drivers/uwb/neh.c

   1 /*
   2  * WUSB Wire Adapter: Radio Control Interface (WUSB[8])
   3  * Notification and Event Handling
   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  * The RC interface of the Host Wire Adapter (USB dongle) or WHCI PCI
  24  * card delivers a stream of notifications and events to the
  25  * notification end event endpoint or area. This code takes care of
  26  * getting a buffer with that data, breaking it up in separate
  27  * notifications and events and then deliver those.
  28  *
  29  * Events are answers to commands and they carry a context ID that
  30  * associates them to the command. Notifications are that,
  31  * notifications, they come out of the blue and have a context ID of
  32  * zero. Think of the context ID kind of like a handler. The
  33  * uwb_rc_neh_* code deals with managing context IDs.
  34  *
  35  * This is why you require a handle to operate on a UWB host. When you
  36  * open a handle a context ID is assigned to you.
  37  *
  38  * So, as it is done is:
  39  *
  40  * 1. Add an event handler [uwb_rc_neh_add()] (assigns a ctx id)
  41  * 2. Issue command [rc->cmd(rc, ...)]
  42  * 3. Arm the timeout timer [uwb_rc_neh_arm()]
  43  * 4, Release the reference to the neh [uwb_rc_neh_put()]
  44  * 5. Wait for the callback
  45  * 6. Command result (RCEB) is passed to the callback
  46  *
  47  * If (2) fails, you should remove the handle [uwb_rc_neh_rm()]
  48  * instead of arming the timer.
  49  *
  50  * Handles are for using in *serialized* code, single thread.
  51  *
  52  * When the notification/event comes, the IRQ handler/endpoint
  53  * callback passes the data read to uwb_rc_neh_grok() which will break
  54  * it up in a discrete series of events, look up who is listening for
  55  * them and execute the pertinent callbacks.
  56  *
  57  * If the reader detects an error while reading the data stream, call
  58  * uwb_rc_neh_error().
  59  *
  60  * CONSTRAINTS/ASSUMPTIONS:
  61  *
  62  * - Most notifications/events are small (less thank .5k), copying
  63  *   around is ok.
  64  *
  65  * - Notifications/events are ALWAYS smaller than PAGE_SIZE
  66  *
  67  * - Notifications/events always come in a single piece (ie: a buffer
  68  *   will always contain entire notifications/events).
  69  *
  70  * - we cannot know in advance how long each event is (because they
  71  *   lack a length field in their header--smart move by the standards
  72  *   body, btw). So we need a facility to get the event size given the
  73  *   header. This is what the EST code does (notif/Event Size
  74  *   Tables), check nest.c--as well, you can associate the size to
  75  *   the handle [w/ neh->extra_size()].
  76  *
  77  * - Most notifications/events are fixed size; only a few are variable
  78  *   size (NEST takes care of that).
  79  *
  80  * - Listeners of events expect them, so they usually provide a
  81  *   buffer, as they know the size. Listeners to notifications don't,
  82  *   so we allocate their buffers dynamically.
  83  */
  84 #include <linux/kernel.h>
  85 #include <linux/timer.h>
  86 #include <linux/slab.h>
  87 #include <linux/err.h>
  88
  89 #include "uwb-internal.h"
  90
  91 /*
  92  * UWB Radio Controller Notification/Event Handle
  93  *
  94  * Represents an entity waiting for an event coming from the UWB Radio
  95  * Controller with a given context id (context) and type (evt_type and
  96  * evt). On reception of the notification/event, the callback (cb) is
  97  * called with the event.
  98  *
  99  * If the timer expires before the event is received, the callback is
 100  * called with -ETIMEDOUT as the event size.
