ALSA: aloop: Avoid unexpected timer event callback tasklets
[sfrench/cifs-2.6.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         substream_play = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?
731                         dpcm_play->substream : NULL;
732         substream_capt = (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) ?
733                         dpcm_capt->substream : NULL;
734
735         if (event == SNDRV_TIMER_EVENT_MSTOP) {
736                 if (!dpcm_play ||
737                     dpcm_play->substream->runtime->status->state !=
738                                 SNDRV_PCM_STATE_DRAINING) {
739                         spin_unlock_irqrestore(&cable->lock, flags);
740                         return;
741                 }
742         }
743
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 timespec *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_params(struct snd_pcm_substream *substream,
909                               struct snd_pcm_hw_params *params)
910 {
911         return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(params));
912 }
913
914 static int loopback_hw_free(struct snd_pcm_substream *substream)
915 {
916         struct snd_pcm_runtime *runtime = substream->runtime;
917         struct loopback_pcm *dpcm = runtime->private_data;
918         struct loopback_cable *cable = dpcm->cable;
919
920         mutex_lock(&dpcm->loopback->cable_lock);
921         cable->valid &= ~(1 << substream->stream);
922         mutex_unlock(&dpcm->loopback->cable_lock);
923         return snd_pcm_lib_free_pages(substream);
924 }
925
926 static unsigned int get_cable_index(struct snd_pcm_substream *substream)
927 {
928         if (!substream->pcm->device)
929                 return substream->stream;
930         else
931                 return !substream->stream;
932 }
933
934 static int rule_format(struct snd_pcm_hw_params *params,
935                        struct snd_pcm_hw_rule *rule)
936 {
937         struct loopback_pcm *dpcm = rule->private;
938         struct loopback_cable *cable = dpcm->cable;
939         struct snd_mask m;
940
941         snd_mask_none(&m);
942         mutex_lock(&dpcm->loopback->cable_lock);
943         m.bits[0] = (u_int32_t)cable->hw.formats;
944         m.bits[1] = (u_int32_t)(cable->hw.formats >> 32);
945         mutex_unlock(&dpcm->loopback->cable_lock);
946         return snd_mask_refine(hw_param_mask(params, rule->var), &m);
947 }
948
949 static int rule_rate(struct snd_pcm_hw_params *params,
950                      struct snd_pcm_hw_rule *rule)
951 {
952         struct loopback_pcm *dpcm = rule->private;
953         struct loopback_cable *cable = dpcm->cable;
954         struct snd_interval t;
955
956         mutex_lock(&dpcm->loopback->cable_lock);
957         t.min = cable->hw.rate_min;
958         t.max = cable->hw.rate_max;
959         mutex_unlock(&dpcm->loopback->cable_lock);
960         t.openmin = t.openmax = 0;
961         t.integer = 0;
962         return snd_interval_refine(hw_param_interval(params, rule->var), &t);
963 }
964
965 static int rule_channels(struct snd_pcm_hw_params *params,
966                          struct snd_pcm_hw_rule *rule)
967 {
968         struct loopback_pcm *dpcm = rule->private;
969         struct loopback_cable *cable = dpcm->cable;
970         struct snd_interval t;
971
972         mutex_lock(&dpcm->loopback->cable_lock);
973         t.min = cable->hw.channels_min;
974         t.max = cable->hw.channels_max;
975         mutex_unlock(&dpcm->loopback->cable_lock);
976         t.openmin = t.openmax = 0;
977         t.integer = 0;
978         return snd_interval_refine(hw_param_interval(params, rule->var), &t);
979 }
980
981 static int rule_period_bytes(struct snd_pcm_hw_params *params,
982                              struct snd_pcm_hw_rule *rule)
983 {
984         struct loopback_pcm *dpcm = rule->private;
985         struct loopback_cable *cable = dpcm->cable;
986         struct snd_interval t;
987
988         mutex_lock(&dpcm->loopback->cable_lock);
989         t.min = cable->hw.period_bytes_min;
990         t.max = cable->hw.period_bytes_max;
991         mutex_unlock(&dpcm->loopback->cable_lock);
992         t.openmin = 0;
993         t.openmax = 0;
994         t.integer = 0;
995         return snd_interval_refine(hw_param_interval(params, rule->var), &t);
996 }
997
998 static void free_cable(struct snd_pcm_substream *substream)
999 {
1000         struct loopback *loopback = substream->private_data;
1001         int dev = get_cable_index(substream);
1002         struct loopback_cable *cable;
1003
1004         cable = loopback->cables[substream->number][dev];
1005         if (!cable)
1006                 return;
1007         if (cable->streams[!substream->stream]) {
1008                 /* other stream is still alive */
1009                 spin_lock_irq(&cable->lock);
1010                 cable->streams[substream->stream] = NULL;
1011                 spin_unlock_irq(&cable->lock);
