drivers/uwb/beacon.c

   1 /*
   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 */
  38 struct uwb_rc_cmd_start_beacon {
  39         struct uwb_rccb rccb;
  40         __le16 wBPSTOffset;
  41         u8 bChannelNumber;
  42 } __attribute__((packed));
  43
  44
  45 static 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         }
  70 error_cmd:
  71         kfree(cmd);
  72         return result;
  73 }
  74
  75 static 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         }
  98 error_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  */
 117 int 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
 151 out_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
 171 struct uwb_beca uwb_beca = {
 172         .list = LIST_HEAD_INIT(uwb_beca.list),
 173         .mutex = __MUTEX_INITIALIZER(uwb_beca.mutex)
 174 };
 175
 176
 177 void 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 */
 187 static
 188 struct 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;
 199 out:
 200         return bce;
 201 }
 202
 203 /* Find a beacon by dev addr in the cache */
 204 static
 205 struct 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,
 210                             sizeof(struct uwb_mac_addr)))
 211                         goto out;
 212         }
 213         bce = NULL;
 214 out:
 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  */
 226 struct 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  */
 246 struct 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 */
 262 static 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  */
 277 struct 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  */
 298 void uwb_beca_purge(void)
 299 {
 300         struct uwb_beca_e *bce, *next;
 301         unsigned long expires;
 302
 303         mutex_lock(&uwb_beca.mutex);
 304         list_for_each_entry_safe(bce, next, &uwb_beca.list, node) {
 305                 expires = bce->ts_jiffies + msecs_to_jiffies(beacon_timeout_ms);
 306                 if (time_after(jiffies, expires)) {
 307                         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 */
 316 void 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
 327 static 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  */
 346 ssize_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         int ies_len;
 353         struct uwb_ie_hdr *ies;
 354
 355         mutex_lock(&bce->mutex);
 356
 357         be = bce->be;
 358         if (be) {
 359                 bf = (struct uwb_beacon_frame *)bce->be->BeaconInfo;
 360                 ies_len = be->wBeaconInfoLength - sizeof(struct uwb_beacon_frame);
 361                 ies = (struct uwb_ie_hdr *)bf->IEData;
 362
 363                 result = uwb_ie_dump_hex(ies, ies_len, buf, size);
 364         }
 365
 366         mutex_unlock(&bce->mutex);
 367
 368         return result;
 369 }
 370
 371 /*
 372  * Verify that the beacon event, frame and IEs are ok
 373  */
 374 static 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;
 391 error:
 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  */
 406 int 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;
 413         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
 421         /* FIXME: handle alien beacons. */
 422         if (be->bBeaconType == UWB_RC_BEACON_TYPE_OL_ALIEN ||
 423             be->bBeaconType == UWB_RC_BEACON_TYPE_NOL_ALIEN) {
 424                 return -ENOSYS;
 425         }
 426
 427         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  */
 485 int 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;
 510 error:
 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  */
 522 int 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  */
 550 struct uwb_ie_bpo {
 551         struct uwb_ie_hdr hdr;
 552         u8                bp_length;
 553         u8                data[];
 554 } __attribute__((packed));
 555
 556 int 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;
 587 error:
 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  */
 598 int uwb_bg_joined(struct uwb_rc *rc)
 599 {
 600         return rc->beaconing != -1;
 601 }
 602 EXPORT_SYMBOL_GPL(uwb_bg_joined);
 603
 604 /*
 605  * Print beaconing state.
 606  */
 607 static 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  */
 626 static 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 }
 642 DEVICE_ATTR(beacon, S_IRUGO | S_IWUSR, uwb_rc_beacon_show, uwb_rc_beacon_store);