blob: 46b18eec50260789b3084df02397b2c4fd57dc38 [file] [log] [blame]
Inaky Perez-Gonzalez22d203e2008-09-17 16:34:08 +01001/*
2 * Ultra Wide Band
3 * Beacon management
4 *
5 * Copyright (C) 2005-2006 Intel Corporation
6 * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License version
10 * 2 as published by the Free Software Foundation.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
20 * 02110-1301, USA.
21 *
22 *
23 * FIXME: docs
24 */
25
26#include <linux/kernel.h>
27#include <linux/init.h>
28#include <linux/module.h>
29#include <linux/device.h>
30#include <linux/err.h>
31#include <linux/kdev_t.h>
32#include "uwb-internal.h"
33
34#define D_LOCAL 0
35#include <linux/uwb/debug.h>
36
37/** Start Beaconing command structure */
38struct uwb_rc_cmd_start_beacon {
39 struct uwb_rccb rccb;
40 __le16 wBPSTOffset;
41 u8 bChannelNumber;
42} __attribute__((packed));
43
44
45static int uwb_rc_start_beacon(struct uwb_rc *rc, u16 bpst_offset, u8 channel)
46{
47 int result;
48 struct uwb_rc_cmd_start_beacon *cmd;
49 struct uwb_rc_evt_confirm reply;
50
51 cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
52 if (cmd == NULL)
53 return -ENOMEM;
54 cmd->rccb.bCommandType = UWB_RC_CET_GENERAL;
55 cmd->rccb.wCommand = cpu_to_le16(UWB_RC_CMD_START_BEACON);
56 cmd->wBPSTOffset = cpu_to_le16(bpst_offset);
57 cmd->bChannelNumber = channel;
58 reply.rceb.bEventType = UWB_RC_CET_GENERAL;
59 reply.rceb.wEvent = UWB_RC_CMD_START_BEACON;
60 result = uwb_rc_cmd(rc, "START-BEACON", &cmd->rccb, sizeof(*cmd),
61 &reply.rceb, sizeof(reply));
62 if (result < 0)
63 goto error_cmd;
64 if (reply.bResultCode != UWB_RC_RES_SUCCESS) {
65 dev_err(&rc->uwb_dev.dev,
66 "START-BEACON: command execution failed: %s (%d)\n",
67 uwb_rc_strerror(reply.bResultCode), reply.bResultCode);
68 result = -EIO;
69 }
70error_cmd:
71 kfree(cmd);
72 return result;
73}
74
75static int uwb_rc_stop_beacon(struct uwb_rc *rc)
76{
77 int result;
78 struct uwb_rccb *cmd;
79 struct uwb_rc_evt_confirm reply;
80
81 cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
82 if (cmd == NULL)
83 return -ENOMEM;
84 cmd->bCommandType = UWB_RC_CET_GENERAL;
85 cmd->wCommand = cpu_to_le16(UWB_RC_CMD_STOP_BEACON);
86 reply.rceb.bEventType = UWB_RC_CET_GENERAL;
87 reply.rceb.wEvent = UWB_RC_CMD_STOP_BEACON;
88 result = uwb_rc_cmd(rc, "STOP-BEACON", cmd, sizeof(*cmd),
89 &reply.rceb, sizeof(reply));
90 if (result < 0)
91 goto error_cmd;
92 if (reply.bResultCode != UWB_RC_RES_SUCCESS) {
93 dev_err(&rc->uwb_dev.dev,
94 "STOP-BEACON: command execution failed: %s (%d)\n",
95 uwb_rc_strerror(reply.bResultCode), reply.bResultCode);
96 result = -EIO;
97 }
98error_cmd:
99 kfree(cmd);
100 return result;
101}
102
103/*
104 * Start/stop beacons
105 *
106 * @rc: UWB Radio Controller to operate on
107 * @channel: UWB channel on which to beacon (WUSB[table
108 * 5-12]). If -1, stop beaconing.
109 * @bpst_offset: Beacon Period Start Time offset; FIXME-do zero
110 *
111 * According to WHCI 0.95 [4.13.6] the driver will only receive the RCEB
112 * of a SET IE command after the device sent the first beacon that includes
113 * the IEs specified in the SET IE command. So, after we start beaconing we
114 * check if there is anything in the IE cache and call the SET IE command
115 * if needed.