1012         } else {
1013                 struct loopback_pcm *dpcm = substream->runtime->private_data;
1014
1015                 if (cable->ops && cable->ops->close_cable && dpcm)
1016                         cable->ops->close_cable(dpcm);
1017                 /* free the cable */
1018                 loopback->cables[substream->number][dev] = NULL;
1019                 kfree(cable);
1020         }
1021 }
1022
1023 static int loopback_jiffies_timer_open(struct loopback_pcm *dpcm)
1024 {
1025         timer_setup(&dpcm->timer, loopback_jiffies_timer_function, 0);
1026
1027         return 0;
1028 }
1029
1030 static struct loopback_ops loopback_jiffies_timer_ops = {
1031         .open = loopback_jiffies_timer_open,
1032         .start = loopback_jiffies_timer_start,
1033         .stop = loopback_jiffies_timer_stop,
1034         .stop_sync = loopback_jiffies_timer_stop_sync,
1035         .close_substream = loopback_jiffies_timer_stop_sync,
1036         .pos_update = loopback_jiffies_timer_pos_update,
1037         .dpcm_info = loopback_jiffies_timer_dpcm_info,
1038 };
1039
1040 static int loopback_parse_timer_id(const char *str,
1041                                    struct snd_timer_id *tid)
1042 {
1043         /* [<pref>:](<card name>|<card idx>)[{.,}<dev idx>[{.,}<subdev idx>]] */
1044         const char * const sep_dev = ".,";
1045         const char * const sep_pref = ":";
1046         const char *name = str;
1047         char *sep, save = '\0';
1048         int card_idx = 0, dev = 0, subdev = 0;
1049         int err;
1050
1051         sep = strpbrk(str, sep_pref);
1052         if (sep)
1053                 name = sep + 1;
1054         sep = strpbrk(name, sep_dev);
1055         if (sep) {
1056                 save = *sep;
1057                 *sep = '\0';
1058         }
1059         err = kstrtoint(name, 0, &card_idx);
1060         if (err == -EINVAL) {
1061                 /* Must be the name, not number */
1062                 for (card_idx = 0; card_idx < snd_ecards_limit; card_idx++) {
1063                         struct snd_card *card = snd_card_ref(card_idx);
1064
1065                         if (card) {
1066                                 if (!strcmp(card->id, name))
1067                                         err = 0;
1068                                 snd_card_unref(card);
1069                         }
1070                         if (!err)
1071                                 break;
1072                 }
1073         }
1074         if (sep) {
1075                 *sep = save;
1076                 if (!err) {
1077                         char *sep2, save2 = '\0';
1078
1079                         sep2 = strpbrk(sep + 1, sep_dev);
1080                         if (sep2) {
1081                                 save2 = *sep2;
1082                                 *sep2 = '\0';
1083                         }
1084                         err = kstrtoint(sep + 1, 0, &dev);
1085                         if (sep2) {
1086                                 *sep2 = save2;
1087                                 if (!err)
1088                                         err = kstrtoint(sep2 + 1, 0, &subdev);
1089                         }
1090                 }
1091         }
1092         if (!err && tid) {
1093                 tid->card = card_idx;
1094                 tid->device = dev;
1095                 tid->subdevice = subdev;
1096         }
1097         return err;
1098 }
1099
1100 /* call in loopback->cable_lock */
1101 static int loopback_snd_timer_open(struct loopback_pcm *dpcm)
1102 {
1103         int err = 0;
1104         struct snd_timer_id tid = {
1105                 .dev_class = SNDRV_TIMER_CLASS_PCM,
1106                 .dev_sclass = SNDRV_TIMER_SCLASS_APPLICATION,
1107         };
1108         struct snd_timer_instance *timeri;
1109         struct loopback_cable *cable = dpcm->cable;
1110
1111         /* check if timer was already opened. It is only opened once
1112          * per playback and capture subdevice (aka cable).
1113          */
1114         if (cable->snd_timer.instance)
1115                 goto exit;
1116
1117         err = loopback_parse_timer_id(dpcm->loopback->timer_source, &tid);
1118         if (err < 0) {
1119                 pcm_err(dpcm->substream->pcm,
1120                         "Parsing timer source \'%s\' failed with %d",
1121                         dpcm->loopback->timer_source, err);
1122                 goto exit;
1123         }
1124
1125         cable->snd_timer.stream = dpcm->substream->stream;
1126         cable->snd_timer.id = tid;
1127
1128         timeri = snd_timer_instance_new(dpcm->loopback->card->id);
1129         if (!timeri) {
1130                 err = -ENOMEM;
1131                 goto exit;
1132         }
1133         /* The callback has to be called from another tasklet. If
1134          * SNDRV_TIMER_IFLG_FAST is specified it will be called from the
1135          * snd_pcm_period_elapsed() call of the selected sound card.
