drivers/most/most_snd.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * sound.c - Sound component for Mostcore
   4  *
   5  * Copyright (C) 2015 Microchip Technology Germany II GmbH & Co. KG
   6  */
   7
   8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   9
  10 #include <linux/module.h>
  11 #include <linux/printk.h>
  12 #include <linux/kernel.h>
  13 #include <linux/slab.h>
  14 #include <linux/init.h>
  15 #include <sound/core.h>
  16 #include <sound/pcm.h>
  17 #include <sound/pcm_params.h>
  18 #include <linux/sched.h>
  19 #include <linux/kthread.h>
  20 #include <linux/most.h>
  21
  22 #define DRIVER_NAME "sound"
  23 #define STRING_SIZE     80
  24
  25 static struct most_component comp;
  26
  27 /**
  28  * struct channel - private structure to keep channel specific data
  29  * @substream: stores the substream structure
  30  * @pcm_hardware: low-level hardware description
  31  * @iface: interface for which the channel belongs to
  32  * @cfg: channel configuration
  33  * @card: registered sound card
  34  * @list: list for private use
  35  * @id: channel index
  36  * @period_pos: current period position (ring buffer)
  37  * @buffer_pos: current buffer position (ring buffer)
  38  * @is_stream_running: identifies whether a stream is running or not
  39  * @opened: set when the stream is opened
  40  * @playback_task: playback thread
  41  * @playback_waitq: waitq used by playback thread
  42  * @copy_fn: copy function for PCM-specific format and width
  43  */
  44 struct channel {
  45         struct snd_pcm_substream *substream;
  46         struct snd_pcm_hardware pcm_hardware;
  47         struct most_interface *iface;
  48         struct most_channel_config *cfg;
  49         struct snd_card *card;
  50         struct list_head list;
  51         int id;
  52         unsigned int period_pos;
  53         unsigned int buffer_pos;
  54         bool is_stream_running;
  55         struct task_struct *playback_task;
  56         wait_queue_head_t playback_waitq;
  57         void (*copy_fn)(void *alsa, void *most, unsigned int bytes);
  58 };
  59
  60 struct sound_adapter {
  61         struct list_head dev_list;
  62         struct most_interface *iface;
  63         struct snd_card *card;
  64         struct list_head list;
  65         bool registered;
  66         int pcm_dev_idx;
  67 };
  68
  69 static struct list_head adpt_list;
  70
  71 #define MOST_PCM_INFO (SNDRV_PCM_INFO_MMAP | \
  72                        SNDRV_PCM_INFO_MMAP_VALID | \
  73                        SNDRV_PCM_INFO_BATCH | \
  74                        SNDRV_PCM_INFO_INTERLEAVED | \
  75                        SNDRV_PCM_INFO_BLOCK_TRANSFER)
  76
  77 static void swap_copy16(u16 *dest, const u16 *source, unsigned int bytes)
  78 {
  79         unsigned int i = 0;
  80
  81         while (i < (bytes / 2)) {
  82                 dest[i] = swab16(source[i]);
  83                 i++;
  84         }
  85 }
  86
  87 static void swap_copy24(u8 *dest, const u8 *source, unsigned int bytes)
  88 {
  89         unsigned int i = 0;
  90
  91         if (bytes < 2)
  92                 return;
  93         while (i < bytes - 2) {
  94                 dest[i] = source[i + 2];
  95                 dest[i + 1] = source[i + 1];
  96                 dest[i + 2] = source[i];
  97                 i += 3;
  98         }
  99 }
 100
 101 static void swap_copy32(u32 *dest, const u32 *source, unsigned int bytes)
 102 {
 103         unsigned int i = 0;
 104
 105         while (i < bytes / 4) {
 106                 dest[i] = swab32(source[i]);
 107                 i++;
 108         }
 109 }
 110
 111 static void alsa_to_most_memcpy(void *alsa, void *most, unsigned int bytes)
 112 {
 113         memcpy(most, alsa, bytes);
 114 }
 115
 116 static void alsa_to_most_copy16(void *alsa, void *most, unsigned int bytes)