116 */
117int uwb_rc_beacon(struct uwb_rc *rc, int channel, unsigned bpst_offset)
118{
119 int result;
120 struct device *dev = &rc->uwb_dev.dev;
121
122 mutex_lock(&rc->uwb_dev.mutex);
123 if (channel < 0)
124 channel = -1;
125 if (channel == -1)
126 result = uwb_rc_stop_beacon(rc);
127 else {
128 /* channel >= 0...dah */
129 result = uwb_rc_start_beacon(rc, bpst_offset, channel);
130 if (result < 0)
131 goto out_up;
132 if (le16_to_cpu(rc->ies->wIELength) > 0) {
133 result = uwb_rc_set_ie(rc, rc->ies);
134 if (result < 0) {
135 dev_err(dev, "Cannot set new IE on device: "
136 "%d\n", result);
137 result = uwb_rc_stop_beacon(rc);
138 channel = -1;
139 bpst_offset = 0;
140 } else
141 result = 0;
142 }
143 }
144
145 if (result < 0)
146 goto out_up;
147 rc->beaconing = channel;
148
149 uwb_notify(rc, NULL, uwb_bg_joined(rc) ? UWB_NOTIF_BG_JOIN : UWB_NOTIF_BG_LEAVE);
150
151out_up:
152 mutex_unlock(&rc->uwb_dev.mutex);
153 return result;
154}
155
156/*
157 * Beacon cache
158 *
159 * The purpose of this is to speed up the lookup of becon information
160 * when a new beacon arrives. The UWB Daemon uses it also to keep a
161 * tab of which devices are in radio distance and which not. When a
162 * device's beacon stays present for more than a certain amount of
163 * time, it is considered a new, usable device. When a beacon ceases
164 * to be received for a certain amount of time, it is considered that
165 * the device is gone.
166 *
167 * FIXME: use an allocator for the entries
168 * FIXME: use something faster for search than a list
169 */
170
171struct uwb_beca uwb_beca = {
172 .list = LIST_HEAD_INIT(uwb_beca.list),
173 .mutex = __MUTEX_INITIALIZER(uwb_beca.mutex)
174};
175
176
177void uwb_bce_kfree(struct kref *_bce)
178{
179 struct uwb_beca_e *bce = container_of(_bce, struct uwb_beca_e, refcnt);
180
181 kfree(bce->be);
182 kfree(bce);
183}
184
185
186/* Find a beacon by dev addr in the cache */
187static
188struct uwb_beca_e *__uwb_beca_find_bydev(const struct uwb_dev_addr *dev_addr)
189{
190 struct uwb_beca_e *bce, *next;
191 list_for_each_entry_safe(bce, next, &uwb_beca.list, node) {
192 d_printf(6, NULL, "looking for addr %02x:%02x in %02x:%02x\n",
193 dev_addr->data[0], dev_addr->data[1],
194 bce->dev_addr.data[0], bce->dev_addr.data[1]);
195 if (!memcmp(&bce->dev_addr, dev_addr, sizeof(bce->dev_addr)))
196 goto out;
197 }
198 bce = NULL;
199out:
200 return bce;
201}
202
203/* Find a beacon by dev addr in the cache */
204static
205struct uwb_beca_e *__uwb_beca_find_bymac(const struct uwb_mac_addr *mac_addr)
206{
207 struct uwb_beca_e *bce, *next;
208 list_for_each_entry_safe(bce, next, &uwb_beca.list, node) {
209 if (!memcmp(bce->mac_addr, mac_addr->data,
Frank Leipoldc15895e2008-10-20 14:37:53 +0100210 sizeof(struct uwb_mac_addr)))
Inaky Perez-Gonzalez22d203e2008-09-17 16:34:08 +0100211 goto out;
212 }
213 bce = NULL;
214out:
215 return bce;
216}
217
218/**
219 * uwb_dev_get_by_devaddr - get a UWB device with a specific DevAddr
220 * @rc: the radio controller that saw the device
221 * @devaddr: DevAddr of the UWB device to find
222 *
223 * There may be more than one matching device (in the case of a
224 * DevAddr conflict), but only the first one is returned.
