drivers/staging/uwb/beacon.c

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This source file includes following definitions.
uwb_rc_start_beacon
uwb_rc_stop_beacon
uwb_rc_beacon
uwb_bce_kfree
__uwb_beca_find_bydev
__uwb_beca_find_bymac
uwb_dev_get_by_devaddr
uwb_dev_get_by_macaddr
uwb_beca_e_init
__uwb_beca_add
uwb_beca_purge
uwb_beca_release
uwb_beacon_print
uwb_bce_print_IEs
uwb_verify_beacon
uwbd_evt_handle_rc_beacon
uwbd_evt_handle_rc_beacon_size
uwbd_evt_handle_rc_bp_slot_change
uwbd_evt_handle_rc_bpoie_change
uwb_rc_beacon_show
uwb_rc_beacon_store
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Ultra Wide Band
   4  * Beacon management
   5  *
   6  * Copyright (C) 2005-2006 Intel Corporation
   7  * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
   8  *
   9  * FIXME: docs
  10  */
  11 #include <linux/kernel.h>
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/device.h>
  15 #include <linux/err.h>
  16 #include <linux/kdev_t.h>
  17 #include <linux/slab.h>
  18 
  19 #include "uwb-internal.h"
  20 
  21 /* Start Beaconing command structure */
  22 struct uwb_rc_cmd_start_beacon {
  23         struct uwb_rccb rccb;
  24         __le16 wBPSTOffset;
  25         u8 bChannelNumber;
  26 } __attribute__((packed));
  27 
  28 
  29 static int uwb_rc_start_beacon(struct uwb_rc *rc, u16 bpst_offset, u8 channel)
  30 {
  31         int result;
  32         struct uwb_rc_cmd_start_beacon *cmd;
  33         struct uwb_rc_evt_confirm reply;
  34 
  35         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
  36         if (cmd == NULL)
  37                 return -ENOMEM;
  38         cmd->rccb.bCommandType = UWB_RC_CET_GENERAL;
  39         cmd->rccb.wCommand = cpu_to_le16(UWB_RC_CMD_START_BEACON);
  40         cmd->wBPSTOffset = cpu_to_le16(bpst_offset);
  41         cmd->bChannelNumber = channel;
  42         reply.rceb.bEventType = UWB_RC_CET_GENERAL;
  43         reply.rceb.wEvent = UWB_RC_CMD_START_BEACON;
  44         result = uwb_rc_cmd(rc, "START-BEACON", &cmd->rccb, sizeof(*cmd),
  45                             &reply.rceb, sizeof(reply));
  46         if (result < 0)
  47                 goto error_cmd;
  48         if (reply.bResultCode != UWB_RC_RES_SUCCESS) {
  49                 dev_err(&rc->uwb_dev.dev,
  50                         "START-BEACON: command execution failed: %s (%d)\n",
  51                         uwb_rc_strerror(reply.bResultCode), reply.bResultCode);
  52                 result = -EIO;
  53         }
  54 error_cmd:
  55         kfree(cmd);
  56         return result;
  57 }
  58 
  59 static int uwb_rc_stop_beacon(struct uwb_rc *rc)
  60 {
  61         int result;
  62         struct uwb_rccb *cmd;
  63         struct uwb_rc_evt_confirm reply;
  64 
  65         cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
  66         if (cmd == NULL)
  67                 return -ENOMEM;
  68         cmd->bCommandType = UWB_RC_CET_GENERAL;
  69         cmd->wCommand = cpu_to_le16(UWB_RC_CMD_STOP_BEACON);
  70         reply.rceb.bEventType = UWB_RC_CET_GENERAL;
  71         reply.rceb.wEvent = UWB_RC_CMD_STOP_BEACON;
  72         result = uwb_rc_cmd(rc, "STOP-BEACON", cmd, sizeof(*cmd),
  73                             &reply.rceb, sizeof(reply));
  74         if (result < 0)
  75                 goto error_cmd;
  76         if (reply.bResultCode != UWB_RC_RES_SUCCESS) {
  77                 dev_err(&rc->uwb_dev.dev,
  78                         "STOP-BEACON: command execution failed: %s (%d)\n",
  79                         uwb_rc_strerror(reply.bResultCode), reply.bResultCode);
  80                 result = -EIO;
  81         }
  82 error_cmd:
  83         kfree(cmd);
  84         return result;
  85 }
  86 
  87 /*
  88  * Start/stop beacons
  89  *
  90  * @rc:          UWB Radio Controller to operate on
  91  * @channel:     UWB channel on which to beacon (WUSB[table
  92  *               5-12]). If -1, stop beaconing.
