summaryrefslogtreecommitdiffstats
path: root/drivers/uwb/neh.c
blob: a269937be1b8230898f991eb5f430e3f79ac9824 (plain) (blame)
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
/*
 * WUSB Wire Adapter: Radio Control Interface (WUSB[8])
 * Notification and Event Handling
 *
 * 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.
 *
 *
 * The RC interface of the Host Wire Adapter (USB dongle) or WHCI PCI
 * card delivers a stream of notifications and events to the
 * notification end event endpoint or area. This code takes care of
 * getting a buffer with that data, breaking it up in separate
 * notifications and events and then deliver those.
 *
 * Events are answers to commands and they carry a context ID that
 * associates them to the command. Notifications are that,
 * notifications, they come out of the blue and have a context ID of
 * zero. Think of the context ID kind of like a handler. The
 * uwb_rc_neh_* code deals with managing context IDs.
 *
 * This is why you require a handle to operate on a UWB host. When you
 * open a handle a context ID is assigned to you.
 *
 * So, as it is done is:
 *
 * 1. Add an event handler [uwb_rc_neh_add()] (assigns a ctx id)
 * 2. Issue command [rc->cmd(rc, ...)]
 * 3. Arm the timeout timer [uwb_rc_neh_arm()]
 * 4, Release the reference to the neh [uwb_rc_neh_put()]
 * 5. Wait for the callback
 * 6. Command result (RCEB) is passed to the callback
 *
 * If (2) fails, you should remove the handle [uwb_rc_neh_rm()]
 * instead of arming the timer.
 *
 * Handles are for using in *serialized* code, single thread.
 *
 * When the notification/event comes, the IRQ handler/endpoint
 * callback passes the data read to uwb_rc_neh_grok() which will break
 * it up in a discrete series of events, look up who is listening for
 * them and execute the pertinent callbacks.
 *
 * If the reader detects an error while reading the data stream, call
 * uwb_rc_neh_error().
 *
 * CONSTRAINTS/ASSUMPTIONS:
 *
 * - Most notifications/events are small (less thank .5k), copying
 *   around is ok.
 *
 * - Notifications/events are ALWAYS smaller than PAGE_SIZE
 *
 * - Notifications/events always come in a single piece (ie: a buffer
 *   will always contain entire notifications/events).
 *
 * - we cannot know in advance how long each event is (because they
 *   lack a length field in their header--smart move by the standards
 *   body, btw). So we need a facility to get the event size given the
 *   header. This is what the EST code does (notif/Event Size
 *   Tables), check nest.c--as well, you can associate the size to
 *   the handle [w/ neh->extra_size()].
 *
 * - Most notifications/events are fixed size; only a few are variable
 *   size (NEST takes care of that).
 *
 * - Listeners of events expect them, so they usually provide a
 *   buffer, as they know the size. Listeners to notifications don't,
 *   so we allocate their buffers dynamically.
 */
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/export.h>

#include "uwb-internal.h"

/*
 * UWB Radio Controller Notification/Event Handle
 *
 * Represents an entity waiting for an event coming from the UWB Radio
 * Controller with a given context id (context) and type (evt_type and
 * evt). On reception of the notification/event, the callback (cb) is
 * called with the event.
 *
 * If the timer expires before the event is received, the callback is
 * called with -ETIMEDOUT as the event size.
 */
struct uwb_rc_neh {
	struct kref kref;

	struct uwb_rc *rc;
	u8 evt_type;
	__le16 evt;
	u8 context;
	uwb_rc_cmd_cb_f cb;
	void *arg;

	struct timer_list timer;
	struct list_head list_node;
};

static void uwb_rc_neh_timer(unsigned long arg);

static void uwb_rc_neh_release(struct kref *kref)
{
	struct uwb_rc_neh *neh = container_of(kref, struct uwb_rc_neh, kref);

	kfree(neh);
}

static void uwb_rc_neh_get(struct uwb_rc_neh *neh)
{
	kref_get(&neh->kref);
}

/**
 * uwb_rc_neh_put - release reference to a neh
 * @neh: the neh
 */
void uwb_rc_neh_put(struct uwb_rc_neh *neh)
{
	kref_put(&neh->kref, uwb_rc_neh_release);
}