1136          * snd_pcm_period_elapsed() helds snd_pcm_stream_lock_irqsave().
1137          * Due to our callback loopback_snd_timer_function() also calls
1138          * snd_pcm_period_elapsed() which calls snd_pcm_stream_lock_irqsave().
1139          * This would end up in a dead lock.
1140          */
1141         timeri->flags |= SNDRV_TIMER_IFLG_AUTO;
1142         timeri->callback = loopback_snd_timer_function;
1143         timeri->callback_data = (void *)cable;
1144         timeri->ccallback = loopback_snd_timer_event;
1145
1146         /* initialise a tasklet used for draining */
1147         tasklet_init(&cable->snd_timer.event_tasklet,
1148                      loopback_snd_timer_tasklet, (unsigned long)timeri);
1149
1150         /* The mutex loopback->cable_lock is kept locked.
1151          * Therefore snd_timer_open() cannot be called a second time
1152          * by the other device of the same cable.
1153          * Therefore the following issue cannot happen:
1154          * [proc1] Call loopback_timer_open() ->
1155          *         Unlock cable->lock for snd_timer_close/open() call
1156          * [proc2] Call loopback_timer_open() -> snd_timer_open(),
1157          *         snd_timer_start()
1158          * [proc1] Call snd_timer_open() and overwrite running timer
1159          *         instance
1160          */
1161         err = snd_timer_open(timeri, &cable->snd_timer.id, current->pid);
1162         if (err < 0) {
1163                 pcm_err(dpcm->substream->pcm,
1164                         "snd_timer_open (%d,%d,%d) failed with %d",
1165                         cable->snd_timer.id.card,
1166                         cable->snd_timer.id.device,
1167                         cable->snd_timer.id.subdevice,
1168                         err);
1169                 snd_timer_instance_free(timeri);
1170                 goto exit;
1171         }
1172
1173         cable->snd_timer.instance = timeri;
1174
1175 exit:
1176         return err;
1177 }
1178
1179 /* stop_sync() is not required for sound timer because it does not need to be
1180  * restarted in loopback_prepare() on Xrun recovery
1181  */
1182 static struct loopback_ops loopback_snd_timer_ops = {
1183         .open = loopback_snd_timer_open,
1184         .start = loopback_snd_timer_start,
1185         .stop = loopback_snd_timer_stop,
1186         .close_cable = loopback_snd_timer_close_cable,
1187         .dpcm_info = loopback_snd_timer_dpcm_info,
1188 };
1189
1190 static int loopback_open(struct snd_pcm_substream *substream)
1191 {
1192         struct snd_pcm_runtime *runtime = substream->runtime;
1193         struct loopback *loopback = substream->private_data;
1194         struct loopback_pcm *dpcm;
1195         struct loopback_cable *cable = NULL;
1196         int err = 0;
1197         int dev = get_cable_index(substream);
1198
1199         mutex_lock(&loopback->cable_lock);
1200         dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
1201         if (!dpcm) {
1202                 err = -ENOMEM;
1203                 goto unlock;
1204         }
1205         dpcm->loopback = loopback;
1206         dpcm->substream = substream;
1207
1208         cable = loopback->cables[substream->number][dev];
1209         if (!cable) {
1210                 cable = kzalloc(sizeof(*cable), GFP_KERNEL);
1211                 if (!cable) {
1212                         err = -ENOMEM;
1213                         goto unlock;
1214                 }
1215                 spin_lock_init(&cable->lock);
1216                 cable->hw = loopback_pcm_hardware;
1217                 if (loopback->timer_source)
1218                         cable->ops = &loopback_snd_timer_ops;
1219                 else
1220                         cable->ops = &loopback_jiffies_timer_ops;
1221                 loopback->cables[substream->number][dev] = cable;
1222         }
1223         dpcm->cable = cable;
1224         runtime->private_data = dpcm;
1225
1226         if (cable->ops->open) {
1227                 err = cable->ops->open(dpcm);
1228                 if (err < 0)
1229                         goto unlock;
1230         }
1231
1232         snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
1233
1234         /* use dynamic rules based on actual runtime->hw values */
1235         /* note that the default rules created in the PCM midlevel code */
1236         /* are cached -> they do not reflect the actual state */
1237         err = snd_pcm_hw_rule_add(runtime, 0,
1238                                   SNDRV_PCM_HW_PARAM_FORMAT,
1239                                   rule_format, dpcm,
1240                                   SNDRV_PCM_HW_PARAM_FORMAT, -1);
1241         if (err < 0)
1242                 goto unlock;
1243         err = snd_pcm_hw_rule_add(runtime, 0,
1244                                   SNDRV_PCM_HW_PARAM_RATE,
1245                                   rule_rate, dpcm,
1246                                   SNDRV_PCM_HW_PARAM_RATE, -1);
1247         if (err < 0)
1248                 goto unlock;
1249         err = snd_pcm_hw_rule_add(runtime, 0,
1250                                   SNDRV_PCM_HW_PARAM_CHANNELS,
1251                                   rule_channels, dpcm,
1252                                   SNDRV_PCM_HW_PARAM_CHANNELS, -1);
1253         if (err < 0)
1254                 goto unlock;
1255
1256         /* In case of sound timer the period time of both devices of the same
1257          * loop has to be the same.