 117 {
 118         swap_copy16(most, alsa, bytes);
 119 }
 120
 121 static void alsa_to_most_copy24(void *alsa, void *most, unsigned int bytes)
 122 {
 123         swap_copy24(most, alsa, bytes);
 124 }
 125
 126 static void alsa_to_most_copy32(void *alsa, void *most, unsigned int bytes)
 127 {
 128         swap_copy32(most, alsa, bytes);
 129 }
 130
 131 static void most_to_alsa_memcpy(void *alsa, void *most, unsigned int bytes)
 132 {
 133         memcpy(alsa, most, bytes);
 134 }
 135
 136 static void most_to_alsa_copy16(void *alsa, void *most, unsigned int bytes)
 137 {
 138         swap_copy16(alsa, most, bytes);
 139 }
 140
 141 static void most_to_alsa_copy24(void *alsa, void *most, unsigned int bytes)
 142 {
 143         swap_copy24(alsa, most, bytes);
 144 }
 145
 146 static void most_to_alsa_copy32(void *alsa, void *most, unsigned int bytes)
 147 {
 148         swap_copy32(alsa, most, bytes);
 149 }
 150
 151 /**
 152  * get_channel - get pointer to channel
 153  * @iface: interface structure
 154  * @channel_id: channel ID
 155  *
 156  * This traverses the channel list and returns the channel matching the
 157  * ID and interface.
 158  *
 159  * Returns pointer to channel on success or NULL otherwise.
 160  */
 161 static struct channel *get_channel(struct most_interface *iface,
 162                                    int channel_id)
 163 {
 164         struct sound_adapter *adpt = iface->priv;
 165         struct channel *channel;
 166
 167         list_for_each_entry(channel, &adpt->dev_list, list) {
 168                 if ((channel->iface == iface) && (channel->id == channel_id))
 169                         return channel;
 170         }
 171         return NULL;
 172 }
 173
 174 /**
 175  * copy_data - implements data copying function
 176  * @channel: channel
 177  * @mbo: MBO from core
 178  *
 179  * Copy data from/to ring buffer to/from MBO and update the buffer position
 180  */
 181 static bool copy_data(struct channel *channel, struct mbo *mbo)
 182 {
 183         struct snd_pcm_runtime *const runtime = channel->substream->runtime;
 184         unsigned int const frame_bytes = channel->cfg->subbuffer_size;
 185         unsigned int const buffer_size = runtime->buffer_size;
 186         unsigned int frames;
 187         unsigned int fr0;
 188
 189         if (channel->cfg->direction & MOST_CH_RX)
 190                 frames = mbo->processed_length / frame_bytes;
 191         else
 192                 frames = mbo->buffer_length / frame_bytes;
 193         fr0 = min(buffer_size - channel->buffer_pos, frames);
 194
 195         channel->copy_fn(runtime->dma_area + channel->buffer_pos * frame_bytes,
 196                          mbo->virt_address,
 197                          fr0 * frame_bytes);
 198
 199         if (frames > fr0) {
 200                 /* wrap around at end of ring buffer */
 201                 channel->copy_fn(runtime->dma_area,
 202                                  mbo->virt_address + fr0 * frame_bytes,
 203                                  (frames - fr0) * frame_bytes);
 204         }
 205
 206         channel->buffer_pos += frames;
 207         if (channel->buffer_pos >= buffer_size)
 208                 channel->buffer_pos -= buffer_size;
 209         channel->period_pos += frames;
 210         if (channel->period_pos >= runtime->period_size) {
 211                 channel->period_pos -= runtime->period_size;
 212                 return true;
 213         }
 214         return false;
 215 }
 216
 217 /**
 218  * playback_thread - function implements the playback thread
 219  * @data: private data
 220  *
 221  * Thread which does the playback functionality in a loop. It waits for a free
 222  * MBO from mostcore for a particular channel and copy the data from ring buffer
 223  * to MBO. Submit the MBO back to mostcore, after copying the data.
