48 address of this device.
 * @dev_addr: the current DevAddr used by this device.
 * @beacon_slot: the slot number the beacon is using.
 * @streams: bitmap of streams allocated to reservations targeted at
 *     this device.  For an RC, this is the streams allocated for
 *     reservations targeted at DevAddrs.
 *
 * A UWB device may either by a neighbor or part of a local radio
 * controller.
 */
struct uwb_dev {
	struct mutex mutex;
	struct list_head list_node;
	struct device dev;
	struct uwb_rc *rc;		/* radio controller */
	struct uwb_beca_e *bce;		/* Beacon Cache Entry */

	struct uwb_mac_addr mac_addr;
	struct uwb_dev_addr dev_addr;
	int beacon_slot;
	DECLARE_BITMAP(streams, UWB_NUM_STREAMS);
};
#define to_uwb_dev(d) container_of(d, struct uwb_dev, dev)

/**
 * UWB HWA/WHCI Radio Control {Command|Event} Block context IDs
 *
 * RC[CE]Bs have a 'context ID' field that matches the command with
 * the event received to confirm it.
 *
 * Maximum number of context IDs
 */
enum { UWB_RC_CTX_MAX = 256 };


/** Notification chain head for UWB generated events to listeners */
struct uwb_notifs_chain {
	struct list_head list;
	struct mutex mutex;
};

/**
 * struct uwb_mas_bm - a bitmap of all MAS in a superframe
 * @bm: a bitmap of length #UWB_NUM_MAS
 */
struct uwb_mas_bm {
	DECLARE_BITMAP(bm, UWB_NUM_MAS);
};

/**
 * uwb_rsv_state - UWB Reservation state.
 *
 * NONE - reservation is not active (no DRP IE being transmitted).
 *
 * Owner reservation states:
 *
 * INITIATED - owner has sent an initial DRP request.
 * PENDING - target responded with pending Reason Code.
 * MODIFIED - reservation manager is modifying an established
 * reservation with a different MAS allocation.
 * ESTABLISHED - the reservation has been successfully negotiated.
 *
 * Target reservation states:
 *
 * DENIED - request is denied.
 * ACCEPTED - request is accepted.
 * PENDING - PAL has yet to make a decision to whether to accept or
 * deny.
 *
 * FIXME: further target states TBD.
 */
enum uwb_rsv_state {
	UWB_RSV_STATE_NONE,
	UWB_RSV_STATE_O_INITIATED,
	UWB_RSV_STATE_O_PENDING,
	UWB_RSV_STATE_O_MODIFIED,
	UWB_RSV_STATE_O_ESTABLISHED,
	UWB_RSV_STATE_T_ACCEPTED,
	UWB_RSV_STATE_T_DENIED,
	UWB_RSV_STATE_T_PENDING,

	UWB_RSV_STATE_LAST,
};

enum uwb_rsv_target_type {
	UWB_RSV_TARGET_DEV,
	UWB_RSV_TARGET_DEVADDR,
};

/**
 * struct uwb_rsv_target - the target of a reservation.
 *
 * Reservations unicast and targeted at a single device
 * (UWB_RSV_TARGET_DEV); or (e.g., in the case of WUSB) targeted at a
 * specific (private) DevAddr (UWB_RSV_TARGET_DEVADDR).
 */
struct uwb_rsv_target {
	enum uwb_rsv_target_type type;
	union {
		struct uwb_dev *dev;
		struct uwb_dev_addr devaddr;
	};
};

/*
 * Number of streams reserved for reservations targeted at DevAddrs.
 */
#define UWB_NUM_GLOBAL_STREAMS 1

typedef void (*uwb_rsv_cb_f)(struct uwb_rsv *rsv);