1258          * This rule only takes effect if a sound timer was chosen
1259          */
1260         if (cable->snd_timer.instance) {
1261                 err = snd_pcm_hw_rule_add(runtime, 0,
1262                                           SNDRV_PCM_HW_PARAM_PERIOD_BYTES,
1263                                           rule_period_bytes, dpcm,
1264                                           SNDRV_PCM_HW_PARAM_PERIOD_BYTES, -1);
1265                 if (err < 0)
1266                         goto unlock;
1267         }
1268
1269         /* loopback_runtime_free() has not to be called if kfree(dpcm) was
1270          * already called here. Otherwise it will end up with a double free.
1271          */
1272         runtime->private_free = loopback_runtime_free;
1273         if (get_notify(dpcm))
1274                 runtime->hw = loopback_pcm_hardware;
1275         else
1276                 runtime->hw = cable->hw;
1277
1278         spin_lock_irq(&cable->lock);
1279         cable->streams[substream->stream] = dpcm;
1280         spin_unlock_irq(&cable->lock);
1281
1282  unlock:
1283         if (err < 0) {
1284                 free_cable(substream);
1285                 kfree(dpcm);
1286         }
1287         mutex_unlock(&loopback->cable_lock);
1288         return err;
1289 }
1290
1291 static int loopback_close(struct snd_pcm_substream *substream)
1292 {
1293         struct loopback *loopback = substream->private_data;
1294         struct loopback_pcm *dpcm = substream->runtime->private_data;
1295         int err = 0;
1296
1297         if (dpcm->cable->ops->close_substream)
1298                 err = dpcm->cable->ops->close_substream(dpcm);
1299         mutex_lock(&loopback->cable_lock);
1300         free_cable(substream);
1301         mutex_unlock(&loopback->cable_lock);
1302         return err;
1303 }
1304
1305 static const struct snd_pcm_ops loopback_pcm_ops = {
1306         .open =         loopback_open,
1307         .close =        loopback_close,
1308         .ioctl =        snd_pcm_lib_ioctl,
1309         .hw_params =    loopback_hw_params,
1310         .hw_free =      loopback_hw_free,
1311         .prepare =      loopback_prepare,
1312         .trigger =      loopback_trigger,
1313         .pointer =      loopback_pointer,
1314 };
1315
1316 static int loopback_pcm_new(struct loopback *loopback,
1317                             int device, int substreams)
1318 {
1319         struct snd_pcm *pcm;
1320         int err;
1321
1322         err = snd_pcm_new(loopback->card, "Loopback PCM", device,
1323                           substreams, substreams, &pcm);
1324         if (err < 0)
1325                 return err;
1326         snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &loopback_pcm_ops);
1327         snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &loopback_pcm_ops);
1328         snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_VMALLOC,
1329                                               NULL, 0, 0);
1330
1331         pcm->private_data = loopback;
1332         pcm->info_flags = 0;
1333         strcpy(pcm->name, "Loopback PCM");
1334
1335         loopback->pcm[device] = pcm;
1336         return 0;
1337 }
1338
1339 static int loopback_rate_shift_info(struct snd_kcontrol *kcontrol,   
1340                                     struct snd_ctl_elem_info *uinfo) 
1341 {
1342         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1343         uinfo->count = 1;
1344         uinfo->value.integer.min = 80000;
1345         uinfo->value.integer.max = 120000;
1346         uinfo->value.integer.step = 1;
1347         return 0;
1348 }                                  
1349
1350 static int loopback_rate_shift_get(struct snd_kcontrol *kcontrol,
1351                                    struct snd_ctl_elem_value *ucontrol)
1352 {
1353         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1354         
1355         mutex_lock(&loopback->cable_lock);
1356         ucontrol->value.integer.value[0] =
1357                 loopback->setup[kcontrol->id.subdevice]
1358                                [kcontrol->id.device].rate_shift;
1359         mutex_unlock(&loopback->cable_lock);
1360         return 0;
1361 }
1362
1363 static int loopback_rate_shift_put(struct snd_kcontrol *kcontrol,
1364                                    struct snd_ctl_elem_value *ucontrol)
1365 {
1366         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1367         unsigned int val;
1368         int change = 0;
1369
1370         val = ucontrol->value.integer.value[0];
1371         if (val < 80000)
1372                 val = 80000;
1373         if (val > 120000)
1374                 val = 120000;   
1375         mutex_lock(&loopback->cable_lock);
1376         if (val != loopback->setup[kcontrol->id.subdevice]
