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
37	#define MAX_PCM_SUBSTREAMS 8
38
39	static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX; /* Index 0-MAX */
40	static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR; /* ID for this card */
41	static bool enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
42	static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
43	static int pcm_notify[SNDRV_CARDS];
44	static char *timer_source[SNDRV_CARDS];
45
46	module_param_array(index, int, NULL, 0444);
47	MODULE_PARM_DESC(index, "Index value for loopback soundcard.");
48	module_param_array(id, charp, NULL, 0444);
49	MODULE_PARM_DESC(id, "ID string for loopback soundcard.");
50	module_param_array(enable, bool, NULL, 0444);
51	MODULE_PARM_DESC(enable, "Enable this loopback soundcard.");
52	module_param_array(pcm_substreams, int, NULL, 0444);
53	MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-8) for loopback driver.");
54	module_param_array(pcm_notify, int, NULL, 0444);
55	MODULE_PARM_DESC(pcm_notify, "Break capture when PCM format/rate/channels changes.");
56	module_param_array(timer_source, charp, NULL, 0444);
57	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].");
58
59	#define NO_PITCH 100000
60
61	#define CABLE_VALID_PLAYBACK BIT(SNDRV_PCM_STREAM_PLAYBACK)
62	#define CABLE_VALID_CAPTURE BIT(SNDRV_PCM_STREAM_CAPTURE)
63	#define CABLE_VALID_BOTH (CABLE_VALID_PLAYBACK | CABLE_VALID_CAPTURE)
64
65	struct loopback_cable;
66	struct loopback_pcm;
67
68	struct loopback_ops {
69	/* optional
70	* call in loopback->cable_lock
71	*/
72	int (*open)(struct loopback_pcm *dpcm);
73	/* required
74	* call in cable->lock
75	*/
76	int (*start)(struct loopback_pcm *dpcm);
77	/* required
78	* call in cable->lock
79	*/
80	int (*stop)(struct loopback_pcm *dpcm);
81	/* optional */
82	int (*stop_sync)(struct loopback_pcm *dpcm);
83	/* optional */
84	int (*close_substream)(struct loopback_pcm *dpcm);
85	/* optional
86	* call in loopback->cable_lock
87	*/
88	int (*close_cable)(struct loopback_pcm *dpcm);
89	/* optional
90	* call in cable->lock
91	*/
92	unsigned int (*pos_update)(struct loopback_cable *cable);
93	/* optional */
94	void (*dpcm_info)(struct loopback_pcm *dpcm,
95	struct snd_info_buffer *buffer);
96	};
97
98	struct loopback_cable {
99	spinlock_t lock;
100	struct loopback_pcm *streams[2];
101	struct snd_pcm_hardware hw;
102	/* flags */
103	unsigned int valid;
104	unsigned int running;
105	unsigned int pause;
106	/* timer specific */
107	const struct loopback_ops *ops;
108	/* If sound timer is used */
109	struct {
110	int stream;
111	struct snd_timer_id id;
112	struct work_struct event_work;
113	struct snd_timer_instance *instance;
114	} snd_timer;
115	};
116
117	struct loopback_setup {
118	unsigned int notify: 1;
119	unsigned int rate_shift;
120	snd_pcm_format_t format;
121	unsigned int rate;
122	snd_pcm_access_t access;
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	struct snd_ctl_elem_id access_id;
129	};
130
131	struct loopback {
132	struct snd_card *card;
133	struct mutex cable_lock;
134	struct loopback_cable *cables[MAX_PCM_SUBSTREAMS][2];
135	struct snd_pcm *pcm[2];
136	struct loopback_setup setup[MAX_PCM_SUBSTREAMS][2];
137	const char *timer_source;
138	};
139
140	struct loopback_pcm {
141	struct loopback *loopback;
142	struct snd_pcm_substream *substream;
143	struct loopback_cable *cable;
144	unsigned int pcm_buffer_size;
145	unsigned int buf_pos; /* position in buffer */
146	unsigned int silent_size;
147	/* PCM parameters */
148	unsigned int pcm_period_size;
149	unsigned int pcm_bps; /* bytes per second */
150	unsigned int pcm_salign; /* bytes per sample * channels */
151	unsigned int pcm_rate_shift; /* rate shift value */
152	/* flags */
153	unsigned int period_update_pending :1;
154	/* timer stuff */
155	unsigned int irq_pos; /* fractional IRQ position in jiffies
156	* ticks
157	*/
158	unsigned int period_size_frac; /* period size in jiffies ticks */
159	unsigned int last_drift;
160	unsigned long last_jiffies;
161	/* If jiffies timer is used */
162	struct timer_list timer;
163
164	/* size of per channel buffer in case of non-interleaved access */
165	unsigned int channel_buf_n;
166	};
167
168	static struct platform_device *devices[SNDRV_CARDS];
169
170	static inline unsigned int byte_pos(struct loopback_pcm *dpcm, unsigned int x)
171	{
172	if (dpcm->pcm_rate_shift == NO_PITCH) {
173	x /= HZ;
174	} else {
175	x = div_u64(NO_PITCH * (unsigned long long)x,
176	HZ * (unsigned long long)dpcm->pcm_rate_shift);
177	}
178	return x - (x % dpcm->pcm_salign);
179	}
180
181	static inline unsigned int frac_pos(struct loopback_pcm *dpcm, unsigned int x)
182	{
183	if (dpcm->pcm_rate_shift == NO_PITCH) { /* no pitch */
184	return x * HZ;
185	} else {
186	x = div_u64(dividend: dpcm->pcm_rate_shift * (unsigned long long)x * HZ,
187	NO_PITCH);
188	}
189	return x;
190	}
191
192	static inline struct loopback_setup *get_setup(struct loopback_pcm *dpcm)
193	{
194	int device = dpcm->substream->pstr->pcm->device;
195
196	if (dpcm->substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
197	device ^= 1;
198	return &dpcm->loopback->setup[dpcm->substream->number][device];
199	}
200
201	static inline unsigned int get_notify(struct loopback_pcm *dpcm)
202	{
203	return get_setup(dpcm)->notify;
204	}
205
206	static inline unsigned int get_rate_shift(struct loopback_pcm *dpcm)
207	{
208	return get_setup(dpcm)->rate_shift;
209	}
210
211	/* call in cable->lock */
212	static int loopback_jiffies_timer_start(struct loopback_pcm *dpcm)
213	{
214	unsigned long tick;
215	unsigned int rate_shift = get_rate_shift(dpcm);
216
217	if (rate_shift != dpcm->pcm_rate_shift) {
218	dpcm->pcm_rate_shift = rate_shift;
219	dpcm->period_size_frac = frac_pos(dpcm, x: dpcm->pcm_period_size);
220	}
221	if (dpcm->period_size_frac <= dpcm->irq_pos) {
222	dpcm->irq_pos %= dpcm->period_size_frac;
223	dpcm->period_update_pending = 1;
224	}
225	tick = dpcm->period_size_frac - dpcm->irq_pos;
226	tick = DIV_ROUND_UP(tick, dpcm->pcm_bps);
227	mod_timer(timer: &dpcm->timer, expires: jiffies + tick);
228
229	return 0;
230	}
231
232	/* call in cable->lock */
233	static int loopback_snd_timer_start(struct loopback_pcm *dpcm)
234	{
235	struct loopback_cable *cable = dpcm->cable;
236	int err;
237
238	/* Loopback device has to use same period as timer card. Therefore
239	* wake up for each snd_pcm_period_elapsed() call of timer card.