/**
 * struct uwb_rsv - a DRP reservation
 *
 * Data structure management:
 *
 * @rc:             the radio controller this reservation is for
 *                  (as target or owner)
 * @rc_node:        a list node for the RC
 * @pal_node:       a list node for the PAL
 *
 * Owner and target parameters:
 *
 * @owner:          the UWB device owning this reservation
 * @target:         the target UWB device
 * @type:           reservation type
 *
 * Owner parameters:
 *
 * @max_mas:        maxiumum number of MAS
 * @min_mas:        minimum number of MAS
 * @sparsity:       owner selected sparsity
 * @is_multicast:   true iff multicast
 *
 * @callback:       callback function when the reservation completes
 * @pal_priv:       private data for the PAL making the reservation
 *
 * Reservation status:
 *
 * @status:         negotiation status
 * @stream:         stream index allocated for this reservation
 * @mas:            reserved MAS
 * @drp_ie:         the DRP IE
 * @ie_valid:       true iff the DRP IE matches the reservation parameters
 *
 * DRP reservations are uniquely identified by the owner, target and
 * stream index.  However, when using a DevAddr as a target (e.g., for
 * a WUSB cluster reservation) the responses may be received from
 * devices with different DevAddrs.  In this case, reservations are
 * uniquely identified by just the stream index.  A number of stream
 * indexes (UWB_NUM_GLOBAL_STREAMS) are reserved for this.
 */
struct uwb_rsv {
	struct uwb_rc *rc;
	struct list_head rc_node;
	struct list_head pal_node;

	struct uwb_dev *owner;
	struct uwb_rsv_target target;
	enum uwb_drp_type type;
	int max_mas;
	int min_mas;
	int sparsity;
	bool is_multicast;

	uwb_rsv_cb_f callback;
	void *pal_priv;

	enum uwb_rsv_state state;
	u8 stream;
	struct uwb_mas_bm mas;
	struct uwb_ie_drp *drp_ie;
	bool ie_valid;
	struct timer_list timer;
	bool expired;
};

static const
struct uwb_mas_bm uwb_mas_bm_zero = { .bm = { 0 } };

static inline void uwb_mas_bm_copy_le(void *dst, const struct uwb_mas_bm *mas)
{
	bitmap_copy_le(dst, mas->bm, UWB_NUM_MAS);
}

/**
 * struct uwb_drp_avail - a radio controller's view of MAS usage
 * @global:   MAS unused by neighbors (excluding reservations targetted
 *            or owned by the local radio controller) or the beaon period
 * @local:    MAS unused by local established reservations
 * @pending:  MAS unused by local pending reservations
 * @ie:       DRP Availability IE to be included in the beacon
 * @ie_valid: true iff @ie is valid and does not need to regenerated from
 *            @global and @local
 *
 * Each radio controller maintains a view of MAS usage or
 * availability. MAS available for a new reservation are determined
 * from the intersection of @global, @local, and @pending.
 *
 * The radio controller must transmit a DRP Availability IE that's the
 * intersection of @global and @local.
 *
 * A set bit indicates the MAS is unused and available.
 *
 * rc->rsvs_mutex should be held before accessing this data structure.
 *
 * [ECMA-368] section 17.4.3.
 */
struct uwb_drp_avail {
	DECLARE_BITMAP(global, UWB_NUM_MAS);
	DECLARE_BITMAP(local, UWB_NUM_MAS);
	DECLARE_BITMAP(pending, UWB_NUM_MAS);
	struct uwb_ie_drp_avail ie;
	bool ie_valid;
};


const char *uwb_rsv_state_str(enum uwb_rsv_state state);
const char *uwb_rsv_type_str(enum uwb_drp_type type);

struct uwb_rsv *uwb_rsv_create(struct uwb_rc *rc, uwb_rsv_cb_f cb,
			       void *pal_priv);
void uwb_rsv_destroy(struct uwb_rsv *rsv);

int uwb_rsv_establish(struct uwb_rsv *rsv);
int uwb_rsv_modify(struct uwb_rsv *rsv,
		   int max_mas, int min_mas, int sparsity);
void uwb_rsv_terminate(struct uwb_rsv *rsv);

void uwb_rsv_accept(struct uwb_rsv *rsv, uwb_rsv_cb_f cb, void *pal_priv);