 101  */
 102 struct uwb_rc_neh {
 103         struct kref kref;
 104
 105         struct uwb_rc *rc;
 106         u8 evt_type;
 107         __le16 evt;
 108         u8 context;
 109         uwb_rc_cmd_cb_f cb;
 110         void *arg;
 111
 112         struct timer_list timer;
 113         struct list_head list_node;
 114 };
 115
 116 static void uwb_rc_neh_timer(unsigned long arg);
 117
 118 static void uwb_rc_neh_release(struct kref *kref)
 119 {
 120         struct uwb_rc_neh *neh = container_of(kref, struct uwb_rc_neh, kref);
 121
 122         kfree(neh);
 123 }
 124
 125 static void uwb_rc_neh_get(struct uwb_rc_neh *neh)
 126 {
 127         kref_get(&neh->kref);
 128 }
 129
 130 /**
 131  * uwb_rc_neh_put - release reference to a neh
 132  * @neh: the neh
 133  */
 134 void uwb_rc_neh_put(struct uwb_rc_neh *neh)
 135 {
 136         kref_put(&neh->kref, uwb_rc_neh_release);
 137 }
 138
 139
 140 /**
 141  * Assigns @neh a context id from @rc's pool
 142  *
 143  * @rc:     UWB Radio Controller descriptor; @rc->neh_lock taken
 144  * @neh:    Notification/Event Handle
 145  * @returns 0 if context id was assigned ok; < 0 errno on error (if
 146  *          all the context IDs are taken).
 147  *
 148  * (assumes @wa is locked).
 149  *
 150  * NOTE: WUSB spec reserves context ids 0x00 for notifications and
 151  *       0xff is invalid, so they must not be used. Initialization
 152  *       fills up those two in the bitmap so they are not allocated.
 153  *
 154  * We spread the allocation around to reduce the possibility of two
 155  * consecutive opened @neh's getting the same context ID assigned (to
 156  * avoid surprises with late events that timed out long time ago). So
 157  * first we search from where @rc->ctx_roll is, if not found, we
 158  * search from zero.
 159  */
 160 static
 161 int __uwb_rc_ctx_get(struct uwb_rc *rc, struct uwb_rc_neh *neh)
 162 {
 163         int result;
 164         result = find_next_zero_bit(rc->ctx_bm, UWB_RC_CTX_MAX,
 165                                     rc->ctx_roll++);
 166         if (result < UWB_RC_CTX_MAX)
 167                 goto found;
 168         result = find_first_zero_bit(rc->ctx_bm, UWB_RC_CTX_MAX);
 169         if (result < UWB_RC_CTX_MAX)
 170                 goto found;
 171         return -ENFILE;
 172 found:
 173         set_bit(result, rc->ctx_bm);
 174         neh->context = result;
 175         return 0;
 176 }
 177
 178
 179 /** Releases @neh's context ID back to @rc (@rc->neh_lock is locked). */
 180 static
 181 void __uwb_rc_ctx_put(struct uwb_rc *rc, struct uwb_rc_neh *neh)
 182 {
 183         struct device *dev = &rc->uwb_dev.dev;
 184         if (neh->context == 0)
 185                 return;
 186         if (test_bit(neh->context, rc->ctx_bm) == 0) {
 187                 dev_err(dev, "context %u not set in bitmap\n",
 188                         neh->context);
 189                 WARN_ON(1);
 190         }
 191         clear_bit(neh->context, rc->ctx_bm);
 192         neh->context = 0;
 193 }
 194
 195 /**
 196  * uwb_rc_neh_add - add a neh for a radio controller command
 197  * @rc:             the radio controller
 198  * @cmd:            the radio controller command
 199  * @expected_type:  the type of the expected response event
 200  * @expected_event: the expected event ID
 201  * @cb:             callback for when the event is received
 202  * @arg:            argument for the callback
 203  *
 204  * Creates a neh and adds it to the list of those waiting for an
 205  * event.  A context ID will be assigned to the command.
