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TOMOYO Linux Cross Reference
Linux/sound/drivers/aloop.c

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  1 /*
  2  *  Loopback soundcard
  3  *
  4  *  Original code:
  5  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
  6  *
  7  *  More accurate positioning and full-duplex support:
  8  *  Copyright (c) Ahmet ─░nan <ainan at mathematik.uni-freiburg.de>
  9  *
 10  *  Major (almost complete) rewrite:
 11  *  Copyright (c) by Takashi Iwai <tiwai@suse.de>
 12  *
 13  *  A next major update in 2010 (separate timers for playback and capture):
 14  *  Copyright (c) Jaroslav Kysela <perex@perex.cz>
 15  *
 16  *   This program is free software; you can redistribute it and/or modify
 17  *   it under the terms of the GNU General Public License as published by
 18  *   the Free Software Foundation; either version 2 of the License, or
 19  *   (at your option) any later version.
 20  *
 21  *   This program is distributed in the hope that it will be useful,
 22  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 23  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 24  *   GNU General Public License for more details.
 25  *
 26  *   You should have received a copy of the GNU General Public License
 27  *   along with this program; if not, write to the Free Software
 28  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 29  *
 30  */
 31 
 32 #include <linux/init.h>
 33 #include <linux/jiffies.h>
 34 #include <linux/slab.h>
 35 #include <linux/time.h>
 36 #include <linux/wait.h>
 37 #include <linux/module.h>
 38 #include <linux/platform_device.h>
 39 #include <sound/core.h>
 40 #include <sound/control.h>
 41 #include <sound/pcm.h>
 42 #include <sound/info.h>
 43 #include <sound/initval.h>
 44 
 45 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
 46 MODULE_DESCRIPTION("A loopback soundcard");
 47 MODULE_LICENSE("GPL");
 48 MODULE_SUPPORTED_DEVICE("{{ALSA,Loopback soundcard}}");
 49 
 50 #define MAX_PCM_SUBSTREAMS      8
 51 
 52 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;      /* Index 0-MAX */
 53 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;       /* ID for this card */
 54 static bool enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
 55 static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
 56 static int pcm_notify[SNDRV_CARDS];
 57 
 58 module_param_array(index, int, NULL, 0444);
 59 MODULE_PARM_DESC(index, "Index value for loopback soundcard.");
 60 module_param_array(id, charp, NULL, 0444);
 61 MODULE_PARM_DESC(id, "ID string for loopback soundcard.");
 62 module_param_array(enable, bool, NULL, 0444);
 63 MODULE_PARM_DESC(enable, "Enable this loopback soundcard.");
 64 module_param_array(pcm_substreams, int, NULL, 0444);
 65 MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-8) for loopback driver.");
 66 module_param_array(pcm_notify, int, NULL, 0444);
 67 MODULE_PARM_DESC(pcm_notify, "Break capture when PCM format/rate/channels changes.");
 68 
 69 #define NO_PITCH 100000
 70 
 71 struct loopback_pcm;
 72 
 73 struct loopback_cable {
 74         spinlock_t lock;
 75         struct loopback_pcm *streams[2];
 76         struct snd_pcm_hardware hw;
 77         /* flags */
 78         unsigned int valid;
 79         unsigned int running;
 80         unsigned int pause;
 81 };
 82 
 83 struct loopback_setup {
 84         unsigned int notify: 1;
 85         unsigned int rate_shift;
 86         unsigned int format;
 87         unsigned int rate;
 88         unsigned int channels;
 89         struct snd_ctl_elem_id active_id;
 90         struct snd_ctl_elem_id format_id;
 91         struct snd_ctl_elem_id rate_id;
 92         struct snd_ctl_elem_id channels_id;
 93 };
 94 
 95 struct loopback {
 96         struct snd_card *card;
 97         struct mutex cable_lock;
 98         struct loopback_cable *cables[MAX_PCM_SUBSTREAMS][2];
 99         struct snd_pcm *pcm[2];
100         struct loopback_setup setup[MAX_PCM_SUBSTREAMS][2];
101 };
102 
103 struct loopback_pcm {
104         struct loopback *loopback;
105         struct snd_pcm_substream *substream;
106         struct loopback_cable *cable;
107         unsigned int pcm_buffer_size;
108         unsigned int buf_pos;   /* position in buffer */
109         unsigned int silent_size;
110         /* PCM parameters */
111         unsigned int pcm_period_size;
112         unsigned int pcm_bps;           /* bytes per second */
113         unsigned int pcm_salign;        /* bytes per sample * channels */
114         unsigned int pcm_rate_shift;    /* rate shift value */
115         /* flags */
116         unsigned int period_update_pending :1;
117         /* timer stuff */
118         unsigned int irq_pos;           /* fractional IRQ position */
119         unsigned int period_size_frac;
120         unsigned int last_drift;
121         unsigned long last_jiffies;
122         struct timer_list timer;
123         spinlock_t timer_lock;
124 };
125 
126 static struct platform_device *devices[SNDRV_CARDS];
127 
128 static inline unsigned int byte_pos(struct loopback_pcm *dpcm, unsigned int x)
129 {
130         if (dpcm->pcm_rate_shift == NO_PITCH) {
131                 x /= HZ;
132         } else {
133                 x = div_u64(NO_PITCH * (unsigned long long)x,
134                             HZ * (unsigned long long)dpcm->pcm_rate_shift);
135         }
136         return x - (x % dpcm->pcm_salign);
137 }
138 
139 static inline unsigned int frac_pos(struct loopback_pcm *dpcm, unsigned int x)
140 {
141         if (dpcm->pcm_rate_shift == NO_PITCH) { /* no pitch */
142                 return x * HZ;
143         } else {
144                 x = div_u64(dpcm->pcm_rate_shift * (unsigned long long)x * HZ,
145                             NO_PITCH);
146         }
147         return x;
148 }
149 
150 static inline struct loopback_setup *get_setup(struct loopback_pcm *dpcm)
151 {
152         int device = dpcm->substream->pstr->pcm->device;
153         
154         if (dpcm->substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
155                 device ^= 1;
156         return &dpcm->loopback->setup[dpcm->substream->number][device];
157 }
158 
159 static inline unsigned int get_notify(struct loopback_pcm *dpcm)
160 {
161         return get_setup(dpcm)->notify;
162 }
163 
164 static inline unsigned int get_rate_shift(struct loopback_pcm *dpcm)
165 {
166         return get_setup(dpcm)->rate_shift;
167 }
168 
169 static void loopback_timer_start(struct loopback_pcm *dpcm)
170 {
171         unsigned long tick;
