summaryrefslogtreecommitdiffstats
path: root/drivers/uwb/beacon.c
blob: 1ccf9eb3e08694256ed8079232de27939eaa1511 (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
/*
 * Ultra Wide Band
 * Beacon management
 *
 * 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: docs
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/kdev_t.h>
#include "uwb-internal.h"

#define D_LOCAL 0
#include <linux/uwb/debug.h>

/** Start Beaconing command structure */
struct uwb_rc_cmd_start_beacon {
	struct uwb_rccb rccb;
	__le16 wBPSTOffset;
	u8 bChannelNumber;
} __attribute__((packed));


static int uwb_rc_start_beacon(struct uwb_rc *rc, u16 bpst_offset, u8 channel)
{
	int result;
	struct uwb_rc_cmd_start_beacon *cmd;
	struct uwb_rc_evt_confirm reply;

	cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
	if (cmd == NULL)
		return -ENOMEM;
	cmd->rccb.bCommandType = UWB_RC_CET_GENERAL;
	cmd->rccb.wCommand = cpu_to_le16(UWB_RC_CMD_START_BEACON);
	cmd->wBPSTOffset = cpu_to_le16(bpst_offset);
	cmd->bChannelNumber = channel;
	reply.rceb.bEventType = UWB_RC_CET_GENERAL;
	reply.rceb.wEvent = UWB_RC_CMD_START_BEACON;
	result = uwb_rc_cmd(rc, "START-BEACON", &cmd->rccb, sizeof(*cmd),
			    &reply.rceb, sizeof(reply));
	if (result < 0)
		goto error_cmd;
	if (reply.bResultCode != UWB_RC_RES_SUCCESS) {
		dev_err(&rc->uwb_dev.dev,
			"START-BEACON: command execution failed: %s (%d)\n",
			uwb_rc_strerror(reply.bResultCode), reply.bResultCode);
		result = -EIO;
	}
error_cmd:
	kfree(cmd);
	return result;
}

static int uwb_rc_stop_beacon(struct uwb_rc *rc)
{
	int result;
	struct uwb_rccb *cmd;
	struct uwb_rc_evt_confirm reply;

	cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
	if (cmd == NULL)
		return -ENOMEM;
	cmd->bCommandType = UWB_RC_CET_GENERAL;
	cmd->wCommand = cpu_to_le16(UWB_RC_CMD_STOP_BEACON);
	reply.rceb.bEventType = UWB_RC_CET_GENERAL;
	reply.rceb.wEvent = UWB_RC_CMD_STOP_BEACON;
	result = uwb_rc_cmd(rc, "STOP-BEACON", cmd, sizeof(*cmd),
			    &reply.rceb, sizeof(reply));
	if (result < 0)
		goto error_cmd;
	if (reply.bResultCode != UWB_RC_RES_SUCCESS) {
		dev_err(&rc->uwb_dev.dev,
			"STOP-BEACON: command execution failed: %s (%d)\n",
			uwb_rc_strerror(reply.bResultCode), reply.bResultCode);
		result = -EIO;
	}
error_cmd:
	kfree(cmd);
	return result;
}

/*
 * Start/stop beacons
 *
 * @rc:          UWB Radio Controller to operate on
 * @channel:     UWB channel on which to beacon (WUSB[table
 *               5-12]). If -1, stop beaconing.
 * @bpst_offset: Beacon Period Start Time offset; FIXME-do zero
 *
 * According to WHCI 0.95 [4.13.6] the driver will only receive the RCEB
 * of a SET IE command after the device sent the first beacon that includes
 * the IEs specified in the SET IE command. So, after we start beaconing we
 * check if there is anything in the IE cache and call the SET IE command
 * if needed.
 */
int uwb_rc_beacon(struct uwb_rc *rc, int channel, unsigned bpst_offset)
{
	int result;
	struct device *dev = &rc->uwb_dev.dev;

	mutex_lock(&rc->uwb_dev.mutex);
	if (channel < 0)
		channel = -1;
	if (channel == -1)
		result = uwb_rc_stop_beacon(rc);
	else {
		/* channel >= 0...dah */
		result = uwb_rc_start_beacon(rc, bpst_offset, channel);
		if (result < 0)
			goto out_up;
		if (le16_to_cpu(rc->ies->wIELength) > 0) {
			result = uwb_rc_set_ie(rc, rc->ies);
			if (result < 0) {
				dev_err(dev, "Cannot set new IE on device: "
					"%d\n", result);
				result = uwb_rc_stop_beacon(rc);
				channel = -1;
				bpst_offset = 0;
			} else
				result = 0;
		}
	}