/**
 * Radio Control Interface instance
 *
 *
 * Life cycle rules: those of the UWB Device.
 *
 * @index:    an index number for this radio controller, as used in the
 *            device name.
 * @version:  version of protocol supported by this device
 * @priv:     Backend implementation; rw with uwb_dev.dev.sem taken.
 * @cmd:      Backend implementation to execute commands; rw and call
 *            only  with uwb_dev.dev.sem taken.
 * @reset:    Hardware reset of radio controller and any PAL controllers.
 * @filter:   Backend implementation to manipulate data to and from device
 *            to be compliant to specification assumed by driver (WHCI
 *            0.95).
 *
 *            uwb_dev.dev.mutex is used to execute commands and update
 *            the corresponding structures; can't use a spinlock
 *            because rc->cmd() can sleep.
 * @ies:         This is a dynamically allocated array cacheing the
 *               IEs (settable by the host) that the beacon of this
 *               radio controller is currently sending.
 *
 *               In reality, we store here the full command we set to
 *               the radio controller (which is basically a command
 *               prefix followed by all the IEs the beacon currently
 *               contains). This way we don't have to realloc and
 *               memcpy when setting it.
 *
 *               We set this up in uwb_rc_ie_setup(), where we alloc
 *               this struct, call get_ie() [so we know which IEs are
 *               currently being sent, if any].
 *
 * @ies_capacity:Amount of space (in bytes) allocated in @ies. The
 *               amount used is given by sizeof(*ies) plus ies->wIELength
 *               (which is a little endian quantity all the time).
 * @ies_mutex:   protect the IE cache
 * @dbg:         information for the debug interface
 */
struct uwb_rc {
	struct uwb_dev uwb_dev;
	int index;
	u16 version;

	struct module *owner;
	void *priv;
	int (*start)(struct uwb_rc *rc);
	void (*stop)(struct uwb_rc *rc);
	int (*cmd)(struct uwb_rc *, const struct uwb_rccb *, size_t);
	int (*reset)(struct uwb_rc *rc);
	int (*filter_cmd)(struct uwb_rc *, struct uwb_rccb **, size_t *);
	int (*filter_event)(struct uwb_rc *, struct uwb_rceb **, const size_t,
			    size_t *, size_t *);

	spinlock_t neh_lock;		/* protects neh_* and ctx_* */
	struct list_head neh_list;	/* Open NE handles */
	unsigned long ctx_bm[UWB_RC_CTX_MAX / 8 / sizeof(unsigned long)];
	u8 ctx_roll;

	int beaconing;			/* Beaconing state [channel number] */
	int scanning;
	enum uwb_scan_type scan_type:3;
	unsigned ready:1;
	struct uwb_notifs_chain notifs_chain;

	struct uwb_drp_avail drp_avail;
	struct list_head reservations;
	struct mutex rsvs_mutex;
	struct workqueue_struct *rsv_workq;
	struct work_struct rsv_update_work;

	struct mutex ies_mutex;
	struct uwb_rc_cmd_set_ie *ies;
	size_t ies_capacity;

	spinlock_t pal_lock;
	struct list_head pals;

	struct uwb_dbg *dbg;
};


/**
 * struct uwb_pal - a UWB PAL
 * @new_rsv: called when a peer requests a reservation (may be NULL if
 *           the PAL cannot accept reservation requests).
 *
 * A Protocol Adaptation Layer (PAL) is a user of the WiMedia UWB
 * radio platform (e.g., WUSB, WLP or Bluetooth UWB AMP).
 *
 * The PALs using a radio controller must register themselves to
 * permit the UWB stack to coordinate usage of the radio between the
 * various PALs or to allow PALs to response to certain requests from
 * peers.
 *
 * A struct uwb_pal should be embedded in a containing structure
 * belonging to the PAL and initialized with uwb_pal_init()).  Fields
 * should be set appropriately by the PAL before registering the PAL
 * with uwb_pal_register().
 */
struct uwb_pal {
	struct list_head node;

	void (*new_rsv)(struct uwb_rsv *rsv);
};

void uwb_pal_init(struct uwb_pal *pal);
int uwb_pal_register(struct uwb_rc *rc, struct uwb_pal *pal);
void uwb_pal_unregister(struct uwb_rc *rc, struct uwb_pal *pal);

/*
 * General public API
 *
 * This API can be used by UWB device drivers or by those implementing
 * UWB Radio Controllers
 */
struct uwb_dev *uwb_dev_get_by_devaddr(struct uwb_rc *rc,
				       const struct uwb_dev_addr *devaddr);
struct uwb_dev *uwb_dev_get_by_rc(struct uwb_dev *, struct uwb_rc *);
static inline void uwb_dev_get(struct uwb_dev *uwb_dev)
{
	get_device(&uwb_dev->dev);
}
static inline void uwb_dev_put(struct uwb_dev *uwb_dev)
{
	put_device(&uwb_dev->dev);
}
struct uwb_dev *uwb_dev_try_get(struct uwb_rc *rc, struct uwb_dev *uwb_dev);