172         unsigned int rate_shift = get_rate_shift(dpcm);
173 
174         spin_lock(&dpcm->timer_lock);
175         if (rate_shift != dpcm->pcm_rate_shift) {
176                 dpcm->pcm_rate_shift = rate_shift;
177                 dpcm->period_size_frac = frac_pos(dpcm, dpcm->pcm_period_size);
178         }
179         if (dpcm->period_size_frac <= dpcm->irq_pos) {
180                 dpcm->irq_pos %= dpcm->period_size_frac;
181                 dpcm->period_update_pending = 1;
182         }
183         tick = dpcm->period_size_frac - dpcm->irq_pos;
184         tick = (tick + dpcm->pcm_bps - 1) / dpcm->pcm_bps;
185         dpcm->timer.expires = jiffies + tick;
186         add_timer(&dpcm->timer);
187         spin_unlock(&dpcm->timer_lock);
188 }
189 
190 static inline void loopback_timer_stop(struct loopback_pcm *dpcm)
191 {
192         spin_lock(&dpcm->timer_lock);
193         del_timer(&dpcm->timer);
194         dpcm->timer.expires = 0;
195         spin_unlock(&dpcm->timer_lock);
196 }
197 
198 #define CABLE_VALID_PLAYBACK    (1 << SNDRV_PCM_STREAM_PLAYBACK)
199 #define CABLE_VALID_CAPTURE     (1 << SNDRV_PCM_STREAM_CAPTURE)
200 #define CABLE_VALID_BOTH        (CABLE_VALID_PLAYBACK|CABLE_VALID_CAPTURE)
201 
202 static int loopback_check_format(struct loopback_cable *cable, int stream)
203 {
204         struct snd_pcm_runtime *runtime, *cruntime;
205         struct loopback_setup *setup;
206         struct snd_card *card;
207         int check;
208 
209         if (cable->valid != CABLE_VALID_BOTH) {
210                 if (stream == SNDRV_PCM_STREAM_PLAYBACK)
211                         goto __notify;
212                 return 0;
213         }
214         runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->
215                                                         substream->runtime;
216         cruntime = cable->streams[SNDRV_PCM_STREAM_CAPTURE]->
217                                                         substream->runtime;
218         check = runtime->format != cruntime->format ||
219                 runtime->rate != cruntime->rate ||
220                 runtime->channels != cruntime->channels;
221         if (!check)
222                 return 0;
223         if (stream == SNDRV_PCM_STREAM_CAPTURE) {
224                 return -EIO;
225         } else {
226                 snd_pcm_stop(cable->streams[SNDRV_PCM_STREAM_CAPTURE]->
227                                         substream, SNDRV_PCM_STATE_DRAINING);
228               __notify:
229                 runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->
230                                                         substream->runtime;
231                 setup = get_setup(cable->streams[SNDRV_PCM_STREAM_PLAYBACK]);
232                 card = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->loopback->card;
233                 if (setup->format != runtime->format) {
234                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
235                                                         &setup->format_id);
236                         setup->format = runtime->format;
237                 }
238                 if (setup->rate != runtime->rate) {
239                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
240                                                         &setup->rate_id);
241                         setup->rate = runtime->rate;
242                 }
243                 if (setup->channels != runtime->channels) {
244                         snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
245                                                         &setup->channels_id);
246                         setup->channels = runtime->channels;
247                 }
248         }
249         return 0;
250 }
251 
252 static void loopback_active_notify(struct loopback_pcm *dpcm)
253 {
254         snd_ctl_notify(dpcm->loopback->card,
255                        SNDRV_CTL_EVENT_MASK_VALUE,
256                        &get_setup(dpcm)->active_id);
257 }
258 
259 static int loopback_trigger(struct snd_pcm_substream *substream, int cmd)
260 {
261         struct snd_pcm_runtime *runtime = substream->runtime;
262         struct loopback_pcm *dpcm = runtime->private_data;
263         struct loopback_cable *cable = dpcm->cable;
264         int err, stream = 1 << substream->stream;
265 
266         switch (cmd) {
267         case SNDRV_PCM_TRIGGER_START:
268                 err = loopback_check_format(cable, substream->stream);
269                 if (err < 0)
270                         return err;
271                 dpcm->last_jiffies = jiffies;
272                 dpcm->pcm_rate_shift = 0;
273                 dpcm->last_drift = 0;
274                 spin_lock(&cable->lock);        
275                 cable->running |= stream;
276                 cable->pause &= ~stream;
277                 spin_unlock(&cable->lock);
278                 loopback_timer_start(dpcm);
279                 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
280                         loopback_active_notify(dpcm);
281                 break;
282         case SNDRV_PCM_TRIGGER_STOP:
283                 spin_lock(&cable->lock);        
284                 cable->running &= ~stream;
285                 cable->pause &= ~stream;
286                 spin_unlock(&cable->lock);
287                 loopback_timer_stop(dpcm);
288                 if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
289                         loopback_active_notify(dpcm);
290                 break;
291         case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
292                 spin_lock(&cable->lock);        
293                 cable->pause |= stream;
294                 spin_unlock(&cable->lock);
295                 loopback_timer_stop(dpcm);
296                 break;
297         case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
298                 spin_lock(&cable->lock);
299                 dpcm->last_jiffies = jiffies;
300                 cable->pause &= ~stream;
301                 spin_unlock(&cable->lock);
302                 loopback_timer_start(dpcm);
303                 break;
304         default:
305                 return -EINVAL;
306         }
307         return 0;
308 }
309 
310 static void params_change_substream(struct loopback_pcm *dpcm,
311                                     struct snd_pcm_runtime *runtime)
312 {
313         struct snd_pcm_runtime *dst_runtime;
314 
315         if (dpcm == NULL || dpcm->substream == NULL)
316                 return;