240	*/
241	err = snd_timer_start(timeri: cable->snd_timer.instance, ticks: 1);
242	if (err < 0) {
243	/* do not report error if trying to start but already
244	* running. For example called by opposite substream
245	* of the same cable
246	*/
247	if (err == -EBUSY)
248	return 0;
249
250	pcm_err(dpcm->substream->pcm,
251	"snd_timer_start(%d,%d,%d) failed with %d",
252	cable->snd_timer.id.card,
253	cable->snd_timer.id.device,
254	cable->snd_timer.id.subdevice,
255	err);
256	}
257
258	return err;
259	}
260
261	/* call in cable->lock */
262	static inline int loopback_jiffies_timer_stop(struct loopback_pcm *dpcm)
263	{
264	del_timer(timer: &dpcm->timer);
265	dpcm->timer.expires = 0;
266
267	return 0;
268	}
269
270	/* call in cable->lock */
271	static int loopback_snd_timer_stop(struct loopback_pcm *dpcm)
272	{
273	struct loopback_cable *cable = dpcm->cable;
274	int err;
275
276	/* only stop if both devices (playback and capture) are not running */
277	if (cable->running ^ cable->pause)
278	return 0;
279
280	err = snd_timer_stop(timeri: cable->snd_timer.instance);
281	if (err < 0) {
282	pcm_err(dpcm->substream->pcm,
283	"snd_timer_stop(%d,%d,%d) failed with %d",
284	cable->snd_timer.id.card,
285	cable->snd_timer.id.device,
286	cable->snd_timer.id.subdevice,
287	err);
288	}
289
290	return err;
291	}
292
293	static inline int loopback_jiffies_timer_stop_sync(struct loopback_pcm *dpcm)
294	{
295	del_timer_sync(timer: &dpcm->timer);
296
297	return 0;
298	}
299
300	/* call in loopback->cable_lock */
301	static int loopback_snd_timer_close_cable(struct loopback_pcm *dpcm)
302	{
303	struct loopback_cable *cable = dpcm->cable;
304
305	/* snd_timer was not opened */
306	if (!cable->snd_timer.instance)
307	return 0;
308
309	/* will only be called from free_cable() when other stream was
310	* already closed. Other stream cannot be reopened as long as
311	* loopback->cable_lock is locked. Therefore no need to lock
312	* cable->lock;
313	*/
314	snd_timer_close(timeri: cable->snd_timer.instance);
315
316	/* wait till drain work has finished if requested */
317	cancel_work_sync(work: &cable->snd_timer.event_work);
318
319	snd_timer_instance_free(timeri: cable->snd_timer.instance);
320	memset(&cable->snd_timer, 0, sizeof(cable->snd_timer));
321
322	return 0;
323	}
324
325	static bool is_access_interleaved(snd_pcm_access_t access)
326	{
327	switch (access) {
328	case SNDRV_PCM_ACCESS_MMAP_INTERLEAVED:
329	case SNDRV_PCM_ACCESS_RW_INTERLEAVED:
330	return true;
331	default:
332	return false;
333	}
334	};
335
336	static int loopback_check_format(struct loopback_cable *cable, int stream)
337	{
338	struct snd_pcm_runtime *runtime, *cruntime;
339	struct loopback_setup *setup;
340	struct snd_card *card;
341	int check;
342
343	if (cable->valid != CABLE_VALID_BOTH) {
344	if (stream == SNDRV_PCM_STREAM_PLAYBACK)
345	goto __notify;
346	return 0;
347	}
348	runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->
349	substream->runtime;
350	cruntime = cable->streams[SNDRV_PCM_STREAM_CAPTURE]->
351	substream->runtime;
352	check = runtime->format != cruntime->format ||
353	runtime->rate != cruntime->rate ||
354	runtime->channels != cruntime->channels ||
355	is_access_interleaved(access: runtime->access) !=
356	is_access_interleaved(access: cruntime->access);
357	if (!check)
358	return 0;
359	if (stream == SNDRV_PCM_STREAM_CAPTURE) {
360	return -EIO;
361	} else {
362	snd_pcm_stop(substream: cable->streams[SNDRV_PCM_STREAM_CAPTURE]->
363	substream, SNDRV_PCM_STATE_DRAINING);
364	__notify:
365	runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->
366	substream->runtime;
367	setup = get_setup(dpcm: cable->streams[SNDRV_PCM_STREAM_PLAYBACK]);
368	card = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->loopback->card;
369	if (setup->format != runtime->format) {
370	snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
371	id: &setup->format_id);
372	setup->format = runtime->format;
373	}
374	if (setup->rate != runtime->rate) {
375	snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
376	id: &setup->rate_id);
377	setup->rate = runtime->rate;
378	}
379	if (setup->channels != runtime->channels) {
380	snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
381	id: &setup->channels_id);
382	setup->channels = runtime->channels;
383	}
384	if (is_access_interleaved(access: setup->access) !=
385	is_access_interleaved(access: runtime->access)) {
386	snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
387	id: &setup->access_id);
388	setup->access = runtime->access;
389	}
390	}
391	return 0;
392	}
393
394	static void loopback_active_notify(struct loopback_pcm *dpcm)
395	{
396	snd_ctl_notify(card: dpcm->loopback->card,
397	SNDRV_CTL_EVENT_MASK_VALUE,
398	id: &get_setup(dpcm)->active_id);
399	}
400
401	static int loopback_trigger(struct snd_pcm_substream *substream, int cmd)
402	{
403	struct snd_pcm_runtime *runtime = substream->runtime;
404	struct loopback_pcm *dpcm = runtime->private_data;
405	struct loopback_cable *cable = dpcm->cable;
406	int err = 0, stream = 1 << substream->stream;
407
408	switch (cmd) {
409	case SNDRV_PCM_TRIGGER_START:
410	err = loopback_check_format(cable, stream: substream->stream);
411	if (err < 0)
412	return err;
413	dpcm->last_jiffies = jiffies;
414	dpcm->pcm_rate_shift = 0;
415	dpcm->last_drift = 0;
416	spin_lock(lock: &cable->lock);
417	cable->running |= stream;
418	cable->pause &= ~stream;
419	err = cable->ops->start(dpcm);
420	spin_unlock(lock: &cable->lock);
421	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
422	loopback_active_notify(dpcm);
423	break;
424	case SNDRV_PCM_TRIGGER_STOP:
425	spin_lock(lock: &cable->lock);
426	cable->running &= ~stream;
427	cable->pause &= ~stream;
428	err = cable->ops->stop(dpcm);
429	spin_unlock(lock: &cable->lock);
430	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
431	loopback_active_notify(dpcm);
432	break;
433	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