 224  *
 225  * Returns 0 on success or error code otherwise.
 226  */
 227 static int playback_thread(void *data)
 228 {
 229         struct channel *const channel = data;
 230
 231         while (!kthread_should_stop()) {
 232                 struct mbo *mbo = NULL;
 233                 bool period_elapsed = false;
 234
 235                 wait_event_interruptible(
 236                         channel->playback_waitq,
 237                         kthread_should_stop() ||
 238                         (channel->is_stream_running &&
 239                          (mbo = most_get_mbo(channel->iface, channel->id,
 240                                              &comp))));
 241                 if (!mbo)
 242                         continue;
 243
 244                 if (channel->is_stream_running)
 245                         period_elapsed = copy_data(channel, mbo);
 246                 else
 247                         memset(mbo->virt_address, 0, mbo->buffer_length);
 248
 249                 most_submit_mbo(mbo);
 250                 if (period_elapsed)
 251                         snd_pcm_period_elapsed(channel->substream);
 252         }
 253         return 0;
 254 }
 255
 256 /**
 257  * pcm_open - implements open callback function for PCM middle layer
 258  * @substream: pointer to ALSA PCM substream
 259  *
 260  * This is called when a PCM substream is opened. At least, the function should
 261  * initialize the runtime->hw record.
 262  *
 263  * Returns 0 on success or error code otherwise.
 264  */
 265 static int pcm_open(struct snd_pcm_substream *substream)
 266 {
 267         struct channel *channel = substream->private_data;
 268         struct snd_pcm_runtime *runtime = substream->runtime;
 269         struct most_channel_config *cfg = channel->cfg;
 270         int ret;
 271
 272         channel->substream = substream;
 273
 274         if (cfg->direction == MOST_CH_TX) {
 275                 channel->playback_task = kthread_run(playback_thread, channel,
 276                                                      "most_audio_playback");
 277                 if (IS_ERR(channel->playback_task)) {
 278                         pr_err("Couldn't start thread\n");
 279                         return PTR_ERR(channel->playback_task);
 280                 }
 281         }
 282
 283         ret = most_start_channel(channel->iface, channel->id, &comp);
 284         if (ret) {
 285                 pr_err("most_start_channel() failed!\n");
 286                 if (cfg->direction == MOST_CH_TX)
 287                         kthread_stop(channel->playback_task);
 288                 return ret;
 289         }
 290
 291         runtime->hw = channel->pcm_hardware;
 292         return 0;
 293 }
 294
 295 /**
 296  * pcm_close - implements close callback function for PCM middle layer
 297  * @substream: sub-stream pointer
 298  *
 299  * Obviously, this is called when a PCM substream is closed. Any private
 300  * instance for a PCM substream allocated in the open callback will be
 301  * released here.
 302  *
 303  * Returns 0 on success or error code otherwise.
 304  */
 305 static int pcm_close(struct snd_pcm_substream *substream)
 306 {
 307         struct channel *channel = substream->private_data;
 308
 309         if (channel->cfg->direction == MOST_CH_TX)
 310                 kthread_stop(channel->playback_task);
 311         most_stop_channel(channel->iface, channel->id, &comp);
 312         return 0;
 313 }
 314
 315 /**
 316  * pcm_prepare - implements prepare callback function for PCM middle layer
 317  * @substream: substream pointer
 318  *
 319  * This callback is called when the PCM is "prepared". Format rate, sample rate,
 320  * etc., can be set here. This callback can be called many times at each setup.
 321  *
 322  * Returns 0 on success or error code otherwise.