317         dst_runtime = dpcm->substream->runtime;
318         if (dst_runtime == NULL)
319                 return;
320         dst_runtime->hw = dpcm->cable->hw;
321 }
322 
323 static void params_change(struct snd_pcm_substream *substream)
324 {
325         struct snd_pcm_runtime *runtime = substream->runtime;
326         struct loopback_pcm *dpcm = runtime->private_data;
327         struct loopback_cable *cable = dpcm->cable;
328 
329         cable->hw.formats = (1ULL << runtime->format);
330         cable->hw.rate_min = runtime->rate;
331         cable->hw.rate_max = runtime->rate;
332         cable->hw.channels_min = runtime->channels;
333         cable->hw.channels_max = runtime->channels;
334         params_change_substream(cable->streams[SNDRV_PCM_STREAM_PLAYBACK],
335                                 runtime);
336         params_change_substream(cable->streams[SNDRV_PCM_STREAM_CAPTURE],
337                                 runtime);
338 }
339 
340 static int loopback_prepare(struct snd_pcm_substream *substream)
341 {
342         struct snd_pcm_runtime *runtime = substream->runtime;
343         struct loopback_pcm *dpcm = runtime->private_data;
344         struct loopback_cable *cable = dpcm->cable;
345         int bps, salign;
346 
347         salign = (snd_pcm_format_width(runtime->format) *
348                                                 runtime->channels) / 8;
349         bps = salign * runtime->rate;
350         if (bps <= 0 || salign <= 0)
351                 return -EINVAL;
352 
353         dpcm->buf_pos = 0;
354         dpcm->pcm_buffer_size = frames_to_bytes(runtime, runtime->buffer_size);
355         if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
356                 /* clear capture buffer */
357                 dpcm->silent_size = dpcm->pcm_buffer_size;
358                 snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
359                                            runtime->buffer_size * runtime->channels);
360         }
361 
362         dpcm->irq_pos = 0;
363         dpcm->period_update_pending = 0;
364         dpcm->pcm_bps = bps;
365         dpcm->pcm_salign = salign;
366         dpcm->pcm_period_size = frames_to_bytes(runtime, runtime->period_size);
367 
368         mutex_lock(&dpcm->loopback->cable_lock);
369         if (!(cable->valid & ~(1 << substream->stream)) ||
370             (get_setup(dpcm)->notify &&
371              substream->stream == SNDRV_PCM_STREAM_PLAYBACK))
372                 params_change(substream);
373         cable->valid |= 1 << substream->stream;
374         mutex_unlock(&dpcm->loopback->cable_lock);
375 
376         return 0;
377 }
378 
379 static void clear_capture_buf(struct loopback_pcm *dpcm, unsigned int bytes)
380 {
381         struct snd_pcm_runtime *runtime = dpcm->substream->runtime;
382         char *dst = runtime->dma_area;
383         unsigned int dst_off = dpcm->buf_pos;
384 
385         if (dpcm->silent_size >= dpcm->pcm_buffer_size)
386                 return;
387         if (dpcm->silent_size + bytes > dpcm->pcm_buffer_size)
388                 bytes = dpcm->pcm_buffer_size - dpcm->silent_size;
389 
390         for (;;) {
391                 unsigned int size = bytes;
392                 if (dst_off + size > dpcm->pcm_buffer_size)
393                         size = dpcm->pcm_buffer_size - dst_off;
394                 snd_pcm_format_set_silence(runtime->format, dst + dst_off,
395                                            bytes_to_frames(runtime, size) *
396                                                 runtime->channels);
397                 dpcm->silent_size += size;
398                 bytes -= size;
399                 if (!bytes)
400                         break;
401                 dst_off = 0;
402         }
403 }
404 
405 static void copy_play_buf(struct loopback_pcm *play,
406                           struct loopback_pcm *capt,
407                           unsigned int bytes)
408 {
409         struct snd_pcm_runtime *runtime = play->substream->runtime;
410         char *src = runtime->dma_area;
411         char *dst = capt->substream->runtime->dma_area;
412         unsigned int src_off = play->buf_pos;
413         unsigned int dst_off = capt->buf_pos;
414         unsigned int clear_bytes = 0;
415 
416         /* check if playback is draining, trim the capture copy size
417          * when our pointer is at the end of playback ring buffer */
418         if (runtime->status->state == SNDRV_PCM_STATE_DRAINING &&
419             snd_pcm_playback_hw_avail(runtime) < runtime->buffer_size) { 
420                 snd_pcm_uframes_t appl_ptr, appl_ptr1, diff;
421                 appl_ptr = appl_ptr1 = runtime->control->appl_ptr;
422                 appl_ptr1 -= appl_ptr1 % runtime->buffer_size;
423                 appl_ptr1 += play->buf_pos / play->pcm_salign;
424                 if (appl_ptr < appl_ptr1)
425                         appl_ptr1 -= runtime->buffer_size;
426                 diff = (appl_ptr - appl_ptr1) * play->pcm_salign;
427                 if (diff < bytes) {
428                         clear_bytes = bytes - diff;
429                         bytes = diff;
430                 }
431         }
432 
433         for (;;) {
434                 unsigned int size = bytes;
435                 if (src_off + size > play->pcm_buffer_size)
436                         size = play->pcm_buffer_size - src_off;
437                 if (dst_off + size > capt->pcm_buffer_size)
438                         size = capt->pcm_buffer_size - dst_off;
439                 memcpy(dst + dst_off, src + src_off, size);
440                 capt->silent_size = 0;
441                 bytes -= size;
442                 if (!bytes)
443                         break;
444                 src_off = (src_off + size) % play->pcm_buffer_size;
445                 dst_off = (dst_off + size) % capt->pcm_buffer_size;
446         }
447 
448         if (clear_bytes > 0) {
449                 clear_capture_buf(capt, clear_bytes);
450                 capt->silent_size = 0;
451         }
452 }
453 
454 static inline unsigned int bytepos_delta(struct loopback_pcm *dpcm,
455                                          unsigned int jiffies_delta)
456 {
457         unsigned long last_pos;
458         unsigned int delta;
459 
460         last_pos = byte_pos(dpcm, dpcm->irq_pos);
461         dpcm->irq_pos += jiffies_delta * dpcm->pcm_bps;
462         delta = byte_pos(dpcm, dpcm->irq_pos) - last_pos;
463         if (delta >= dpcm->last_drift)
464                 delta -= dpcm->last_drift;