434	case SNDRV_PCM_TRIGGER_SUSPEND:
435	spin_lock(lock: &cable->lock);
436	cable->pause |= stream;
437	err = cable->ops->stop(dpcm);
438	spin_unlock(lock: &cable->lock);
439	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
440	loopback_active_notify(dpcm);
441	break;
442	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
443	case SNDRV_PCM_TRIGGER_RESUME:
444	spin_lock(lock: &cable->lock);
445	dpcm->last_jiffies = jiffies;
446	cable->pause &= ~stream;
447	err = cable->ops->start(dpcm);
448	spin_unlock(lock: &cable->lock);
449	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
450	loopback_active_notify(dpcm);
451	break;
452	default:
453	return -EINVAL;
454	}
455	return err;
456	}
457
458	static void params_change(struct snd_pcm_substream *substream)
459	{
460	struct snd_pcm_runtime *runtime = substream->runtime;
461	struct loopback_pcm *dpcm = runtime->private_data;
462	struct loopback_cable *cable = dpcm->cable;
463
464	cable->hw.formats = pcm_format_to_bits(pcm_format: runtime->format);
465	cable->hw.rate_min = runtime->rate;
466	cable->hw.rate_max = runtime->rate;
467	cable->hw.channels_min = runtime->channels;
468	cable->hw.channels_max = runtime->channels;
469
470	if (cable->snd_timer.instance) {
471	cable->hw.period_bytes_min =
472	frames_to_bytes(runtime, size: runtime->period_size);
473	cable->hw.period_bytes_max = cable->hw.period_bytes_min;
474	}
475
476	}
477
478	static int loopback_prepare(struct snd_pcm_substream *substream)
479	{
480	struct snd_pcm_runtime *runtime = substream->runtime;
481	struct loopback_pcm *dpcm = runtime->private_data;
482	struct loopback_cable *cable = dpcm->cable;
483	int err, bps, salign;
484
485	if (cable->ops->stop_sync) {
486	err = cable->ops->stop_sync(dpcm);
487	if (err < 0)
488	return err;
489	}
490
491	salign = (snd_pcm_format_physical_width(format: runtime->format) *
492	runtime->channels) / 8;
493	bps = salign * runtime->rate;
494	if (bps <= 0 || salign <= 0)
495	return -EINVAL;
496
497	dpcm->buf_pos = 0;
498	dpcm->pcm_buffer_size = frames_to_bytes(runtime, size: runtime->buffer_size);
499	dpcm->channel_buf_n = dpcm->pcm_buffer_size / runtime->channels;
500	if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
501	/* clear capture buffer */
502	dpcm->silent_size = dpcm->pcm_buffer_size;
503	snd_pcm_format_set_silence(format: runtime->format, buf: runtime->dma_area,
504	frames: runtime->buffer_size * runtime->channels);
505	}
506
507	dpcm->irq_pos = 0;
508	dpcm->period_update_pending = 0;
509	dpcm->pcm_bps = bps;
510	dpcm->pcm_salign = salign;
511	dpcm->pcm_period_size = frames_to_bytes(runtime, size: runtime->period_size);
512
513	mutex_lock(&dpcm->loopback->cable_lock);
514	if (!(cable->valid & ~(1 << substream->stream)) ||
515	(get_setup(dpcm)->notify &&
516	substream->stream == SNDRV_PCM_STREAM_PLAYBACK))
517	params_change(substream);
518	cable->valid |= 1 << substream->stream;
519	mutex_unlock(lock: &dpcm->loopback->cable_lock);
520
521	return 0;
522	}
523
524	static void clear_capture_buf(struct loopback_pcm *dpcm, unsigned int bytes)
525	{
526	struct snd_pcm_runtime *runtime = dpcm->substream->runtime;
527	char *dst = runtime->dma_area;
528	unsigned int dst_off = dpcm->buf_pos;
529
530	if (dpcm->silent_size >= dpcm->pcm_buffer_size)
531	return;
532	if (dpcm->silent_size + bytes > dpcm->pcm_buffer_size)
533	bytes = dpcm->pcm_buffer_size - dpcm->silent_size;
534
535	for (;;) {
536	unsigned int size = bytes;
537	if (dst_off + size > dpcm->pcm_buffer_size)
538	size = dpcm->pcm_buffer_size - dst_off;
539	snd_pcm_format_set_silence(format: runtime->format, buf: dst + dst_off,
540	frames: bytes_to_frames(runtime, size) *
541	runtime->channels);
542	dpcm->silent_size += size;
543	bytes -= size;
544	if (!bytes)
545	break;
546	dst_off = 0;
547	}
548	}
549
550	static void copy_play_buf_part_n(struct loopback_pcm *play, struct loopback_pcm *capt,
551	unsigned int size, unsigned int src_off, unsigned int dst_off)
552	{
553	unsigned int channels = capt->substream->runtime->channels;
554	unsigned int size_p_ch = size / channels;
555	unsigned int src_off_ch = src_off / channels;
556	unsigned int dst_off_ch = dst_off / channels;
557	int i;
558
559	for (i = 0; i < channels; i++) {
560	memcpy(capt->substream->runtime->dma_area + capt->channel_buf_n * i + dst_off_ch,
561	play->substream->runtime->dma_area + play->channel_buf_n * i + src_off_ch,
562	size_p_ch);
563	}
564	}
565
566	static void copy_play_buf(struct loopback_pcm *play,
567	struct loopback_pcm *capt,
568	unsigned int bytes)
569	{
570	struct snd_pcm_runtime *runtime = play->substream->runtime;
571	char *src = runtime->dma_area;
572	char *dst = capt->substream->runtime->dma_area;
573	unsigned int src_off = play->buf_pos;
574	unsigned int dst_off = capt->buf_pos;
575	unsigned int clear_bytes = 0;
576
577	/* check if playback is draining, trim the capture copy size
578	* when our pointer is at the end of playback ring buffer */
579	if (runtime->state == SNDRV_PCM_STATE_DRAINING &&
580	snd_pcm_playback_hw_avail(runtime) < runtime->buffer_size) {
581	snd_pcm_uframes_t appl_ptr, appl_ptr1, diff;
582	appl_ptr = appl_ptr1 = runtime->control->appl_ptr;
583	appl_ptr1 -= appl_ptr1 % runtime->buffer_size;
584	appl_ptr1 += play->buf_pos / play->pcm_salign;
585	if (appl_ptr < appl_ptr1)
586	appl_ptr1 -= runtime->buffer_size;
587	diff = (appl_ptr - appl_ptr1) * play->pcm_salign;
588	if (diff < bytes) {
589	clear_bytes = bytes - diff;
590	bytes = diff;
591	}
592	}
593
594	for (;;) {
595	unsigned int size = bytes;
596	if (src_off + size > play->pcm_buffer_size)
597	size = play->pcm_buffer_size - src_off;
598	if (dst_off + size > capt->pcm_buffer_size)
599	size = capt->pcm_buffer_size - dst_off;
600	if (!is_access_interleaved(access: runtime->access))
601	copy_play_buf_part_n(play, capt, size, src_off, dst_off);
602	else
603	memcpy(dst + dst_off, src + src_off, size);
604	capt->silent_size = 0;
605	bytes -= size;