  93  * @bpst_offset: Beacon Period Start Time offset; FIXME-do zero
  94  *
  95  * According to WHCI 0.95 [4.13.6] the driver will only receive the RCEB
  96  * of a SET IE command after the device sent the first beacon that includes
  97  * the IEs specified in the SET IE command. So, after we start beaconing we
  98  * check if there is anything in the IE cache and call the SET IE command
  99  * if needed.
 100  */
 101 int uwb_rc_beacon(struct uwb_rc *rc, int channel, unsigned bpst_offset)
 102 {
 103         int result;
 104         struct device *dev = &rc->uwb_dev.dev;
 105 
 106         dev_dbg(dev, "%s: channel = %d\n", __func__, channel);
 107         if (channel < 0)
 108                 channel = -1;
 109         if (channel == -1)
 110                 result = uwb_rc_stop_beacon(rc);
 111         else {
 112                 /* channel >= 0...dah */
 113                 result = uwb_rc_start_beacon(rc, bpst_offset, channel);
 114                 if (result < 0) {
 115                         dev_err(dev, "Cannot start beaconing: %d\n", result);
 116                         return result;
 117                 }
 118                 if (le16_to_cpu(rc->ies->wIELength) > 0) {
 119                         result = uwb_rc_set_ie(rc, rc->ies);
 120                         if (result < 0) {
 121                                 dev_err(dev, "Cannot set new IE on device: "
 122                                         "%d\n", result);
 123                                 result = uwb_rc_stop_beacon(rc);
 124                                 channel = -1;
 125                                 bpst_offset = 0;
 126                         }
 127                 }
 128         }
 129 
 130         if (result >= 0)
 131                 rc->beaconing = channel;
 132         return result;
 133 }
 134 
 135 /*
 136  * Beacon cache
 137  *
 138  * The purpose of this is to speed up the lookup of becon information
 139  * when a new beacon arrives. The UWB Daemon uses it also to keep a
 140  * tab of which devices are in radio distance and which not. When a
 141  * device's beacon stays present for more than a certain amount of
 142  * time, it is considered a new, usable device. When a beacon ceases
 143  * to be received for a certain amount of time, it is considered that
 144  * the device is gone.
 145  *
 146  * FIXME: use an allocator for the entries
 147  * FIXME: use something faster for search than a list
 148  */
 149 
 150 void uwb_bce_kfree(struct kref *_bce)
 151 {
 152         struct uwb_beca_e *bce = container_of(_bce, struct uwb_beca_e, refcnt);
 153 
 154         kfree(bce->be);
 155         kfree(bce);
 156 }
 157 
 158 
 159 /* Find a beacon by dev addr in the cache */
 160 static
 161 struct uwb_beca_e *__uwb_beca_find_bydev(struct uwb_rc *rc,
 162                                          const struct uwb_dev_addr *dev_addr)
 163 {
 164         struct uwb_beca_e *bce, *next;
 165         list_for_each_entry_safe(bce, next, &rc->uwb_beca.list, node) {
 166                 if (!memcmp(&bce->dev_addr, dev_addr, sizeof(bce->dev_addr)))
 167                         goto out;
 168         }
 169         bce = NULL;
 170 out:
 171         return bce;
 172 }
 173 
 174 /* Find a beacon by dev addr in the cache */
 175 static
 176 struct uwb_beca_e *__uwb_beca_find_bymac(struct uwb_rc *rc,
 177                                          const struct uwb_mac_addr *mac_addr)
 178 {
 179         struct uwb_beca_e *bce, *next;
 180         list_for_each_entry_safe(bce, next, &rc->uwb_beca.list, node) {
 181                 if (!memcmp(bce->mac_addr, mac_addr->data,
 182                             sizeof(struct uwb_mac_addr)))
 183                         goto out;
 184         }
 185         bce = NULL;
 186 out:
 187         return bce;
 188 }
 189 
 190 /**
 191  * uwb_dev_get_by_devaddr - get a UWB device with a specific DevAddr
 192  * @rc:      the radio controller that saw the device
 193  * @devaddr: DevAddr of the UWB device to find
 194  *
 195  * There may be more than one matching device (in the case of a
 196  * DevAddr conflict), but only the first one is returned.