465         dpcm->last_drift = 0;
466         if (dpcm->irq_pos >= dpcm->period_size_frac) {
467                 dpcm->irq_pos %= dpcm->period_size_frac;
468                 dpcm->period_update_pending = 1;
469         }
470         return delta;
471 }
472 
473 static inline void bytepos_finish(struct loopback_pcm *dpcm,
474                                   unsigned int delta)
475 {
476         dpcm->buf_pos += delta;
477         dpcm->buf_pos %= dpcm->pcm_buffer_size;
478 }
479 
480 static unsigned int loopback_pos_update(struct loopback_cable *cable)
481 {
482         struct loopback_pcm *dpcm_play =
483                         cable->streams[SNDRV_PCM_STREAM_PLAYBACK];
484         struct loopback_pcm *dpcm_capt =
485                         cable->streams[SNDRV_PCM_STREAM_CAPTURE];
486         unsigned long delta_play = 0, delta_capt = 0;
487         unsigned int running, count1, count2;
488         unsigned long flags;
489 
490         spin_lock_irqsave(&cable->lock, flags);
491         running = cable->running ^ cable->pause;
492         if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {
493                 delta_play = jiffies - dpcm_play->last_jiffies;
494                 dpcm_play->last_jiffies += delta_play;
495         }
496 
497         if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {
498                 delta_capt = jiffies - dpcm_capt->last_jiffies;
499                 dpcm_capt->last_jiffies += delta_capt;
500         }
501 
502         if (delta_play == 0 && delta_capt == 0)
503                 goto unlock;
504                 
505         if (delta_play > delta_capt) {
506                 count1 = bytepos_delta(dpcm_play, delta_play - delta_capt);
507                 bytepos_finish(dpcm_play, count1);
508                 delta_play = delta_capt;
509         } else if (delta_play < delta_capt) {
510                 count1 = bytepos_delta(dpcm_capt, delta_capt - delta_play);
511                 clear_capture_buf(dpcm_capt, count1);
512                 bytepos_finish(dpcm_capt, count1);
513                 delta_capt = delta_play;
514         }
515 
516         if (delta_play == 0 && delta_capt == 0)
517                 goto unlock;
518 
519         /* note delta_capt == delta_play at this moment */
520         count1 = bytepos_delta(dpcm_play, delta_play);
521         count2 = bytepos_delta(dpcm_capt, delta_capt);
522         if (count1 < count2) {
523                 dpcm_capt->last_drift = count2 - count1;
524                 count1 = count2;
525         } else if (count1 > count2) {
526                 dpcm_play->last_drift = count1 - count2;
527         }
528         copy_play_buf(dpcm_play, dpcm_capt, count1);
529         bytepos_finish(dpcm_play, count1);
530         bytepos_finish(dpcm_capt, count1);
531  unlock:
532         spin_unlock_irqrestore(&cable->lock, flags);
533         return running;
534 }
535 
536 static void loopback_timer_function(unsigned long data)
537 {
538         struct loopback_pcm *dpcm = (struct loopback_pcm *)data;
539         unsigned int running;
540 
541         running = loopback_pos_update(dpcm->cable);
542         if (running & (1 << dpcm->substream->stream)) {
543                 loopback_timer_start(dpcm);
544                 if (dpcm->period_update_pending) {
545                         dpcm->period_update_pending = 0;
546                         snd_pcm_period_elapsed(dpcm->substream);
547                 }
548         }
549 }
550 
551 static snd_pcm_uframes_t loopback_pointer(struct snd_pcm_substream *substream)
552 {
553         struct snd_pcm_runtime *runtime = substream->runtime;
554         struct loopback_pcm *dpcm = runtime->private_data;
555 
556         loopback_pos_update(dpcm->cable);
557         return bytes_to_frames(runtime, dpcm->buf_pos);
558 }
559 
560 static struct snd_pcm_hardware loopback_pcm_hardware =
561 {
562         .info =         (SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_MMAP |
563                          SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_PAUSE),
564         .formats =      (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE |
565                          SNDRV_PCM_FMTBIT_S32_LE | SNDRV_PCM_FMTBIT_S32_BE |
566                          SNDRV_PCM_FMTBIT_FLOAT_LE | SNDRV_PCM_FMTBIT_FLOAT_BE),
567         .rates =        SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000,
568         .rate_min =             8000,
569         .rate_max =             192000,
570         .channels_min =         1,
571         .channels_max =         32,
572         .buffer_bytes_max =     2 * 1024 * 1024,
573         .period_bytes_min =     64,
574         /* note check overflow in frac_pos() using pcm_rate_shift before
575            changing period_bytes_max value */
576         .period_bytes_max =     1024 * 1024,
577         .periods_min =          1,
578         .periods_max =          1024,
579         .fifo_size =            0,
580 };
581 
582 static void loopback_runtime_free(struct snd_pcm_runtime *runtime)
583 {
584         struct loopback_pcm *dpcm = runtime->private_data;
585         kfree(dpcm);
586 }
587 
588 static int loopback_hw_params(struct snd_pcm_substream *substream,
589                               struct snd_pcm_hw_params *params)
590 {
591         return snd_pcm_lib_alloc_vmalloc_buffer(substream,
592                                                 params_buffer_bytes(params));
593 }
594 
595 static int loopback_hw_free(struct snd_pcm_substream *substream)
596 {
597         struct snd_pcm_runtime *runtime = substream->runtime;
598         struct loopback_pcm *dpcm = runtime->private_data;
599         struct loopback_cable *cable = dpcm->cable;
600 
601         mutex_lock(&dpcm->loopback->cable_lock);
602         cable->valid &= ~(1 << substream->stream);
603         mutex_unlock(&dpcm->loopback->cable_lock);
604         return snd_pcm_lib_free_vmalloc_buffer(substream);
605 }
606 
607 static unsigned int get_cable_index(struct snd_pcm_substream *substream)
608 {
609         if (!substream->pcm->device)
610                 return substream->stream;
611         else
612                 return !substream->stream;
613 }
614 
615 static int rule_format(struct snd_pcm_hw_params *params,
616                        struct snd_pcm_hw_rule *rule)
617 {
618 
619         struct snd_pcm_hardware *hw = rule->private;
620         struct snd_mask *maskp = hw_param_mask(params, rule->var);
621 
622         maskp->bits[0] &= (u_int32_t)hw->formats;
623         maskp->bits[1] &= (u_int32_t)(hw->formats >> 32);