606	if (!bytes)
607	break;
608	src_off = (src_off + size) % play->pcm_buffer_size;
609	dst_off = (dst_off + size) % capt->pcm_buffer_size;
610	}
611
612	if (clear_bytes > 0) {
613	clear_capture_buf(dpcm: capt, bytes: clear_bytes);
614	capt->silent_size = 0;
615	}
616	}
617
618	static inline unsigned int bytepos_delta(struct loopback_pcm *dpcm,
619	unsigned int jiffies_delta)
620	{
621	unsigned long last_pos;
622	unsigned int delta;
623
624	last_pos = byte_pos(dpcm, x: dpcm->irq_pos);
625	dpcm->irq_pos += jiffies_delta * dpcm->pcm_bps;
626	delta = byte_pos(dpcm, x: dpcm->irq_pos) - last_pos;
627	if (delta >= dpcm->last_drift)
628	delta -= dpcm->last_drift;
629	dpcm->last_drift = 0;
630	if (dpcm->irq_pos >= dpcm->period_size_frac) {
631	dpcm->irq_pos %= dpcm->period_size_frac;
632	dpcm->period_update_pending = 1;
633	}
634	return delta;
635	}
636
637	static inline void bytepos_finish(struct loopback_pcm *dpcm,
638	unsigned int delta)
639	{
640	dpcm->buf_pos += delta;
641	dpcm->buf_pos %= dpcm->pcm_buffer_size;
642	}
643
644	/* call in cable->lock */
645	static unsigned int loopback_jiffies_timer_pos_update
646	(struct loopback_cable *cable)
647	{
648	struct loopback_pcm *dpcm_play =
649	cable->streams[SNDRV_PCM_STREAM_PLAYBACK];
650	struct loopback_pcm *dpcm_capt =
651	cable->streams[SNDRV_PCM_STREAM_CAPTURE];
652	unsigned long delta_play = 0, delta_capt = 0, cur_jiffies;
653	unsigned int running, count1, count2;
654
655	cur_jiffies = jiffies;
656	running = cable->running ^ cable->pause;
657	if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {
658	delta_play = cur_jiffies - dpcm_play->last_jiffies;
659	dpcm_play->last_jiffies += delta_play;
660	}
661
662	if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {
663	delta_capt = cur_jiffies - dpcm_capt->last_jiffies;
664	dpcm_capt->last_jiffies += delta_capt;
665	}
666
667	if (delta_play == 0 && delta_capt == 0)
668	goto unlock;
669
670	if (delta_play > delta_capt) {
671	count1 = bytepos_delta(dpcm: dpcm_play, jiffies_delta: delta_play - delta_capt);
672	bytepos_finish(dpcm: dpcm_play, delta: count1);
673	delta_play = delta_capt;
674	} else if (delta_play < delta_capt) {
675	count1 = bytepos_delta(dpcm: dpcm_capt, jiffies_delta: delta_capt - delta_play);
676	clear_capture_buf(dpcm: dpcm_capt, bytes: count1);
677	bytepos_finish(dpcm: dpcm_capt, delta: count1);
678	delta_capt = delta_play;
679	}
680
681	if (delta_play == 0 && delta_capt == 0)
682	goto unlock;
683
684	/* note delta_capt == delta_play at this moment */
685	count1 = bytepos_delta(dpcm: dpcm_play, jiffies_delta: delta_play);
686	count2 = bytepos_delta(dpcm: dpcm_capt, jiffies_delta: delta_capt);
687	if (count1 < count2) {
688	dpcm_capt->last_drift = count2 - count1;
689	count1 = count2;
690	} else if (count1 > count2) {
691	dpcm_play->last_drift = count1 - count2;
692	}
693	copy_play_buf(play: dpcm_play, capt: dpcm_capt, bytes: count1);
694	bytepos_finish(dpcm: dpcm_play, delta: count1);
695	bytepos_finish(dpcm: dpcm_capt, delta: count1);
696	unlock:
697	return running;
698	}
699
700	static void loopback_jiffies_timer_function(struct timer_list *t)
701	{
702	struct loopback_pcm *dpcm = from_timer(dpcm, t, timer);
703	unsigned long flags;
704
705	spin_lock_irqsave(&dpcm->cable->lock, flags);
706	if (loopback_jiffies_timer_pos_update(cable: dpcm->cable) &
707	(1 << dpcm->substream->stream)) {
708	loopback_jiffies_timer_start(dpcm);
709	if (dpcm->period_update_pending) {
710	dpcm->period_update_pending = 0;
711	spin_unlock_irqrestore(lock: &dpcm->cable->lock, flags);
712	/* need to unlock before calling below */
713	snd_pcm_period_elapsed(substream: dpcm->substream);
714	return;
715	}
716	}
717	spin_unlock_irqrestore(lock: &dpcm->cable->lock, flags);
718	}
719
720	/* call in cable->lock */
721	static int loopback_snd_timer_check_resolution(struct snd_pcm_runtime *runtime,
722	unsigned long resolution)
723	{
724	if (resolution != runtime->timer_resolution) {
725	struct loopback_pcm *dpcm = runtime->private_data;
726	struct loopback_cable *cable = dpcm->cable;
727	/* Worst case estimation of possible values for resolution
728	* resolution <= (512 * 1024) frames / 8kHz in nsec
729	* resolution <= 65.536.000.000 nsec
730	*
731	* period_size <= 65.536.000.000 nsec / 1000nsec/usec * 192kHz +
732	* 500.000
733	* period_size <= 12.582.912.000.000 <64bit
734	* / 1.000.000 usec/sec
735	*/
736	snd_pcm_uframes_t period_size_usec =
737	resolution / 1000 * runtime->rate;
738	/* round to nearest sample rate */
739	snd_pcm_uframes_t period_size =
740	(period_size_usec + 500 * 1000) / (1000 * 1000);
741
742	pcm_err(dpcm->substream->pcm,
743	"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.",
744	runtime->period_size, resolution, period_size,
745	cable->snd_timer.id.card,
746	cable->snd_timer.id.device,
747	cable->snd_timer.id.subdevice,
748	period_size);
749	return -EINVAL;
750	}
751	return 0;
752	}
753
754	static void loopback_snd_timer_period_elapsed(struct loopback_cable *cable,
755	int event,
756	unsigned long resolution)
757	{
758	struct loopback_pcm *dpcm_play, *dpcm_capt;
759	struct snd_pcm_substream *substream_play, *substream_capt;
760	struct snd_pcm_runtime *valid_runtime;
761	unsigned int running, elapsed_bytes;
762	unsigned long flags;
763
764	spin_lock_irqsave(&cable->lock, flags);
765	running = cable->running ^ cable->pause;
766	/* no need to do anything if no stream is running */
767	if (!running) {
768	spin_unlock_irqrestore(lock: &cable->lock, flags);
769	return;
770	}
771
772	dpcm_play = cable->streams[SNDRV_PCM_STREAM_PLAYBACK];
773	dpcm_capt = cable->streams[SNDRV_PCM_STREAM_CAPTURE];
774
775	if (event == SNDRV_TIMER_EVENT_MSTOP) {
776	if (!dpcm_play ||
777	dpcm_play->substream->runtime->state !=
778	SNDRV_PCM_STATE_DRAINING) {
779	spin_unlock_irqrestore(lock: &cable->lock, flags);
780	return;
781	}
782	}
783
784	substream_play = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?