 197  */
 198 struct uwb_dev *uwb_dev_get_by_devaddr(struct uwb_rc *rc,
 199                                        const struct uwb_dev_addr *devaddr)
 200 {
 201         struct uwb_dev *found = NULL;
 202         struct uwb_beca_e *bce;
 203 
 204         mutex_lock(&rc->uwb_beca.mutex);
 205         bce = __uwb_beca_find_bydev(rc, devaddr);
 206         if (bce)
 207                 found = uwb_dev_try_get(rc, bce->uwb_dev);
 208         mutex_unlock(&rc->uwb_beca.mutex);
 209 
 210         return found;
 211 }
 212 
 213 /**
 214  * uwb_dev_get_by_macaddr - get a UWB device with a specific EUI-48
 215  * @rc:      the radio controller that saw the device
 216  * @devaddr: EUI-48 of the UWB device to find
 217  */
 218 struct uwb_dev *uwb_dev_get_by_macaddr(struct uwb_rc *rc,
 219                                        const struct uwb_mac_addr *macaddr)
 220 {
 221         struct uwb_dev *found = NULL;
 222         struct uwb_beca_e *bce;
 223 
 224         mutex_lock(&rc->uwb_beca.mutex);
 225         bce = __uwb_beca_find_bymac(rc, macaddr);
 226         if (bce)
 227                 found = uwb_dev_try_get(rc, bce->uwb_dev);
 228         mutex_unlock(&rc->uwb_beca.mutex);
 229 
 230         return found;
 231 }
 232 
 233 /* Initialize a beacon cache entry */
 234 static void uwb_beca_e_init(struct uwb_beca_e *bce)
 235 {
 236         mutex_init(&bce->mutex);
 237         kref_init(&bce->refcnt);
 238         stats_init(&bce->lqe_stats);
 239         stats_init(&bce->rssi_stats);
 240 }
 241 
 242 /*
 243  * Add a beacon to the cache
 244  *
 245  * @be:         Beacon event information
 246  * @bf:         Beacon frame (part of b, really)
 247  * @ts_jiffies: Timestamp (in jiffies) when the beacon was received
 248  */
 249 static
 250 struct uwb_beca_e *__uwb_beca_add(struct uwb_rc *rc,
 251                                   struct uwb_rc_evt_beacon *be,
 252                                   struct uwb_beacon_frame *bf,
 253                                   unsigned long ts_jiffies)
 254 {
 255         struct uwb_beca_e *bce;
 256 
 257         bce = kzalloc(sizeof(*bce), GFP_KERNEL);
 258         if (bce == NULL)
 259                 return NULL;
 260         uwb_beca_e_init(bce);
 261         bce->ts_jiffies = ts_jiffies;
 262         bce->uwb_dev = NULL;
 263         list_add(&bce->node, &rc->uwb_beca.list);
 264         return bce;
 265 }
 266 
 267 /*
 268  * Wipe out beacon entries that became stale
 269  *
 270  * Remove associated devicest too.
 271  */
 272 void uwb_beca_purge(struct uwb_rc *rc)
 273 {
 274         struct uwb_beca_e *bce, *next;
 275         unsigned long expires;
 276 
 277         mutex_lock(&rc->uwb_beca.mutex);
 278         list_for_each_entry_safe(bce, next, &rc->uwb_beca.list, node) {
 279                 expires = bce->ts_jiffies + msecs_to_jiffies(beacon_timeout_ms);
 280                 if (time_after(jiffies, expires)) {
 281                         uwbd_dev_offair(bce);
 282                 }
 283         }
 284         mutex_unlock(&rc->uwb_beca.mutex);
 285 }
 286 
 287 /* Clean up the whole beacon cache. Called on shutdown */
 288 void uwb_beca_release(struct uwb_rc *rc)
 289 {
 290         struct uwb_beca_e *bce, *next;
 291 
 292         mutex_lock(&rc->uwb_beca.mutex);
 293         list_for_each_entry_safe(bce, next, &rc->uwb_beca.list, node) {
 294                 list_del(&bce->node);
 295                 uwb_bce_put(bce);
 296         }
 297         mutex_unlock(&rc->uwb_beca.mutex);
 298 }
 299 
 300 static void uwb_beacon_print(struct uwb_rc *rc, struct uwb_rc_evt_beacon *be,
 301                              struct uwb_beacon_frame *bf)
 302 {
 303         char macbuf[UWB_ADDR_STRSIZE];