 323  */
 324 static int pcm_prepare(struct snd_pcm_substream *substream)
 325 {
 326         struct channel *channel = substream->private_data;
 327         struct snd_pcm_runtime *runtime = substream->runtime;
 328         struct most_channel_config *cfg = channel->cfg;
 329         int width = snd_pcm_format_physical_width(runtime->format);
 330
 331         channel->copy_fn = NULL;
 332
 333         if (cfg->direction == MOST_CH_TX) {
 334                 if (snd_pcm_format_big_endian(runtime->format) || width == 8)
 335                         channel->copy_fn = alsa_to_most_memcpy;
 336                 else if (width == 16)
 337                         channel->copy_fn = alsa_to_most_copy16;
 338                 else if (width == 24)
 339                         channel->copy_fn = alsa_to_most_copy24;
 340                 else if (width == 32)
 341                         channel->copy_fn = alsa_to_most_copy32;
 342         } else {
 343                 if (snd_pcm_format_big_endian(runtime->format) || width == 8)
 344                         channel->copy_fn = most_to_alsa_memcpy;
 345                 else if (width == 16)
 346                         channel->copy_fn = most_to_alsa_copy16;
 347                 else if (width == 24)
 348                         channel->copy_fn = most_to_alsa_copy24;
 349                 else if (width == 32)
 350                         channel->copy_fn = most_to_alsa_copy32;
 351         }
 352
 353         if (!channel->copy_fn)
 354                 return -EINVAL;
 355         channel->period_pos = 0;
 356         channel->buffer_pos = 0;
 357         return 0;
 358 }
 359
 360 /**
 361  * pcm_trigger - implements trigger callback function for PCM middle layer
 362  * @substream: substream pointer
 363  * @cmd: action to perform
 364  *
 365  * This is called when the PCM is started, stopped or paused. The action will be
 366  * specified in the second argument, SNDRV_PCM_TRIGGER_XXX
 367  *
 368  * Returns 0 on success or error code otherwise.
 369  */
 370 static int pcm_trigger(struct snd_pcm_substream *substream, int cmd)
 371 {
 372         struct channel *channel = substream->private_data;
 373
 374         switch (cmd) {
 375         case SNDRV_PCM_TRIGGER_START:
 376                 channel->is_stream_running = true;
 377                 wake_up_interruptible(&channel->playback_waitq);
 378                 return 0;
 379
 380         case SNDRV_PCM_TRIGGER_STOP:
 381                 channel->is_stream_running = false;
 382                 return 0;
 383
 384         default:
 385                 return -EINVAL;
 386         }
 387         return 0;
 388 }
 389
 390 /**
 391  * pcm_pointer - implements pointer callback function for PCM middle layer
 392  * @substream: substream pointer
 393  *
 394  * This callback is called when the PCM middle layer inquires the current
 395  * hardware position on the buffer. The position must be returned in frames,
 396  * ranging from 0 to buffer_size-1.