/**
 * Callback function for 'uwb_{dev,rc}_foreach()'.
 *
 * @dev:  Linux device instance
 *        'uwb_dev = container_of(dev, struct uwb_dev, dev)'
 * @priv: Data passed by the caller to 'uwb_{dev,rc}_foreach()'.
 *
 * @returns: 0 to continue the iterations, any other val to stop
 *           iterating and return the value to the caller of
 *           _foreach().
 */
typedef int (*uwb_dev_for_each_f)(struct device *dev, void *priv);
int uwb_dev_for_each(struct uwb_rc *rc, uwb_dev_for_each_f func, void *priv);

struct uwb_rc *uwb_rc_alloc(void);
struct uwb_rc *uwb_rc_get_by_dev(const struct uwb_dev_addr *);
struct uwb_rc *uwb_rc_get_by_grandpa(const struct device *);
void uwb_rc_put(struct uwb_rc *rc);

typedef void (*uwb_rc_cmd_cb_f)(struct uwb_rc *rc, void *arg,
                                struct uwb_rceb *reply, ssize_t reply_size);

int uwb_rc_cmd_async(struct uwb_rc *rc, const char *cmd_name,
		     struct uwb_rccb *cmd, size_t cmd_size,
		     u8 expected_type, u16 expected_event,
		     uwb_rc_cmd_cb_f cb, void *arg);
ssize_t uwb_rc_cmd(struct uwb_rc *rc, const char *cmd_name,
		   struct uwb_rccb *cmd, size_t cmd_size,
		   struct uwb_rceb *reply, size_t reply_size);
ssize_t uwb_rc_vcmd(struct uwb_rc *rc, const char *cmd_name,
		    struct uwb_rccb *cmd, size_t cmd_size,
		    u8 expected_type, u16 expected_event,
		    struct uwb_rceb **preply);
ssize_t uwb_rc_get_ie(struct uwb_rc *, struct uwb_rc_evt_get_ie **);
int uwb_bg_joined(struct uwb_rc *rc);

size_t __uwb_addr_print(char *, size_t, const unsigned char *, int);

int uwb_rc_dev_addr_set(struct uwb_rc *, const struct uwb_dev_addr *);
int uwb_rc_dev_addr_get(struct uwb_rc *, struct uwb_dev_addr *);
int uwb_rc_mac_addr_set(struct uwb_rc *, const struct uwb_mac_addr *);
int uwb_rc_mac_addr_get(struct uwb_rc *, struct uwb_mac_addr *);
int __uwb_mac_addr_assigned_check(struct device *, void *);
int __uwb_dev_addr_assigned_check(struct device *, void *);

/* Print in @buf a pretty repr of @addr */
static inline size_t uwb_dev_addr_print(char *buf, size_t buf_size,
					const struct uwb_dev_addr *addr)
{
	return __uwb_addr_print(buf, buf_size, addr->data, 0);
}

/* Print in @buf a pretty repr of @addr */
static inline size_t uwb_mac_addr_print(char *buf, size_t buf_size,
					const struct uwb_mac_addr *addr)
{
	return __uwb_addr_print(buf, buf_size, addr->data, 1);
}

/* @returns 0 if device addresses @addr2 and @addr1 are equal */
static inline int uwb_dev_addr_cmp(const struct uwb_dev_addr *addr1,
				   const struct uwb_dev_addr *addr2)
{
	return memcmp(addr1, addr2, sizeof(*addr1));
}

/* @returns 0 if MAC addresses @addr2 and @addr1 are equal */
static inline int uwb_mac_addr_cmp(const struct uwb_mac_addr *addr1,
				   const struct uwb_mac_addr *addr2)
{
	return memcmp(addr1, addr2, sizeof(*addr1));
}

/* @returns !0 if a MAC @addr is a broadcast address */
static inline int uwb_mac_addr_bcast(const struct uwb_mac_addr *addr)
{
	struct uwb_mac_addr bcast = {
		.data = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff }
	};
	return !uwb_mac_addr_cmp(addr, &bcast);
}

/* @returns !0 if a MAC @addr is all zeroes*/
static inline int uwb_mac_addr_unset(const struct uwb_mac_addr *addr)
{
	struct uwb_mac_addr unset = {
		.data = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 }
	};
	return !uwb_mac_addr_cmp(addr, &unset);
}