 206  */
 207 struct uwb_rc_neh *uwb_rc_neh_add(struct uwb_rc *rc, struct uwb_rccb *cmd,
 208                                   u8 expected_type, u16 expected_event,
 209                                   uwb_rc_cmd_cb_f cb, void *arg)
 210 {
 211         int result;
 212         unsigned long flags;
 213         struct device *dev = &rc->uwb_dev.dev;
 214         struct uwb_rc_neh *neh;
 215
 216         neh = kzalloc(sizeof(*neh), GFP_KERNEL);
 217         if (neh == NULL) {
 218                 result = -ENOMEM;
 219                 goto error_kzalloc;
 220         }
 221
 222         kref_init(&neh->kref);
 223         INIT_LIST_HEAD(&neh->list_node);
 224         init_timer(&neh->timer);
 225         neh->timer.function = uwb_rc_neh_timer;
 226         neh->timer.data     = (unsigned long)neh;
 227
 228         neh->rc = rc;
 229         neh->evt_type = expected_type;
 230         neh->evt = cpu_to_le16(expected_event);
 231         neh->cb = cb;
 232         neh->arg = arg;
 233
 234         spin_lock_irqsave(&rc->neh_lock, flags);
 235         result = __uwb_rc_ctx_get(rc, neh);
 236         if (result >= 0) {
 237                 cmd->bCommandContext = neh->context;
 238                 list_add_tail(&neh->list_node, &rc->neh_list);
 239                 uwb_rc_neh_get(neh);
 240         }
 241         spin_unlock_irqrestore(&rc->neh_lock, flags);
 242         if (result < 0)
 243                 goto error_ctx_get;
 244
 245         return neh;
 246
 247 error_ctx_get:
 248         kfree(neh);
 249 error_kzalloc:
 250         dev_err(dev, "cannot open handle to radio controller: %d\n", result);
 251         return ERR_PTR(result);
 252 }
 253
 254 static void __uwb_rc_neh_rm(struct uwb_rc *rc, struct uwb_rc_neh *neh)
 255 {
 256         __uwb_rc_ctx_put(rc, neh);
 257         list_del(&neh->list_node);
 258 }
 259
 260 /**
 261  * uwb_rc_neh_rm - remove a neh.
 262  * @rc:  the radio controller
 263  * @neh: the neh to remove
 264  *
 265  * Remove an active neh immediately instead of waiting for the event
 266  * (or a time out).
 267  */
 268 void uwb_rc_neh_rm(struct uwb_rc *rc, struct uwb_rc_neh *neh)
 269 {
 270         unsigned long flags;
 271
 272         spin_lock_irqsave(&rc->neh_lock, flags);
 273         __uwb_rc_neh_rm(rc, neh);
 274         spin_unlock_irqrestore(&rc->neh_lock, flags);
 275
 276         del_timer_sync(&neh->timer);
 277         uwb_rc_neh_put(neh);
 278 }
 279
 280 /**
 281  * uwb_rc_neh_arm - arm an event handler timeout timer
 282  *
 283  * @rc:     UWB Radio Controller
 284  * @neh:    Notification/event handler for @rc
 285  *
 286  * The timer is only armed if the neh is active.
 287  */
 288 void uwb_rc_neh_arm(struct uwb_rc *rc, struct uwb_rc_neh *neh)
 289 {
 290         unsigned long flags;
 291
 292         spin_lock_irqsave(&rc->neh_lock, flags);
 293         if (neh->context)
 294                 mod_timer(&neh->timer,
 295                           jiffies + msecs_to_jiffies(UWB_RC_CMD_TIMEOUT_MS));
 296         spin_unlock_irqrestore(&rc->neh_lock, flags);
 297 }
 298
 299 static void uwb_rc_neh_cb(struct uwb_rc_neh *neh, struct uwb_rceb *rceb, size_t size)
 300 {
 301         (*neh->cb)(neh->rc, neh->arg, rceb, size);
 302         uwb_rc_neh_put(neh);
 303 }
 304
 305 static bool uwb_rc_neh_match(struct uwb_rc_neh *neh, const struct uwb_rceb *rceb)
 306 {
 307         return neh->evt_type == rceb->bEventType
 308                 && neh->evt == rceb->wEvent
 309                 && neh->context == rceb->bEventContext;
 310 }
 311
 312 /**
 313  * Find the handle waiting for a RC Radio Control Event
 314  *
 315  * @rc:         UWB Radio Controller
 316  * @rceb:       Pointer to the RCEB buffer
 317  * @event_size: Pointer to the size of the RCEB buffer. Might be
 318  *              adjusted to take into account the @neh->extra_size
 319  *              settings.