 304         char devbuf[UWB_ADDR_STRSIZE];
 305         char dstbuf[UWB_ADDR_STRSIZE];
 306 
 307         uwb_mac_addr_print(macbuf, sizeof(macbuf), &bf->Device_Identifier);
 308         uwb_dev_addr_print(devbuf, sizeof(devbuf), &bf->hdr.SrcAddr);
 309         uwb_dev_addr_print(dstbuf, sizeof(dstbuf), &bf->hdr.DestAddr);
 310         dev_info(&rc->uwb_dev.dev,
 311                  "BEACON from %s to %s (ch%u offset %u slot %u MAC %s)\n",
 312                  devbuf, dstbuf, be->bChannelNumber, be->wBPSTOffset,
 313                  bf->Beacon_Slot_Number, macbuf);
 314 }
 315 
 316 /*
 317  * @bce: beacon cache entry, referenced
 318  */
 319 ssize_t uwb_bce_print_IEs(struct uwb_dev *uwb_dev, struct uwb_beca_e *bce,
 320                           char *buf, size_t size)
 321 {
 322         ssize_t result = 0;
 323         struct uwb_rc_evt_beacon *be;
 324         struct uwb_beacon_frame *bf;
 325         int ies_len;
 326         struct uwb_ie_hdr *ies;
 327 
 328         mutex_lock(&bce->mutex);
 329 
 330         be = bce->be;
 331         if (be) {
 332                 bf = (struct uwb_beacon_frame *)bce->be->BeaconInfo;
 333                 ies_len = be->wBeaconInfoLength - sizeof(struct uwb_beacon_frame);
 334                 ies = (struct uwb_ie_hdr *)bf->IEData;
 335 
 336                 result = uwb_ie_dump_hex(ies, ies_len, buf, size);
 337         }
 338 
 339         mutex_unlock(&bce->mutex);
 340 
 341         return result;
 342 }
 343 
 344 /*
 345  * Verify that the beacon event, frame and IEs are ok
 346  */
 347 static int uwb_verify_beacon(struct uwb_rc *rc, struct uwb_event *evt,
 348                              struct uwb_rc_evt_beacon *be)
 349 {
 350         int result = -EINVAL;
 351         struct uwb_beacon_frame *bf;
 352         struct device *dev = &rc->uwb_dev.dev;
 353 
 354         /* Is there enough data to decode a beacon frame? */
 355         if (evt->notif.size < sizeof(*be) + sizeof(*bf)) {
 356                 dev_err(dev, "BEACON event: Not enough data to decode "
 357                         "(%zu vs %zu bytes needed)\n", evt->notif.size,
 358                         sizeof(*be) + sizeof(*bf));
 359                 goto error;
 360         }
 361         /* FIXME: make sure beacon frame IEs are fine and that the whole thing
 362          * is consistent */
 363         result = 0;
 364 error:
 365         return result;
 366 }
 367 
 368 /*
 369  * Handle UWB_RC_EVT_BEACON events
 370  *
 371  * We check the beacon cache to see how the received beacon fares. If
 372  * is there already we refresh the timestamp. If not we create a new
 373  * entry.
 374  *
 375  * According to the WHCI and WUSB specs, only one beacon frame is
 376  * allowed per notification block, so we don't bother about scanning
 377  * for more.
 378  */
 379 int uwbd_evt_handle_rc_beacon(struct uwb_event *evt)
 380 {
 381         int result = -EINVAL;
 382         struct uwb_rc *rc;
 383         struct uwb_rc_evt_beacon *be;
 384         struct uwb_beacon_frame *bf;
 385         struct uwb_beca_e *bce;
 386 
 387         rc = evt->rc;
 388         be = container_of(evt->notif.rceb, struct uwb_rc_evt_beacon, rceb);
 389         result = uwb_verify_beacon(rc, evt, be);
 390         if (result < 0)
 391                 return result;
 392 
 393         /* FIXME: handle alien beacons. */
 394         if (be->bBeaconType == UWB_RC_BEACON_TYPE_OL_ALIEN ||
 395             be->bBeaconType == UWB_RC_BEACON_TYPE_NOL_ALIEN) {
 396                 return -ENOSYS;
 397         }
 398 
 399         bf = (struct uwb_beacon_frame *) be->BeaconInfo;
 400 
 401         /*
 402          * Drop beacons from devices with a NULL EUI-48 -- they cannot
 403          * be uniquely identified.