	if (result < 0)
		goto out_up;
	rc->beaconing = channel;

	uwb_notify(rc, NULL, uwb_bg_joined(rc) ? UWB_NOTIF_BG_JOIN : UWB_NOTIF_BG_LEAVE);

out_up:
	mutex_unlock(&rc->uwb_dev.mutex);
	return result;
}

/*
 * Beacon cache
 *
 * The purpose of this is to speed up the lookup of becon information
 * when a new beacon arrives. The UWB Daemon uses it also to keep a
 * tab of which devices are in radio distance and which not. When a
 * device's beacon stays present for more than a certain amount of
 * time, it is considered a new, usable device. When a beacon ceases
 * to be received for a certain amount of time, it is considered that
 * the device is gone.
 *
 * FIXME: use an allocator for the entries
 * FIXME: use something faster for search than a list
 */

struct uwb_beca uwb_beca = {
	.list = LIST_HEAD_INIT(uwb_beca.list),
	.mutex = __MUTEX_INITIALIZER(uwb_beca.mutex)
};


void uwb_bce_kfree(struct kref *_bce)
{
	struct uwb_beca_e *bce = container_of(_bce, struct uwb_beca_e, refcnt);

	kfree(bce->be);
	kfree(bce);
}


/* Find a beacon by dev addr in the cache */
static
struct uwb_beca_e *__uwb_beca_find_bydev(const struct uwb_dev_addr *dev_addr)
{
	struct uwb_beca_e *bce, *next;
	list_for_each_entry_safe(bce, next, &uwb_beca.list, node) {
		d_printf(6, NULL, "looking for addr %02x:%02x in %02x:%02x\n",
			 dev_addr->data[0], dev_addr->data[1],
			 bce->dev_addr.data[0], bce->dev_addr.data[1]);
		if (!memcmp(&bce->dev_addr, dev_addr, sizeof(bce->dev_addr)))
			goto out;
	}
	bce = NULL;
out:
	return bce;
}

/* Find a beacon by dev addr in the cache */
static
struct uwb_beca_e *__uwb_beca_find_bymac(const struct uwb_mac_addr *mac_addr)
{
	struct uwb_beca_e *bce, *next;
	list_for_each_entry_safe(bce, next, &uwb_beca.list, node) {
		if (!memcmp(bce->mac_addr, mac_addr->data,
			    sizeof(bce->mac_addr)))
			goto out;
	}
	bce = NULL;
out:
	return bce;
}

/**
 * uwb_dev_get_by_devaddr - get a UWB device with a specific DevAddr
 * @rc:      the radio controller that saw the device
 * @devaddr: DevAddr of the UWB device to find
 *
 * There may be more than one matching device (in the case of a
 * DevAddr conflict), but only the first one is returned.
 */
struct uwb_dev *uwb_dev_get_by_devaddr(struct uwb_rc *rc,
				       const struct uwb_dev_addr *devaddr)
{
	struct uwb_dev *found = NULL;
	struct uwb_beca_e *bce;

	mutex_lock(&uwb_beca.mutex);
	bce = __uwb_beca_find_bydev(devaddr);
	if (bce)
		found = uwb_dev_try_get(rc, bce->uwb_dev);
	mutex_unlock(&uwb_beca.mutex);

	return found;
}

/**
 * uwb_dev_get_by_macaddr - get a UWB device with a specific EUI-48
 * @rc:      the radio controller that saw the device
 * @devaddr: EUI-48 of the UWB device to find
 */
struct uwb_dev *uwb_dev_get_by_macaddr(struct uwb_rc *rc,
				       const struct uwb_mac_addr *macaddr)
{
	struct uwb_dev *found = NULL;
	struct uwb_beca_e *bce;

	mutex_lock(&uwb_beca.mutex);
	bce = __uwb_beca_find_bymac(macaddr);
	if (bce)
		found = uwb_dev_try_get(rc, bce->uwb_dev);
	mutex_unlock(&uwb_beca.mutex);

	return found;
}

/* Initialize a beacon cache entry */
static void uwb_beca_e_init(struct uwb_beca_e *bce)
{
	mutex_init(&bce->mutex);
	kref_init(&bce->refcnt);
	stats_init(&bce->lqe_stats);
	stats_init(&bce->rssi_stats);
}