/**
 * Assigns @neh a context id from @rc's pool
 *
 * @rc:	    UWB Radio Controller descriptor; @rc->neh_lock taken
 * @neh:    Notification/Event Handle
 * @returns 0 if context id was assigned ok; < 0 errno on error (if
 *	    all the context IDs are taken).
 *
 * (assumes @wa is locked).
 *
 * NOTE: WUSB spec reserves context ids 0x00 for notifications and
 *	 0xff is invalid, so they must not be used. Initialization
 *	 fills up those two in the bitmap so they are not allocated.
 *
 * We spread the allocation around to reduce the possibility of two
 * consecutive opened @neh's getting the same context ID assigned (to
 * avoid surprises with late events that timed out long time ago). So
 * first we search from where @rc->ctx_roll is, if not found, we
 * search from zero.
 */
static
int __uwb_rc_ctx_get(struct uwb_rc *rc, struct uwb_rc_neh *neh)
{
	int result;
	result = find_next_zero_bit(rc->ctx_bm, UWB_RC_CTX_MAX,
				    rc->ctx_roll++);
	if (result < UWB_RC_CTX_MAX)
		goto found;
	result = find_first_zero_bit(rc->ctx_bm, UWB_RC_CTX_MAX);
	if (result < UWB_RC_CTX_MAX)
		goto found;
	return -ENFILE;
found:
	set_bit(result, rc->ctx_bm);
	neh->context = result;
	return 0;
}


/** Releases @neh's context ID back to @rc (@rc->neh_lock is locked). */
static
void __uwb_rc_ctx_put(struct uwb_rc *rc, struct uwb_rc_neh *neh)
{
	struct device *dev = &rc->uwb_dev.dev;
	if (neh->context == 0)
		return;
	if (test_bit(neh->context, rc->ctx_bm) == 0) {
		dev_err(dev, "context %u not set in bitmap\n",
			neh->context);
		WARN_ON(1);
	}
	clear_bit(neh->context, rc->ctx_bm);
	neh->context = 0;
}

/**
 * uwb_rc_neh_add - add a neh for a radio controller command
 * @rc:             the radio controller
 * @cmd:            the radio controller command
 * @expected_type:  the type of the expected response event
 * @expected_event: the expected event ID
 * @cb:             callback for when the event is received
 * @arg:            argument for the callback
 *
 * Creates a neh and adds it to the list of those waiting for an
 * event.  A context ID will be assigned to the command.
 */
struct uwb_rc_neh *uwb_rc_neh_add(struct uwb_rc *rc, struct uwb_rccb *cmd,
				  u8 expected_type, u16 expected_event,
				  uwb_rc_cmd_cb_f cb, void *arg)
{
	int result;
	unsigned long flags;
	struct device *dev = &rc->uwb_dev.dev;
	struct uwb_rc_neh *neh;

	neh = kzalloc(sizeof(*neh), GFP_KERNEL);
	if (neh == NULL) {
		result = -ENOMEM;
		goto error_kzalloc;
	}

	kref_init(&neh->kref);
	INIT_LIST_HEAD(&neh->list_node);
	init_timer(&neh->timer);
	neh->timer.function = uwb_rc_neh_timer;
	neh->timer.data     = (unsigned long)neh;

	neh->rc = rc;
	neh->evt_type = expected_type;
	neh->evt = cpu_to_le16(expected_event);
	neh->cb = cb;
	neh->arg = arg;

	spin_lock_irqsave(&rc->neh_lock, flags);
	result = __uwb_rc_ctx_get(rc, neh);
	if (result >= 0) {
		cmd->bCommandContext = neh->context;
		list_add_tail(&neh->list_node, &rc->neh_list);
		uwb_rc_neh_get(neh);
	}
	spin_unlock_irqrestore(&rc->neh_lock, flags);
	if (result < 0)
		goto error_ctx_get;

	return neh;

error_ctx_get:
	kfree(neh);
error_kzalloc:
	dev_err(dev, "cannot open handle to radio controller: %d\n", result);
	return ERR_PTR(result);
}

static void __uwb_rc_neh_rm(struct uwb_rc *rc, struct uwb_rc_neh *neh)
{
	__uwb_rc_ctx_put(rc, neh);
	list_del(&neh->list_node);
}