 397  */
 398 static snd_pcm_uframes_t pcm_pointer(struct snd_pcm_substream *substream)
 399 {
 400         struct channel *channel = substream->private_data;
 401
 402         return channel->buffer_pos;
 403 }
 404
 405 /*
 406  * Initialization of struct snd_pcm_ops
 407  */
 408 static const struct snd_pcm_ops pcm_ops = {
 409         .open       = pcm_open,
 410         .close      = pcm_close,
 411         .prepare    = pcm_prepare,
 412         .trigger    = pcm_trigger,
 413         .pointer    = pcm_pointer,
 414 };
 415
 416 static int split_arg_list(char *buf, u16 *ch_num, char **sample_res)
 417 {
 418         char *num;
 419         int ret;
 420
 421         num = strsep(&buf, "x");
 422         if (!num)
 423                 goto err;
 424         ret = kstrtou16(num, 0, ch_num);
 425         if (ret)
 426                 goto err;
 427         *sample_res = strsep(&buf, ".\n");
 428         if (!*sample_res)
 429                 goto err;
 430         return 0;
 431
 432 err:
 433         pr_err("Bad PCM format\n");
 434         return -EINVAL;
 435 }
 436
 437 static const struct sample_resolution_info {
 438         const char *sample_res;
 439         int bytes;
 440         u64 formats;
 441 } sinfo[] = {
 442         { "8", 1, SNDRV_PCM_FMTBIT_S8 },
 443         { "16", 2, SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE },
 444         { "24", 3, SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_3BE },
 445         { "32", 4, SNDRV_PCM_FMTBIT_S32_LE | SNDRV_PCM_FMTBIT_S32_BE },
 446 };
 447
 448 static int audio_set_hw_params(struct snd_pcm_hardware *pcm_hw,
 449                                u16 ch_num, char *sample_res,
 450                                struct most_channel_config *cfg)
 451 {
 452         int i;
 453
 454         for (i = 0; i < ARRAY_SIZE(sinfo); i++) {
 455                 if (!strcmp(sample_res, sinfo[i].sample_res))
 456                         goto found;
 457         }
 458         pr_err("Unsupported PCM format\n");
 459         return -EINVAL;
 460
 461 found:
 462         if (!ch_num) {
 463                 pr_err("Bad number of channels\n");
 464                 return -EINVAL;
 465         }
 466
 467         if (cfg->subbuffer_size != ch_num * sinfo[i].bytes) {
 468                 pr_err("Audio resolution doesn't fit subbuffer size\n");
 469                 return -EINVAL;
 470         }
 471
 472         pcm_hw->info = MOST_PCM_INFO;
 473         pcm_hw->rates = SNDRV_PCM_RATE_48000;
 474         pcm_hw->rate_min = 48000;
 475         pcm_hw->rate_max = 48000;
 476         pcm_hw->buffer_bytes_max = cfg->num_buffers * cfg->buffer_size;
 477         pcm_hw->period_bytes_min = cfg->buffer_size;
 478         pcm_hw->period_bytes_max = cfg->buffer_size;
 479         pcm_hw->periods_min = 1;
 480         pcm_hw->periods_max = cfg->num_buffers;
 481         pcm_hw->channels_min = ch_num;
 482         pcm_hw->channels_max = ch_num;
 483         pcm_hw->formats = sinfo[i].formats;
 484         return 0;
 485 }
 486
 487 static void release_adapter(struct sound_adapter *adpt)
 488 {
 489         struct channel *channel, *tmp;
 490
 491         list_for_each_entry_safe(channel, tmp, &adpt->dev_list, list) {
 492                 list_del(&channel->list);
 493                 kfree(channel);
 494         }
 495         if (adpt->card)
 496                 snd_card_free(adpt->card);
 497         list_del(&adpt->list);
 498         kfree(adpt);
 499 }
 500
 501 /**
 502  * audio_probe_channel - probe function of the driver module
 503  * @iface: pointer to interface instance
 504  * @channel_id: channel index/ID
 505  * @cfg: pointer to actual channel configuration
 506  * @device_name: name of the device to be created in /dev
 507  * @arg_list: string that provides the desired audio resolution
 508  *
 509  * Creates sound card, pcm device, sets pcm ops and registers sound card.
 510  *
 511  * Returns 0 on success or error code otherwise.