624         memset(maskp->bits + 2, 0, (SNDRV_MASK_MAX-64) / 8); /* clear rest */
625         if (! maskp->bits[0] && ! maskp->bits[1])
626                 return -EINVAL;
627         return 0;
628 }
629 
630 static int rule_rate(struct snd_pcm_hw_params *params,
631                      struct snd_pcm_hw_rule *rule)
632 {
633         struct snd_pcm_hardware *hw = rule->private;
634         struct snd_interval t;
635 
636         t.min = hw->rate_min;
637         t.max = hw->rate_max;
638         t.openmin = t.openmax = 0;
639         t.integer = 0;
640         return snd_interval_refine(hw_param_interval(params, rule->var), &t);
641 }
642 
643 static int rule_channels(struct snd_pcm_hw_params *params,
644                          struct snd_pcm_hw_rule *rule)
645 {
646         struct snd_pcm_hardware *hw = rule->private;
647         struct snd_interval t;
648 
649         t.min = hw->channels_min;
650         t.max = hw->channels_max;
651         t.openmin = t.openmax = 0;
652         t.integer = 0;
653         return snd_interval_refine(hw_param_interval(params, rule->var), &t);
654 }
655 
656 static int loopback_open(struct snd_pcm_substream *substream)
657 {
658         struct snd_pcm_runtime *runtime = substream->runtime;
659         struct loopback *loopback = substream->private_data;
660         struct loopback_pcm *dpcm;
661         struct loopback_cable *cable;
662         int err = 0;
663         int dev = get_cable_index(substream);
664 
665         mutex_lock(&loopback->cable_lock);
666         dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
667         if (!dpcm) {
668                 err = -ENOMEM;
669                 goto unlock;
670         }
671         dpcm->loopback = loopback;
672         dpcm->substream = substream;
673         setup_timer(&dpcm->timer, loopback_timer_function,
674                     (unsigned long)dpcm);
675         spin_lock_init(&dpcm->timer_lock);
676 
677         cable = loopback->cables[substream->number][dev];
678         if (!cable) {
679                 cable = kzalloc(sizeof(*cable), GFP_KERNEL);
680                 if (!cable) {
681                         kfree(dpcm);
682                         err = -ENOMEM;
683                         goto unlock;
684                 }
685                 spin_lock_init(&cable->lock);
686                 cable->hw = loopback_pcm_hardware;
687                 loopback->cables[substream->number][dev] = cable;
688         }
689         dpcm->cable = cable;
690         cable->streams[substream->stream] = dpcm;
691 
692         snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
693 
694         /* use dynamic rules based on actual runtime->hw values */
695         /* note that the default rules created in the PCM midlevel code */
696         /* are cached -> they do not reflect the actual state */
697         err = snd_pcm_hw_rule_add(runtime, 0,
698                                   SNDRV_PCM_HW_PARAM_FORMAT,
699                                   rule_format, &runtime->hw,
700                                   SNDRV_PCM_HW_PARAM_FORMAT, -1);
701         if (err < 0)
702                 goto unlock;
703         err = snd_pcm_hw_rule_add(runtime, 0,
704                                   SNDRV_PCM_HW_PARAM_RATE,
705                                   rule_rate, &runtime->hw,
706                                   SNDRV_PCM_HW_PARAM_RATE, -1);
707         if (err < 0)
708                 goto unlock;
709         err = snd_pcm_hw_rule_add(runtime, 0,
710                                   SNDRV_PCM_HW_PARAM_CHANNELS,
711                                   rule_channels, &runtime->hw,
712                                   SNDRV_PCM_HW_PARAM_CHANNELS, -1);
713         if (err < 0)
714                 goto unlock;
715 
716         runtime->private_data = dpcm;
717         runtime->private_free = loopback_runtime_free;
718         if (get_notify(dpcm))
719                 runtime->hw = loopback_pcm_hardware;
720         else
721                 runtime->hw = cable->hw;
722  unlock:
723         mutex_unlock(&loopback->cable_lock);
724         return err;
725 }
726 
727 static int loopback_close(struct snd_pcm_substream *substream)
728 {
729         struct loopback *loopback = substream->private_data;
730         struct loopback_pcm *dpcm = substream->runtime->private_data;
731         struct loopback_cable *cable;
732         int dev = get_cable_index(substream);
733 
734         loopback_timer_stop(dpcm);
735         mutex_lock(&loopback->cable_lock);
736         cable = loopback->cables[substream->number][dev];
737         if (cable->streams[!substream->stream]) {
738                 /* other stream is still alive */
739                 cable->streams[substream->stream] = NULL;
740         } else {
741                 /* free the cable */
742                 loopback->cables[substream->number][dev] = NULL;
743                 kfree(cable);
744         }
745         mutex_unlock(&loopback->cable_lock);
746         return 0;
747 }
748 
749 static struct snd_pcm_ops loopback_playback_ops = {
750         .open =         loopback_open,
751         .close =        loopback_close,
752         .ioctl =        snd_pcm_lib_ioctl,
753         .hw_params =    loopback_hw_params,
754         .hw_free =      loopback_hw_free,
755         .prepare =      loopback_prepare,
756         .trigger =      loopback_trigger,
757         .pointer =      loopback_pointer,
758         .page =         snd_pcm_lib_get_vmalloc_page,
759         .mmap =         snd_pcm_lib_mmap_vmalloc,
760 };
761 
762 static struct snd_pcm_ops loopback_capture_ops = {
763         .open =         loopback_open,
764         .close =        loopback_close,
765         .ioctl =        snd_pcm_lib_ioctl,
766         .hw_params =    loopback_hw_params,
767         .hw_free =      loopback_hw_free,
768         .prepare =      loopback_prepare,
769         .trigger =      loopback_trigger,
770         .pointer =      loopback_pointer,
771         .page =         snd_pcm_lib_get_vmalloc_page,
772         .mmap =         snd_pcm_lib_mmap_vmalloc,
773 };
774 
775 static int __devinit loopback_pcm_new(struct loopback *loopback,
776                                       int device, int substreams)
777 {
778         struct snd_pcm *pcm;
779         int err;
780 
781         err = snd_pcm_new(loopback->card, "Loopback PCM", device,
782                           substreams, substreams, &pcm);
783         if (err < 0)
784                 return err;
785         snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &loopback_playback_ops);
