sound/drivers/aloop.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Loopback soundcard
   4  *
   5  *  Original code:
   6  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
   7  *
   8  *  More accurate positioning and full-duplex support:
   9  *  Copyright (c) Ahmet İnan <ainan at mathematik.uni-freiburg.de>
  10  *
  11  *  Major (almost complete) rewrite:
  12  *  Copyright (c) by Takashi Iwai <tiwai@suse.de>
  13  *
  14  *  A next major update in 2010 (separate timers for playback and capture):
  15  *  Copyright (c) Jaroslav Kysela <perex@perex.cz>
  16  */
  17
  18 #include <linux/init.h>
  19 #include <linux/jiffies.h>
  20 #include <linux/slab.h>
  21 #include <linux/time.h>
  22 #include <linux/wait.h>
  23 #include <linux/module.h>
  24 #include <linux/platform_device.h>
  25 #include <sound/core.h>
  26 #include <sound/control.h>
  27 #include <sound/pcm.h>
  28 #include <sound/pcm_params.h>
  29 #include <sound/info.h>
  30 #include <sound/initval.h>
  31 #include <sound/timer.h>
  32
  33 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
  34 MODULE_DESCRIPTION("A loopback soundcard");
  35 MODULE_LICENSE("GPL");
  36 MODULE_SUPPORTED_DEVICE("{{ALSA,Loopback soundcard}}");
  37
  38 #define MAX_PCM_SUBSTREAMS      8
  39
  40 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;      /* Index 0-MAX */
  41 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;       /* ID for this card */
  42 static bool enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
  43 static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
  44 static int pcm_notify[SNDRV_CARDS];
  45 static char *timer_source[SNDRV_CARDS];
  46
  47 module_param_array(index, int, NULL, 0444);
  48 MODULE_PARM_DESC(index, "Index value for loopback soundcard.");
  49 module_param_array(id, charp, NULL, 0444);
  50 MODULE_PARM_DESC(id, "ID string for loopback soundcard.");
  51 module_param_array(enable, bool, NULL, 0444);
  52 MODULE_PARM_DESC(enable, "Enable this loopback soundcard.");
  53 module_param_array(pcm_substreams, int, NULL, 0444);
  54 MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-8) for loopback driver.");
  55 module_param_array(pcm_notify, int, NULL, 0444);
  56 MODULE_PARM_DESC(pcm_notify, "Break capture when PCM format/rate/channels changes.");
  57 module_param_array(timer_source, charp, NULL, 0444);
  58 MODULE_PARM_DESC(timer_source, "Sound card name or number and device/subdevice number of timer to be used. Empty string for jiffies timer [default].");
  59
  60 #define NO_PITCH 100000
  61
  62 #define CABLE_VALID_PLAYBACK    BIT(SNDRV_PCM_STREAM_PLAYBACK)
  63 #define CABLE_VALID_CAPTURE     BIT(SNDRV_PCM_STREAM_CAPTURE)
  64 #define CABLE_VALID_BOTH        (CABLE_VALID_PLAYBACK | CABLE_VALID_CAPTURE)
  65
  66 struct loopback_cable;
  67 struct loopback_pcm;
  68
  69 struct loopback_ops {
  70         /* optional
  71          * call in loopback->cable_lock
  72          */
  73         int (*open)(struct loopback_pcm *dpcm);
  74         /* required
  75          * call in cable->lock
  76          */
  77         int (*start)(struct loopback_pcm *dpcm);
  78         /* required
  79          * call in cable->lock
  80          */
  81         int (*stop)(struct loopback_pcm *dpcm);
  82         /* optional */
  83         int (*stop_sync)(struct loopback_pcm *dpcm);
  84         /* optional */
  85         int (*close_substream)(struct loopback_pcm *dpcm);
  86         /* optional
  87          * call in loopback->cable_lock
  88          */
  89         int (*close_cable)(struct loopback_pcm *dpcm);
  90         /* optional
  91          * call in cable->lock
  92          */
  93         unsigned int (*pos_update)(struct loopback_cable *cable);
  94         /* optional */
  95         void (*dpcm_info)(struct loopback_pcm *dpcm,
  96                           struct snd_info_buffer *buffer);
  97 };
  98
  99 struct loopback_cable {
 100         spinlock_t lock;
 101         struct loopback_pcm *streams[2];
 102         struct snd_pcm_hardware hw;
 103         /* flags */
 104         unsigned int valid;
 105         unsigned int running;
 106         unsigned int pause;
 107         /* timer specific */
 108         struct loopback_ops *ops;
 109         /* If sound timer is used */
 110         struct {
 111                 int stream;
 112                 struct snd_timer_id id;
 113                 struct tasklet_struct event_tasklet;
 114                 struct snd_timer_instance *instance;
 115         } snd_timer;
 116 };
 117
 118 struct loopback_setup {
 119         unsigned int notify: 1;
 120         unsigned int rate_shift;
 121         snd_pcm_format_t format;
 122         unsigned int rate;
 123         unsigned int channels;
 124         struct snd_ctl_elem_id active_id;
 125         struct snd_ctl_elem_id format_id;
 126         struct snd_ctl_elem_id rate_id;
 127         struct snd_ctl_elem_id channels_id;
 128 };
 129
 130 struct loopback {
 131         struct snd_card *card;
 132         struct mutex cable_lock;
 133         struct loopback_cable *cables[MAX_PCM_SUBSTREAMS][2];
 134         struct snd_pcm *pcm[2];
 135         struct loopback_setup setup[MAX_PCM_SUBSTREAMS][2];
 136         const char *timer_source;
 137 };
 138
 139 struct loopback_pcm {
 140         struct loopback *loopback;
 141         struct snd_pcm_substream *substream;
 142         struct loopback_cable *cable;
 143         unsigned int pcm_buffer_size;
 144         unsigned int buf_pos;   /* position in buffer */
 145         unsigned int silent_size;
 146         /* PCM parameters */
 147         unsigned int pcm_period_size;
 148         unsigned int pcm_bps;           /* bytes per second */
 149         unsigned int pcm_salign;        /* bytes per sample * channels */
 150         unsigned int pcm_rate_shift;    /* rate shift value */
 151         /* flags */
 152         unsigned int period_update_pending :1;
 153         /* timer stuff */
 154         unsigned int irq_pos;           /* fractional IRQ position in jiffies
 155                                          * ticks
 156                                          */
 157         unsigned int period_size_frac;  /* period size in jiffies ticks */
 158         unsigned int last_drift;
 159         unsigned long last_jiffies;
 160         /* If jiffies timer is used */
 161         struct timer_list timer;
 162 };
 163
 164 static struct platform_device *devices[SNDRV_CARDS];
 165
 166 static inline unsigned int byte_pos(struct loopback_pcm *dpcm, unsigned int x)
 167 {
 168         if (dpcm->pcm_rate_shift == NO_PITCH) {
 169                 x /= HZ;
 170         } else {
 171                 x = div_u64(NO_PITCH * (unsigned long long)x,
 172                             HZ * (unsigned long long)dpcm->pcm_rate_shift);
 173         }
 174         return x - (x % dpcm->pcm_salign);
 175 }
 176
 177 static inline unsigned int frac_pos(struct loopback_pcm *dpcm, unsigned int x)
 178 {
 179         if (dpcm->pcm_rate_shift == NO_PITCH) { /* no pitch */
 180                 return x * HZ;
 181         } else {
 182                 x = div_u64(dpcm->pcm_rate_shift * (unsigned long long)x * HZ,
 183                             NO_PITCH);
 184         }
 185         return x;
 186 }
 187
 188 static inline struct loopback_setup *get_setup(struct loopback_pcm *dpcm)
 189 {
 190         int device = dpcm->substream->pstr->pcm->device;
 191
 192         if (dpcm->substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 193                 device ^= 1;
 194         return &dpcm->loopback->setup[dpcm->substream->number][device];
 195 }
 196
 197 static inline unsigned int get_notify(struct loopback_pcm *dpcm)
 198 {
 199         return get_setup(dpcm)->notify;
 200 }
 201
 202 static inline unsigned int get_rate_shift(struct loopback_pcm *dpcm)
 203 {
 204         return get_setup(dpcm)->rate_shift;
 205 }
 206
 207 /* call in cable->lock */
 208 static int loopback_jiffies_timer_start(struct loopback_pcm *dpcm)
 209 {
 210         unsigned long tick;
 211         unsigned int rate_shift = get_rate_shift(dpcm);
 212
 213         if (rate_shift != dpcm->pcm_rate_shift) {
 214                 dpcm->pcm_rate_shift = rate_shift;
 215                 dpcm->period_size_frac = frac_pos(dpcm, dpcm->pcm_period_size);
 216         }
 217         if (dpcm->period_size_frac <= dpcm->irq_pos) {
 218                 dpcm->irq_pos %= dpcm->period_size_frac;
 219                 dpcm->period_update_pending = 1;
 220         }
 221         tick = dpcm->period_size_frac - dpcm->irq_pos;
 222         tick = (tick + dpcm->pcm_bps - 1) / dpcm->pcm_bps;
 223         mod_timer(&dpcm->timer, jiffies + tick);
 224
 225         return 0;
 226 }
 227
 228 /* call in cable->lock */
 229 static int loopback_snd_timer_start(struct loopback_pcm *dpcm)
 230 {
 231         struct loopback_cable *cable = dpcm->cable;
 232         int err;
 233
 234         /* Loopback device has to use same period as timer card. Therefore
 235          * wake up for each snd_pcm_period_elapsed() call of timer card.