/* @returns !0 if the address is in use. */
static inline unsigned __uwb_dev_addr_assigned(struct uwb_rc *rc,
					       struct uwb_dev_addr *addr)
{
	return uwb_dev_for_each(rc, __uwb_dev_addr_assigned_check, addr);
}

/*
 * UWB Radio Controller API
 *
 * This API is used (in addition to the general API) to implement UWB
 * Radio Controllers.
 */
void uwb_rc_init(struct uwb_rc *);
int uwb_rc_add(struct uwb_rc *, struct device *dev, void *rc_priv);
void uwb_rc_rm(struct uwb_rc *);
void uwb_rc_neh_grok(struct uwb_rc *, void *, size_t);
void uwb_rc_neh_error(struct uwb_rc *, int);
void uwb_rc_reset_all(struct uwb_rc *rc);

/**
 * uwb_rsv_is_owner - is the owner of this reservation the RC?
 * @rsv: the reservation
 */
static inline bool uwb_rsv_is_owner(struct uwb_rsv *rsv)
{
	return rsv->owner == &rsv->rc->uwb_dev;
}

/**
 * Events generated by UWB that can be passed to any listeners
 *
 * Higher layers can register callback functions with the radio
 * controller using uwb_notifs_register(). The radio controller
 * maintains a list of all registered handlers and will notify all
 * nodes when an event occurs.
 */
enum uwb_notifs {
	UWB_NOTIF_BG_JOIN = 0,	/* radio controller joined a beacon group */
	UWB_NOTIF_BG_LEAVE = 1,	/* radio controller left a beacon group */
	UWB_NOTIF_ONAIR,
	UWB_NOTIF_OFFAIR,
};

/* Callback function registered with UWB */
struct uwb_notifs_handler {
	struct list_head list_node;
	void (*cb)(void *, struct uwb_dev *, enum uwb_notifs);
	void *data;
};

int uwb_notifs_register(struct uwb_rc *, struct uwb_notifs_handler *);
int uwb_notifs_deregister(struct uwb_rc *, struct uwb_notifs_handler *);


/**
 * UWB radio controller Event Size Entry (for creating entry tables)
 *
 * WUSB and WHCI define events and notifications, and they might have
 * fixed or variable size.
 *
 * Each event/notification has a size which is not necessarily known
 * in advance based on the event code. As well, vendor specific
 * events/notifications will have a size impossible to determine
 * unless we know about the device's specific details.
 *
 * It was way too smart of the spec writers not to think that it would
 * be impossible for a generic driver to skip over vendor specific
 * events/notifications if there are no LENGTH fields in the HEADER of
 * each message...the transaction size cannot be counted on as the
 * spec does not forbid to pack more than one event in a single
 * transaction.
 *
 * Thus, we guess sizes with tables (or for events, when you know the
 * size ahead of time you can use uwb_rc_neh_extra_size*()). We
 * register tables with the known events and their sizes, and then we
 * traverse those tables. For those with variable length, we provide a
 * way to lookup the size inside the event/notification's
 * payload. This allows device-specific event size tables to be
 * registered.
 *
 * @size:   Size of the payload
 *
 * @offset: if != 0, at offset @offset-1 starts a field with a length
 *          that has to be added to @size. The format of the field is
 *          given by @type.
 *
 * @type:   Type and length of the offset field. Most common is LE 16
 *          bits (that's why that is zero); others are there mostly to
 *          cover for bugs and weirdos.
 */
struct uwb_est_entry {
	size_t size;
	unsigned offset;
	enum { UWB_EST_16 = 0, UWB_EST_8 = 1 } type;
};

int uwb_est_register(u8 type, u8 code_high, u16 vendor, u16 product,
		     const struct uwb_est_entry *, size_t entries);
int uwb_est_unregister(u8 type, u8 code_high, u16 vendor, u16 product,
		       const struct uwb_est_entry *, size_t entries);
ssize_t uwb_est_find_size(struct uwb_rc *rc, const struct uwb_rceb *rceb,
			  size_t len);

/* -- Misc */

enum {
	EDC_MAX_ERRORS = 10,
	EDC_ERROR_TIMEFRAME = HZ,
};