 512  */
 513 static int audio_probe_channel(struct most_interface *iface, int channel_id,
 514                                struct most_channel_config *cfg,
 515                                char *device_name, char *arg_list)
 516 {
 517         struct channel *channel;
 518         struct sound_adapter *adpt;
 519         struct snd_pcm *pcm;
 520         int playback_count = 0;
 521         int capture_count = 0;
 522         int ret;
 523         int direction;
 524         u16 ch_num;
 525         char *sample_res;
 526         char arg_list_cpy[STRING_SIZE];
 527
 528         if (cfg->data_type != MOST_CH_SYNC) {
 529                 pr_err("Incompatible channel type\n");
 530                 return -EINVAL;
 531         }
 532         strscpy(arg_list_cpy, arg_list, STRING_SIZE);
 533         ret = split_arg_list(arg_list_cpy, &ch_num, &sample_res);
 534         if (ret < 0)
 535                 return ret;
 536
 537         list_for_each_entry(adpt, &adpt_list, list) {
 538                 if (adpt->iface != iface)
 539                         continue;
 540                 if (adpt->registered)
 541                         return -ENOSPC;
 542                 adpt->pcm_dev_idx++;
 543                 goto skip_adpt_alloc;
 544         }
 545         adpt = kzalloc(sizeof(*adpt), GFP_KERNEL);
 546         if (!adpt)
 547                 return -ENOMEM;
 548
 549         adpt->iface = iface;
 550         INIT_LIST_HEAD(&adpt->dev_list);
 551         iface->priv = adpt;
 552         list_add_tail(&adpt->list, &adpt_list);
 553         ret = snd_card_new(iface->driver_dev, -1, "INIC", THIS_MODULE,
 554                            sizeof(*channel), &adpt->card);
 555         if (ret < 0)
 556                 goto err_free_adpt;
 557         snprintf(adpt->card->driver, sizeof(adpt->card->driver),
 558                  "%s", DRIVER_NAME);
 559         snprintf(adpt->card->shortname, sizeof(adpt->card->shortname),
 560                  "Microchip INIC");
 561         snprintf(adpt->card->longname, sizeof(adpt->card->longname),
 562                  "%s at %s", adpt->card->shortname, iface->description);
 563 skip_adpt_alloc:
 564         if (get_channel(iface, channel_id)) {
 565                 pr_err("channel (%s:%d) is already linked\n",
 566                        iface->description, channel_id);
 567                 return -EEXIST;
 568         }
 569
 570         if (cfg->direction == MOST_CH_TX) {
 571                 playback_count = 1;
 572                 direction = SNDRV_PCM_STREAM_PLAYBACK;
 573         } else {
 574                 capture_count = 1;
 575                 direction = SNDRV_PCM_STREAM_CAPTURE;
 576         }
 577         channel = kzalloc(sizeof(*channel), GFP_KERNEL);
 578         if (!channel) {
 579                 ret = -ENOMEM;
 580                 goto err_free_adpt;
 581         }
 582         channel->card = adpt->card;
 583         channel->cfg = cfg;
 584         channel->iface = iface;
 585         channel->id = channel_id;
 586         init_waitqueue_head(&channel->playback_waitq);
 587         list_add_tail(&channel->list, &adpt->dev_list);
 588
 589         ret = audio_set_hw_params(&channel->pcm_hardware, ch_num, sample_res,
 590                                   cfg);
 591         if (ret)
 592                 goto err_free_adpt;
 593
 594         ret = snd_pcm_new(adpt->card, device_name, adpt->pcm_dev_idx,
 595                           playback_count, capture_count, &pcm);
 596
 597         if (ret < 0)
 598                 goto err_free_adpt;
 599
 600         pcm->private_data = channel;
 601         strscpy(pcm->name, device_name, sizeof(pcm->name));
 602         snd_pcm_set_ops(pcm, direction, &pcm_ops);
 603         snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, 0, 0);
 604         return 0;
 605
 606 err_free_adpt:
 607         release_adapter(adpt);
 608         return ret;
 609 }
 610
 611 static int audio_create_sound_card(void)
 612 {
 613         int ret;
 614         struct sound_adapter *adpt;
 615
 616         list_for_each_entry(adpt, &adpt_list, list) {
 617                 if (!adpt->registered)
 618                         goto adpt_alloc;
 619         }
 620         return -ENODEV;
 621 adpt_alloc:
 622         ret = snd_card_register(adpt->card);
 623         if (ret < 0) {
 624                 release_adapter(adpt);
 625                 return ret;
 626         }
 627         adpt->registered = true;
 628         return 0;
 629 }
 630
 631 /**
 632  * audio_disconnect_channel - function to disconnect a channel
 633  * @iface: pointer to interface instance
 634  * @channel_id: channel index
 635  *
 636  * This frees allocated memory and removes the sound card from ALSA
 637  *
 638  * Returns 0 on success or error code otherwise.