786         snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &loopback_capture_ops);
787 
788         pcm->private_data = loopback;
789         pcm->info_flags = 0;
790         strcpy(pcm->name, "Loopback PCM");
791 
792         loopback->pcm[device] = pcm;
793         return 0;
794 }
795 
796 static int loopback_rate_shift_info(struct snd_kcontrol *kcontrol,   
797                                     struct snd_ctl_elem_info *uinfo) 
798 {
799         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
800         uinfo->count = 1;
801         uinfo->value.integer.min = 80000;
802         uinfo->value.integer.max = 120000;
803         uinfo->value.integer.step = 1;
804         return 0;
805 }                                  
806 
807 static int loopback_rate_shift_get(struct snd_kcontrol *kcontrol,
808                                    struct snd_ctl_elem_value *ucontrol)
809 {
810         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
811         
812         ucontrol->value.integer.value[0] =
813                 loopback->setup[kcontrol->id.subdevice]
814                                [kcontrol->id.device].rate_shift;
815         return 0;
816 }
817 
818 static int loopback_rate_shift_put(struct snd_kcontrol *kcontrol,
819                                    struct snd_ctl_elem_value *ucontrol)
820 {
821         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
822         unsigned int val;
823         int change = 0;
824 
825         val = ucontrol->value.integer.value[0];
826         if (val < 80000)
827                 val = 80000;
828         if (val > 120000)
829                 val = 120000;   
830         mutex_lock(&loopback->cable_lock);
831         if (val != loopback->setup[kcontrol->id.subdevice]
832                                   [kcontrol->id.device].rate_shift) {
833                 loopback->setup[kcontrol->id.subdevice]
834                                [kcontrol->id.device].rate_shift = val;
835                 change = 1;
836         }
837         mutex_unlock(&loopback->cable_lock);
838         return change;
839 }
840 
841 static int loopback_notify_get(struct snd_kcontrol *kcontrol,
842                                struct snd_ctl_elem_value *ucontrol)
843 {
844         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
845         
846         ucontrol->value.integer.value[0] =
847                 loopback->setup[kcontrol->id.subdevice]
848                                [kcontrol->id.device].notify;
849         return 0;
850 }
851 
852 static int loopback_notify_put(struct snd_kcontrol *kcontrol,
853                                struct snd_ctl_elem_value *ucontrol)
854 {
855         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
856         unsigned int val;
857         int change = 0;
858 
859         val = ucontrol->value.integer.value[0] ? 1 : 0;
860         if (val != loopback->setup[kcontrol->id.subdevice]
861                                 [kcontrol->id.device].notify) {
862                 loopback->setup[kcontrol->id.subdevice]
863                         [kcontrol->id.device].notify = val;
864                 change = 1;
865         }
866         return change;
867 }
868 
869 static int loopback_active_get(struct snd_kcontrol *kcontrol,
870                                struct snd_ctl_elem_value *ucontrol)
871 {
872         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
873         struct loopback_cable *cable = loopback->cables
874                         [kcontrol->id.subdevice][kcontrol->id.device ^ 1];
875         unsigned int val = 0;
876 
877         if (cable != NULL)
878                 val = (cable->running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?
879                                                                         1 : 0;
880         ucontrol->value.integer.value[0] = val;
881         return 0;
882 }
883 
884 static int loopback_format_info(struct snd_kcontrol *kcontrol,   
885                                 struct snd_ctl_elem_info *uinfo) 
886 {
887         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
888         uinfo->count = 1;
889         uinfo->value.integer.min = 0;
890         uinfo->value.integer.max = SNDRV_PCM_FORMAT_LAST;
891         uinfo->value.integer.step = 1;
892         return 0;
893 }                                  
894 
895 static int loopback_format_get(struct snd_kcontrol *kcontrol,
896                                struct snd_ctl_elem_value *ucontrol)
897 {
898         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
899         
900         ucontrol->value.integer.value[0] =
901                 loopback->setup[kcontrol->id.subdevice]
902                                [kcontrol->id.device].format;
903         return 0;
904 }
905 
906 static int loopback_rate_info(struct snd_kcontrol *kcontrol,   
907                               struct snd_ctl_elem_info *uinfo) 
908 {
909         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
910         uinfo->count = 1;
911         uinfo->value.integer.min = 0;
912         uinfo->value.integer.max = 192000;
913         uinfo->value.integer.step = 1;
914         return 0;
915 }                                  
916 
917 static int loopback_rate_get(struct snd_kcontrol *kcontrol,
918                              struct snd_ctl_elem_value *ucontrol)
919 {
920         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
921         
922         ucontrol->value.integer.value[0] =
923                 loopback->setup[kcontrol->id.subdevice]
924                                [kcontrol->id.device].rate;
925         return 0;
926 }
927 
928 static int loopback_channels_info(struct snd_kcontrol *kcontrol,   
929                                   struct snd_ctl_elem_info *uinfo) 
930 {
931         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
932         uinfo->count = 1;
933         uinfo->value.integer.min = 1;
934         uinfo->value.integer.max = 1024;
935         uinfo->value.integer.step = 1;
936         return 0;
937 }                                  
938 
939 static int loopback_channels_get(struct snd_kcontrol *kcontrol,
940                                  struct snd_ctl_elem_value *ucontrol)
941 {
942         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
943         
944         ucontrol->value.integer.value[0] =
945                 loopback->setup[kcontrol->id.subdevice]
946                                [kcontrol->id.device].channels;
947         return 0;
948 }
949 