 404          *
 405          * It's expected that these will all be WUSB devices and they
 406          * have a WUSB specific connection method so ignoring them
 407          * here shouldn't be a problem.
 408          */
 409         if (uwb_mac_addr_bcast(&bf->Device_Identifier))
 410                 return 0;
 411 
 412         mutex_lock(&rc->uwb_beca.mutex);
 413         bce = __uwb_beca_find_bymac(rc, &bf->Device_Identifier);
 414         if (bce == NULL) {
 415                 /* Not in there, a new device is pinging */
 416                 uwb_beacon_print(evt->rc, be, bf);
 417                 bce = __uwb_beca_add(rc, be, bf, evt->ts_jiffies);
 418                 if (bce == NULL) {
 419                         mutex_unlock(&rc->uwb_beca.mutex);
 420                         return -ENOMEM;
 421                 }
 422         }
 423         mutex_unlock(&rc->uwb_beca.mutex);
 424 
 425         mutex_lock(&bce->mutex);
 426         /* purge old beacon data */
 427         kfree(bce->be);
 428 
 429         /* Update commonly used fields */
 430         bce->ts_jiffies = evt->ts_jiffies;
 431         bce->be = be;
 432         bce->dev_addr = bf->hdr.SrcAddr;
 433         bce->mac_addr = &bf->Device_Identifier;
 434         be->wBPSTOffset = le16_to_cpu(be->wBPSTOffset);
 435         be->wBeaconInfoLength = le16_to_cpu(be->wBeaconInfoLength);
 436         stats_add_sample(&bce->lqe_stats, be->bLQI - 7);
 437         stats_add_sample(&bce->rssi_stats, be->bRSSI + 18);
 438 
 439         /*
 440          * This might be a beacon from a new device.
 441          */
 442         if (bce->uwb_dev == NULL)
 443                 uwbd_dev_onair(evt->rc, bce);
 444 
 445         mutex_unlock(&bce->mutex);
 446 
 447         return 1; /* we keep the event data */
 448 }
 449 
 450 /*
 451  * Handle UWB_RC_EVT_BEACON_SIZE events
 452  *
 453  * XXXXX
 454  */
 455 int uwbd_evt_handle_rc_beacon_size(struct uwb_event *evt)
 456 {
 457         int result = -EINVAL;
 458         struct device *dev = &evt->rc->uwb_dev.dev;
 459         struct uwb_rc_evt_beacon_size *bs;
 460 
 461         /* Is there enough data to decode the event? */
 462         if (evt->notif.size < sizeof(*bs)) {
 463                 dev_err(dev, "BEACON SIZE notification: Not enough data to "
 464                         "decode (%zu vs %zu bytes needed)\n",
 465                         evt->notif.size, sizeof(*bs));
 466                 goto error;
 467         }
 468         bs = container_of(evt->notif.rceb, struct uwb_rc_evt_beacon_size, rceb);
 469         if (0)
 470                 dev_info(dev, "Beacon size changed to %u bytes "
 471                         "(FIXME: action?)\n", le16_to_cpu(bs->wNewBeaconSize));
 472         else {
 473                 /* temporary hack until we do something with this message... */
 474                 static unsigned count;
 475                 if (++count % 1000 == 0)
 476                         dev_info(dev, "Beacon size changed %u times "
 477                                 "(FIXME: action?)\n", count);
 478         }
 479         result = 0;
 480 error:
 481         return result;
 482 }
 483 
 484 /**
 485  * uwbd_evt_handle_rc_bp_slot_change - handle a BP_SLOT_CHANGE event
 486  * @evt: the BP_SLOT_CHANGE notification from the radio controller
 487  *
 488  * If the event indicates that no beacon period slots were available
 489  * then radio controller has transitioned to a non-beaconing state.
 490  * Otherwise, simply save the current beacon slot.