1377                                   [kcontrol->id.device].rate_shift) {
1378                 loopback->setup[kcontrol->id.subdevice]
1379                                [kcontrol->id.device].rate_shift = val;
1380                 change = 1;
1381         }
1382         mutex_unlock(&loopback->cable_lock);
1383         return change;
1384 }
1385
1386 static int loopback_notify_get(struct snd_kcontrol *kcontrol,
1387                                struct snd_ctl_elem_value *ucontrol)
1388 {
1389         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1390         
1391         mutex_lock(&loopback->cable_lock);
1392         ucontrol->value.integer.value[0] =
1393                 loopback->setup[kcontrol->id.subdevice]
1394                                [kcontrol->id.device].notify;
1395         mutex_unlock(&loopback->cable_lock);
1396         return 0;
1397 }
1398
1399 static int loopback_notify_put(struct snd_kcontrol *kcontrol,
1400                                struct snd_ctl_elem_value *ucontrol)
1401 {
1402         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1403         unsigned int val;
1404         int change = 0;
1405
1406         val = ucontrol->value.integer.value[0] ? 1 : 0;
1407         mutex_lock(&loopback->cable_lock);
1408         if (val != loopback->setup[kcontrol->id.subdevice]
1409                                 [kcontrol->id.device].notify) {
1410                 loopback->setup[kcontrol->id.subdevice]
1411                         [kcontrol->id.device].notify = val;
1412                 change = 1;
1413         }
1414         mutex_unlock(&loopback->cable_lock);
1415         return change;
1416 }
1417
1418 static int loopback_active_get(struct snd_kcontrol *kcontrol,
1419                                struct snd_ctl_elem_value *ucontrol)
1420 {
1421         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1422         struct loopback_cable *cable;
1423
1424         unsigned int val = 0;
1425
1426         mutex_lock(&loopback->cable_lock);
1427         cable = loopback->cables[kcontrol->id.subdevice][kcontrol->id.device ^ 1];
1428         if (cable != NULL) {
1429                 unsigned int running = cable->running ^ cable->pause;
1430
1431                 val = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ? 1 : 0;
1432         }
1433         mutex_unlock(&loopback->cable_lock);
1434         ucontrol->value.integer.value[0] = val;
1435         return 0;
1436 }
1437
1438 static int loopback_format_info(struct snd_kcontrol *kcontrol,   
1439                                 struct snd_ctl_elem_info *uinfo) 
1440 {
1441         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1442         uinfo->count = 1;
1443         uinfo->value.integer.min = 0;
1444         uinfo->value.integer.max = SNDRV_PCM_FORMAT_LAST;
1445         uinfo->value.integer.step = 1;
1446         return 0;
1447 }                                  
1448
1449 static int loopback_format_get(struct snd_kcontrol *kcontrol,
1450                                struct snd_ctl_elem_value *ucontrol)
1451 {
1452         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1453         
1454         ucontrol->value.integer.value[0] =
1455                 loopback->setup[kcontrol->id.subdevice]
1456                                [kcontrol->id.device].format;
1457         return 0;
1458 }
1459
1460 static int loopback_rate_info(struct snd_kcontrol *kcontrol,   
1461                               struct snd_ctl_elem_info *uinfo) 
1462 {
1463         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1464         uinfo->count = 1;
1465         uinfo->value.integer.min = 0;
1466         uinfo->value.integer.max = 192000;
1467         uinfo->value.integer.step = 1;
1468         return 0;
1469 }                                  
1470
1471 static int loopback_rate_get(struct snd_kcontrol *kcontrol,
1472                              struct snd_ctl_elem_value *ucontrol)
1473 {
1474         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1475         
1476         mutex_lock(&loopback->cable_lock);
1477         ucontrol->value.integer.value[0] =
1478                 loopback->setup[kcontrol->id.subdevice]
1479                                [kcontrol->id.device].rate;
1480         mutex_unlock(&loopback->cable_lock);
1481         return 0;
1482 }
1483
1484 static int loopback_channels_info(struct snd_kcontrol *kcontrol,   
1485                                   struct snd_ctl_elem_info *uinfo) 
1486 {
1487         uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1488         uinfo->count = 1;
1489         uinfo->value.integer.min = 1;
1490         uinfo->value.integer.max = 1024;
1491         uinfo->value.integer.step = 1;
1492         return 0;
1493 }                                  
1494
1495 static int loopback_channels_get(struct snd_kcontrol *kcontrol,