/**
 * uwb_rc_neh_rm - remove a neh.
 * @rc:  the radio controller
 * @neh: the neh to remove
 *
 * Remove an active neh immediately instead of waiting for the event
 * (or a time out).
 */
void uwb_rc_neh_rm(struct uwb_rc *rc, struct uwb_rc_neh *neh)
{
	unsigned long flags;

	spin_lock_irqsave(&rc->neh_lock, flags);
	__uwb_rc_neh_rm(rc, neh);
	spin_unlock_irqrestore(&rc->neh_lock, flags);

	del_timer_sync(&neh->timer);
	uwb_rc_neh_put(neh);
}

/**
 * uwb_rc_neh_arm - arm an event handler timeout timer
 *
 * @rc:     UWB Radio Controller
 * @neh:    Notification/event handler for @rc
 *
 * The timer is only armed if the neh is active.
 */
void uwb_rc_neh_arm(struct uwb_rc *rc, struct uwb_rc_neh *neh)
{
	unsigned long flags;

	spin_lock_irqsave(&rc->neh_lock, flags);
	if (neh->context)
		mod_timer(&neh->timer,
			  jiffies + msecs_to_jiffies(UWB_RC_CMD_TIMEOUT_MS));
	spin_unlock_irqrestore(&rc->neh_lock, flags);
}

static void uwb_rc_neh_cb(struct uwb_rc_neh *neh, struct uwb_rceb *rceb, size_t size)
{
	(*neh->cb)(neh->rc, neh->arg, rceb, size);
	uwb_rc_neh_put(neh);
}

static bool uwb_rc_neh_match(struct uwb_rc_neh *neh, const struct uwb_rceb *rceb)
{
	return neh->evt_type == rceb->bEventType
		&& neh->evt == rceb->wEvent
		&& neh->context == rceb->bEventContext;
}

/**
 * Find the handle waiting for a RC Radio Control Event
 *
 * @rc:         UWB Radio Controller
 * @rceb:       Pointer to the RCEB buffer
 * @event_size: Pointer to the size of the RCEB buffer. Might be
 *              adjusted to take into account the @neh->extra_size
 *              settings.
 *
 * If the listener has no buffer (NULL buffer), one is allocated for
 * the right size (the amount of data received). @neh->ptr will point
 * to the event payload, which always starts with a 'struct
 * uwb_rceb'. kfree() it when done.
 */
static
struct uwb_rc_neh *uwb_rc_neh_lookup(struct uwb_rc *rc,
				     const struct uwb_rceb *rceb)
{
	struct uwb_rc_neh *neh = NULL, *h;
	unsigned long flags;

	spin_lock_irqsave(&rc->neh_lock, flags);

	list_for_each_entry(h, &rc->neh_list, list_node) {
		if (uwb_rc_neh_match(h, rceb)) {
			neh = h;
			break;
		}
	}

	if (neh)
		__uwb_rc_neh_rm(rc, neh);

	spin_unlock_irqrestore(&rc->neh_lock, flags);

	return neh;
}


/*
 * Process notifications coming from the radio control interface
 *
 * @rc:    UWB Radio Control Interface descriptor
 * @neh:   Notification/Event Handler @neh->ptr points to
 *         @uwb_evt->buffer.
 *
 * This function is called by the event/notif handling subsystem when
 * notifications arrive (hwarc_probe() arms a notification/event handle
 * that calls back this function for every received notification; this
 * function then will rearm itself).
 *
 * Notification data buffers are dynamically allocated by the NEH
 * handling code in neh.c [uwb_rc_neh_lookup()]. What is actually
 * allocated is space to contain the notification data.
 *
 * Buffers are prefixed with a Radio Control Event Block (RCEB) as
 * defined by the WUSB Wired-Adapter Radio Control interface. We
 * just use it for the notification code.
 *
 * On each case statement we just transcode endianess of the different
 * fields. We declare a pointer to a RCI definition of an event, and
 * then to a UWB definition of the same event (which are the same,
 * remember). Event if we use different pointers
 */
static
void uwb_rc_notif(struct uwb_rc *rc, struct uwb_rceb *rceb, ssize_t size)
{
	struct device *dev = &rc->uwb_dev.dev;
	struct uwb_event *uwb_evt;