 491  */
 492 int uwbd_evt_handle_rc_bp_slot_change(struct uwb_event *evt)
 493 {
 494         struct uwb_rc *rc = evt->rc;
 495         struct device *dev = &rc->uwb_dev.dev;
 496         struct uwb_rc_evt_bp_slot_change *bpsc;
 497 
 498         if (evt->notif.size < sizeof(*bpsc)) {
 499                 dev_err(dev, "BP SLOT CHANGE event: Not enough data\n");
 500                 return -EINVAL;
 501         }
 502         bpsc = container_of(evt->notif.rceb, struct uwb_rc_evt_bp_slot_change, rceb);
 503 
 504         if (uwb_rc_evt_bp_slot_change_no_slot(bpsc)) {
 505                 dev_err(dev, "stopped beaconing: No free slots in BP\n");
 506                 mutex_lock(&rc->uwb_dev.mutex);
 507                 rc->beaconing = -1;
 508                 mutex_unlock(&rc->uwb_dev.mutex);
 509         } else
 510                 rc->uwb_dev.beacon_slot = uwb_rc_evt_bp_slot_change_slot_num(bpsc);
 511 
 512         return 0;
 513 }
 514 
 515 /**
 516  * Handle UWB_RC_EVT_BPOIE_CHANGE events
 517  *
 518  * XXXXX
 519  */
 520 struct uwb_ie_bpo {
 521         struct uwb_ie_hdr hdr;
 522         u8                bp_length;
 523         u8                data[];
 524 } __attribute__((packed));
 525 
 526 int uwbd_evt_handle_rc_bpoie_change(struct uwb_event *evt)
 527 {
 528         int result = -EINVAL;
 529         struct device *dev = &evt->rc->uwb_dev.dev;
 530         struct uwb_rc_evt_bpoie_change *bpoiec;
 531         struct uwb_ie_bpo *bpoie;
 532         static unsigned count;  /* FIXME: this is a temp hack */
 533         size_t iesize;
 534 
 535         /* Is there enough data to decode it? */
 536         if (evt->notif.size < sizeof(*bpoiec)) {
 537                 dev_err(dev, "BPOIEC notification: Not enough data to "
 538                         "decode (%zu vs %zu bytes needed)\n",
 539                         evt->notif.size, sizeof(*bpoiec));
 540                 goto error;
 541         }
 542         bpoiec = container_of(evt->notif.rceb, struct uwb_rc_evt_bpoie_change, rceb);
 543         iesize = le16_to_cpu(bpoiec->wBPOIELength);
 544         if (iesize < sizeof(*bpoie)) {
 545                 dev_err(dev, "BPOIEC notification: Not enough IE data to "
 546                         "decode (%zu vs %zu bytes needed)\n",
 547                         iesize, sizeof(*bpoie));
 548                 goto error;
 549         }
 550         if (++count % 1000 == 0)        /* Lame placeholder */
 551                 dev_info(dev, "BPOIE: %u changes received\n", count);
 552         /*
 553          * FIXME: At this point we should go over all the IEs in the
 554          *        bpoiec->BPOIE array and act on each.
 555          */
 556         result = 0;
 557 error:
 558         return result;
 559 }
 560 
 561 /*
 562  * Print beaconing state.
 563  */
 564 static ssize_t uwb_rc_beacon_show(struct device *dev,
 565                                   struct device_attribute *attr, char *buf)
 566 {
 567         struct uwb_dev *uwb_dev = to_uwb_dev(dev);
 568         struct uwb_rc *rc = uwb_dev->rc;
 569         ssize_t result;
 570 
 571         mutex_lock(&rc->uwb_dev.mutex);
 572         result = sprintf(buf, "%d\n", rc->beaconing);
 573         mutex_unlock(&rc->uwb_dev.mutex);
 574         return result;
 575 }
 576 
 577 /*
 578  * Start beaconing on the specified channel, or stop beaconing.
 579  */
 580 static ssize_t uwb_rc_beacon_store(struct device *dev,
 581                                    struct device_attribute *attr,
 582                                    const char *buf, size_t size)
 583 {
 584         struct uwb_dev *uwb_dev = to_uwb_dev(dev);
 585         struct uwb_rc *rc = uwb_dev->rc;
 586         int channel;
 587         ssize_t result = -EINVAL;
 588 
 589         result = sscanf(buf, "%d", &channel);
 590         if (result >= 1)
 591                 result = uwb_radio_force_channel(rc, channel);
 592 
 593         return result < 0 ? result : size;
 594 }
 595 DEVICE_ATTR(beacon, S_IRUGO | S_IWUSR, uwb_rc_beacon_show, uwb_rc_beacon_store);
/* [<][>][^][v][top][bottom][index][help] */
root/drivers/staging/uwb/beacon.c

DEFINITIONS