 320  *
 321  * If the listener has no buffer (NULL buffer), one is allocated for
 322  * the right size (the amount of data received). @neh->ptr will point
 323  * to the event payload, which always starts with a 'struct
 324  * uwb_rceb'. kfree() it when done.
 325  */
 326 static
 327 struct uwb_rc_neh *uwb_rc_neh_lookup(struct uwb_rc *rc,
 328                                      const struct uwb_rceb *rceb)
 329 {
 330         struct uwb_rc_neh *neh = NULL, *h;
 331         unsigned long flags;
 332
 333         spin_lock_irqsave(&rc->neh_lock, flags);
 334
 335         list_for_each_entry(h, &rc->neh_list, list_node) {
 336                 if (uwb_rc_neh_match(h, rceb)) {
 337                         neh = h;
 338                         break;
 339                 }
 340         }
 341
 342         if (neh)
 343                 __uwb_rc_neh_rm(rc, neh);
 344
 345         spin_unlock_irqrestore(&rc->neh_lock, flags);
 346
 347         return neh;
 348 }
 349
 350
 351 /*
 352  * Process notifications coming from the radio control interface
 353  *
 354  * @rc:    UWB Radio Control Interface descriptor
 355  * @neh:   Notification/Event Handler @neh->ptr points to
 356  *         @uwb_evt->buffer.
 357  *
 358  * This function is called by the event/notif handling subsystem when
 359  * notifications arrive (hwarc_probe() arms a notification/event handle
 360  * that calls back this function for every received notification; this
 361  * function then will rearm itself).
 362  *
 363  * Notification data buffers are dynamically allocated by the NEH
 364  * handling code in neh.c [uwb_rc_neh_lookup()]. What is actually
 365  * allocated is space to contain the notification data.
 366  *
 367  * Buffers are prefixed with a Radio Control Event Block (RCEB) as
 368  * defined by the WUSB Wired-Adapter Radio Control interface. We
 369  * just use it for the notification code.
 370  *
 371  * On each case statement we just transcode endianess of the different
 372  * fields. We declare a pointer to a RCI definition of an event, and
 373  * then to a UWB definition of the same event (which are the same,
 374  * remember). Event if we use different pointers
 375  */
 376 static
 377 void uwb_rc_notif(struct uwb_rc *rc, struct uwb_rceb *rceb, ssize_t size)
 378 {
 379         struct device *dev = &rc->uwb_dev.dev;
 380         struct uwb_event *uwb_evt;
 381
 382         if (size == -ESHUTDOWN)
 383                 return;
 384         if (size < 0) {
 385                 dev_err(dev, "ignoring event with error code %zu\n",
 386                         size);
 387                 return;
 388         }
 389
 390         uwb_evt = kzalloc(sizeof(*uwb_evt), GFP_ATOMIC);
 391         if (unlikely(uwb_evt == NULL)) {
 392                 dev_err(dev, "no memory to queue event 0x%02x/%04x/%02x\n",
 393                         rceb->bEventType, le16_to_cpu(rceb->wEvent),
 394                         rceb->bEventContext);
 395                 return;
 396         }
 397         uwb_evt->rc = __uwb_rc_get(rc); /* will be put by uwbd's uwbd_event_handle() */
 398         uwb_evt->ts_jiffies = jiffies;
 399         uwb_evt->type = UWB_EVT_TYPE_NOTIF;
 400         uwb_evt->notif.size = size;
 401         uwb_evt->notif.rceb = rceb;
 402
 403         uwbd_event_queue(uwb_evt);
 404 }
 405
 406 static void uwb_rc_neh_grok_event(struct uwb_rc *rc, struct uwb_rceb *rceb, size_t size)
 407 {
 408         struct device *dev = &rc->uwb_dev.dev;
 409         struct uwb_rc_neh *neh;
 410         struct uwb_rceb *notif;
 411
 412         if (rceb->bEventContext == 0) {
 413                 notif = kmalloc(size, GFP_ATOMIC);
 414                 if (notif) {
 415                         memcpy(notif, rceb, size);
 416                         uwb_rc_notif(rc, notif, size);
 417                 } else
 418                         dev_err(dev, "event 0x%02x/%04x/%02x (%zu bytes): no memory\n",
 419                                 rceb->bEventType, le16_to_cpu(rceb->wEvent),
 420                                 rceb->bEventContext, size);
 421         } else {
 422                 neh = uwb_rc_neh_lookup(rc, rceb);
 423                 if (neh) {
 424                         del_timer_sync(&neh->timer);
 425                         uwb_rc_neh_cb(neh, rceb, size);
 426                 } else
 427                         dev_warn(dev, "event 0x%02x/%04x/%02x (%zu bytes): nobody cared\n",
 428                                  rceb->bEventType, le16_to_cpu(rceb->wEvent),
 429                                  rceb->bEventContext, size);
 430         }
 431 }
 432
 433 /**
 434  * Given a buffer with one or more UWB RC events/notifications, break
 435  * them up and dispatch them.