950 static struct snd_kcontrol_new loopback_controls[]  __devinitdata = {
951 {
952         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
953         .name =         "PCM Rate Shift 100000",
954         .info =         loopback_rate_shift_info,
955         .get =          loopback_rate_shift_get,
956         .put =          loopback_rate_shift_put,
957 },
958 {
959         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
960         .name =         "PCM Notify",
961         .info =         snd_ctl_boolean_mono_info,
962         .get =          loopback_notify_get,
963         .put =          loopback_notify_put,
964 },
965 #define ACTIVE_IDX 2
966 {
967         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
968         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
969         .name =         "PCM Slave Active",
970         .info =         snd_ctl_boolean_mono_info,
971         .get =          loopback_active_get,
972 },
973 #define FORMAT_IDX 3
974 {
975         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
976         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
977         .name =         "PCM Slave Format",
978         .info =         loopback_format_info,
979         .get =          loopback_format_get
980 },
981 #define RATE_IDX 4
982 {
983         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
984         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
985         .name =         "PCM Slave Rate",
986         .info =         loopback_rate_info,
987         .get =          loopback_rate_get
988 },
989 #define CHANNELS_IDX 5
990 {
991         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
992         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
993         .name =         "PCM Slave Channels",
994         .info =         loopback_channels_info,
995         .get =          loopback_channels_get
996 }
997 };
998 
999 static int __devinit loopback_mixer_new(struct loopback *loopback, int notify)
1000 {
1001         struct snd_card *card = loopback->card;
1002         struct snd_pcm *pcm;
1003         struct snd_kcontrol *kctl;
1004         struct loopback_setup *setup;
1005         int err, dev, substr, substr_count, idx;
1006 
1007         strcpy(card->mixername, "Loopback Mixer");
1008         for (dev = 0; dev < 2; dev++) {
1009                 pcm = loopback->pcm[dev];
1010                 substr_count =
1011                     pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream_count;
1012                 for (substr = 0; substr < substr_count; substr++) {
1013                         setup = &loopback->setup[substr][dev];
1014                         setup->notify = notify;
1015                         setup->rate_shift = NO_PITCH;
1016                         setup->format = SNDRV_PCM_FORMAT_S16_LE;
1017                         setup->rate = 48000;
1018                         setup->channels = 2;
1019                         for (idx = 0; idx < ARRAY_SIZE(loopback_controls);
1020                                                                         idx++) {
1021                                 kctl = snd_ctl_new1(&loopback_controls[idx],
1022                                                     loopback);
1023                                 if (!kctl)
1024                                         return -ENOMEM;
1025                                 kctl->id.device = dev;
1026                                 kctl->id.subdevice = substr;
1027                                 switch (idx) {
1028                                 case ACTIVE_IDX:
1029                                         setup->active_id = kctl->id;
1030                                         break;
1031                                 case FORMAT_IDX:
1032                                         setup->format_id = kctl->id;
1033                                         break;
1034                                 case RATE_IDX:
1035                                         setup->rate_id = kctl->id;
1036                                         break;
1037                                 case CHANNELS_IDX:
1038                                         setup->channels_id = kctl->id;
1039                                         break;
1040                                 default:
1041                                         break;
1042                                 }
1043                                 err = snd_ctl_add(card, kctl);
1044                                 if (err < 0)
1045                                         return err;
1046                         }
1047                 }
1048         }
1049         return 0;
1050 }
1051 
1052 #ifdef CONFIG_PROC_FS
1053 
1054 static void print_dpcm_info(struct snd_info_buffer *buffer,
1055                             struct loopback_pcm *dpcm,
1056                             const char *id)
1057 {
1058         snd_iprintf(buffer, "  %s\n", id);
1059         if (dpcm == NULL) {
1060                 snd_iprintf(buffer, "    inactive\n");
1061                 return;
1062         }
1063         snd_iprintf(buffer, "    buffer_size:\t%u\n", dpcm->pcm_buffer_size);
1064         snd_iprintf(buffer, "    buffer_pos:\t\t%u\n", dpcm->buf_pos);
1065         snd_iprintf(buffer, "    silent_size:\t%u\n", dpcm->silent_size);
1066         snd_iprintf(buffer, "    period_size:\t%u\n", dpcm->pcm_period_size);
1067         snd_iprintf(buffer, "    bytes_per_sec:\t%u\n", dpcm->pcm_bps);
1068         snd_iprintf(buffer, "    sample_align:\t%u\n", dpcm->pcm_salign);
1069         snd_iprintf(buffer, "    rate_shift:\t\t%u\n", dpcm->pcm_rate_shift);
1070         snd_iprintf(buffer, "    update_pending:\t%u\n",
1071                                                 dpcm->period_update_pending);
1072         snd_iprintf(buffer, "    irq_pos:\t\t%u\n", dpcm->irq_pos);
1073         snd_iprintf(buffer, "    period_frac:\t%u\n", dpcm->period_size_frac);
1074         snd_iprintf(buffer, "    last_jiffies:\t%lu (%lu)\n",
1075                                         dpcm->last_jiffies, jiffies);
1076         snd_iprintf(buffer, "    timer_expires:\t%lu\n", dpcm->timer.expires);
1077 }
1078 
1079 static void print_substream_info(struct snd_info_buffer *buffer,
1080                                  struct loopback *loopback,
1081                                  int sub,
1082                                  int num)
1083 {
1084         struct loopback_cable *cable = loopback->cables[sub][num];
1085 
1086         snd_iprintf(buffer, "Cable %i substream %i:\n", num, sub);
1087         if (cable == NULL) {