225 */
226struct uwb_dev *uwb_dev_get_by_devaddr(struct uwb_rc *rc,
227 const struct uwb_dev_addr *devaddr)
228{
229 struct uwb_dev *found = NULL;
230 struct uwb_beca_e *bce;
231
232 mutex_lock(&uwb_beca.mutex);
233 bce = __uwb_beca_find_bydev(devaddr);
234 if (bce)
235 found = uwb_dev_try_get(rc, bce->uwb_dev);
236 mutex_unlock(&uwb_beca.mutex);
237
238 return found;
239}
240
241/**
242 * uwb_dev_get_by_macaddr - get a UWB device with a specific EUI-48
243 * @rc: the radio controller that saw the device
244 * @devaddr: EUI-48 of the UWB device to find
245 */
246struct uwb_dev *uwb_dev_get_by_macaddr(struct uwb_rc *rc,
247 const struct uwb_mac_addr *macaddr)
248{
249 struct uwb_dev *found = NULL;
250 struct uwb_beca_e *bce;
251
252 mutex_lock(&uwb_beca.mutex);
253 bce = __uwb_beca_find_bymac(macaddr);
254 if (bce)
255 found = uwb_dev_try_get(rc, bce->uwb_dev);
256 mutex_unlock(&uwb_beca.mutex);
257
258 return found;
259}
260
261/* Initialize a beacon cache entry */
262static void uwb_beca_e_init(struct uwb_beca_e *bce)
263{
264 mutex_init(&bce->mutex);
265 kref_init(&bce->refcnt);
266 stats_init(&bce->lqe_stats);
267 stats_init(&bce->rssi_stats);
268}
269
270/*
271 * Add a beacon to the cache
272 *
273 * @be: Beacon event information
274 * @bf: Beacon frame (part of b, really)
275 * @ts_jiffies: Timestamp (in jiffies) when the beacon was received
276 */
277struct uwb_beca_e *__uwb_beca_add(struct uwb_rc_evt_beacon *be,
278 struct uwb_beacon_frame *bf,
279 unsigned long ts_jiffies)
280{
281 struct uwb_beca_e *bce;
282
283 bce = kzalloc(sizeof(*bce), GFP_KERNEL);
284 if (bce == NULL)
285 return NULL;
286 uwb_beca_e_init(bce);
287 bce->ts_jiffies = ts_jiffies;
288 bce->uwb_dev = NULL;
289 list_add(&bce->node, &uwb_beca.list);
290 return bce;
291}
292
293/*
294 * Wipe out beacon entries that became stale
295 *
296 * Remove associated devicest too.
297 */
298void uwb_beca_purge(void)
299{
300 struct uwb_beca_e *bce, *next;
David Vrabel45c16cd2008-10-15 14:41:56 +0100301 unsigned long expires;
302
Inaky Perez-Gonzalez22d203e2008-09-17 16:34:08 +0100303 mutex_lock(&uwb_beca.mutex);
304 list_for_each_entry_safe(bce, next, &uwb_beca.list, node) {
David Vrabel45c16cd2008-10-15 14:41:56 +0100305 expires = bce->ts_jiffies + msecs_to_jiffies(beacon_timeout_ms);
306 if (time_after(jiffies, expires)) {
Inaky Perez-Gonzalez22d203e2008-09-17 16:34:08 +0100307 uwbd_dev_offair(bce);
308 list_del(&bce->node);
309 uwb_bce_put(bce);
310 }
311 }
312 mutex_unlock(&uwb_beca.mutex);
313}
314
315/* Clean up the whole beacon cache. Called on shutdown */
316void uwb_beca_release(void)
317{
318 struct uwb_beca_e *bce, *next;
319 mutex_lock(&uwb_beca.mutex);
320 list_for_each_entry_safe(bce, next, &uwb_beca.list, node) {
321 list_del(&bce->node);
322 uwb_bce_put(bce);
323 }
324 mutex_unlock(&uwb_beca.mutex);
325}
326
327static void uwb_beacon_print(struct uwb_rc *rc, struct uwb_rc_evt_beacon *be,
328 struct uwb_beacon_frame *bf)
329{
330 char macbuf[UWB_ADDR_STRSIZE];
331 char devbuf[UWB_ADDR_STRSIZE];
332 char dstbuf[UWB_ADDR_STRSIZE];
333
334 uwb_mac_addr_print(macbuf, sizeof(macbuf), &bf->Device_Identifier);