 236          */
 237         err = snd_timer_start(cable->snd_timer.instance, 1);
 238         if (err < 0) {
 239                 /* do not report error if trying to start but already
 240                  * running. For example called by opposite substream
 241                  * of the same cable
 242                  */
 243                 if (err == -EBUSY)
 244                         return 0;
 245
 246                 pcm_err(dpcm->substream->pcm,
 247                         "snd_timer_start(%d,%d,%d) failed with %d",
 248                         cable->snd_timer.id.card,
 249                         cable->snd_timer.id.device,
 250                         cable->snd_timer.id.subdevice,
 251                         err);
 252         }
 253
 254         return err;
 255 }
 256
 257 /* call in cable->lock */
 258 static inline int loopback_jiffies_timer_stop(struct loopback_pcm *dpcm)
 259 {
 260         del_timer(&dpcm->timer);
 261         dpcm->timer.expires = 0;
 262
 263         return 0;
 264 }
 265
 266 /* call in cable->lock */
 267 static int loopback_snd_timer_stop(struct loopback_pcm *dpcm)
 268 {
 269         struct loopback_cable *cable = dpcm->cable;
 270         int err;
 271
 272         /* only stop if both devices (playback and capture) are not running */
 273         if (cable->running ^ cable->pause)
 274                 return 0;
 275
 276         err = snd_timer_stop(cable->snd_timer.instance);
 277         if (err < 0) {
 278                 pcm_err(dpcm->substream->pcm,
 279                         "snd_timer_stop(%d,%d,%d) failed with %d",
 280                         cable->snd_timer.id.card,
 281                         cable->snd_timer.id.device,
 282                         cable->snd_timer.id.subdevice,
 283                         err);
 284         }
 285
 286         return err;
 287 }
 288
 289 static inline int loopback_jiffies_timer_stop_sync(struct loopback_pcm *dpcm)
 290 {
 291         del_timer_sync(&dpcm->timer);
 292
 293         return 0;
 294 }
 295
 296 /* call in loopback->cable_lock */
 297 static int loopback_snd_timer_close_cable(struct loopback_pcm *dpcm)
 298 {
 299         struct loopback_cable *cable = dpcm->cable;
 300
 301         /* snd_timer was not opened */
 302         if (!cable->snd_timer.instance)
 303                 return 0;
 304
 305         /* will only be called from free_cable() when other stream was
 306          * already closed. Other stream cannot be reopened as long as
 307          * loopback->cable_lock is locked. Therefore no need to lock
 308          * cable->lock;
 309          */
 310         snd_timer_close(cable->snd_timer.instance);
 311
 312         /* wait till drain tasklet has finished if requested */
 313         tasklet_kill(&cable->snd_timer.event_tasklet);
 314
 315         snd_timer_instance_free(cable->snd_timer.instance);
 316         memset(&cable->snd_timer, 0, sizeof(cable->snd_timer));
 317
 318         return 0;
 319 }
 320
 321 static int loopback_check_format(struct loopback_cable *cable, int stream)
 322 {
 323         struct snd_pcm_runtime *runtime, *cruntime;
 324         struct loopback_setup *setup;
 325         struct snd_card *card;
 326         int check;
 327
 328         if (cable->valid != CABLE_VALID_BOTH) {
 329                 if (stream == SNDRV_PCM_STREAM_PLAYBACK)
 330                         goto __notify;
 331                 return 0;
 332         }
 333         runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->
 334                                                         substream->runtime;
 335         cruntime = cable->streams[SNDRV_PCM_STREAM_CAPTURE]->
 336                                                         substream->runtime;
 337         check = runtime->format != cruntime->format ||
 338                 runtime->rate != cruntime->rate ||
 339                 runtime->channels != cruntime->channels;
 340         if (!check)
 341                 return 0;
 342         if (stream == SNDRV_PCM_STREAM_CAPTURE) {
 343                 return -EIO;
 344         } else {
 345                 snd_pcm_stop(cable->streams[SNDRV_PCM_STREAM_CAPTURE]->
 346                                         substream, SNDRV_PCM_STATE_DRAINING);
 347               __notify:
 348                 runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->
 349                                                         substream->runtime;
 350                 setup = get_setup(cable->streams[SNDRV_PCM_STREAM_PLAYBACK]);
 351                 card = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->loopback->card;
 352                 if (setup->format != runtime->format) {
 353                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
 354                                                         &setup->format_id);
 355                         setup->format = runtime->format;
 356                 }
 357                 if (setup->rate != runtime->rate) {
 358                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
 359                                                         &setup->rate_id);
 360                         setup->rate = runtime->rate;
 361                 }
 362                 if (setup->channels != runtime->channels) {
 363                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
 364                                                         &setup->channels_id);
 365                         setup->channels = runtime->channels;
 366                 }
 367         }
 368         return 0;
 369 }
 370
 371 static void loopback_active_notify(struct loopback_pcm *dpcm)
 372 {
 373         snd_ctl_notify(dpcm->loopback->card,
 374                        SNDRV_CTL_EVENT_MASK_VALUE,
 375                        &get_setup(dpcm)->active_id);
 376 }
 377
 378 static int loopback_trigger(struct snd_pcm_substream *substream, int cmd)
 379 {
 380         struct snd_pcm_runtime *runtime = substream->runtime;
 381         struct loopback_pcm *dpcm = runtime->private_data;
 382         struct loopback_cable *cable = dpcm->cable;
 383         int err = 0, stream = 1 << substream->stream;
 384
 385         switch (cmd) {
 386         case SNDRV_PCM_TRIGGER_START:
 387                 err = loopback_check_format(cable, substream->stream);
 388                 if (err < 0)
 389                         return err;
 390                 dpcm->last_jiffies = jiffies;
 391                 dpcm->pcm_rate_shift = 0;
 392                 dpcm->last_drift = 0;
 393                 spin_lock(&cable->lock);
 394                 cable->running |= stream;
 395                 cable->pause &= ~stream;
 396                 err = cable->ops->start(dpcm);
 397                 spin_unlock(&cable->lock);
 398                 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 399                         loopback_active_notify(dpcm);
 400                 break;
 401         case SNDRV_PCM_TRIGGER_STOP:
 402                 spin_lock(&cable->lock);
 403                 cable->running &= ~stream;
 404                 cable->pause &= ~stream;
 405                 err = cable->ops->stop(dpcm);
 406                 spin_unlock(&cable->lock);
 407                 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 408                         loopback_active_notify(dpcm);
 409                 break;
 410         case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
 411         case SNDRV_PCM_TRIGGER_SUSPEND:
 412                 spin_lock(&cable->lock);
 413                 cable->pause |= stream;
 414                 err = cable->ops->stop(dpcm);
 415                 spin_unlock(&cable->lock);
 416                 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 417                         loopback_active_notify(dpcm);
 418                 break;
 419         case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
 420         case SNDRV_PCM_TRIGGER_RESUME:
 421                 spin_lock(&cable->lock);
 422                 dpcm->last_jiffies = jiffies;
 423                 cable->pause &= ~stream;
 424                 err = cable->ops->start(dpcm);
 425                 spin_unlock(&cable->lock);
 426                 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 427                         loopback_active_notify(dpcm);
 428                 break;
 429         default:
 430                 return -EINVAL;
 431         }
 432         return err;
 433 }
 434
 435 static void params_change(struct snd_pcm_substream *substream)
 436 {
 437         struct snd_pcm_runtime *runtime = substream->runtime;
 438         struct loopback_pcm *dpcm = runtime->private_data;
 439         struct loopback_cable *cable = dpcm->cable;
 440
 441         cable->hw.formats = pcm_format_to_bits(runtime->format);
 442         cable->hw.rate_min = runtime->rate;
 443         cable->hw.rate_max = runtime->rate;
 444         cable->hw.channels_min = runtime->channels;
 445         cable->hw.channels_max = runtime->channels;
 446
 447         if (cable->snd_timer.instance) {
 448                 cable->hw.period_bytes_min =
 449                                 frames_to_bytes(runtime, runtime->period_size);
 450                 cable->hw.period_bytes_max = cable->hw.period_bytes_min;
 451         }
 452
 453 }
 454
 455 static int loopback_prepare(struct snd_pcm_substream *substream)
 456 {
 457         struct snd_pcm_runtime *runtime = substream->runtime;
 458         struct loopback_pcm *dpcm = runtime->private_data;
 459         struct loopback_cable *cable = dpcm->cable;
 460         int err, bps, salign;
 461
 462         if (cable->ops->stop_sync) {
 463                 err = cable->ops->stop_sync(dpcm);
 464                 if (err < 0)
 465                         return err;
 466         }
 467
 468         salign = (snd_pcm_format_physical_width(runtime->format) *
 469                                                 runtime->channels) / 8;
 470         bps = salign * runtime->rate;
 471         if (bps <= 0 || salign <= 0)
 472                 return -EINVAL;
 473
 474         dpcm->buf_pos = 0;
 475         dpcm->pcm_buffer_size = frames_to_bytes(runtime, runtime->buffer_size);
 476         if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
 477                 /* clear capture buffer */
 478                 dpcm->silent_size = dpcm->pcm_buffer_size;
 479                 snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
 480                                            runtime->buffer_size * runtime->channels);
 481         }
 482
 483         dpcm->irq_pos = 0;
 484         dpcm->period_update_pending = 0;
 485         dpcm->pcm_bps = bps;
 486         dpcm->pcm_salign = salign;
 487         dpcm->pcm_period_size = frames_to_bytes(runtime, runtime->period_size);
 488
 489         mutex_lock(&dpcm->loopback->cable_lock);
 490         if (!(cable->valid & ~(1 << substream->stream)) ||
 491             (get_setup(dpcm)->notify &&
 492              substream->stream == SNDRV_PCM_STREAM_PLAYBACK))
 493                 params_change(substream);
 494         cable->valid |= 1 << substream->stream;