/*
 * Add a beacon to the cache
 *
 * @be:         Beacon event information
 * @bf:         Beacon frame (part of b, really)
 * @ts_jiffies: Timestamp (in jiffies) when the beacon was received
 */
struct uwb_beca_e *__uwb_beca_add(struct uwb_rc_evt_beacon *be,
				  struct uwb_beacon_frame *bf,
				  unsigned long ts_jiffies)
{
	struct uwb_beca_e *bce;

	bce = kzalloc(sizeof(*bce), GFP_KERNEL);
	if (bce == NULL)
		return NULL;
	uwb_beca_e_init(bce);
	bce->ts_jiffies = ts_jiffies;
	bce->uwb_dev = NULL;
	list_add(&bce->node, &uwb_beca.list);
	return bce;
}

/*
 * Wipe out beacon entries that became stale
 *
 * Remove associated devicest too.
 */
void uwb_beca_purge(void)
{
	struct uwb_beca_e *bce, *next;
	unsigned long expires;

	mutex_lock(&uwb_beca.mutex);
	list_for_each_entry_safe(bce, next, &uwb_beca.list, node) {
		expires = bce->ts_jiffies + msecs_to_jiffies(beacon_timeout_ms);
		if (time_after(jiffies, expires)) {
			uwbd_dev_offair(bce);
			list_del(&bce->node);
			uwb_bce_put(bce);
		}
	}
	mutex_unlock(&uwb_beca.mutex);
}

/* Clean up the whole beacon cache. Called on shutdown */
void uwb_beca_release(void)
{
	struct uwb_beca_e *bce, *next;
	mutex_lock(&uwb_beca.mutex);
	list_for_each_entry_safe(bce, next, &uwb_beca.list, node) {
		list_del(&bce->node);
		uwb_bce_put(bce);
	}
	mutex_unlock(&uwb_beca.mutex);
}

static void uwb_beacon_print(struct uwb_rc *rc, struct uwb_rc_evt_beacon *be,
			     struct uwb_beacon_frame *bf)
{
	char macbuf[UWB_ADDR_STRSIZE];
	char devbuf[UWB_ADDR_STRSIZE];
	char dstbuf[UWB_ADDR_STRSIZE];

	uwb_mac_addr_print(macbuf, sizeof(macbuf), &bf->Device_Identifier);
	uwb_dev_addr_print(devbuf, sizeof(devbuf), &bf->hdr.SrcAddr);
	uwb_dev_addr_print(dstbuf, sizeof(dstbuf), &bf->hdr.DestAddr);
	dev_info(&rc->uwb_dev.dev,
		 "BEACON from %s to %s (ch%u offset %u slot %u MAC %s)\n",
		 devbuf, dstbuf, be->bChannelNumber, be->wBPSTOffset,
		 bf->Beacon_Slot_Number, macbuf);
}

/*
 * @bce: beacon cache entry, referenced
 */
ssize_t uwb_bce_print_IEs(struct uwb_dev *uwb_dev, struct uwb_beca_e *bce,
			  char *buf, size_t size)
{
	ssize_t result = 0;
	struct uwb_rc_evt_beacon *be;
	struct uwb_beacon_frame *bf;
	struct uwb_buf_ctx ctx = {
		.buf = buf,
		.bytes = 0,
		.size = size
	};

	mutex_lock(&bce->mutex);
	be = bce->be;
	if (be == NULL)
		goto out;
	bf = (void *) be->BeaconInfo;
	uwb_ie_for_each(uwb_dev, uwb_ie_dump_hex, &ctx,
			bf->IEData, be->wBeaconInfoLength - sizeof(*bf));
	result = ctx.bytes;
out:
	mutex_unlock(&bce->mutex);
	return result;
}

/*
 * Verify that the beacon event, frame and IEs are ok
 */
static int uwb_verify_beacon(struct uwb_rc *rc, struct uwb_event *evt,
			     struct uwb_rc_evt_beacon *be)
{
	int result = -EINVAL;
	struct uwb_beacon_frame *bf;
	struct device *dev = &rc->uwb_dev.dev;

	/* Is there enough data to decode a beacon frame? */
	if (evt->notif.size < sizeof(*be) + sizeof(*bf)) {
		dev_err(dev, "BEACON event: Not enough data to decode "
			"(%zu vs %zu bytes needed)\n", evt->notif.size,
			sizeof(*be) + sizeof(*bf));
		goto error;
	}
	/* FIXME: make sure beacon frame IEs are fine and that the whole thing
	 * is consistent */
	result = 0;
error:
	return result;
}