 436  *
 437  * @rc:       UWB Radio Controller
 438  * @buf:      Buffer with the stream of notifications/events
 439  * @buf_size: Amount of data in the buffer
 440  *
 441  * Note each notification/event starts always with a 'struct
 442  * uwb_rceb', so the minimum size if 4 bytes.
 443  *
 444  * The device may pass us events formatted differently than expected.
 445  * These are first filtered, potentially creating a new event in a new
 446  * memory location. If a new event is created by the filter it is also
 447  * freed here.
 448  *
 449  * For each notif/event, tries to guess the size looking at the EST
 450  * tables, then looks for a neh that is waiting for that event and if
 451  * found, copies the payload to the neh's buffer and calls it back. If
 452  * not, the data is ignored.
 453  *
 454  * Note that if we can't find a size description in the EST tables, we
 455  * still might find a size in the 'neh' handle in uwb_rc_neh_lookup().
 456  *
 457  * Assumptions:
 458  *
 459  *   @rc->neh_lock is NOT taken
 460  *
 461  * We keep track of various sizes here:
 462  * size:      contains the size of the buffer that is processed for the
 463  *            incoming event. this buffer may contain events that are not
 464  *            formatted as WHCI.
 465  * real_size: the actual space taken by this event in the buffer.
 466  *            We need to keep track of the real size of an event to be able to
 467  *            advance the buffer correctly.
 468  * event_size: the size of the event as expected by the core layer
 469  *            [OR] the size of the event after filtering. if the filtering
 470  *            created a new event in a new memory location then this is
 471  *            effectively the size of a new event buffer
 472  */
 473 void uwb_rc_neh_grok(struct uwb_rc *rc, void *buf, size_t buf_size)
 474 {
 475         struct device *dev = &rc->uwb_dev.dev;
 476         void *itr;
 477         struct uwb_rceb *rceb;
 478         size_t size, real_size, event_size;
 479         int needtofree;
 480
 481         itr = buf;
 482         size = buf_size;
 483         while (size > 0) {
 484                 if (size < sizeof(*rceb)) {
 485                         dev_err(dev, "not enough data in event buffer to "
 486                                 "process incoming events (%zu left, minimum is "
 487                                 "%zu)\n", size, sizeof(*rceb));
 488                         break;
 489                 }
 490
 491                 rceb = itr;
 492                 if (rc->filter_event) {
 493                         needtofree = rc->filter_event(rc, &rceb, size,
 494                                                       &real_size, &event_size);
 495                         if (needtofree < 0 && needtofree != -ENOANO) {
 496                                 dev_err(dev, "BUG: Unable to filter event "
 497                                         "(0x%02x/%04x/%02x) from "
 498                                         "device. \n", rceb->bEventType,
 499                                         le16_to_cpu(rceb->wEvent),
 500                                         rceb->bEventContext);
 501                                 break;
 502                         }
 503                 } else
 504                         needtofree = -ENOANO;
 505                 /* do real processing if there was no filtering or the
 506                  * filtering didn't act */
 507                 if (needtofree == -ENOANO) {
 508                         ssize_t ret = uwb_est_find_size(rc, rceb, size);
 509                         if (ret < 0)
 510                                 break;
 511                         if (ret > size) {
 512                                 dev_err(dev, "BUG: hw sent incomplete event "
 513                                         "0x%02x/%04x/%02x (%zd bytes), only got "
 514                                         "%zu bytes. We don't handle that.\n",
 515                                         rceb->bEventType, le16_to_cpu(rceb->wEvent),
 516                                         rceb->bEventContext, ret, size);
 517                                 break;
 518                         }
 519                         real_size = event_size = ret;
 520                 }
 521                 uwb_rc_neh_grok_event(rc, rceb, event_size);
 522
 523                 if (needtofree == 1)
 524                         kfree(rceb);
 525
 526                 itr += real_size;
 527                 size -= real_size;
 528         }
 529 }
 530 EXPORT_SYMBOL_GPL(uwb_rc_neh_grok);
 531
 532
 533 /**
 534  * The entity that reads from the device notification/event channel has
 535  * detected an error.