 495         mutex_unlock(&dpcm->loopback->cable_lock);
 496
 497         return 0;
 498 }
 499
 500 static void clear_capture_buf(struct loopback_pcm *dpcm, unsigned int bytes)
 501 {
 502         struct snd_pcm_runtime *runtime = dpcm->substream->runtime;
 503         char *dst = runtime->dma_area;
 504         unsigned int dst_off = dpcm->buf_pos;
 505
 506         if (dpcm->silent_size >= dpcm->pcm_buffer_size)
 507                 return;
 508         if (dpcm->silent_size + bytes > dpcm->pcm_buffer_size)
 509                 bytes = dpcm->pcm_buffer_size - dpcm->silent_size;
 510
 511         for (;;) {
 512                 unsigned int size = bytes;
 513                 if (dst_off + size > dpcm->pcm_buffer_size)
 514                         size = dpcm->pcm_buffer_size - dst_off;
 515                 snd_pcm_format_set_silence(runtime->format, dst + dst_off,
 516                                            bytes_to_frames(runtime, size) *
 517                                                 runtime->channels);
 518                 dpcm->silent_size += size;
 519                 bytes -= size;
 520                 if (!bytes)
 521                         break;
 522                 dst_off = 0;
 523         }
 524 }
 525
 526 static void copy_play_buf(struct loopback_pcm *play,
 527                           struct loopback_pcm *capt,
 528                           unsigned int bytes)
 529 {
 530         struct snd_pcm_runtime *runtime = play->substream->runtime;
 531         char *src = runtime->dma_area;
 532         char *dst = capt->substream->runtime->dma_area;
 533         unsigned int src_off = play->buf_pos;
 534         unsigned int dst_off = capt->buf_pos;
 535         unsigned int clear_bytes = 0;
 536
 537         /* check if playback is draining, trim the capture copy size
 538          * when our pointer is at the end of playback ring buffer */
 539         if (runtime->status->state == SNDRV_PCM_STATE_DRAINING &&
 540             snd_pcm_playback_hw_avail(runtime) < runtime->buffer_size) {
 541                 snd_pcm_uframes_t appl_ptr, appl_ptr1, diff;
 542                 appl_ptr = appl_ptr1 = runtime->control->appl_ptr;
 543                 appl_ptr1 -= appl_ptr1 % runtime->buffer_size;
 544                 appl_ptr1 += play->buf_pos / play->pcm_salign;
 545                 if (appl_ptr < appl_ptr1)
 546                         appl_ptr1 -= runtime->buffer_size;
 547                 diff = (appl_ptr - appl_ptr1) * play->pcm_salign;
 548                 if (diff < bytes) {
 549                         clear_bytes = bytes - diff;
 550                         bytes = diff;
 551                 }
 552         }
 553
 554         for (;;) {
 555                 unsigned int size = bytes;
 556                 if (src_off + size > play->pcm_buffer_size)
 557                         size = play->pcm_buffer_size - src_off;
 558                 if (dst_off + size > capt->pcm_buffer_size)
 559                         size = capt->pcm_buffer_size - dst_off;
 560                 memcpy(dst + dst_off, src + src_off, size);
 561                 capt->silent_size = 0;
 562                 bytes -= size;
 563                 if (!bytes)
 564                         break;
 565                 src_off = (src_off + size) % play->pcm_buffer_size;
 566                 dst_off = (dst_off + size) % capt->pcm_buffer_size;
 567         }
 568
 569         if (clear_bytes > 0) {
 570                 clear_capture_buf(capt, clear_bytes);
 571                 capt->silent_size = 0;
 572         }
 573 }
 574
 575 static inline unsigned int bytepos_delta(struct loopback_pcm *dpcm,
 576                                          unsigned int jiffies_delta)
 577 {
 578         unsigned long last_pos;
 579         unsigned int delta;
 580
 581         last_pos = byte_pos(dpcm, dpcm->irq_pos);
 582         dpcm->irq_pos += jiffies_delta * dpcm->pcm_bps;
 583         delta = byte_pos(dpcm, dpcm->irq_pos) - last_pos;
 584         if (delta >= dpcm->last_drift)
 585                 delta -= dpcm->last_drift;
 586         dpcm->last_drift = 0;
 587         if (dpcm->irq_pos >= dpcm->period_size_frac) {
 588                 dpcm->irq_pos %= dpcm->period_size_frac;
 589                 dpcm->period_update_pending = 1;
 590         }
 591         return delta;
 592 }
 593
 594 static inline void bytepos_finish(struct loopback_pcm *dpcm,
 595                                   unsigned int delta)
 596 {
 597         dpcm->buf_pos += delta;
 598         dpcm->buf_pos %= dpcm->pcm_buffer_size;
 599 }
 600
 601 /* call in cable->lock */
 602 static unsigned int loopback_jiffies_timer_pos_update
 603                 (struct loopback_cable *cable)
 604 {
 605         struct loopback_pcm *dpcm_play =
 606                         cable->streams[SNDRV_PCM_STREAM_PLAYBACK];
 607         struct loopback_pcm *dpcm_capt =
 608                         cable->streams[SNDRV_PCM_STREAM_CAPTURE];
 609         unsigned long delta_play = 0, delta_capt = 0;
 610         unsigned int running, count1, count2;
 611
 612         running = cable->running ^ cable->pause;
 613         if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {
 614                 delta_play = jiffies - dpcm_play->last_jiffies;
 615                 dpcm_play->last_jiffies += delta_play;
 616         }
 617
 618         if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {
 619                 delta_capt = jiffies - dpcm_capt->last_jiffies;
 620                 dpcm_capt->last_jiffies += delta_capt;
 621         }
 622
 623         if (delta_play == 0 && delta_capt == 0)
 624                 goto unlock;
 625
 626         if (delta_play > delta_capt) {
 627                 count1 = bytepos_delta(dpcm_play, delta_play - delta_capt);
 628                 bytepos_finish(dpcm_play, count1);
 629                 delta_play = delta_capt;
 630         } else if (delta_play < delta_capt) {
 631                 count1 = bytepos_delta(dpcm_capt, delta_capt - delta_play);
 632                 clear_capture_buf(dpcm_capt, count1);
 633                 bytepos_finish(dpcm_capt, count1);
 634                 delta_capt = delta_play;
 635         }
 636
 637         if (delta_play == 0 && delta_capt == 0)
 638                 goto unlock;
 639
 640         /* note delta_capt == delta_play at this moment */
 641         count1 = bytepos_delta(dpcm_play, delta_play);
 642         count2 = bytepos_delta(dpcm_capt, delta_capt);
 643         if (count1 < count2) {
 644                 dpcm_capt->last_drift = count2 - count1;
 645                 count1 = count2;
 646         } else if (count1 > count2) {
 647                 dpcm_play->last_drift = count1 - count2;
 648         }
 649         copy_play_buf(dpcm_play, dpcm_capt, count1);
 650         bytepos_finish(dpcm_play, count1);
 651         bytepos_finish(dpcm_capt, count1);
 652  unlock:
 653         return running;
 654 }
 655
 656 static void loopback_jiffies_timer_function(struct timer_list *t)
 657 {
 658         struct loopback_pcm *dpcm = from_timer(dpcm, t, timer);
 659         unsigned long flags;
 660
 661         spin_lock_irqsave(&dpcm->cable->lock, flags);
 662         if (loopback_jiffies_timer_pos_update(dpcm->cable) &
 663                         (1 << dpcm->substream->stream)) {
 664                 loopback_jiffies_timer_start(dpcm);
 665                 if (dpcm->period_update_pending) {
 666                         dpcm->period_update_pending = 0;
 667                         spin_unlock_irqrestore(&dpcm->cable->lock, flags);
 668                         /* need to unlock before calling below */
 669                         snd_pcm_period_elapsed(dpcm->substream);
 670                         return;
 671                 }
 672         }
 673         spin_unlock_irqrestore(&dpcm->cable->lock, flags);
 674 }
 675
 676 /* call in cable->lock */
 677 static int loopback_snd_timer_check_resolution(struct snd_pcm_runtime *runtime,
 678                                                unsigned long resolution)
 679 {
 680         if (resolution != runtime->timer_resolution) {
 681                 struct loopback_pcm *dpcm = runtime->private_data;
 682                 struct loopback_cable *cable = dpcm->cable;
 683                 /* Worst case estimation of possible values for resolution
 684                  * resolution <= (512 * 1024) frames / 8kHz in nsec
 685                  * resolution <= 65.536.000.000 nsec
 686                  *
 687                  * period_size <= 65.536.000.000 nsec / 1000nsec/usec * 192kHz +
 688                  *  500.000
 689                  * period_size <= 12.582.912.000.000  <64bit
 690                  *  / 1.000.000 usec/sec
 691                  */
 692                 snd_pcm_uframes_t period_size_usec =
 693                                 resolution / 1000 * runtime->rate;
 694                 /* round to nearest sample rate */
 695                 snd_pcm_uframes_t period_size =
 696                                 (period_size_usec + 500 * 1000) / (1000 * 1000);
 697
 698                 pcm_err(dpcm->substream->pcm,
 699                         "Period size (%lu frames) of loopback device is not corresponding to timer resolution (%lu nsec = %lu frames) of card timer %d,%d,%d. Use period size of %lu frames for loopback device.",
 700                         runtime->period_size, resolution, period_size,
 701                         cable->snd_timer.id.card,
 702                         cable->snd_timer.id.device,
 703                         cable->snd_timer.id.subdevice,
 704                         period_size);
 705                 return -EINVAL;
 706         }
 707         return 0;
 708 }
 709
 710 static void loopback_snd_timer_period_elapsed(struct loopback_cable *cable,
 711                                               int event,
 712                                               unsigned long resolution)
 713 {
 714         struct loopback_pcm *dpcm_play, *dpcm_capt;
 715         struct snd_pcm_substream *substream_play, *substream_capt;
 716         struct snd_pcm_runtime *valid_runtime;
 717         unsigned int running, elapsed_bytes;
 718         unsigned long flags;
 719
 720         spin_lock_irqsave(&cable->lock, flags);
 721         running = cable->running ^ cable->pause;
 722         /* no need to do anything if no stream is running */
 723         if (!running) {
 724                 spin_unlock_irqrestore(&cable->lock, flags);
 725                 return;
 726         }
 727
 728         dpcm_play = cable->streams[SNDRV_PCM_STREAM_PLAYBACK];
 729         dpcm_capt = cable->streams[SNDRV_PCM_STREAM_CAPTURE];
 730
 731         if (event == SNDRV_TIMER_EVENT_MSTOP) {
 732                 if (!dpcm_play ||
 733                     dpcm_play->substream->runtime->status->state !=
 734                                 SNDRV_PCM_STATE_DRAINING) {
 735                         spin_unlock_irqrestore(&cable->lock, flags);
 736                         return;
 737                 }
 738         }
 739
 740         substream_play = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?