785	dpcm_play->substream : NULL;
786	substream_capt = (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) ?
787	dpcm_capt->substream : NULL;
788	valid_runtime = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?
789	dpcm_play->substream->runtime :
790	dpcm_capt->substream->runtime;
791
792	/* resolution is only valid for SNDRV_TIMER_EVENT_TICK events */
793	if (event == SNDRV_TIMER_EVENT_TICK) {
794	/* The hardware rules guarantee that playback and capture period
795	* are the same. Therefore only one device has to be checked
796	* here.
797	*/
798	if (loopback_snd_timer_check_resolution(runtime: valid_runtime,
799	resolution) < 0) {
800	spin_unlock_irqrestore(lock: &cable->lock, flags);
801	if (substream_play)
802	snd_pcm_stop_xrun(substream: substream_play);
803	if (substream_capt)
804	snd_pcm_stop_xrun(substream: substream_capt);
805	return;
806	}
807	}
808
809	elapsed_bytes = frames_to_bytes(runtime: valid_runtime,
810	size: valid_runtime->period_size);
811	/* The same timer interrupt is used for playback and capture device */
812	if ((running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) &&
813	(running & (1 << SNDRV_PCM_STREAM_CAPTURE))) {
814	copy_play_buf(play: dpcm_play, capt: dpcm_capt, bytes: elapsed_bytes);
815	bytepos_finish(dpcm: dpcm_play, delta: elapsed_bytes);
816	bytepos_finish(dpcm: dpcm_capt, delta: elapsed_bytes);
817	} else if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {
818	bytepos_finish(dpcm: dpcm_play, delta: elapsed_bytes);
819	} else if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {
820	clear_capture_buf(dpcm: dpcm_capt, bytes: elapsed_bytes);
821	bytepos_finish(dpcm: dpcm_capt, delta: elapsed_bytes);
822	}
823	spin_unlock_irqrestore(lock: &cable->lock, flags);
824
825	if (substream_play)
826	snd_pcm_period_elapsed(substream: substream_play);
827	if (substream_capt)
828	snd_pcm_period_elapsed(substream: substream_capt);
829	}
830
831	static void loopback_snd_timer_function(struct snd_timer_instance *timeri,
832	unsigned long resolution,
833	unsigned long ticks)
834	{
835	struct loopback_cable *cable = timeri->callback_data;
836
837	loopback_snd_timer_period_elapsed(cable, event: SNDRV_TIMER_EVENT_TICK,
838	resolution);
839	}
840
841	static void loopback_snd_timer_work(struct work_struct *work)
842	{
843	struct loopback_cable *cable;
844
845	cable = container_of(work, struct loopback_cable, snd_timer.event_work);
846	loopback_snd_timer_period_elapsed(cable, event: SNDRV_TIMER_EVENT_MSTOP, resolution: 0);
847	}
848
849	static void loopback_snd_timer_event(struct snd_timer_instance *timeri,
850	int event,
851	struct timespec64 *tstamp,
852	unsigned long resolution)
853	{
854	/* Do not lock cable->lock here because timer->lock is already hold.
855	* There are other functions which first lock cable->lock and than
856	* timer->lock e.g.
857	* loopback_trigger()
858	* spin_lock(&cable->lock)
859	* loopback_snd_timer_start()
860	* snd_timer_start()
861	* spin_lock(&timer->lock)
862	* Therefore when using the oposit order of locks here it could result
863	* in a deadlock.
864	*/
865
866	if (event == SNDRV_TIMER_EVENT_MSTOP) {
867	struct loopback_cable *cable = timeri->callback_data;
868
869	/* sound card of the timer was stopped. Therefore there will not
870	* be any further timer callbacks. Due to this forward audio
871	* data from here if in draining state. When still in running
872	* state the streaming will be aborted by the usual timeout. It
873	* should not be aborted here because may be the timer sound
874	* card does only a recovery and the timer is back soon.
875	* This work triggers loopback_snd_timer_work()
876	*/
877	schedule_work(work: &cable->snd_timer.event_work);
878	}
879	}
880
881	static void loopback_jiffies_timer_dpcm_info(struct loopback_pcm *dpcm,
882	struct snd_info_buffer *buffer)
883	{
884	snd_iprintf(buffer, " update_pending:\t%u\n",
885	dpcm->period_update_pending);
886	snd_iprintf(buffer, " irq_pos:\t\t%u\n", dpcm->irq_pos);
887	snd_iprintf(buffer, " period_frac:\t%u\n", dpcm->period_size_frac);
888	snd_iprintf(buffer, " last_jiffies:\t%lu (%lu)\n",
889	dpcm->last_jiffies, jiffies);
890	snd_iprintf(buffer, " timer_expires:\t%lu\n", dpcm->timer.expires);
891	}
892
893	static void loopback_snd_timer_dpcm_info(struct loopback_pcm *dpcm,
894	struct snd_info_buffer *buffer)
895	{
896	struct loopback_cable *cable = dpcm->cable;
897
898	snd_iprintf(buffer, " sound timer:\thw:%d,%d,%d\n",
899	cable->snd_timer.id.card,
900	cable->snd_timer.id.device,
901	cable->snd_timer.id.subdevice);
902	snd_iprintf(buffer, " timer open:\t\t%s\n",
903	(cable->snd_timer.stream == SNDRV_PCM_STREAM_CAPTURE) ?