/*
 * Handle UWB_RC_EVT_BEACON events
 *
 * We check the beacon cache to see how the received beacon fares. If
 * is there already we refresh the timestamp. If not we create a new
 * entry.
 *
 * According to the WHCI and WUSB specs, only one beacon frame is
 * allowed per notification block, so we don't bother about scanning
 * for more.
 */
int uwbd_evt_handle_rc_beacon(struct uwb_event *evt)
{
	int result = -EINVAL;
	struct uwb_rc *rc;
	struct uwb_rc_evt_beacon *be;
	struct uwb_beacon_frame *bf;
	struct uwb_beca_e *bce;
	struct device *dev = &evt->rc->uwb_dev.dev;
	unsigned long last_ts;

	rc = evt->rc;
	be = container_of(evt->notif.rceb, struct uwb_rc_evt_beacon, rceb);
	result = uwb_verify_beacon(rc, evt, be);
	if (result < 0)
		return result;

	/* Ignore beacon if it is from an alien. */
	if (be->bBeaconType == UWB_RC_BEACON_TYPE_OL_ALIEN ||
	    be->bBeaconType == UWB_RC_BEACON_TYPE_NOL_ALIEN) {
		if (printk_ratelimit())
			dev_err(dev, "BEACON received from ALIEN. Action? \n");
		result = -ENOSYS;
		return 0;
	}
	bf = (struct uwb_beacon_frame *) be->BeaconInfo;

	/*
	 * Drop beacons from devices with a NULL EUI-48 -- they cannot
	 * be uniquely identified.
	 *
	 * It's expected that these will all be WUSB devices and they
	 * have a WUSB specific connection method so ignoring them
	 * here shouldn't be a problem.
	 */
	if (uwb_mac_addr_bcast(&bf->Device_Identifier))
		return 0;

	mutex_lock(&uwb_beca.mutex);
	bce = __uwb_beca_find_bymac(&bf->Device_Identifier);
	if (bce == NULL) {
		/* Not in there, a new device is pinging */
		uwb_beacon_print(evt->rc, be, bf);
		bce = __uwb_beca_add(be, bf, evt->ts_jiffies);
		if (bce == NULL) {
			mutex_unlock(&uwb_beca.mutex);
			return -ENOMEM;
		}
	}
	mutex_unlock(&uwb_beca.mutex);

	mutex_lock(&bce->mutex);
	/* purge old beacon data */
	kfree(bce->be);

	last_ts = bce->ts_jiffies;

	/* Update commonly used fields */
	bce->ts_jiffies = evt->ts_jiffies;
	bce->be = be;
	bce->dev_addr = bf->hdr.SrcAddr;
	bce->mac_addr = &bf->Device_Identifier;
	be->wBPSTOffset = le16_to_cpu(be->wBPSTOffset);
	be->wBeaconInfoLength = le16_to_cpu(be->wBeaconInfoLength);
	stats_add_sample(&bce->lqe_stats, be->bLQI - 7);
	stats_add_sample(&bce->rssi_stats, be->bRSSI + 18);

	/*
	 * This might be a beacon from a new device.
	 */
	if (bce->uwb_dev == NULL)
		uwbd_dev_onair(evt->rc, bce);

	mutex_unlock(&bce->mutex);

	return 1; /* we keep the event data */
}

/*
 * Handle UWB_RC_EVT_BEACON_SIZE events
 *
 * XXXXX
 */
int uwbd_evt_handle_rc_beacon_size(struct uwb_event *evt)
{
	int result = -EINVAL;
	struct device *dev = &evt->rc->uwb_dev.dev;
	struct uwb_rc_evt_beacon_size *bs;

	/* Is there enough data to decode the event? */
	if (evt->notif.size < sizeof(*bs)) {
		dev_err(dev, "BEACON SIZE notification: Not enough data to "
			"decode (%zu vs %zu bytes needed)\n",
			evt->notif.size, sizeof(*bs));
		goto error;
	}
	bs = container_of(evt->notif.rceb, struct uwb_rc_evt_beacon_size, rceb);
	if (0)
		dev_info(dev, "Beacon size changed to %u bytes "
			"(FIXME: action?)\n", le16_to_cpu(bs->wNewBeaconSize));
	else {
		/* temporary hack until we do something with this message... */
		static unsigned count;
		if (++count % 1000 == 0)
			dev_info(dev, "Beacon size changed %u times "
				"(FIXME: action?)\n", count);
	}
	result = 0;
error:
	return result;
}