 741                         dpcm_play->substream : NULL;
 742         substream_capt = (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) ?
 743                         dpcm_capt->substream : NULL;
 744         valid_runtime = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?
 745                                 dpcm_play->substream->runtime :
 746                                 dpcm_capt->substream->runtime;
 747
 748         /* resolution is only valid for SNDRV_TIMER_EVENT_TICK events */
 749         if (event == SNDRV_TIMER_EVENT_TICK) {
 750                 /* The hardware rules guarantee that playback and capture period
 751                  * are the same. Therefore only one device has to be checked
 752                  * here.
 753                  */
 754                 if (loopback_snd_timer_check_resolution(valid_runtime,
 755                                                         resolution) < 0) {
 756                         spin_unlock_irqrestore(&cable->lock, flags);
 757                         if (substream_play)
 758                                 snd_pcm_stop_xrun(substream_play);
 759                         if (substream_capt)
 760                                 snd_pcm_stop_xrun(substream_capt);
 761                         return;
 762                 }
 763         }
 764
 765         elapsed_bytes = frames_to_bytes(valid_runtime,
 766                                         valid_runtime->period_size);
 767         /* The same timer interrupt is used for playback and capture device */
 768         if ((running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) &&
 769             (running & (1 << SNDRV_PCM_STREAM_CAPTURE))) {
 770                 copy_play_buf(dpcm_play, dpcm_capt, elapsed_bytes);
 771                 bytepos_finish(dpcm_play, elapsed_bytes);
 772                 bytepos_finish(dpcm_capt, elapsed_bytes);
 773         } else if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {
 774                 bytepos_finish(dpcm_play, elapsed_bytes);
 775         } else if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {
 776                 clear_capture_buf(dpcm_capt, elapsed_bytes);
 777                 bytepos_finish(dpcm_capt, elapsed_bytes);
 778         }
 779         spin_unlock_irqrestore(&cable->lock, flags);
 780
 781         if (substream_play)
 782                 snd_pcm_period_elapsed(substream_play);
 783         if (substream_capt)
 784                 snd_pcm_period_elapsed(substream_capt);
 785 }
 786
 787 static void loopback_snd_timer_function(struct snd_timer_instance *timeri,
 788                                         unsigned long resolution,
 789                                         unsigned long ticks)
 790 {
 791         struct loopback_cable *cable = timeri->callback_data;
 792
 793         loopback_snd_timer_period_elapsed(cable, SNDRV_TIMER_EVENT_TICK,
 794                                           resolution);
 795 }
 796
 797 static void loopback_snd_timer_tasklet(unsigned long arg)
 798 {
 799         struct snd_timer_instance *timeri = (struct snd_timer_instance *)arg;
 800         struct loopback_cable *cable = timeri->callback_data;
 801
 802         loopback_snd_timer_period_elapsed(cable, SNDRV_TIMER_EVENT_MSTOP, 0);
 803 }
 804
 805 static void loopback_snd_timer_event(struct snd_timer_instance *timeri,
 806                                      int event,
 807                                      struct timespec64 *tstamp,
 808                                      unsigned long resolution)
 809 {
 810         /* Do not lock cable->lock here because timer->lock is already hold.
 811          * There are other functions which first lock cable->lock and than
 812          * timer->lock e.g.
 813          * loopback_trigger()
 814          * spin_lock(&cable->lock)
 815          * loopback_snd_timer_start()
 816          * snd_timer_start()
 817          * spin_lock(&timer->lock)
 818          * Therefore when using the oposit order of locks here it could result
 819          * in a deadlock.
 820          */
 821
 822         if (event == SNDRV_TIMER_EVENT_MSTOP) {
 823                 struct loopback_cable *cable = timeri->callback_data;
 824
 825                 /* sound card of the timer was stopped. Therefore there will not
 826                  * be any further timer callbacks. Due to this forward audio
 827                  * data from here if in draining state. When still in running
 828                  * state the streaming will be aborted by the usual timeout. It
 829                  * should not be aborted here because may be the timer sound
 830                  * card does only a recovery and the timer is back soon.
 831                  * This tasklet triggers loopback_snd_timer_tasklet()
 832                  */
 833                 tasklet_schedule(&cable->snd_timer.event_tasklet);
 834         }
 835 }
 836
 837 static void loopback_jiffies_timer_dpcm_info(struct loopback_pcm *dpcm,
 838                                              struct snd_info_buffer *buffer)
 839 {
 840         snd_iprintf(buffer, "    update_pending:\t%u\n",
 841                     dpcm->period_update_pending);
 842         snd_iprintf(buffer, "    irq_pos:\t\t%u\n", dpcm->irq_pos);
 843         snd_iprintf(buffer, "    period_frac:\t%u\n", dpcm->period_size_frac);
 844         snd_iprintf(buffer, "    last_jiffies:\t%lu (%lu)\n",
 845                     dpcm->last_jiffies, jiffies);
 846         snd_iprintf(buffer, "    timer_expires:\t%lu\n", dpcm->timer.expires);
 847 }
 848
 849 static void loopback_snd_timer_dpcm_info(struct loopback_pcm *dpcm,
 850                                          struct snd_info_buffer *buffer)
 851 {
 852         struct loopback_cable *cable = dpcm->cable;
 853
 854         snd_iprintf(buffer, "    sound timer:\thw:%d,%d,%d\n",
 855                     cable->snd_timer.id.card,
 856                     cable->snd_timer.id.device,
 857                     cable->snd_timer.id.subdevice);
 858         snd_iprintf(buffer, "    timer open:\t\t%s\n",
 859                     (cable->snd_timer.stream == SNDRV_PCM_STREAM_CAPTURE) ?