904	"capture" : "playback");
905	}
906
907	static snd_pcm_uframes_t loopback_pointer(struct snd_pcm_substream *substream)
908	{
909	struct snd_pcm_runtime *runtime = substream->runtime;
910	struct loopback_pcm *dpcm = runtime->private_data;
911	snd_pcm_uframes_t pos;
912
913	spin_lock(lock: &dpcm->cable->lock);
914	if (dpcm->cable->ops->pos_update)
915	dpcm->cable->ops->pos_update(dpcm->cable);
916	pos = dpcm->buf_pos;
917	spin_unlock(lock: &dpcm->cable->lock);
918	return bytes_to_frames(runtime, size: pos);
919	}
920
921	static const struct snd_pcm_hardware loopback_pcm_hardware =
922	{
923	.info = (SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_MMAP |
924	SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_PAUSE |
925	SNDRV_PCM_INFO_RESUME | SNDRV_PCM_INFO_NONINTERLEAVED),
926	.formats = (SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE |
927	SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S24_BE |
928	SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_3BE |
929	SNDRV_PCM_FMTBIT_S32_LE | SNDRV_PCM_FMTBIT_S32_BE |
930	SNDRV_PCM_FMTBIT_FLOAT_LE | SNDRV_PCM_FMTBIT_FLOAT_BE),
931	.rates = SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000,
932	.rate_min = 8000,
933	.rate_max = 192000,
934	.channels_min = 1,
935	.channels_max = 32,
936	.buffer_bytes_max = 2 * 1024 * 1024,
937	.period_bytes_min = 64,
938	/* note check overflow in frac_pos() using pcm_rate_shift before
939	changing period_bytes_max value */
940	.period_bytes_max = 1024 * 1024,
941	.periods_min = 1,
942	.periods_max = 1024,
943	.fifo_size = 0,
944	};
945
946	static void loopback_runtime_free(struct snd_pcm_runtime *runtime)
947	{
948	struct loopback_pcm *dpcm = runtime->private_data;
949	kfree(objp: dpcm);
950	}
951
952	static int loopback_hw_free(struct snd_pcm_substream *substream)
953	{
954	struct snd_pcm_runtime *runtime = substream->runtime;
955	struct loopback_pcm *dpcm = runtime->private_data;
956	struct loopback_cable *cable = dpcm->cable;
957
958	mutex_lock(&dpcm->loopback->cable_lock);
959	cable->valid &= ~(1 << substream->stream);
960	mutex_unlock(lock: &dpcm->loopback->cable_lock);
961	return 0;
962	}
963
964	static unsigned int get_cable_index(struct snd_pcm_substream *substream)
965	{
966	if (!substream->pcm->device)
967	return substream->stream;
968	else
969	return !substream->stream;
970	}
971
972	static int rule_format(struct snd_pcm_hw_params *params,
973	struct snd_pcm_hw_rule *rule)
974	{
975	struct loopback_pcm *dpcm = rule->private;
976	struct loopback_cable *cable = dpcm->cable;
977	struct snd_mask m;
978
979	snd_mask_none(mask: &m);
980	mutex_lock(&dpcm->loopback->cable_lock);
981	m.bits[0] = (u_int32_t)cable->hw.formats;
982	m.bits[1] = (u_int32_t)(cable->hw.formats >> 32);
983	mutex_unlock(lock: &dpcm->loopback->cable_lock);
984	return snd_mask_refine(mask: hw_param_mask(params, var: rule->var), v: &m);
985	}
986
987	static int rule_rate(struct snd_pcm_hw_params *params,
988	struct snd_pcm_hw_rule *rule)
989	{
990	struct loopback_pcm *dpcm = rule->private;
991	struct loopback_cable *cable = dpcm->cable;
992	struct snd_interval t;
993
994	mutex_lock(&dpcm->loopback->cable_lock);
995	t.min = cable->hw.rate_min;
996	t.max = cable->hw.rate_max;
997	mutex_unlock(lock: &dpcm->loopback->cable_lock);
998	t.openmin = t.openmax = 0;
999	t.integer = 0;
1000	return snd_interval_refine(i: hw_param_interval(params, var: rule->var), v: &t);
1001	}
1002
1003	static int rule_channels(struct snd_pcm_hw_params *params,
1004	struct snd_pcm_hw_rule *rule)
1005	{
1006	struct loopback_pcm *dpcm = rule->private;
1007	struct loopback_cable *cable = dpcm->cable;
1008	struct snd_interval t;
1009
1010	mutex_lock(&dpcm->loopback->cable_lock);
1011	t.min = cable->hw.channels_min;
1012	t.max = cable->hw.channels_max;
1013	mutex_unlock(lock: &dpcm->loopback->cable_lock);
1014	t.openmin = t.openmax = 0;
1015	t.integer = 0;
1016	return snd_interval_refine(i: hw_param_interval(params, var: rule->var), v: &t);
1017	}
1018
1019	static int rule_period_bytes(struct snd_pcm_hw_params *params,
1020	struct snd_pcm_hw_rule *rule)
1021	{
1022	struct loopback_pcm *dpcm = rule->private;
1023	struct loopback_cable *cable = dpcm->cable;
1024	struct snd_interval t;
1025
1026	mutex_lock(&dpcm->loopback->cable_lock);
1027	t.min = cable->hw.period_bytes_min;
1028	t.max = cable->hw.period_bytes_max;
1029	mutex_unlock(lock: &dpcm->loopback->cable_lock);
1030	t.openmin = 0;
1031	t.openmax = 0;
1032	t.integer = 0;
1033	return snd_interval_refine(i: hw_param_interval(params, var: rule->var), v: &t);
1034	}
1035
1036	static void free_cable(struct snd_pcm_substream *substream)
1037	{
1038	struct loopback *loopback = substream->private_data;
1039	int dev = get_cable_index(substream);
1040	struct loopback_cable *cable;
1041
1042	cable = loopback->cables[substream->number][dev];
1043	if (!cable)
1044	return;
1045	if (cable->streams[!substream->stream]) {
1046	/* other stream is still alive */
1047	spin_lock_irq(lock: &cable->lock);
1048	cable->streams[substream->stream] = NULL;
1049	spin_unlock_irq(lock: &cable->lock);
1050	} else {
1051	struct loopback_pcm *dpcm = substream->runtime->private_data;
1052
1053	if (cable->ops && cable->ops->close_cable && dpcm)
1054	cable->ops->close_cable(dpcm);
1055	/* free the cable */
1056	loopback->cables[substream->number][dev] = NULL;
1057	kfree(objp: cable);
1058	}
1059	}
1060
1061	static int loopback_jiffies_timer_open(struct loopback_pcm *dpcm)
1062	{
1063	timer_setup(&dpcm->timer, loopback_jiffies_timer_function, 0);
1064
1065	return 0;
1066	}
1067
1068	static const struct loopback_ops loopback_jiffies_timer_ops = {
1069	.open = loopback_jiffies_timer_open,
1070	.start = loopback_jiffies_timer_start,
1071	.stop = loopback_jiffies_timer_stop,
1072	.stop_sync = loopback_jiffies_timer_stop_sync,
1073	.close_substream = loopback_jiffies_timer_stop_sync,
1074	.pos_update = loopback_jiffies_timer_pos_update,
1075	.dpcm_info = loopback_jiffies_timer_dpcm_info,
1076	};
1077
1078	static int loopback_parse_timer_id(const char *str,
1079	struct snd_timer_id *tid)
1080	{
1081	/* [<pref>:](<card name>|<card idx>)[{.,}<dev idx>[{.,}<subdev idx>]] */
1082	const char * const sep_dev = ".,";
1083	const char * const sep_pref = ":";
1084	const char *name = str;
1085	char *sep, save = '\0';
1086	int card_idx = 0, dev = 0, subdev = 0;
1087	int err;
1088
1089	sep = strpbrk(str, sep_pref);
1090	if (sep)
1091	name = sep + 1;
1092	sep = strpbrk(name, sep_dev);
1093	if (sep) {
1094	save = *sep;
1095	*sep = '\0';
1096	}
1097	err = kstrtoint(s: name, base: 0, res: &card_idx);
1098	if (err == -EINVAL) {
1099	/* Must be the name, not number */
1100	for (card_idx = 0; card_idx < snd_ecards_limit; card_idx++) {
1101	struct snd_card *card = snd_card_ref(card: card_idx);
1102
1103	if (card) {
1104	if (!strcmp(card->id, name))
1105	err = 0;
1106	snd_card_unref(card);
1107	}
1108	if (!err)
1109	break;
1110	}
1111	}
1112	if (sep) {
1113	*sep = save;
1114	if (!err) {
1115	char *sep2, save2 = '\0';
1116
1117	sep2 = strpbrk(sep + 1, sep_dev);
1118	if (sep2) {
1119	save2 = *sep2;
1120	*sep2 = '\0';
1121	}
1122	err = kstrtoint(s: sep + 1, base: 0, res: &dev);
1123	if (sep2) {
1124	*sep2 = save2;
1125	if (!err)
1126	err = kstrtoint(s: sep2 + 1, base: 0, res: &subdev);
1127	}
1128	}
1129	}
1130	if (!err && tid) {
1131	tid->card = card_idx;
1132	tid->device = dev;
1133	tid->subdevice = subdev;
1134	}
1135	return err;
1136	}
1137
1138	/* call in loopback->cable_lock */
1139	static int loopback_snd_timer_open(struct loopback_pcm *dpcm)
1140	{
1141	int err = 0;
1142	struct snd_timer_id tid = {
1143	.dev_class = SNDRV_TIMER_CLASS_PCM,
1144	.dev_sclass = SNDRV_TIMER_SCLASS_APPLICATION,
1145	};
1146	struct snd_timer_instance *timeri;
1147	struct loopback_cable *cable = dpcm->cable;
1148
1149	/* check if timer was already opened. It is only opened once
1150	* per playback and capture subdevice (aka cable).
