ALSA: drivers: Constify snd_kcontrol_new items
[muen/linux.git] / 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 ─░nan <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         unsigned int 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 = 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                 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)