 860                             "capture" : "playback");
 861 }
 862
 863 static snd_pcm_uframes_t loopback_pointer(struct snd_pcm_substream *substream)
 864 {
 865         struct snd_pcm_runtime *runtime = substream->runtime;
 866         struct loopback_pcm *dpcm = runtime->private_data;
 867         snd_pcm_uframes_t pos;
 868
 869         spin_lock(&dpcm->cable->lock);
 870         if (dpcm->cable->ops->pos_update)
 871                 dpcm->cable->ops->pos_update(dpcm->cable);
 872         pos = dpcm->buf_pos;
 873         spin_unlock(&dpcm->cable->lock);
 874         return bytes_to_frames(runtime, pos);
 875 }
 876
 877 static const struct snd_pcm_hardware loopback_pcm_hardware =
 878 {
 879         .info =         (SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_MMAP |
 880                          SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_PAUSE |
 881                          SNDRV_PCM_INFO_RESUME),
 882         .formats =      (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE |
 883                          SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S24_BE |
 884                          SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_3BE |
 885                          SNDRV_PCM_FMTBIT_S32_LE | SNDRV_PCM_FMTBIT_S32_BE |
 886                          SNDRV_PCM_FMTBIT_FLOAT_LE | SNDRV_PCM_FMTBIT_FLOAT_BE),
 887         .rates =        SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000,
 888         .rate_min =             8000,
 889         .rate_max =             192000,
 890         .channels_min =         1,
 891         .channels_max =         32,
 892         .buffer_bytes_max =     2 * 1024 * 1024,
 893         .period_bytes_min =     64,
 894         /* note check overflow in frac_pos() using pcm_rate_shift before
 895            changing period_bytes_max value */
 896         .period_bytes_max =     1024 * 1024,
 897         .periods_min =          1,
 898         .periods_max =          1024,
 899         .fifo_size =            0,
 900 };
 901
 902 static void loopback_runtime_free(struct snd_pcm_runtime *runtime)
 903 {
 904         struct loopback_pcm *dpcm = runtime->private_data;
 905         kfree(dpcm);
 906 }
 907
 908 static int loopback_hw_free(struct snd_pcm_substream *substream)
 909 {
 910         struct snd_pcm_runtime *runtime = substream->runtime;
 911         struct loopback_pcm *dpcm = runtime->private_data;
 912         struct loopback_cable *cable = dpcm->cable;
 913
 914         mutex_lock(&dpcm->loopback->cable_lock);
 915         cable->valid &= ~(1 << substream->stream);
 916         mutex_unlock(&dpcm->loopback->cable_lock);
 917         return 0;
 918 }
 919
 920 static unsigned int get_cable_index(struct snd_pcm_substream *substream)
 921 {
 922         if (!substream->pcm->device)
 923                 return substream->stream;
 924         else
 925                 return !substream->stream;
 926 }
 927
 928 static int rule_format(struct snd_pcm_hw_params *params,
 929                        struct snd_pcm_hw_rule *rule)
 930 {
 931         struct loopback_pcm *dpcm = rule->private;
 932         struct loopback_cable *cable = dpcm->cable;
 933         struct snd_mask m;
 934
 935         snd_mask_none(&m);
 936         mutex_lock(&dpcm->loopback->cable_lock);
 937         m.bits[0] = (u_int32_t)cable->hw.formats;
 938         m.bits[1] = (u_int32_t)(cable->hw.formats >> 32);
 939         mutex_unlock(&dpcm->loopback->cable_lock);
 940         return snd_mask_refine(hw_param_mask(params, rule->var), &m);
 941 }
 942
 943 static int rule_rate(struct snd_pcm_hw_params *params,
 944                      struct snd_pcm_hw_rule *rule)
 945 {
 946         struct loopback_pcm *dpcm = rule->private;
 947         struct loopback_cable *cable = dpcm->cable;
 948         struct snd_interval t;
 949
 950         mutex_lock(&dpcm->loopback->cable_lock);
 951         t.min = cable->hw.rate_min;
 952         t.max = cable->hw.rate_max;
 953         mutex_unlock(&dpcm->loopback->cable_lock);
 954         t.openmin = t.openmax = 0;
 955         t.integer = 0;
 956         return snd_interval_refine(hw_param_interval(params, rule->var), &t);
 957 }
 958
 959 static int rule_channels(struct snd_pcm_hw_params *params,
 960                          struct snd_pcm_hw_rule *rule)
 961 {
 962         struct loopback_pcm *dpcm = rule->private;
 963         struct loopback_cable *cable = dpcm->cable;
 964         struct snd_interval t;
 965
 966         mutex_lock(&dpcm->loopback->cable_lock);
 967         t.min = cable->hw.channels_min;
 968         t.max = cable->hw.channels_max;
 969         mutex_unlock(&dpcm->loopback->cable_lock);
 970         t.openmin = t.openmax = 0;
 971         t.integer = 0;
 972         return snd_interval_refine(hw_param_interval(params, rule->var), &t);
 973 }
 974
 975 static int rule_period_bytes(struct snd_pcm_hw_params *params,
 976                              struct snd_pcm_hw_rule *rule)
 977 {
 978         struct loopback_pcm *dpcm = rule->private;
 979         struct loopback_cable *cable = dpcm->cable;
 980         struct snd_interval t;
 981
 982         mutex_lock(&dpcm->loopback->cable_lock);
 983         t.min = cable->hw.period_bytes_min;
 984         t.max = cable->hw.period_bytes_max;
 985         mutex_unlock(&dpcm->loopback->cable_lock);
 986         t.openmin = 0;
 987         t.openmax = 0;
 988         t.integer = 0;
 989         return snd_interval_refine(hw_param_interval(params, rule->var), &t);
 990 }
 991
 992 static void free_cable(struct snd_pcm_substream *substream)
 993 {
 994         struct loopback *loopback = substream->private_data;
 995         int dev = get_cable_index(substream);
 996         struct loopback_cable *cable;
 997
 998         cable = loopback->cables[substream->number][dev];
 999         if (!cable)
1000                 return;
1001         if (cable->streams[!substream->stream]) {
1002                 /* other stream is still alive */
1003                 spin_lock_irq(&cable->lock);
1004                 cable->streams[substream->stream] = NULL;
1005                 spin_unlock_irq(&cable->lock);
1006         } else {
1007                 struct loopback_pcm *dpcm = substream->runtime->private_data;
1008
1009                 if (cable->ops && cable->ops->close_cable && dpcm)
1010                         cable->ops->close_cable(dpcm);
1011                 /* free the cable */
1012                 loopback->cables[substream->number][dev] = NULL;
1013                 kfree(cable);
1014         }
1015 }
1016
1017 static int loopback_jiffies_timer_open(struct loopback_pcm *dpcm)
1018 {
1019         timer_setup(&dpcm->timer, loopback_jiffies_timer_function, 0);
1020
1021         return 0;
1022 }
1023
1024 static struct loopback_ops loopback_jiffies_timer_ops = {
1025         .open = loopback_jiffies_timer_open,
1026         .start = loopback_jiffies_timer_start,
1027         .stop = loopback_jiffies_timer_stop,
1028         .stop_sync = loopback_jiffies_timer_stop_sync,
1029         .close_substream = loopback_jiffies_timer_stop_sync,
1030         .pos_update = loopback_jiffies_timer_pos_update,
1031         .dpcm_info = loopback_jiffies_timer_dpcm_info,
1032 };
1033
1034 static int loopback_parse_timer_id(const char *str,
1035                                    struct snd_timer_id *tid)
1036 {
1037         /* [<pref>:](<card name>|<card idx>)[{.,}<dev idx>[{.,}<subdev idx>]] */
1038         const char * const sep_dev = ".,";
1039         const char * const sep_pref = ":";
1040         const char *name = str;
1041         char *sep, save = '\0';
1042         int card_idx = 0, dev = 0, subdev = 0;
1043         int err;
1044
1045         sep = strpbrk(str, sep_pref);
1046         if (sep)
1047                 name = sep + 1;
1048         sep = strpbrk(name, sep_dev);
1049         if (sep) {
1050                 save = *sep;
1051                 *sep = '\0';
1052         }
1053         err = kstrtoint(name, 0, &card_idx);
1054         if (err == -EINVAL) {
1055                 /* Must be the name, not number */
1056                 for (card_idx = 0; card_idx < snd_ecards_limit; card_idx++) {
1057                         struct snd_card *card = snd_card_ref(card_idx);
1058
1059                         if (card) {
1060                                 if (!strcmp(card->id, name))
1061                                         err = 0;
1062                                 snd_card_unref(card);
1063                         }
1064                         if (!err)
1065                                 break;
1066                 }
1067         }
1068         if (sep) {
1069                 *sep = save;
1070                 if (!err) {
1071                         char *sep2, save2 = '\0';
1072
1073                         sep2 = strpbrk(sep + 1, sep_dev);
1074                         if (sep2) {
1075                                 save2 = *sep2;
1076                                 *sep2 = '\0';
1077                         }
1078                         err = kstrtoint(sep + 1, 0, &dev);
1079                         if (sep2) {
1080                                 *sep2 = save2;
1081                                 if (!err)
1082                                         err = kstrtoint(sep2 + 1, 0, &subdev);
1083                         }
1084                 }
1085         }
1086         if (!err && tid) {
1087                 tid->card = card_idx;
1088                 tid->device = dev;
1089                 tid->subdevice = subdev;
1090         }
1091         return err;
1092 }
1093
1094 /* call in loopback->cable_lock */
1095 static int loopback_snd_timer_open(struct loopback_pcm *dpcm)
1096 {
1097         int err = 0;
1098         struct snd_timer_id tid = {
1099                 .dev_class = SNDRV_TIMER_CLASS_PCM,
1100                 .dev_sclass = SNDRV_TIMER_SCLASS_APPLICATION,
1101         };
1102         struct snd_timer_instance *timeri;
1103         struct loopback_cable *cable = dpcm->cable;
1104
1105         /* check if timer was already opened. It is only opened once
1106          * per playback and capture subdevice (aka cable).