	if (size == -ESHUTDOWN)
		return;
	if (size < 0) {
		dev_err(dev, "ignoring event with error code %zu\n",
			size);
		return;
	}

	uwb_evt = kzalloc(sizeof(*uwb_evt), GFP_ATOMIC);
	if (unlikely(uwb_evt == NULL)) {
		dev_err(dev, "no memory to queue event 0x%02x/%04x/%02x\n",
			rceb->bEventType, le16_to_cpu(rceb->wEvent),
			rceb->bEventContext);
		return;
	}
	uwb_evt->rc = __uwb_rc_get(rc);	/* will be put by uwbd's uwbd_event_handle() */
	uwb_evt->ts_jiffies = jiffies;
	uwb_evt->type = UWB_EVT_TYPE_NOTIF;
	uwb_evt->notif.size = size;
	uwb_evt->notif.rceb = rceb;

	uwbd_event_queue(uwb_evt);
}

static void uwb_rc_neh_grok_event(struct uwb_rc *rc, struct uwb_rceb *rceb, size_t size)
{
	struct device *dev = &rc->uwb_dev.dev;
	struct uwb_rc_neh *neh;
	struct uwb_rceb *notif;

	if (rceb->bEventContext == 0) {
		notif = kmalloc(size, GFP_ATOMIC);
		if (notif) {
			memcpy(notif, rceb, size);
			uwb_rc_notif(rc, notif, size);
		} else
			dev_err(dev, "event 0x%02x/%04x/%02x (%zu bytes): no memory\n",
				rceb->bEventType, le16_to_cpu(rceb->wEvent),
				rceb->bEventContext, size);
	} else {
		neh = uwb_rc_neh_lookup(rc, rceb);
		if (neh) {
			del_timer_sync(&neh->timer);
			uwb_rc_neh_cb(neh, rceb, size);
		} else
			dev_warn(dev, "event 0x%02x/%04x/%02x (%zu bytes): nobody cared\n",
				 rceb->bEventType, le16_to_cpu(rceb->wEvent),
				 rceb->bEventContext, size);
	}
}

/**
 * Given a buffer with one or more UWB RC events/notifications, break
 * them up and dispatch them.
 *
 * @rc:	      UWB Radio Controller
 * @buf:      Buffer with the stream of notifications/events
 * @buf_size: Amount of data in the buffer
 *
 * Note each notification/event starts always with a 'struct
 * uwb_rceb', so the minimum size if 4 bytes.
 *
 * The device may pass us events formatted differently than expected.
 * These are first filtered, potentially creating a new event in a new
 * memory location. If a new event is created by the filter it is also
 * freed here.
 *
 * For each notif/event, tries to guess the size looking at the EST
 * tables, then looks for a neh that is waiting for that event and if
 * found, copies the payload to the neh's buffer and calls it back. If
 * not, the data is ignored.
 *
 * Note that if we can't find a size description in the EST tables, we
 * still might find a size in the 'neh' handle in uwb_rc_neh_lookup().
 *
 * Assumptions:
 *
 *   @rc->neh_lock is NOT taken
 *
 * We keep track of various sizes here:
 * size:      contains the size of the buffer that is processed for the
 *            incoming event. this buffer may contain events that are not
 *            formatted as WHCI.
 * real_size: the actual space taken by this event in the buffer.
 *            We need to keep track of the real size of an event to be able to
 *            advance the buffer correctly.
 * event_size: the size of the event as expected by the core layer
 *            [OR] the size of the event after filtering. if the filtering
 *            created a new event in a new memory location then this is
 *            effectively the size of a new event buffer
 */
void uwb_rc_neh_grok(struct uwb_rc *rc, void *buf, size_t buf_size)
{
	struct device *dev = &rc->uwb_dev.dev;
	void *itr;
	struct uwb_rceb *rceb;
	size_t size, real_size, event_size;
	int needtofree;

	itr = buf;
	size = buf_size;
	while (size > 0) {
		if (size < sizeof(*rceb)) {
			dev_err(dev, "not enough data in event buffer to "
				"process incoming events (%zu left, minimum is "
				"%zu)\n", size, sizeof(*rceb));
			break;
		}