1496                                  struct snd_ctl_elem_value *ucontrol)
1497 {
1498         struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1499         
1500         mutex_lock(&loopback->cable_lock);
1501         ucontrol->value.integer.value[0] =
1502                 loopback->setup[kcontrol->id.subdevice]
1503                                [kcontrol->id.device].channels;
1504         mutex_unlock(&loopback->cable_lock);
1505         return 0;
1506 }
1507
1508 static struct snd_kcontrol_new loopback_controls[]  = {
1509 {
1510         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1511         .name =         "PCM Rate Shift 100000",
1512         .info =         loopback_rate_shift_info,
1513         .get =          loopback_rate_shift_get,
1514         .put =          loopback_rate_shift_put,
1515 },
1516 {
1517         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1518         .name =         "PCM Notify",
1519         .info =         snd_ctl_boolean_mono_info,
1520         .get =          loopback_notify_get,
1521         .put =          loopback_notify_put,
1522 },
1523 #define ACTIVE_IDX 2
1524 {
1525         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
1526         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1527         .name =         "PCM Slave Active",
1528         .info =         snd_ctl_boolean_mono_info,
1529         .get =          loopback_active_get,
1530 },
1531 #define FORMAT_IDX 3
1532 {
1533         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
1534         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1535         .name =         "PCM Slave Format",
1536         .info =         loopback_format_info,
1537         .get =          loopback_format_get
1538 },
1539 #define RATE_IDX 4
1540 {
1541         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
1542         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1543         .name =         "PCM Slave Rate",
1544         .info =         loopback_rate_info,
1545         .get =          loopback_rate_get
1546 },
1547 #define CHANNELS_IDX 5
1548 {
1549         .access =       SNDRV_CTL_ELEM_ACCESS_READ,
1550         .iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1551         .name =         "PCM Slave Channels",
1552         .info =         loopback_channels_info,
1553         .get =          loopback_channels_get
1554 }
1555 };
1556
1557 static int loopback_mixer_new(struct loopback *loopback, int notify)
1558 {
1559         struct snd_card *card = loopback->card;
1560         struct snd_pcm *pcm;
1561         struct snd_kcontrol *kctl;
1562         struct loopback_setup *setup;
1563         int err, dev, substr, substr_count, idx;
1564
1565         strcpy(card->mixername, "Loopback Mixer");
1566         for (dev = 0; dev < 2; dev++) {
1567                 pcm = loopback->pcm[dev];
1568                 substr_count =
1569                     pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream_count;
1570                 for (substr = 0; substr < substr_count; substr++) {
1571                         setup = &loopback->setup[substr][dev];
1572                         setup->notify = notify;
1573                         setup->rate_shift = NO_PITCH;
1574                         setup->format = SNDRV_PCM_FORMAT_S16_LE;
1575                         setup->rate = 48000;
1576                         setup->channels = 2;
1577                         for (idx = 0; idx < ARRAY_SIZE(loopback_controls);
1578                                                                         idx++) {
1579                                 kctl = snd_ctl_new1(&loopback_controls[idx],
1580                                                     loopback);
1581                                 if (!kctl)
1582                                         return -ENOMEM;
1583                                 kctl->id.device = dev;
1584                                 kctl->id.subdevice = substr;
1585                                 switch (idx) {
1586                                 case ACTIVE_IDX:
1587                                         setup->active_id = kctl->id;
1588                                         break;
1589                                 case FORMAT_IDX:
1590                                         setup->format_id = kctl->id;
1591                                         break;
1592                                 case RATE_IDX:
1593                                         setup->rate_id = kctl->id;
1594                                         break;
1595                                 case CHANNELS_IDX:
1596                                         setup->channels_id = kctl->id;
1597                                         break;
1598                                 default:
1599                                         break;
1600                                 }
1601                                 err = snd_ctl_add(card, kctl);
1602                                 if (err < 0)
1603                                         return err;
1604                         }
1605                 }
1606         }
1607         return 0;
1608 }
1609
1610 static void print_dpcm_info(struct snd_info_buffer *buffer,
1611                             struct loopback_pcm *dpcm,
1612                             const char *id)
1613 {
1614         snd_iprintf(buffer, "  %s\n", id);
1615         if (dpcm == NULL) {
1616                 snd_iprintf(buffer, "    inactive\n");
1617                 return;
1618         }
1619         snd_iprintf(buffer, "    buffer_size:\t%u\n", dpcm->pcm_buffer_size);
1620         snd_iprintf(buffer, "    buffer_pos:\t\t%u\n", dpcm->buf_pos);
1621         snd_iprintf(buffer, "    silent_size:\t%u\n", dpcm->silent_size);
1622         snd_iprintf(buffer, "    period_size:\t%u\n", dpcm->pcm_period_size);
1623         snd_iprintf(buffer, "    bytes_per_sec:\t%u\n", dpcm->pcm_bps);
1624         snd_iprintf(buffer, "    sample_align:\t%u\n", dpcm->pcm_salign);
1625         snd_iprintf(buffer, "    rate_shift:\t\t%u\n", dpcm->pcm_rate_shift);
1626         if (dpcm->cable->ops->dpcm_info)
1627                 dpcm->cable->ops->dpcm_info(dpcm, buffer);
1628 }
1629
1630 static void print_substream_info(struct snd_info_buffer *buffer,
1631                                  struct loopback *loopback,
1632                                  int sub,
1633                                  int num)
1634 {
1635         struct loopback_cable *cable = loopback->cables[sub][num];
1636
1637         snd_iprintf(buffer, "Cable %i substream %i:\n", num, sub);
1638         if (cable == NULL) {
1639                 snd_iprintf(buffer, "  inactive\n");
1640                 return;
1641         }
1642         snd_iprintf(buffer, "  valid: %u\n", cable->valid);
1643         snd_iprintf(buffer, "  running: %u\n", cable->running);
1644         snd_iprintf(buffer, "  pause: %u\n", cable->pause);
1645         print_dpcm_info(buffer, cable->streams[0], "Playback");
1646         print_dpcm_info(buffer, cable->streams[1], "Capture");
1647 }
1648
1649 static void print_cable_info(struct snd_info_entry *entry,
1650                              struct snd_info_buffer *buffer)
1651 {
1652         struct loopback *loopback = entry->private_data;
1653         int sub, num;
1654
1655         mutex_lock(&loopback->cable_lock);
1656         num = entry->name[strlen(entry->name)-1];
1657         num = num == '0' ? 0 : 1;
1658         for (sub = 0; sub < MAX_PCM_SUBSTREAMS; sub++)
1659                 print_substream_info(buffer, loopback, sub, num);
1660         mutex_unlock(&loopback->cable_lock);
1661 }
1662
1663 static int loopback_cable_proc_new(struct loopback *loopback, int cidx)
1664 {
1665         char name[32];
1666
1667         snprintf(name, sizeof(name), "cable#%d", cidx);
1668         return snd_card_ro_proc_new(loopback->card, name, loopback,
1669                                     print_cable_info);
1670 }
1671
1672 static void loopback_set_timer_source(struct loopback *loopback,
1673                                       const char *value)
1674 {
1675         if (loopback->timer_source) {
1676                 devm_kfree(loopback->card->dev, loopback->timer_source);
1677                 loopback->timer_source = NULL;
1678         }
1679         if (value && *value)
1680                 loopback->timer_source = devm_kstrdup(loopback->card->dev,
1681                                                       value, GFP_KERNEL);
1682 }
1683
1684 static void print_timer_source_info(struct snd_info_entry *entry,
1685                                     struct snd_info_buffer *buffer)
1686 {
1687         struct loopback *loopback = entry->private_data;
1688
1689         mutex_lock(&loopback->cable_lock);
1690         snd_iprintf(buffer, "%s\n",
1691                     loopback->timer_source ? loopback->timer_source : "");
1692         mutex_unlock(&loopback->cable_lock);
1693 }
1694
1695 static void change_timer_source_info(struct snd_info_entry *entry,
1696                                      struct snd_info_buffer *buffer)
1697 {
1698         struct loopback *loopback = entry->private_data;
1699         char line[64];
1700
1701         mutex_lock(&loopback->cable_lock);
1702         if (!snd_info_get_line(buffer, line, sizeof(line)))
1703                 loopback_set_timer_source(loopback, strim(line));
1704         mutex_unlock(&loopback->cable_lock);
1705 }
1706
1707 static int loopback_timer_source_proc_new(struct loopback *loopback)
1708 {
1709         return snd_card_rw_proc_new(loopback->card, "timer_source", loopback,