1107          */
1108         if (cable->snd_timer.instance)
1109                 goto exit;
1110
1111         err = loopback_parse_timer_id(dpcm->loopback->timer_source, &tid);
1112         if (err < 0) {
1113                 pcm_err(dpcm->substream->pcm,
1114                         "Parsing timer source \'%s\' failed with %d",
1115                         dpcm->loopback->timer_source, err);
1116                 goto exit;
1117         }
1118
1119         cable->snd_timer.stream = dpcm->substream->stream;
1120         cable->snd_timer.id = tid;
1121
1122         timeri = snd_timer_instance_new(dpcm->loopback->card->id);
1123         if (!timeri) {
1124                 err = -ENOMEM;
1125                 goto exit;
1126         }
1127         /* The callback has to be called from another tasklet. If
1128          * SNDRV_TIMER_IFLG_FAST is specified it will be called from the
1129          * snd_pcm_period_elapsed() call of the selected sound card.
1130          * snd_pcm_period_elapsed() helds snd_pcm_stream_lock_irqsave().
1131          * Due to our callback loopback_snd_timer_function() also calls
1132          * snd_pcm_period_elapsed() which calls snd_pcm_stream_lock_irqsave().
1133          * This would end up in a dead lock.
1134          */
1135         timeri->flags |= SNDRV_TIMER_IFLG_AUTO;
1136         timeri->callback = loopback_snd_timer_function;
1137         timeri->callback_data = (void *)cable;
1138         timeri->ccallback = loopback_snd_timer_event;
1139
1140         /* initialise a tasklet used for draining */
1141         tasklet_init(&cable->snd_timer.event_tasklet,
1142                      loopback_snd_timer_tasklet, (unsigned long)timeri);
1143
1144         /* The mutex loopback->cable_lock is kept locked.
1145          * Therefore snd_timer_open() cannot be called a second time
1146          * by the other device of the same cable.
1147          * Therefore the following issue cannot happen:
1148          * [proc1] Call loopback_timer_open() ->
1149          *         Unlock cable->lock for snd_timer_close/open() call
1150          * [proc2] Call loopback_timer_open() -> snd_timer_open(),
1151          *         snd_timer_start()
1152          * [proc1] Call snd_timer_open() and overwrite running timer
1153          *         instance
1154          */
1155         err = snd_timer_open(timeri, &cable->snd_timer.id, current->pid);
1156         if (err < 0) {
1157                 pcm_err(dpcm->substream->pcm,
1158                         "snd_timer_open (%d,%d,%d) failed with %d",
1159                         cable->snd_timer.id.card,
1160                         cable->snd_timer.id.device,
1161                         cable->snd_timer.id.subdevice,
1162                         err);
1163                 snd_timer_instance_free(timeri);
1164                 goto exit;
1165         }
1166
1167         cable->snd_timer.instance = timeri;
1168
1169 exit:
1170         return err;
1171 }
1172
1173 /* stop_sync() is not required for sound timer because it does not need to be
1174  * restarted in loopback_prepare() on Xrun recovery
1175  */
1176 static struct loopback_ops loopback_snd_timer_ops = {
1177         .open = loopback_snd_timer_open,
1178         .start = loopback_snd_timer_start,
1179         .stop = loopback_snd_timer_stop,
1180         .close_cable = loopback_snd_timer_close_cable,
1181         .dpcm_info = loopback_snd_timer_dpcm_info,
1182 };
1183
1184 static int loopback_open(struct snd_pcm_substream *substream)
1185 {
1186         struct snd_pcm_runtime *runtime = substream->runtime;
1187         struct loopback *loopback = substream->private_data;
1188         struct loopback_pcm *dpcm;
1189         struct loopback_cable *cable = NULL;
1190         int err = 0;
1191         int dev = get_cable_index(substream);
1192
1193         mutex_lock(&loopback->cable_lock);
1194         dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
1195         if (!dpcm) {
1196                 err = -ENOMEM;
1197                 goto unlock;
1198         }
1199         dpcm->loopback = loopback;
1200         dpcm->substream = substream;
1201
1202         cable = loopback->cables[substream->number][dev];
1203         if (!cable) {
1204                 cable = kzalloc(sizeof(*cable), GFP_KERNEL);
1205                 if (!cable) {
1206                         err = -ENOMEM;
1207                         goto unlock;
1208                 }
1209                 spin_lock_init(&cable->lock);
1210                 cable->hw = loopback_pcm_hardware;
1211                 if (loopback->timer_source)
1212                         cable->ops = &loopback_snd_timer_ops;
1213                 else
1214                         cable->ops = &loopback_jiffies_timer_ops;
1215                 loopback->cables[substream->number][dev] = cable;
1216         }
1217         dpcm->cable = cable;
1218         runtime->private_data = dpcm;
1219
1220         if (cable->ops->open) {
1221                 err = cable->ops->open(dpcm);
1222                 if (err < 0)
1223                         goto unlock;
1224         }
1225
1226         snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
1227
1228         /* use dynamic rules based on actual runtime->hw values */
1229         /* note that the default rules created in the PCM midlevel code */
1230         /* are cached -> they do not reflect the actual state */
1231         err = snd_pcm_hw_rule_add(runtime, 0,
1232                                   SNDRV_PCM_HW_PARAM_FORMAT,
1233                                   rule_format, dpcm,
1234                                   SNDRV_PCM_HW_PARAM_FORMAT, -1);
1235         if (err < 0)
1236                 goto unlock;
1237         err = snd_pcm_hw_rule_add(runtime, 0,
1238                                   SNDRV_PCM_HW_PARAM_RATE,
1239                                   rule_rate, dpcm,
1240                                   SNDRV_PCM_HW_PARAM_RATE, -1);
1241         if (err < 0)
1242                 goto unlock;
1243         err = snd_pcm_hw_rule_add(runtime, 0,
1244                                   SNDRV_PCM_HW_PARAM_CHANNELS,
1245                                   rule_channels, dpcm,
1246                                   SNDRV_PCM_HW_PARAM_CHANNELS, -1);
1247         if (err < 0)
1248                 goto unlock;
1249
1250         /* In case of sound timer the period time of both devices of the same
1251          * loop has to be the same.
1252          * This rule only takes effect if a sound timer was chosen
1253          */
1254         if (cable->snd_timer.instance) {
1255                 err = snd_pcm_hw_rule_add(runtime, 0,
1256                                           SNDRV_PCM_HW_PARAM_PERIOD_BYTES,
1257                                           rule_period_bytes, dpcm,
1258                                           SNDRV_PCM_HW_PARAM_PERIOD_BYTES, -1);
1259                 if (err < 0)
1260                         goto unlock;
1261         }
1262
1263         /* loopback_runtime_free() has not to be called if kfree(dpcm) was
1264          * already called here. Otherwise it will end up with a double free.
1265          */
1266         runtime->private_free = loopback_runtime_free;
1267         if (get_notify(dpcm))
1268                 runtime->hw = loopback_pcm_hardware;
1269         else
1270                 runtime->hw = cable->hw;
1271
1272         spin_lock_irq(&cable->lock);
1273         cable->streams[substream->stream] = dpcm;
1274         spin_unlock_irq(&cable->lock);
1275
1276  unlock:
1277         if (err < 0) {
1278                 free_cable(substream);
1279                 kfree(dpcm);
1280         }
1281         mutex_unlock(&loopback->cable_lock);
1282         return err;
1283 }
1284
1285 static int loopback_close(struct snd_pcm_substream *substream)
1286 {
1287         struct loopback *loopback = substream->private_data;
1288         struct loopback_pcm *dpcm = substream->runtime->private_data;
1289         int err = 0;
1290
1291         if (dpcm->cable->ops->close_substream)
1292                 err = dpcm->cable->ops->close_substream(dpcm);
1293         mutex_lock(&loopback->cable_lock);
1294         free_cable(substream);
1295         mutex_unlock(&loopback->cable_lock);
1296         return err;
1297 }
1298
1299 static const struct snd_pcm_ops loopback_pcm_ops = {
1300         .open =         loopback_open,
1301         .close =        loopback_close,
1302         .hw_free =      loopback_hw_free,
1303         .prepare =      loopback_prepare,
1304         .trigger =      loopback_trigger,
1305         .pointer =      loopback_pointer,
1306 };
1307
1308 static int loopback_pcm_new(struct loopback *loopback,
1309                             int device, int substreams)
1310 {
1311         struct snd_pcm *pcm;
1312         int err;
1313
1314         err = snd_pcm_new(loopback->card, "Loopback PCM", device,
1315                           substreams, substreams, &pcm);
1316         if (err < 0)
1317                 return err;
1318         snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &loopback_pcm_ops);
1319         snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &loopback_pcm_ops);
1320         snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, 0, 0);
1321
1322         pcm->private_data = loopback;
1323         pcm->info_flags = 0;
1324         strcpy(pcm->name, "Loopback PCM");
1325
1326         loopback->pcm[device] = pcm;
1327         return 0;
1328 }
1329
1330 static int loopback_rate_shift_info(struct snd_kcontrol *kcontrol,
1331                                     struct snd_ctl_elem_info *uinfo)
1332 {
1333         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1334         uinfo->count = 1;
1335         uinfo->value.integer.min = 80000;
1336         uinfo->value.integer.max = 120000;
1337         uinfo->value.integer.step = 1;
1338         return 0;
1339 }
1340
1341 static int loopback_rate_shift_get(struct snd_kcontrol *kcontrol,
1342                                    struct snd_ctl_elem_value *ucontrol)
1343 {
