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