335 uwb_dev_addr_print(devbuf, sizeof(devbuf), &bf->hdr.SrcAddr);
336 uwb_dev_addr_print(dstbuf, sizeof(dstbuf), &bf->hdr.DestAddr);
337 dev_info(&rc->uwb_dev.dev,
338 "BEACON from %s to %s (ch%u offset %u slot %u MAC %s)\n",
339 devbuf, dstbuf, be->bChannelNumber, be->wBPSTOffset,
340 bf->Beacon_Slot_Number, macbuf);
341}
342
343/*
344 * @bce: beacon cache entry, referenced
345 */
346ssize_t uwb_bce_print_IEs(struct uwb_dev *uwb_dev, struct uwb_beca_e *bce,
347 char *buf, size_t size)
348{
349 ssize_t result = 0;
350 struct uwb_rc_evt_beacon *be;
351 struct uwb_beacon_frame *bf;
352 struct uwb_buf_ctx ctx = {
353 .buf = buf,
354 .bytes = 0,
355 .size = size
356 };
357
358 mutex_lock(&bce->mutex);
359 be = bce->be;
360 if (be == NULL)
361 goto out;
362 bf = (void *) be->BeaconInfo;
363 uwb_ie_for_each(uwb_dev, uwb_ie_dump_hex, &ctx,
364 bf->IEData, be->wBeaconInfoLength - sizeof(*bf));
365 result = ctx.bytes;
366out:
367 mutex_unlock(&bce->mutex);
368 return result;
369}
370
371/*
372 * Verify that the beacon event, frame and IEs are ok
373 */
374static int uwb_verify_beacon(struct uwb_rc *rc, struct uwb_event *evt,
375 struct uwb_rc_evt_beacon *be)
376{
377 int result = -EINVAL;
378 struct uwb_beacon_frame *bf;
379 struct device *dev = &rc->uwb_dev.dev;
380
381 /* Is there enough data to decode a beacon frame? */
382 if (evt->notif.size < sizeof(*be) + sizeof(*bf)) {
383 dev_err(dev, "BEACON event: Not enough data to decode "
384 "(%zu vs %zu bytes needed)\n", evt->notif.size,
385 sizeof(*be) + sizeof(*bf));
386 goto error;
387 }
388 /* FIXME: make sure beacon frame IEs are fine and that the whole thing
389 * is consistent */
390 result = 0;
391error:
392 return result;
393}
394
395/*
396 * Handle UWB_RC_EVT_BEACON events
397 *
398 * We check the beacon cache to see how the received beacon fares. If
399 * is there already we refresh the timestamp. If not we create a new
400 * entry.
401 *
402 * According to the WHCI and WUSB specs, only one beacon frame is
403 * allowed per notification block, so we don't bother about scanning
404 * for more.
405 */
406int uwbd_evt_handle_rc_beacon(struct uwb_event *evt)
407{
408 int result = -EINVAL;
409 struct uwb_rc *rc;
410 struct uwb_rc_evt_beacon *be;
411 struct uwb_beacon_frame *bf;
412 struct uwb_beca_e *bce;
Inaky Perez-Gonzalez22d203e2008-09-17 16:34:08 +0100413 unsigned long last_ts;
414
415 rc = evt->rc;
416 be = container_of(evt->notif.rceb, struct uwb_rc_evt_beacon, rceb);
417 result = uwb_verify_beacon(rc, evt, be);
418 if (result < 0)
419 return result;
420
David Vrabel8092d7c2008-10-16 13:56:53 +0100421 /* FIXME: handle alien beacons. */
Inaky Perez-Gonzalez22d203e2008-09-17 16:34:08 +0100422 if (be->bBeaconType == UWB_RC_BEACON_TYPE_OL_ALIEN ||
423 be->bBeaconType == UWB_RC_BEACON_TYPE_NOL_ALIEN) {
David Vrabel8092d7c2008-10-16 13:56:53 +0100424 return -ENOSYS;
Inaky Perez-Gonzalez22d203e2008-09-17 16:34:08 +0100425 }
David Vrabel8092d7c2008-10-16 13:56:53 +0100426
Inaky Perez-Gonzalez22d203e2008-09-17 16:34:08 +0100427 bf = (struct uwb_beacon_frame *) be->BeaconInfo;
428
429 /*
430 * Drop beacons from devices with a NULL EUI-48 -- they cannot
431 * be uniquely identified.