		rceb = itr;
		if (rc->filter_event) {
			needtofree = rc->filter_event(rc, &rceb, size,
						      &real_size, &event_size);
			if (needtofree < 0 && needtofree != -ENOANO) {
				dev_err(dev, "BUG: Unable to filter event "
					"(0x%02x/%04x/%02x) from "
					"device. \n", rceb->bEventType,
					le16_to_cpu(rceb->wEvent),
					rceb->bEventContext);
				break;
			}
		} else
			needtofree = -ENOANO;
		/* do real processing if there was no filtering or the
		 * filtering didn't act */
		if (needtofree == -ENOANO) {
			ssize_t ret = uwb_est_find_size(rc, rceb, size);
			if (ret < 0)
				break;
			if (ret > size) {
				dev_err(dev, "BUG: hw sent incomplete event "
					"0x%02x/%04x/%02x (%zd bytes), only got "
					"%zu bytes. We don't handle that.\n",
					rceb->bEventType, le16_to_cpu(rceb->wEvent),
					rceb->bEventContext, ret, size);
				break;
			}
			real_size = event_size = ret;
		}
		uwb_rc_neh_grok_event(rc, rceb, event_size);

		if (needtofree == 1)
			kfree(rceb);

		itr += real_size;
		size -= real_size;
	}
}
EXPORT_SYMBOL_GPL(uwb_rc_neh_grok);


/**
 * The entity that reads from the device notification/event channel has
 * detected an error.
 *
 * @rc:    UWB Radio Controller
 * @error: Errno error code
 *
 */
void uwb_rc_neh_error(struct uwb_rc *rc, int error)
{
	struct uwb_rc_neh *neh;
	unsigned long flags;

	for (;;) {
		spin_lock_irqsave(&rc->neh_lock, flags);
		if (list_empty(&rc->neh_list)) {
			spin_unlock_irqrestore(&rc->neh_lock, flags);
			break;
		}
		neh = list_first_entry(&rc->neh_list, struct uwb_rc_neh, list_node);
		__uwb_rc_neh_rm(rc, neh);
		spin_unlock_irqrestore(&rc->neh_lock, flags);

		del_timer_sync(&neh->timer);
		uwb_rc_neh_cb(neh, NULL, error);
	}
}
EXPORT_SYMBOL_GPL(uwb_rc_neh_error);


static void uwb_rc_neh_timer(unsigned long arg)
{
	struct uwb_rc_neh *neh = (struct uwb_rc_neh *)arg;
	struct uwb_rc *rc = neh->rc;
	unsigned long flags;

	spin_lock_irqsave(&rc->neh_lock, flags);
	if (neh->context)
		__uwb_rc_neh_rm(rc, neh);
	else
		neh = NULL;
	spin_unlock_irqrestore(&rc->neh_lock, flags);

	if (neh)
		uwb_rc_neh_cb(neh, NULL, -ETIMEDOUT);
}

/** Initializes the @rc's neh subsystem
 */
void uwb_rc_neh_create(struct uwb_rc *rc)
{
	spin_lock_init(&rc->neh_lock);
	INIT_LIST_HEAD(&rc->neh_list);
	set_bit(0, rc->ctx_bm);		/* 0 is reserved (see [WUSB] table 8-65) */
	set_bit(0xff, rc->ctx_bm);	/* and 0xff is invalid */
	rc->ctx_roll = 1;
}


/** Release's the @rc's neh subsystem */
void uwb_rc_neh_destroy(struct uwb_rc *rc)
{
	unsigned long flags;
	struct uwb_rc_neh *neh;

	for (;;) {
		spin_lock_irqsave(&rc->neh_lock, flags);
		if (list_empty(&rc->neh_list)) {
			spin_unlock_irqrestore(&rc->neh_lock, flags);
			break;
		}
		neh = list_first_entry(&rc->neh_list, struct uwb_rc_neh, list_node);
		__uwb_rc_neh_rm(rc, neh);
		spin_unlock_irqrestore(&rc->neh_lock, flags);

		del_timer_sync(&neh->timer);
		uwb_rc_neh_put(neh);
	}
}