1151	*/
1152	if (cable->snd_timer.instance)
1153	goto exit;
1154
1155	err = loopback_parse_timer_id(str: dpcm->loopback->timer_source, tid: &tid);
1156	if (err < 0) {
1157	pcm_err(dpcm->substream->pcm,
1158	"Parsing timer source \'%s\' failed with %d",
1159	dpcm->loopback->timer_source, err);
1160	goto exit;
1161	}
1162
1163	cable->snd_timer.stream = dpcm->substream->stream;
1164	cable->snd_timer.id = tid;
1165
1166	timeri = snd_timer_instance_new(owner: dpcm->loopback->card->id);
1167	if (!timeri) {
1168	err = -ENOMEM;
1169	goto exit;
1170	}
1171	/* The callback has to be called from another work. If
1172	* SNDRV_TIMER_IFLG_FAST is specified it will be called from the
1173	* snd_pcm_period_elapsed() call of the selected sound card.
1174	* snd_pcm_period_elapsed() helds snd_pcm_stream_lock_irqsave().
1175	* Due to our callback loopback_snd_timer_function() also calls
1176	* snd_pcm_period_elapsed() which calls snd_pcm_stream_lock_irqsave().
1177	* This would end up in a dead lock.
1178	*/
1179	timeri->flags |= SNDRV_TIMER_IFLG_AUTO;
1180	timeri->callback = loopback_snd_timer_function;
1181	timeri->callback_data = (void *)cable;
1182	timeri->ccallback = loopback_snd_timer_event;
1183
1184	/* initialise a work used for draining */
1185	INIT_WORK(&cable->snd_timer.event_work, loopback_snd_timer_work);
1186
1187	/* The mutex loopback->cable_lock is kept locked.
1188	* Therefore snd_timer_open() cannot be called a second time
1189	* by the other device of the same cable.
1190	* Therefore the following issue cannot happen:
1191	* [proc1] Call loopback_timer_open() ->
1192	* Unlock cable->lock for snd_timer_close/open() call
1193	* [proc2] Call loopback_timer_open() -> snd_timer_open(),
1194	* snd_timer_start()
1195	* [proc1] Call snd_timer_open() and overwrite running timer
1196	* instance
1197	*/
1198	err = snd_timer_open(timeri, tid: &cable->snd_timer.id, current->pid);
1199	if (err < 0) {
1200	pcm_err(dpcm->substream->pcm,
1201	"snd_timer_open (%d,%d,%d) failed with %d",
1202	cable->snd_timer.id.card,
1203	cable->snd_timer.id.device,
1204	cable->snd_timer.id.subdevice,
1205	err);
1206	snd_timer_instance_free(timeri);
1207	goto exit;
1208	}
1209
1210	cable->snd_timer.instance = timeri;
1211
1212	exit:
1213	return err;
1214	}
1215
1216	/* stop_sync() is not required for sound timer because it does not need to be
1217	* restarted in loopback_prepare() on Xrun recovery
1218	*/
1219	static const struct loopback_ops loopback_snd_timer_ops = {
1220	.open = loopback_snd_timer_open,
1221	.start = loopback_snd_timer_start,
1222	.stop = loopback_snd_timer_stop,
1223	.close_cable = loopback_snd_timer_close_cable,
1224	.dpcm_info = loopback_snd_timer_dpcm_info,
1225	};
1226
1227	static int loopback_open(struct snd_pcm_substream *substream)
1228	{
1229	struct snd_pcm_runtime *runtime = substream->runtime;
1230	struct loopback *loopback = substream->private_data;
1231	struct loopback_pcm *dpcm;
1232	struct loopback_cable *cable = NULL;
1233	int err = 0;
1234	int dev = get_cable_index(substream);
1235
1236	mutex_lock(&loopback->cable_lock);
1237	dpcm = kzalloc(size: sizeof(*dpcm), GFP_KERNEL);
1238	if (!dpcm) {
1239	err = -ENOMEM;
1240	goto unlock;
1241	}
1242	dpcm->loopback = loopback;
1243	dpcm->substream = substream;
1244
1245	cable = loopback->cables[substream->number][dev];
1246	if (!cable) {
1247	cable = kzalloc(size: sizeof(*cable), GFP_KERNEL);
1248	if (!cable) {
1249	err = -ENOMEM;
1250	goto unlock;
1251	}
1252	spin_lock_init(&cable->lock);
1253	cable->hw = loopback_pcm_hardware;
1254	if (loopback->timer_source)
1255	cable->ops = &loopback_snd_timer_ops;
1256	else
1257	cable->ops = &loopback_jiffies_timer_ops;
1258	loopback->cables[substream->number][dev] = cable;
1259	}
1260	dpcm->cable = cable;
1261	runtime->private_data = dpcm;
1262
1263	if (cable->ops->open) {
1264	err = cable->ops->open(dpcm);
1265	if (err < 0)
1266	goto unlock;
1267	}
1268
1269	snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
1270
1271	/* use dynamic rules based on actual runtime->hw values */
1272	/* note that the default rules created in the PCM midlevel code */
1273	/* are cached -> they do not reflect the actual state */
1274	err = snd_pcm_hw_rule_add(runtime, cond: 0,
1275	SNDRV_PCM_HW_PARAM_FORMAT,
1276	func: rule_format, private: dpcm,
1277	SNDRV_PCM_HW_PARAM_FORMAT, -1);
1278	if (err < 0)
1279	goto unlock;
1280	err = snd_pcm_hw_rule_add(runtime, cond: 0,
1281	SNDRV_PCM_HW_PARAM_RATE,
1282	func: rule_rate, private: dpcm,
1283	SNDRV_PCM_HW_PARAM_RATE, -1);
1284	if (err < 0)
1285	goto unlock;
1286	err = snd_pcm_hw_rule_add(runtime, cond: 0,
1287	SNDRV_PCM_HW_PARAM_CHANNELS,
1288	func: rule_channels, private: dpcm,
1289	SNDRV_PCM_HW_PARAM_CHANNELS, -1);
1290	if (err < 0)
1291	goto unlock;
1292
1293	/* In case of sound timer the period time of both devices of the same
1294	* loop has to be the same.