1088                 snd_iprintf(buffer, "  inactive\n");
1089                 return;
1090         }
1091         snd_iprintf(buffer, "  valid: %u\n", cable->valid);
1092         snd_iprintf(buffer, "  running: %u\n", cable->running);
1093         snd_iprintf(buffer, "  pause: %u\n", cable->pause);
1094         print_dpcm_info(buffer, cable->streams[0], "Playback");
1095         print_dpcm_info(buffer, cable->streams[1], "Capture");
1096 }
1097 
1098 static void print_cable_info(struct snd_info_entry *entry,
1099                              struct snd_info_buffer *buffer)
1100 {
1101         struct loopback *loopback = entry->private_data;
1102         int sub, num;
1103 
1104         mutex_lock(&loopback->cable_lock);
1105         num = entry->name[strlen(entry->name)-1];
1106         num = num == '' ? 0 : 1;
1107         for (sub = 0; sub < MAX_PCM_SUBSTREAMS; sub++)
1108                 print_substream_info(buffer, loopback, sub, num);
1109         mutex_unlock(&loopback->cable_lock);
1110 }
1111 
1112 static int __devinit loopback_proc_new(struct loopback *loopback, int cidx)
1113 {
1114         char name[32];
1115         struct snd_info_entry *entry;
1116         int err;
1117 
1118         snprintf(name, sizeof(name), "cable#%d", cidx);
1119         err = snd_card_proc_new(loopback->card, name, &entry);
1120         if (err < 0)
1121                 return err;
1122 
1123         snd_info_set_text_ops(entry, loopback, print_cable_info);
1124         return 0;
1125 }
1126 
1127 #else /* !CONFIG_PROC_FS */
1128 
1129 #define loopback_proc_new(loopback, cidx) do { } while (0)
1130 
1131 #endif
1132 
1133 static int __devinit loopback_probe(struct platform_device *devptr)
1134 {
1135         struct snd_card *card;
1136         struct loopback *loopback;
1137         int dev = devptr->id;
1138         int err;
1139 
1140         err = snd_card_create(index[dev], id[dev], THIS_MODULE,
1141                               sizeof(struct loopback), &card);
1142         if (err < 0)
1143                 return err;
1144         loopback = card->private_data;
1145 
1146         if (pcm_substreams[dev] < 1)
1147                 pcm_substreams[dev] = 1;
1148         if (pcm_substreams[dev] > MAX_PCM_SUBSTREAMS)
1149                 pcm_substreams[dev] = MAX_PCM_SUBSTREAMS;
1150         
1151         loopback->card = card;
1152         mutex_init(&loopback->cable_lock);
1153 
1154         err = loopback_pcm_new(loopback, 0, pcm_substreams[dev]);
1155         if (err < 0)
1156                 goto __nodev;
1157         err = loopback_pcm_new(loopback, 1, pcm_substreams[dev]);
1158         if (err < 0)
1159                 goto __nodev;
1160         err = loopback_mixer_new(loopback, pcm_notify[dev] ? 1 : 0);
1161         if (err < 0)
1162                 goto __nodev;
1163         loopback_proc_new(loopback, 0);
1164         loopback_proc_new(loopback, 1);
1165         strcpy(card->driver, "Loopback");
1166         strcpy(card->shortname, "Loopback");
1167         sprintf(card->longname, "Loopback %i", dev + 1);
1168         err = snd_card_register(card);
1169         if (!err) {
1170                 platform_set_drvdata(devptr, card);
1171                 return 0;
1172         }
1173       __nodev:
1174         snd_card_free(card);
1175         return err;
1176 }
1177 
1178 static int __devexit loopback_remove(struct platform_device *devptr)
1179 {
1180         snd_card_free(platform_get_drvdata(devptr));
1181         platform_set_drvdata(devptr, NULL);
1182         return 0;
1183 }
1184 
1185 #ifdef CONFIG_PM_SLEEP
1186 static int loopback_suspend(struct device *pdev)
1187 {
1188         struct snd_card *card = dev_get_drvdata(pdev);
1189         struct loopback *loopback = card->private_data;
1190 
1191         snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
1192 
1193         snd_pcm_suspend_all(loopback->pcm[0]);
1194         snd_pcm_suspend_all(loopback->pcm[1]);
1195         return 0;
1196 }
1197         
1198 static int loopback_resume(struct device *pdev)
1199 {
1200         struct snd_card *card = dev_get_drvdata(pdev);
1201 
1202         snd_power_change_state(card, SNDRV_CTL_POWER_D0);
1203         return 0;
1204 }
1205 
1206 static SIMPLE_DEV_PM_OPS(loopback_pm, loopback_suspend, loopback_resume);
1207 #define LOOPBACK_PM_OPS &loopback_pm
1208 #else
1209 #define LOOPBACK_PM_OPS NULL
1210 #endif
1211 
1212 #define SND_LOOPBACK_DRIVER     "snd_aloop"
1213 
1214 static struct platform_driver loopback_driver = {
1215         .probe          = loopback_probe,
1216         .remove         = __devexit_p(loopback_remove),
1217         .driver         = {
1218                 .name   = SND_LOOPBACK_DRIVER,
1219                 .owner  = THIS_MODULE,
1220                 .pm     = LOOPBACK_PM_OPS,
1221         },
1222 };
1223 
1224 static void loopback_unregister_all(void)
1225 {
1226         int i;
1227 
1228         for (i = 0; i < ARRAY_SIZE(devices); ++i)
1229                 platform_device_unregister(devices[i]);
1230         platform_driver_unregister(&loopback_driver);
1231 }
1232 
1233 static int __init alsa_card_loopback_init(void)
1234 {
1235         int i, err, cards;
1236 
1237         err = platform_driver_register(&loopback_driver);
1238         if (err < 0)
1239                 return err;
1240 
1241 
1242         cards = 0;
1243         for (i = 0; i < SNDRV_CARDS; i++) {
1244                 struct platform_device *device;
1245                 if (!enable[i])
1246                         continue;
1247                 device = platform_device_register_simple(SND_LOOPBACK_DRIVER,
1248                                                          i, NULL, 0);
1249                 if (IS_ERR(device))
1250                         continue;
1251                 if (!platform_get_drvdata(device)) {
1252                         platform_device_unregister(device);
1253                         continue;
1254                 }
1255                 devices[i] = device;
1256                 cards++;
1257         }
1258         if (!cards) {
1259 #ifdef MODULE
1260                 printk(KERN_ERR "aloop: No loopback enabled\n");
1261 #endif
1262                 loopback_unregister_all();
1263                 return -ENODEV;
1264         }
1265         return 0;
1266 }
1267 
1268 static void __exit alsa_card_loopback_exit(void)
1269 {
1270         loopback_unregister_all();
1271 }
1272 
1273 module_init(alsa_card_loopback_init)
1274 module_exit(alsa_card_loopback_exit)
1275 

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