432 *
433 * It's expected that these will all be WUSB devices and they
434 * have a WUSB specific connection method so ignoring them
435 * here shouldn't be a problem.
436 */
437 if (uwb_mac_addr_bcast(&bf->Device_Identifier))
438 return 0;
439
440 mutex_lock(&uwb_beca.mutex);
441 bce = __uwb_beca_find_bymac(&bf->Device_Identifier);
442 if (bce == NULL) {
443 /* Not in there, a new device is pinging */
444 uwb_beacon_print(evt->rc, be, bf);
445 bce = __uwb_beca_add(be, bf, evt->ts_jiffies);
446 if (bce == NULL) {
447 mutex_unlock(&uwb_beca.mutex);
448 return -ENOMEM;
449 }
450 }
451 mutex_unlock(&uwb_beca.mutex);
452
453 mutex_lock(&bce->mutex);
454 /* purge old beacon data */
455 kfree(bce->be);
456
457 last_ts = bce->ts_jiffies;
458
459 /* Update commonly used fields */
460 bce->ts_jiffies = evt->ts_jiffies;
461 bce->be = be;
462 bce->dev_addr = bf->hdr.SrcAddr;
463 bce->mac_addr = &bf->Device_Identifier;
464 be->wBPSTOffset = le16_to_cpu(be->wBPSTOffset);
465 be->wBeaconInfoLength = le16_to_cpu(be->wBeaconInfoLength);
466 stats_add_sample(&bce->lqe_stats, be->bLQI - 7);
467 stats_add_sample(&bce->rssi_stats, be->bRSSI + 18);
468
469 /*
470 * This might be a beacon from a new device.
471 */
472 if (bce->uwb_dev == NULL)
473 uwbd_dev_onair(evt->rc, bce);
474
475 mutex_unlock(&bce->mutex);
476
477 return 1; /* we keep the event data */
478}
479
480/*
481 * Handle UWB_RC_EVT_BEACON_SIZE events
482 *
483 * XXXXX
484 */
485int uwbd_evt_handle_rc_beacon_size(struct uwb_event *evt)
486{
487 int result = -EINVAL;
488 struct device *dev = &evt->rc->uwb_dev.dev;
489 struct uwb_rc_evt_beacon_size *bs;
490
491 /* Is there enough data to decode the event? */
492 if (evt->notif.size < sizeof(*bs)) {
493 dev_err(dev, "BEACON SIZE notification: Not enough data to "
494 "decode (%zu vs %zu bytes needed)\n",
495 evt->notif.size, sizeof(*bs));
496 goto error;
497 }
498 bs = container_of(evt->notif.rceb, struct uwb_rc_evt_beacon_size, rceb);
499 if (0)
500 dev_info(dev, "Beacon size changed to %u bytes "
501 "(FIXME: action?)\n", le16_to_cpu(bs->wNewBeaconSize));
502 else {
503 /* temporary hack until we do something with this message... */
504 static unsigned count;
505 if (++count % 1000 == 0)
506 dev_info(dev, "Beacon size changed %u times "
507 "(FIXME: action?)\n", count);
508 }
509 result = 0;
510error:
511 return result;
512}
513
514/**
515 * uwbd_evt_handle_rc_bp_slot_change - handle a BP_SLOT_CHANGE event
516 * @evt: the BP_SLOT_CHANGE notification from the radio controller
517 *
518 * If the event indicates that no beacon period slots were available
519 * then radio controller has transitioned to a non-beaconing state.
520 * Otherwise, simply save the current beacon slot.