/* error density counter */
struct edc {
	unsigned long timestart;
	u16 errorcount;
};

static inline
void edc_init(struct edc *edc)
{
	edc->timestart = jiffies;
}

/* Called when an error occured.
 * This is way to determine if the number of acceptable errors per time
 * period has been exceeded. It is not accurate as there are cases in which
 * this scheme will not work, for example if there are periodic occurences
 * of errors that straddle updates to the start time. This scheme is
 * sufficient for our usage.
 *
 * @returns 1 if maximum acceptable errors per timeframe has been exceeded.
 */
static inline int edc_inc(struct edc *err_hist, u16 max_err, u16 timeframe)
{
	unsigned long now;

	now = jiffies;
	if (now - err_hist->timestart > timeframe) {
		err_hist->errorcount = 1;
		err_hist->timestart = now;
	} else if (++err_hist->errorcount > max_err) {
			err_hist->errorcount = 0;
			err_hist->timestart = now;
			return 1;
	}
	return 0;
}


/* Information Element handling */

/* For representing the state of writing to a buffer when iterating */
struct uwb_buf_ctx {
	char *buf;
	size_t bytes, size;
};

typedef int (*uwb_ie_f)(struct uwb_dev *, const struct uwb_ie_hdr *,
			size_t, void *);
struct uwb_ie_hdr *uwb_ie_next(void **ptr, size_t *len);
ssize_t uwb_ie_for_each(struct uwb_dev *uwb_dev, uwb_ie_f fn, void *data,
			const void *buf, size_t size);
int uwb_ie_dump_hex(struct uwb_dev *, const struct uwb_ie_hdr *,
		    size_t, void *);
int uwb_rc_set_ie(struct uwb_rc *, struct uwb_rc_cmd_set_ie *);
struct uwb_ie_hdr *uwb_ie_next(void **ptr, size_t *len);


/*
 * Transmission statistics
 *
 * UWB uses LQI and RSSI (one byte values) for reporting radio signal
 * strength and line quality indication. We do quick and dirty
 * averages of those. They are signed values, btw.
 *
 * For 8 bit quantities, we keep the min, the max, an accumulator
 * (@sigma) and a # of samples. When @samples gets to 255, we compute
 * the average (@sigma / @samples), place it in @sigma and reset
 * @samples to 1 (so we use it as the first sample).
 *
 * Now, statistically speaking, probably I am kicking the kidneys of
 * some books I have in my shelves collecting dust, but I just want to
 * get an approx, not the Nobel.
 *
 * LOCKING: there is no locking per se, but we try to keep a lockless
 * schema. Only _add_samples() modifies the values--as long as you
 * have other locking on top that makes sure that no two calls of
 * _add_sample() happen at the same time, then we are fine. Now, for
 * resetting the values we just set @samples to 0 and that makes the
 * next _add_sample() to start with defaults. Reading the values in
 * _show() currently can race, so you need to make sure the calls are
 * under the same lock that protects calls to _add_sample(). FIXME:
 * currently unlocked (It is not ultraprecise but does the trick. Bite
 * me).
 */
struct stats {
	s8 min, max;
	s16 sigma;
	atomic_t samples;
};

static inline
void stats_init(struct stats *stats)
{
	atomic_set(&stats->samples, 0);
	wmb();
}

static inline
void stats_add_sample(struct stats *stats, s8 sample)
{
	s8 min, max;
	s16 sigma;
	unsigned samples = atomic_read(&stats->samples);
	if (samples == 0) {	/* it was zero before, so we initialize */
		min = 127;
		max = -128;
		sigma = 0;
	} else {
		min = stats->min;
		max = stats->max;
		sigma = stats->sigma;
	}

	if (sample < min)	/* compute new values */
		min = sample;
	else if (sample > max)
		max = sample;
	sigma += sample;

	stats->min = min;	/* commit */
	stats->max = max;
	stats->sigma = sigma;
	if (atomic_add_return(1, &stats->samples) > 255) {
		/* wrapped around! reset */
		stats->sigma = sigma / 256;
		atomic_set(&stats->samples, 1);
	}
}

static inline ssize_t stats_show(struct stats *stats, char *buf)
{
	int min, max, avg;
	int samples = atomic_read(&stats->samples);
	if (samples == 0)
		min = max = avg = 0;
	else {
		min = stats->min;
		max = stats->max;
		avg = stats->sigma / samples;
	}
	return scnprintf(buf, PAGE_SIZE, "%d %d %d\n", min, max, avg);
}

static inline ssize_t stats_store(struct stats *stats, const char *buf,
				  size_t size)
{
	stats_init(stats);
	return size;
}

#endif /* #ifndef __LINUX__UWB_H__ */