1710                                     print_timer_source_info,
1711                                     change_timer_source_info);
1712 }
1713
1714 static int loopback_probe(struct platform_device *devptr)
1715 {
1716         struct snd_card *card;
1717         struct loopback *loopback;
1718         int dev = devptr->id;
1719         int err;
1720
1721         err = snd_card_new(&devptr->dev, index[dev], id[dev], THIS_MODULE,
1722                            sizeof(struct loopback), &card);
1723         if (err < 0)
1724                 return err;
1725         loopback = card->private_data;
1726
1727         if (pcm_substreams[dev] < 1)
1728                 pcm_substreams[dev] = 1;
1729         if (pcm_substreams[dev] > MAX_PCM_SUBSTREAMS)
1730                 pcm_substreams[dev] = MAX_PCM_SUBSTREAMS;
1731         
1732         loopback->card = card;
1733         loopback_set_timer_source(loopback, timer_source[dev]);
1734
1735         mutex_init(&loopback->cable_lock);
1736
1737         err = loopback_pcm_new(loopback, 0, pcm_substreams[dev]);
1738         if (err < 0)
1739                 goto __nodev;
1740         err = loopback_pcm_new(loopback, 1, pcm_substreams[dev]);
1741         if (err < 0)
1742                 goto __nodev;
1743         err = loopback_mixer_new(loopback, pcm_notify[dev] ? 1 : 0);
1744         if (err < 0)
1745                 goto __nodev;
1746         loopback_cable_proc_new(loopback, 0);
1747         loopback_cable_proc_new(loopback, 1);
1748         loopback_timer_source_proc_new(loopback);
1749         strcpy(card->driver, "Loopback");
1750         strcpy(card->shortname, "Loopback");
1751         sprintf(card->longname, "Loopback %i", dev + 1);
1752         err = snd_card_register(card);
1753         if (!err) {
1754                 platform_set_drvdata(devptr, card);
1755                 return 0;
1756         }
1757       __nodev:
1758         snd_card_free(card);
1759         return err;
1760 }
1761
1762 static int loopback_remove(struct platform_device *devptr)
1763 {
1764         snd_card_free(platform_get_drvdata(devptr));
1765         return 0;
1766 }
1767
1768 #ifdef CONFIG_PM_SLEEP
1769 static int loopback_suspend(struct device *pdev)
1770 {
1771         struct snd_card *card = dev_get_drvdata(pdev);
1772
1773         snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
1774         return 0;
1775 }
1776         
1777 static int loopback_resume(struct device *pdev)
1778 {
1779         struct snd_card *card = dev_get_drvdata(pdev);
1780
1781         snd_power_change_state(card, SNDRV_CTL_POWER_D0);
1782         return 0;
1783 }
1784
1785 static SIMPLE_DEV_PM_OPS(loopback_pm, loopback_suspend, loopback_resume);
1786 #define LOOPBACK_PM_OPS &loopback_pm
1787 #else
1788 #define LOOPBACK_PM_OPS NULL
1789 #endif
1790
1791 #define SND_LOOPBACK_DRIVER     "snd_aloop"
1792
1793 static struct platform_driver loopback_driver = {
1794         .probe          = loopback_probe,
1795         .remove         = loopback_remove,
1796         .driver         = {
1797                 .name   = SND_LOOPBACK_DRIVER,
1798                 .pm     = LOOPBACK_PM_OPS,
1799         },
1800 };
1801
1802 static void loopback_unregister_all(void)
1803 {
1804         int i;
1805
1806         for (i = 0; i < ARRAY_SIZE(devices); ++i)
1807                 platform_device_unregister(devices[i]);
1808         platform_driver_unregister(&loopback_driver);
1809 }
1810
1811 static int __init alsa_card_loopback_init(void)
1812 {
1813         int i, err, cards;
1814
1815         err = platform_driver_register(&loopback_driver);
1816         if (err < 0)
1817                 return err;
1818
1819
1820         cards = 0;
1821         for (i = 0; i < SNDRV_CARDS; i++) {
1822                 struct platform_device *device;
1823                 if (!enable[i])
1824                         continue;
1825                 device = platform_device_register_simple(SND_LOOPBACK_DRIVER,
1826                                                          i, NULL, 0);
1827                 if (IS_ERR(device))
1828                         continue;
1829                 if (!platform_get_drvdata(device)) {
1830                         platform_device_unregister(device);
1831                         continue;
1832                 }
1833                 devices[i] = device;
1834                 cards++;
1835         }
1836         if (!cards) {
1837 #ifdef MODULE
1838                 printk(KERN_ERR "aloop: No loopback enabled\n");
1839 #endif
1840                 loopback_unregister_all();
1841                 return -ENODEV;
1842         }
1843         return 0;
1844 }
1845
1846 static void __exit alsa_card_loopback_exit(void)
1847 {
1848         loopback_unregister_all();
1849 }
1850
1851 module_init(alsa_card_loopback_init)
1852 module_exit(alsa_card_loopback_exit)