/**
 * uwbd_evt_handle_rc_bp_slot_change - handle a BP_SLOT_CHANGE event
 * @evt: the BP_SLOT_CHANGE notification from the radio controller
 *
 * If the event indicates that no beacon period slots were available
 * then radio controller has transitioned to a non-beaconing state.
 * Otherwise, simply save the current beacon slot.
 */
int uwbd_evt_handle_rc_bp_slot_change(struct uwb_event *evt)
{
	struct uwb_rc *rc = evt->rc;
	struct device *dev = &rc->uwb_dev.dev;
	struct uwb_rc_evt_bp_slot_change *bpsc;

	if (evt->notif.size < sizeof(*bpsc)) {
		dev_err(dev, "BP SLOT CHANGE event: Not enough data\n");
		return -EINVAL;
	}
	bpsc = container_of(evt->notif.rceb, struct uwb_rc_evt_bp_slot_change, rceb);

	mutex_lock(&rc->uwb_dev.mutex);
	if (uwb_rc_evt_bp_slot_change_no_slot(bpsc)) {
		dev_info(dev, "stopped beaconing: No free slots in BP\n");
		rc->beaconing = -1;
	} else
		rc->uwb_dev.beacon_slot = uwb_rc_evt_bp_slot_change_slot_num(bpsc);
	mutex_unlock(&rc->uwb_dev.mutex);

	return 0;
}

/**
 * Handle UWB_RC_EVT_BPOIE_CHANGE events
 *
 * XXXXX
 */
struct uwb_ie_bpo {
	struct uwb_ie_hdr hdr;
	u8                bp_length;
	u8                data[];
} __attribute__((packed));

int uwbd_evt_handle_rc_bpoie_change(struct uwb_event *evt)
{
	int result = -EINVAL;
	struct device *dev = &evt->rc->uwb_dev.dev;
	struct uwb_rc_evt_bpoie_change *bpoiec;
	struct uwb_ie_bpo *bpoie;
	static unsigned count;	/* FIXME: this is a temp hack */
	size_t iesize;

	/* Is there enough data to decode it? */
	if (evt->notif.size < sizeof(*bpoiec)) {
		dev_err(dev, "BPOIEC notification: Not enough data to "
			"decode (%zu vs %zu bytes needed)\n",
			evt->notif.size, sizeof(*bpoiec));
		goto error;
	}
	bpoiec = container_of(evt->notif.rceb, struct uwb_rc_evt_bpoie_change, rceb);
	iesize = le16_to_cpu(bpoiec->wBPOIELength);
	if (iesize < sizeof(*bpoie)) {
		dev_err(dev, "BPOIEC notification: Not enough IE data to "
			"decode (%zu vs %zu bytes needed)\n",
			iesize, sizeof(*bpoie));
		goto error;
	}
	if (++count % 1000 == 0)	/* Lame placeholder */
		dev_info(dev, "BPOIE: %u changes received\n", count);
	/*
	 * FIXME: At this point we should go over all the IEs in the
	 *        bpoiec->BPOIE array and act on each.
	 */
	result = 0;
error:
	return result;
}

/**
 * uwb_bg_joined - is the RC in a beacon group?
 * @rc: the radio controller
 *
 * Returns true if the radio controller is in a beacon group (even if
 * it's the sole member).
 */
int uwb_bg_joined(struct uwb_rc *rc)
{
	return rc->beaconing != -1;
}
EXPORT_SYMBOL_GPL(uwb_bg_joined);

/*
 * Print beaconing state.
 */
static ssize_t uwb_rc_beacon_show(struct device *dev,
				  struct device_attribute *attr, char *buf)
{
	struct uwb_dev *uwb_dev = to_uwb_dev(dev);
	struct uwb_rc *rc = uwb_dev->rc;
	ssize_t result;

	mutex_lock(&rc->uwb_dev.mutex);
	result = sprintf(buf, "%d\n", rc->beaconing);
	mutex_unlock(&rc->uwb_dev.mutex);
	return result;
}

/*
 * Start beaconing on the specified channel, or stop beaconing.
 *
 * The BPST offset of when to start searching for a beacon group to
 * join may be specified.
 */
static ssize_t uwb_rc_beacon_store(struct device *dev,
				   struct device_attribute *attr,
				   const char *buf, size_t size)
{
	struct uwb_dev *uwb_dev = to_uwb_dev(dev);
	struct uwb_rc *rc = uwb_dev->rc;
	int channel;
	unsigned bpst_offset = 0;
	ssize_t result = -EINVAL;

	result = sscanf(buf, "%d %u\n", &channel, &bpst_offset);
	if (result >= 1)
		result = uwb_rc_beacon(rc, channel, bpst_offset);

	return result < 0 ? result : size;
}
DEVICE_ATTR(beacon, S_IRUGO | S_IWUSR, uwb_rc_beacon_show, uwb_rc_beacon_store);
OpenPOWER on IntegriCloud