1344         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1345
1346         mutex_lock(&loopback->cable_lock);
1347         ucontrol->value.integer.value[0] =
1348                 loopback->setup[kcontrol->id.subdevice]
1349                                [kcontrol->id.device].rate_shift;
1350         mutex_unlock(&loopback->cable_lock);
1351         return 0;
1352 }
1353
1354 static int loopback_rate_shift_put(struct snd_kcontrol *kcontrol,
1355                                    struct snd_ctl_elem_value *ucontrol)
1356 {
1357         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1358         unsigned int val;
1359         int change = 0;
1360
1361         val = ucontrol->value.integer.value[0];
1362         if (val < 80000)
1363                 val = 80000;
1364         if (val > 120000)
1365                 val = 120000;
1366         mutex_lock(&loopback->cable_lock);
1367         if (val != loopback->setup[kcontrol->id.subdevice]
1368                                   [kcontrol->id.device].rate_shift) {
1369                 loopback->setup[kcontrol->id.subdevice]
1370                                [kcontrol->id.device].rate_shift = val;
1371                 change = 1;
1372         }
1373         mutex_unlock(&loopback->cable_lock);
1374         return change;
1375 }
1376
1377 static int loopback_notify_get(struct snd_kcontrol *kcontrol,
1378                                struct snd_ctl_elem_value *ucontrol)
1379 {
1380         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1381
1382         mutex_lock(&loopback->cable_lock);
1383         ucontrol->value.integer.value[0] =
1384                 loopback->setup[kcontrol->id.subdevice]
1385                                [kcontrol->id.device].notify;
1386         mutex_unlock(&loopback->cable_lock);
1387         return 0;
1388 }
1389
1390 static int loopback_notify_put(struct snd_kcontrol *kcontrol,
1391                                struct snd_ctl_elem_value *ucontrol)
1392 {
1393         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1394         unsigned int val;
1395         int change = 0;
1396
1397         val = ucontrol->value.integer.value[0] ? 1 : 0;
1398         mutex_lock(&loopback->cable_lock);
1399         if (val != loopback->setup[kcontrol->id.subdevice]
1400                                 [kcontrol->id.device].notify) {
1401                 loopback->setup[kcontrol->id.subdevice]
1402                         [kcontrol->id.device].notify = val;
1403                 change = 1;
1404         }
1405         mutex_unlock(&loopback->cable_lock);
1406         return change;
1407 }
1408
1409 static int loopback_active_get(struct snd_kcontrol *kcontrol,
1410                                struct snd_ctl_elem_value *ucontrol)
1411 {
1412         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1413         struct loopback_cable *cable;
1414
1415         unsigned int val = 0;
1416
1417         mutex_lock(&loopback->cable_lock);
1418         cable = loopback->cables[kcontrol->id.subdevice][kcontrol->id.device ^ 1];
1419         if (cable != NULL) {
1420                 unsigned int running = cable->running ^ cable->pause;
1421
1422                 val = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ? 1 : 0;
1423         }
1424         mutex_unlock(&loopback->cable_lock);
1425         ucontrol->value.integer.value[0] = val;
1426         return 0;
1427 }
1428
1429 static int loopback_format_info(struct snd_kcontrol *kcontrol,
1430                                 struct snd_ctl_elem_info *uinfo)
1431 {
1432         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1433         uinfo->count = 1;
1434         uinfo->value.integer.min = 0;
1435         uinfo->value.integer.max = (__force int)SNDRV_PCM_FORMAT_LAST;
1436         uinfo->value.integer.step = 1;
1437         return 0;
1438 }
1439
1440 static int loopback_format_get(struct snd_kcontrol *kcontrol,
1441                                struct snd_ctl_elem_value *ucontrol)
1442 {
1443         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1444
1445         ucontrol->value.integer.value[0] =
1446                 (__force int)loopback->setup[kcontrol->id.subdevice]
1447                                [kcontrol->id.device].format;
1448         return 0;
1449 }
1450
1451 static int loopback_rate_info(struct snd_kcontrol *kcontrol,
1452                               struct snd_ctl_elem_info *uinfo)
1453 {
1454         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1455         uinfo->count = 1;
1456         uinfo->value.integer.min = 0;
1457         uinfo->value.integer.max = 192000;
1458         uinfo->value.integer.step = 1;
1459         return 0;
1460 }
1461
1462 static int loopback_rate_get(struct snd_kcontrol *kcontrol,
1463                              struct snd_ctl_elem_value *ucontrol)
1464 {
1465         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1466
1467         mutex_lock(&loopback->cable_lock);
1468         ucontrol->value.integer.value[0] =
1469                 loopback->setup[kcontrol->id.subdevice]
1470                                [kcontrol->id.device].rate;
1471         mutex_unlock(&loopback->cable_lock);
1472         return 0;
1473 }
1474
1475 static int loopback_channels_info(struct snd_kcontrol *kcontrol,
1476                                   struct snd_ctl_elem_info *uinfo)
1477 {
1478         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1479         uinfo->count = 1;
1480         uinfo->value.integer.min = 1;
1481         uinfo->value.integer.max = 1024;
1482         uinfo->value.integer.step = 1;
1483         return 0;
1484 }
1485
1486 static int loopback_channels_get(struct snd_kcontrol *kcontrol,
1487                                  struct snd_ctl_elem_value *ucontrol)
1488 {
1489         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1490
1491         mutex_lock(&loopback->cable_lock);
1492         ucontrol->value.integer.value[0] =
1493                 loopback->setup[kcontrol->id.subdevice]
1494                                [kcontrol->id.device].channels;
1495         mutex_unlock(&loopback->cable_lock);
1496         return 0;
1497 }
1498
1499 static const struct snd_kcontrol_new loopback_controls[]  = {
1500 {
1501         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1502         .name =         "PCM Rate Shift 100000",
1503         .info =         loopback_rate_shift_info,
1504         .get =          loopback_rate_shift_get,
1505         .put =          loopback_rate_shift_put,
1506 },
1507 {
1508         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1509         .name =         "PCM Notify",
1510         .info =         snd_ctl_boolean_mono_info,
1511         .get =          loopback_notify_get,
1512         .put =          loopback_notify_put,
1513 },
1514 #define ACTIVE_IDX 2
1515 {
1516         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
1517         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1518         .name =         "PCM Slave Active",
1519         .info =         snd_ctl_boolean_mono_info,
1520         .get =          loopback_active_get,
1521 },
1522 #define FORMAT_IDX 3
1523 {
1524         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
1525         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1526         .name =         "PCM Slave Format",
1527         .info =         loopback_format_info,
1528         .get =          loopback_format_get
1529 },
1530 #define RATE_IDX 4
1531 {
1532         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
1533         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1534         .name =         "PCM Slave Rate",
1535         .info =         loopback_rate_info,
1536         .get =          loopback_rate_get
1537 },
1538 #define CHANNELS_IDX 5
1539 {
1540         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
1541         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1542         .name =         "PCM Slave Channels",
1543         .info =         loopback_channels_info,
1544         .get =          loopback_channels_get
1545 }
1546 };
1547
1548 static int loopback_mixer_new(struct loopback *loopback, int notify)
1549 {
1550         struct snd_card *card = loopback->card;
1551         struct snd_pcm *pcm;
1552         struct snd_kcontrol *kctl;
1553         struct loopback_setup *setup;
1554         int err, dev, substr, substr_count, idx;
1555
1556         strcpy(card->mixername, "Loopback Mixer");
1557         for (dev = 0; dev < 2; dev++) {
1558                 pcm = loopback->pcm[dev];
1559                 substr_count =
1560                     pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream_count;
1561                 for (substr = 0; substr < substr_count; substr++) {
1562                         setup = &loopback->setup[substr][dev];
1563                         setup->notify = notify;
1564                         setup->rate_shift = NO_PITCH;
1565                         setup->format = SNDRV_PCM_FORMAT_S16_LE;
1566                         setup->rate = 48000;
1567                         setup->channels = 2;
1568                         for (idx = 0; idx < ARRAY_SIZE(loopback_controls);
1569                                                                         idx++) {
1570                                 kctl = snd_ctl_new1(&loopback_controls[idx],
1571                                                     loopback);
1572                                 if (!kctl)
1573                                         return -ENOMEM;
1574                                 kctl->id.device = dev;
1575                                 kctl->id.subdevice = substr;
1576                                 switch (idx) {
1577                                 case ACTIVE_IDX:
1578                                         setup->active_id = kctl->id;
1579                                         break;
1580                                 case FORMAT_IDX:
1581                                         setup->format_id = kctl->id;
1582                                         break;