521 */
522int uwbd_evt_handle_rc_bp_slot_change(struct uwb_event *evt)
523{
524 struct uwb_rc *rc = evt->rc;
525 struct device *dev = &rc->uwb_dev.dev;
526 struct uwb_rc_evt_bp_slot_change *bpsc;
527
528 if (evt->notif.size < sizeof(*bpsc)) {
529 dev_err(dev, "BP SLOT CHANGE event: Not enough data\n");
530 return -EINVAL;
531 }
532 bpsc = container_of(evt->notif.rceb, struct uwb_rc_evt_bp_slot_change, rceb);
533
534 mutex_lock(&rc->uwb_dev.mutex);
535 if (uwb_rc_evt_bp_slot_change_no_slot(bpsc)) {
536 dev_info(dev, "stopped beaconing: No free slots in BP\n");
537 rc->beaconing = -1;
538 } else
539 rc->uwb_dev.beacon_slot = uwb_rc_evt_bp_slot_change_slot_num(bpsc);
540 mutex_unlock(&rc->uwb_dev.mutex);
541
542 return 0;
543}
544
545/**
546 * Handle UWB_RC_EVT_BPOIE_CHANGE events
547 *
548 * XXXXX
549 */
550struct uwb_ie_bpo {
551 struct uwb_ie_hdr hdr;
552 u8 bp_length;
553 u8 data[];
554} __attribute__((packed));
555
556int uwbd_evt_handle_rc_bpoie_change(struct uwb_event *evt)
557{
558 int result = -EINVAL;
559 struct device *dev = &evt->rc->uwb_dev.dev;
560 struct uwb_rc_evt_bpoie_change *bpoiec;
561 struct uwb_ie_bpo *bpoie;
562 static unsigned count; /* FIXME: this is a temp hack */
563 size_t iesize;
564
565 /* Is there enough data to decode it? */
566 if (evt->notif.size < sizeof(*bpoiec)) {
567 dev_err(dev, "BPOIEC notification: Not enough data to "
568 "decode (%zu vs %zu bytes needed)\n",
569 evt->notif.size, sizeof(*bpoiec));
570 goto error;
571 }
572 bpoiec = container_of(evt->notif.rceb, struct uwb_rc_evt_bpoie_change, rceb);
573 iesize = le16_to_cpu(bpoiec->wBPOIELength);
574 if (iesize < sizeof(*bpoie)) {
575 dev_err(dev, "BPOIEC notification: Not enough IE data to "
576 "decode (%zu vs %zu bytes needed)\n",
577 iesize, sizeof(*bpoie));
578 goto error;
579 }
580 if (++count % 1000 == 0) /* Lame placeholder */
581 dev_info(dev, "BPOIE: %u changes received\n", count);
582 /*
583 * FIXME: At this point we should go over all the IEs in the
584 * bpoiec->BPOIE array and act on each.
585 */
586 result = 0;
587error:
588 return result;
589}
590
591/**
592 * uwb_bg_joined - is the RC in a beacon group?
593 * @rc: the radio controller
594 *
595 * Returns true if the radio controller is in a beacon group (even if
596 * it's the sole member).
597 */
598int uwb_bg_joined(struct uwb_rc *rc)
599{
600 return rc->beaconing != -1;
601}
602EXPORT_SYMBOL_GPL(uwb_bg_joined);
603
604/*
605 * Print beaconing state.
606 */
607static ssize_t uwb_rc_beacon_show(struct device *dev,
608 struct device_attribute *attr, char *buf)
609{
610 struct uwb_dev *uwb_dev = to_uwb_dev(dev);
611 struct uwb_rc *rc = uwb_dev->rc;
612 ssize_t result;
613
614 mutex_lock(&rc->uwb_dev.mutex);
615 result = sprintf(buf, "%d\n", rc->beaconing);
616 mutex_unlock(&rc->uwb_dev.mutex);
617 return result;
618}
619
620/*
621 * Start beaconing on the specified channel, or stop beaconing.
622 *
623 * The BPST offset of when to start searching for a beacon group to
624 * join may be specified.
625 */
626static ssize_t uwb_rc_beacon_store(struct device *dev,
627 struct device_attribute *attr,
628 const char *buf, size_t size)
629{
630 struct uwb_dev *uwb_dev = to_uwb_dev(dev);
631 struct uwb_rc *rc = uwb_dev->rc;
632 int channel;
633 unsigned bpst_offset = 0;
634 ssize_t result = -EINVAL;
635
636 result = sscanf(buf, "%d %u\n", &channel, &bpst_offset);
637 if (result >= 1)
638 result = uwb_rc_beacon(rc, channel, bpst_offset);
639
640 return result < 0 ? result : size;
641}
642DEVICE_ATTR(beacon, S_IRUGO | S_IWUSR, uwb_rc_beacon_show, uwb_rc_beacon_store);