xref: /openbmc/linux/sound/drivers/aloop.c (revision d23015c1)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Loopback soundcard
4  *
5  *  Original code:
6  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
7  *
8  *  More accurate positioning and full-duplex support:
9  *  Copyright (c) Ahmet İnan <ainan at mathematik.uni-freiburg.de>
10  *
11  *  Major (almost complete) rewrite:
12  *  Copyright (c) by Takashi Iwai <tiwai@suse.de>
13  *
14  *  A next major update in 2010 (separate timers for playback and capture):
15  *  Copyright (c) Jaroslav Kysela <perex@perex.cz>
16  */
17 
18 #include <linux/init.h>
19 #include <linux/jiffies.h>
20 #include <linux/slab.h>
21 #include <linux/time.h>
22 #include <linux/wait.h>
23 #include <linux/module.h>
24 #include <linux/platform_device.h>
25 #include <sound/core.h>
26 #include <sound/control.h>
27 #include <sound/pcm.h>
28 #include <sound/pcm_params.h>
29 #include <sound/info.h>
30 #include <sound/initval.h>
31 #include <sound/timer.h>
32 
33 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
34 MODULE_DESCRIPTION("A loopback soundcard");
35 MODULE_LICENSE("GPL");
36 MODULE_SUPPORTED_DEVICE("{{ALSA,Loopback soundcard}}");
37 
38 #define MAX_PCM_SUBSTREAMS	8
39 
40 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;	/* Index 0-MAX */
41 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;	/* ID for this card */
42 static bool enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
43 static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
44 static int pcm_notify[SNDRV_CARDS];
45 static char *timer_source[SNDRV_CARDS];
46 
47 module_param_array(index, int, NULL, 0444);
48 MODULE_PARM_DESC(index, "Index value for loopback soundcard.");
49 module_param_array(id, charp, NULL, 0444);
50 MODULE_PARM_DESC(id, "ID string for loopback soundcard.");
51 module_param_array(enable, bool, NULL, 0444);
52 MODULE_PARM_DESC(enable, "Enable this loopback soundcard.");
53 module_param_array(pcm_substreams, int, NULL, 0444);
54 MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-8) for loopback driver.");
55 module_param_array(pcm_notify, int, NULL, 0444);
56 MODULE_PARM_DESC(pcm_notify, "Break capture when PCM format/rate/channels changes.");
57 module_param_array(timer_source, charp, NULL, 0444);
58 MODULE_PARM_DESC(timer_source, "Sound card name or number and device/subdevice number of timer to be used. Empty string for jiffies timer [default].");
59 
60 #define NO_PITCH 100000
61 
62 #define CABLE_VALID_PLAYBACK	BIT(SNDRV_PCM_STREAM_PLAYBACK)
63 #define CABLE_VALID_CAPTURE	BIT(SNDRV_PCM_STREAM_CAPTURE)
64 #define CABLE_VALID_BOTH	(CABLE_VALID_PLAYBACK | CABLE_VALID_CAPTURE)
65 
66 struct loopback_cable;
67 struct loopback_pcm;
68 
69 struct loopback_ops {
70 	/* optional
71 	 * call in loopback->cable_lock
72 	 */
73 	int (*open)(struct loopback_pcm *dpcm);
74 	/* required
75 	 * call in cable->lock
76 	 */
77 	int (*start)(struct loopback_pcm *dpcm);
78 	/* required
79 	 * call in cable->lock
80 	 */
81 	int (*stop)(struct loopback_pcm *dpcm);
82 	/* optional */
83 	int (*stop_sync)(struct loopback_pcm *dpcm);
84 	/* optional */
85 	int (*close_substream)(struct loopback_pcm *dpcm);
86 	/* optional
87 	 * call in loopback->cable_lock
88 	 */
89 	int (*close_cable)(struct loopback_pcm *dpcm);
90 	/* optional
91 	 * call in cable->lock
92 	 */
93 	unsigned int (*pos_update)(struct loopback_cable *cable);
94 	/* optional */
95 	void (*dpcm_info)(struct loopback_pcm *dpcm,
96 			  struct snd_info_buffer *buffer);
97 };
98 
99 struct loopback_cable {
100 	spinlock_t lock;
101 	struct loopback_pcm *streams[2];
102 	struct snd_pcm_hardware hw;
103 	/* flags */
104 	unsigned int valid;
105 	unsigned int running;
106 	unsigned int pause;
107 	/* timer specific */
108 	struct loopback_ops *ops;
109 	/* If sound timer is used */
110 	struct {
111 		int stream;
112 		struct snd_timer_id id;
113 		struct tasklet_struct event_tasklet;
114 		struct snd_timer_instance *instance;
115 	} snd_timer;
116 };
117 
118 struct loopback_setup {
119 	unsigned int notify: 1;
120 	unsigned int rate_shift;
121 	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 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)
1844