1583                                 case RATE_IDX:
1584                                         setup->rate_id = kctl->id;
1585                                         break;
1586                                 case CHANNELS_IDX:
1587                                         setup->channels_id = kctl->id;
1588                                         break;
1589                                 default:
1590                                         break;
1591                                 }
1592                                 err = snd_ctl_add(card, kctl);
1593                                 if (err < 0)
1594                                         return err;
1595                         }
1596                 }
1597         }
1598         return 0;
1599 }
1600
1601 static void print_dpcm_info(struct snd_info_buffer *buffer,
1602                             struct loopback_pcm *dpcm,
1603                             const char *id)
1604 {
1605         snd_iprintf(buffer, "  %s\n", id);
1606         if (dpcm == NULL) {
1607                 snd_iprintf(buffer, "    inactive\n");
1608                 return;
1609         }
1610         snd_iprintf(buffer, "    buffer_size:\t%u\n", dpcm->pcm_buffer_size);
1611         snd_iprintf(buffer, "    buffer_pos:\t\t%u\n", dpcm->buf_pos);
1612         snd_iprintf(buffer, "    silent_size:\t%u\n", dpcm->silent_size);
1613         snd_iprintf(buffer, "    period_size:\t%u\n", dpcm->pcm_period_size);
1614         snd_iprintf(buffer, "    bytes_per_sec:\t%u\n", dpcm->pcm_bps);
1615         snd_iprintf(buffer, "    sample_align:\t%u\n", dpcm->pcm_salign);
1616         snd_iprintf(buffer, "    rate_shift:\t\t%u\n", dpcm->pcm_rate_shift);
1617         if (dpcm->cable->ops->dpcm_info)
1618                 dpcm->cable->ops->dpcm_info(dpcm, buffer);
1619 }
1620
1621 static void print_substream_info(struct snd_info_buffer *buffer,
1622                                  struct loopback *loopback,
1623                                  int sub,
1624                                  int num)
1625 {
1626         struct loopback_cable *cable = loopback->cables[sub][num];
1627
1628         snd_iprintf(buffer, "Cable %i substream %i:\n", num, sub);
1629         if (cable == NULL) {
1630                 snd_iprintf(buffer, "  inactive\n");
1631                 return;
1632         }
1633         snd_iprintf(buffer, "  valid: %u\n", cable->valid);
1634         snd_iprintf(buffer, "  running: %u\n", cable->running);
1635         snd_iprintf(buffer, "  pause: %u\n", cable->pause);
1636         print_dpcm_info(buffer, cable->streams[0], "Playback");
1637         print_dpcm_info(buffer, cable->streams[1], "Capture");
1638 }
1639
1640 static void print_cable_info(struct snd_info_entry *entry,
1641                              struct snd_info_buffer *buffer)
1642 {
1643         struct loopback *loopback = entry->private_data;
1644         int sub, num;
1645
1646         mutex_lock(&loopback->cable_lock);
1647         num = entry->name[strlen(entry->name)-1];
1648         num = num == '0' ? 0 : 1;
1649         for (sub = 0; sub < MAX_PCM_SUBSTREAMS; sub++)
1650                 print_substream_info(buffer, loopback, sub, num);
1651         mutex_unlock(&loopback->cable_lock);
1652 }
1653
1654 static int loopback_cable_proc_new(struct loopback *loopback, int cidx)
1655 {
1656         char name[32];
1657
1658         snprintf(name, sizeof(name), "cable#%d", cidx);
1659         return snd_card_ro_proc_new(loopback->card, name, loopback,
1660                                     print_cable_info);
1661 }
1662
1663 static void loopback_set_timer_source(struct loopback *loopback,
1664                                       const char *value)
1665 {
1666         if (loopback->timer_source) {
1667                 devm_kfree(loopback->card->dev, loopback->timer_source);
1668                 loopback->timer_source = NULL;
1669         }
1670         if (value && *value)
1671                 loopback->timer_source = devm_kstrdup(loopback->card->dev,
1672                                                       value, GFP_KERNEL);
1673 }
1674
1675 static void print_timer_source_info(struct snd_info_entry *entry,
1676                                     struct snd_info_buffer *buffer)
1677 {
1678         struct loopback *loopback = entry->private_data;
1679
1680         mutex_lock(&loopback->cable_lock);
1681         snd_iprintf(buffer, "%s\n",
1682                     loopback->timer_source ? loopback->timer_source : "");
1683         mutex_unlock(&loopback->cable_lock);
1684 }
1685
1686 static void change_timer_source_info(struct snd_info_entry *entry,
1687                                      struct snd_info_buffer *buffer)
1688 {
1689         struct loopback *loopback = entry->private_data;
1690         char line[64];
1691
1692         mutex_lock(&loopback->cable_lock);
1693         if (!snd_info_get_line(buffer, line, sizeof(line)))
1694                 loopback_set_timer_source(loopback, strim(line));
1695         mutex_unlock(&loopback->cable_lock);
1696 }
1697
1698 static int loopback_timer_source_proc_new(struct loopback *loopback)
1699 {
1700         return snd_card_rw_proc_new(loopback->card, "timer_source", loopback,
1701                                     print_timer_source_info,
1702                                     change_timer_source_info);
1703 }
1704
1705 static int loopback_probe(struct platform_device *devptr)
1706 {
1707         struct snd_card *card;
1708         struct loopback *loopback;
1709         int dev = devptr->id;
1710         int err;
1711
1712         err = snd_card_new(&devptr->dev, index[dev], id[dev], THIS_MODULE,
1713                            sizeof(struct loopback), &card);
1714         if (err < 0)
1715                 return err;
1716         loopback = card->private_data;
1717
1718         if (pcm_substreams[dev] < 1)
1719                 pcm_substreams[dev] = 1;
1720         if (pcm_substreams[dev] > MAX_PCM_SUBSTREAMS)
1721                 pcm_substreams[dev] = MAX_PCM_SUBSTREAMS;
1722
1723         loopback->card = card;
1724         loopback_set_timer_source(loopback, timer_source[dev]);
1725
1726         mutex_init(&loopback->cable_lock);
1727
1728         err = loopback_pcm_new(loopback, 0, pcm_substreams[dev]);
1729         if (err < 0)
1730                 goto __nodev;
1731         err = loopback_pcm_new(loopback, 1, pcm_substreams[dev]);
1732         if (err < 0)
1733                 goto __nodev;
1734         err = loopback_mixer_new(loopback, pcm_notify[dev] ? 1 : 0);
1735         if (err < 0)
1736                 goto __nodev;
1737         loopback_cable_proc_new(loopback, 0);
1738         loopback_cable_proc_new(loopback, 1);
1739         loopback_timer_source_proc_new(loopback);
1740         strcpy(card->driver, "Loopback");
1741         strcpy(card->shortname, "Loopback");
1742         sprintf(card->longname, "Loopback %i", dev + 1);
1743         err = snd_card_register(card);
1744         if (!err) {
1745                 platform_set_drvdata(devptr, card);
1746                 return 0;
1747         }
1748       __nodev:
1749         snd_card_free(card);
1750         return err;
1751 }
1752
1753 static int loopback_remove(struct platform_device *devptr)
1754 {
1755         snd_card_free(platform_get_drvdata(devptr));
1756         return 0;
1757 }
1758
1759 #ifdef CONFIG_PM_SLEEP
1760 static int loopback_suspend(struct device *pdev)
1761 {
1762         struct snd_card *card = dev_get_drvdata(pdev);
1763
1764         snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
1765         return 0;
1766 }
1767
1768 static int loopback_resume(struct device *pdev)
1769 {
1770         struct snd_card *card = dev_get_drvdata(pdev);
1771
1772         snd_power_change_state(card, SNDRV_CTL_POWER_D0);
1773         return 0;
1774 }
1775
1776 static SIMPLE_DEV_PM_OPS(loopback_pm, loopback_suspend, loopback_resume);
1777 #define LOOPBACK_PM_OPS &loopback_pm
1778 #else
1779 #define LOOPBACK_PM_OPS NULL
1780 #endif
1781
1782 #define SND_LOOPBACK_DRIVER     "snd_aloop"
1783
1784 static struct platform_driver loopback_driver = {
1785         .probe          = loopback_probe,
1786         .remove         = loopback_remove,
1787         .driver         = {
1788                 .name   = SND_LOOPBACK_DRIVER,
1789                 .pm     = LOOPBACK_PM_OPS,
1790         },
1791 };
1792
1793 static void loopback_unregister_all(void)
1794 {
1795         int i;
1796
1797         for (i = 0; i < ARRAY_SIZE(devices); ++i)
1798                 platform_device_unregister(devices[i]);
1799         platform_driver_unregister(&loopback_driver);
1800 }
1801
1802 static int __init alsa_card_loopback_init(void)
1803 {
1804         int i, err, cards;
1805
1806         err = platform_driver_register(&loopback_driver);
1807         if (err < 0)
1808                 return err;
1809
1810
1811         cards = 0;
1812         for (i = 0; i < SNDRV_CARDS; i++) {
1813                 struct platform_device *device;
1814                 if (!enable[i])
1815                         continue;
1816                 device = platform_device_register_simple(SND_LOOPBACK_DRIVER,
1817                                                          i, NULL, 0);
1818                 if (IS_ERR(device))
1819                         continue;
1820                 if (!platform_get_drvdata(device)) {
1821                         platform_device_unregister(device);
1822                         continue;
1823                 }
1824                 devices[i] = device;
1825                 cards++;
1826         }
1827         if (!cards) {
1828 #ifdef MODULE
1829                 printk(KERN_ERR "aloop: No loopback enabled\n");
1830 #endif
1831                 loopback_unregister_all();
1832                 return -ENODEV;
1833         }
1834         return 0;
1835 }
1836
1837 static void __exit alsa_card_loopback_exit(void)
1838 {
1839         loopback_unregister_all();
1840 }
1841
1842 module_init(alsa_card_loopback_init)
1843 module_exit(alsa_card_loopback_exit)