 536  *
 537  * @rc:    UWB Radio Controller
 538  * @error: Errno error code
 539  *
 540  */
 541 void uwb_rc_neh_error(struct uwb_rc *rc, int error)
 542 {
 543         struct uwb_rc_neh *neh;
 544         unsigned long flags;
 545
 546         for (;;) {
 547                 spin_lock_irqsave(&rc->neh_lock, flags);
 548                 if (list_empty(&rc->neh_list)) {
 549                         spin_unlock_irqrestore(&rc->neh_lock, flags);
 550                         break;
 551                 }
 552                 neh = list_first_entry(&rc->neh_list, struct uwb_rc_neh, list_node);
 553                 __uwb_rc_neh_rm(rc, neh);
 554                 spin_unlock_irqrestore(&rc->neh_lock, flags);
 555
 556                 del_timer_sync(&neh->timer);
 557                 uwb_rc_neh_cb(neh, NULL, error);
 558         }
 559 }
 560 EXPORT_SYMBOL_GPL(uwb_rc_neh_error);
 561
 562
 563 static void uwb_rc_neh_timer(unsigned long arg)
 564 {
 565         struct uwb_rc_neh *neh = (struct uwb_rc_neh *)arg;
 566         struct uwb_rc *rc = neh->rc;
 567         unsigned long flags;
 568
 569         spin_lock_irqsave(&rc->neh_lock, flags);
 570         if (neh->context)
 571                 __uwb_rc_neh_rm(rc, neh);
 572         else
 573                 neh = NULL;
 574         spin_unlock_irqrestore(&rc->neh_lock, flags);
 575
 576         if (neh)
 577                 uwb_rc_neh_cb(neh, NULL, -ETIMEDOUT);
 578 }
 579
 580 /** Initializes the @rc's neh subsystem
 581  */
 582 void uwb_rc_neh_create(struct uwb_rc *rc)
 583 {
 584         spin_lock_init(&rc->neh_lock);
 585         INIT_LIST_HEAD(&rc->neh_list);
 586         set_bit(0, rc->ctx_bm);         /* 0 is reserved (see [WUSB] table 8-65) */
 587         set_bit(0xff, rc->ctx_bm);      /* and 0xff is invalid */
 588         rc->ctx_roll = 1;
 589 }
 590
 591
 592 /** Release's the @rc's neh subsystem */
 593 void uwb_rc_neh_destroy(struct uwb_rc *rc)
 594 {
 595         unsigned long flags;
 596         struct uwb_rc_neh *neh;
 597
 598         for (;;) {
 599                 spin_lock_irqsave(&rc->neh_lock, flags);
 600                 if (list_empty(&rc->neh_list)) {
 601                         spin_unlock_irqrestore(&rc->neh_lock, flags);
 602                         break;
 603                 }
 604                 neh = list_first_entry(&rc->neh_list, struct uwb_rc_neh, list_node);
 605                 __uwb_rc_neh_rm(rc, neh);
 606                 spin_unlock_irqrestore(&rc->neh_lock, flags);
 607
 608                 del_timer_sync(&neh->timer);
 609                 uwb_rc_neh_put(neh);
 610         }
 611 }