 639  */
 640 static int audio_disconnect_channel(struct most_interface *iface,
 641                                     int channel_id)
 642 {
 643         struct channel *channel;
 644         struct sound_adapter *adpt = iface->priv;
 645
 646         channel = get_channel(iface, channel_id);
 647         if (!channel)
 648                 return -EINVAL;
 649
 650         list_del(&channel->list);
 651
 652         kfree(channel);
 653         if (list_empty(&adpt->dev_list))
 654                 release_adapter(adpt);
 655         return 0;
 656 }
 657
 658 /**
 659  * audio_rx_completion - completion handler for rx channels
 660  * @mbo: pointer to buffer object that has completed
 661  *
 662  * This searches for the channel this MBO belongs to and copy the data from MBO
 663  * to ring buffer
 664  *
 665  * Returns 0 on success or error code otherwise.
 666  */
 667 static int audio_rx_completion(struct mbo *mbo)
 668 {
 669         struct channel *channel = get_channel(mbo->ifp, mbo->hdm_channel_id);
 670         bool period_elapsed = false;
 671
 672         if (!channel)
 673                 return -EINVAL;
 674         if (channel->is_stream_running)
 675                 period_elapsed = copy_data(channel, mbo);
 676         most_put_mbo(mbo);
 677         if (period_elapsed)
 678                 snd_pcm_period_elapsed(channel->substream);
 679         return 0;
 680 }
 681
 682 /**
 683  * audio_tx_completion - completion handler for tx channels
 684  * @iface: pointer to interface instance
 685  * @channel_id: channel index/ID
 686  *
 687  * This searches the channel that belongs to this combination of interface
 688  * pointer and channel ID and wakes a process sitting in the wait queue of
 689  * this channel.
 690  *
 691  * Returns 0 on success or error code otherwise.
 692  */
 693 static int audio_tx_completion(struct most_interface *iface, int channel_id)
 694 {
 695         struct channel *channel = get_channel(iface, channel_id);
 696
 697         if (!channel)
 698                 return -EINVAL;
 699
 700         wake_up_interruptible(&channel->playback_waitq);
 701         return 0;
 702 }
 703
 704 /*
 705  * Initialization of the struct most_component
 706  */
 707 static struct most_component comp = {
 708         .mod = THIS_MODULE,
 709         .name = DRIVER_NAME,
 710         .probe_channel = audio_probe_channel,
 711         .disconnect_channel = audio_disconnect_channel,
 712         .rx_completion = audio_rx_completion,
 713         .tx_completion = audio_tx_completion,
 714         .cfg_complete = audio_create_sound_card,
 715 };
 716
 717 static int __init audio_init(void)
 718 {
 719         int ret;
 720
 721         INIT_LIST_HEAD(&adpt_list);
 722
 723         ret = most_register_component(&comp);
 724         if (ret) {
 725                 pr_err("Failed to register %s\n", comp.name);
 726                 return ret;
 727         }
 728         ret = most_register_configfs_subsys(&comp);
 729         if (ret) {
 730                 pr_err("Failed to register %s configfs subsys\n", comp.name);
 731                 most_deregister_component(&comp);
 732         }
 733         return ret;
 734 }
 735
 736 static void __exit audio_exit(void)
 737 {
 738         most_deregister_configfs_subsys(&comp);
 739         most_deregister_component(&comp);
 740 }
 741
 742 module_init(audio_init);
 743 module_exit(audio_exit);
 744
 745 MODULE_LICENSE("GPL");
 746 MODULE_AUTHOR("Christian Gromm <christian.gromm@microchip.com>");
 747 MODULE_DESCRIPTION("Sound Component Module for Mostcore");