1295	* This rule only takes effect if a sound timer was chosen
1296	*/
1297	if (cable->snd_timer.instance) {
1298	err = snd_pcm_hw_rule_add(runtime, cond: 0,
1299	SNDRV_PCM_HW_PARAM_PERIOD_BYTES,
1300	func: rule_period_bytes, private: dpcm,
1301	SNDRV_PCM_HW_PARAM_PERIOD_BYTES, -1);
1302	if (err < 0)
1303	goto unlock;
1304	}
1305
1306	/* loopback_runtime_free() has not to be called if kfree(dpcm) was
1307	* already called here. Otherwise it will end up with a double free.
1308	*/
1309	runtime->private_free = loopback_runtime_free;
1310	if (get_notify(dpcm))
1311	runtime->hw = loopback_pcm_hardware;
1312	else
1313	runtime->hw = cable->hw;
1314
1315	spin_lock_irq(lock: &cable->lock);
1316	cable->streams[substream->stream] = dpcm;
1317	spin_unlock_irq(lock: &cable->lock);
1318
1319	unlock:
1320	if (err < 0) {
1321	free_cable(substream);
1322	kfree(objp: dpcm);
1323	}
1324	mutex_unlock(lock: &loopback->cable_lock);
1325	return err;
1326	}
1327
1328	static int loopback_close(struct snd_pcm_substream *substream)
1329	{
1330	struct loopback *loopback = substream->private_data;
1331	struct loopback_pcm *dpcm = substream->runtime->private_data;
1332	int err = 0;
1333
1334	if (dpcm->cable->ops->close_substream)
1335	err = dpcm->cable->ops->close_substream(dpcm);
1336	mutex_lock(&loopback->cable_lock);
1337	free_cable(substream);
1338	mutex_unlock(lock: &loopback->cable_lock);
1339	return err;
1340	}
1341
1342	static const struct snd_pcm_ops loopback_pcm_ops = {
1343	.open = loopback_open,
1344	.close = loopback_close,
1345	.hw_free = loopback_hw_free,
1346	.prepare = loopback_prepare,
1347	.trigger = loopback_trigger,
1348	.pointer = loopback_pointer,
1349	};
1350
1351	static int loopback_pcm_new(struct loopback *loopback,
1352	int device, int substreams)
1353	{
1354	struct snd_pcm *pcm;
1355	int err;
1356
1357	err = snd_pcm_new(card: loopback->card, id: "Loopback PCM", device,
1358	playback_count: substreams, capture_count: substreams, rpcm: &pcm);
1359	if (err < 0)
1360	return err;
1361	snd_pcm_set_ops(pcm, direction: SNDRV_PCM_STREAM_PLAYBACK, ops: &loopback_pcm_ops);
1362	snd_pcm_set_ops(pcm, direction: SNDRV_PCM_STREAM_CAPTURE, ops: &loopback_pcm_ops);
1363	snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, size: 0, max: 0);
1364
1365	pcm->private_data = loopback;
1366	pcm->info_flags = 0;
1367	strcpy(p: pcm->name, q: "Loopback PCM");
1368
1369	loopback->pcm[device] = pcm;
1370	return 0;
1371	}
1372
1373	static int loopback_rate_shift_info(struct snd_kcontrol *kcontrol,
1374	struct snd_ctl_elem_info *uinfo)
1375	{
1376	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1377	uinfo->count = 1;
1378	uinfo->value.integer.min = 80000;
1379	uinfo->value.integer.max = 120000;
1380	uinfo->value.integer.step = 1;
1381	return 0;
1382	}
1383
1384	static int loopback_rate_shift_get(struct snd_kcontrol *kcontrol,
1385	struct snd_ctl_elem_value *ucontrol)
1386	{
1387	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1388
1389	mutex_lock(&loopback->cable_lock);
1390	ucontrol->value.integer.value[0] =
1391	loopback->setup[kcontrol->id.subdevice]
1392	[kcontrol->id.device].rate_shift;
1393	mutex_unlock(lock: &loopback->cable_lock);
1394	return 0;
1395	}
1396
1397	static int loopback_rate_shift_put(struct snd_kcontrol *kcontrol,
1398	struct snd_ctl_elem_value *ucontrol)
1399	{
1400	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1401	unsigned int val;
1402	int change = 0;
1403
1404	val = ucontrol->value.integer.value[0];
1405	if (val < 80000)
1406	val = 80000;
1407	if (val > 120000)
1408	val = 120000;
1409	mutex_lock(&loopback->cable_lock);
1410	if (val != loopback->setup[kcontrol->id.subdevice]
1411	[kcontrol->id.device].rate_shift) {
1412	loopback->setup[kcontrol->id.subdevice]
1413	[kcontrol->id.device].rate_shift = val;
1414	change = 1;
1415	}
1416	mutex_unlock(lock: &loopback->cable_lock);
1417	return change;
1418	}
1419
1420	static int loopback_notify_get(struct snd_kcontrol *kcontrol,
1421	struct snd_ctl_elem_value *ucontrol)
1422	{
1423	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1424
1425	mutex_lock(&loopback->cable_lock);
1426	ucontrol->value.integer.value[0] =
1427	loopback->setup[kcontrol->id.subdevice]
1428	[kcontrol->id.device].notify;
1429	mutex_unlock(lock: &loopback->cable_lock);
1430	return 0;
1431	}
1432
1433	static int loopback_notify_put(struct snd_kcontrol *kcontrol,
1434	struct snd_ctl_elem_value *ucontrol)
1435	{
1436	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1437	unsigned int val;
1438	int change = 0;
1439
1440	val = ucontrol->value.integer.value[0] ? 1 : 0;
1441	mutex_lock(&loopback->cable_lock);
1442	if (val != loopback->setup[kcontrol->id.subdevice]
1443	[kcontrol->id.device].notify) {
1444	loopback->setup[kcontrol->id.subdevice]
1445	[kcontrol->id.device].notify = val;
1446	change = 1;
1447	}
1448	mutex_unlock(lock: &loopback->cable_lock);
1449	return change;
1450	}
1451
1452	static int loopback_active_get(struct snd_kcontrol *kcontrol,
1453	struct snd_ctl_elem_value *ucontrol)
1454	{
1455	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1456	struct loopback_cable *cable;
1457
1458	unsigned int val = 0;
1459
1460	mutex_lock(&loopback->cable_lock);
1461	cable = loopback->cables[kcontrol->id.subdevice][kcontrol->id.device ^ 1];
1462	if (cable != NULL) {
1463	unsigned int running = cable->running ^ cable->pause;
1464
1465	val = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ? 1 : 0;
1466	}
1467	mutex_unlock(lock: &loopback->cable_lock);
1468	ucontrol->value.integer.value[0] = val;
1469	return 0;
1470	}
1471
1472	static int loopback_format_info(struct snd_kcontrol *kcontrol,
1473	struct snd_ctl_elem_info *uinfo)
1474	{
1475	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1476	uinfo->count = 1;
1477	uinfo->value.integer.min = 0;
1478	uinfo->value.integer.max = (__force int)SNDRV_PCM_FORMAT_LAST;
1479	uinfo->value.integer.step = 1;
1480	return 0;
1481	}
1482
1483	static int loopback_format_get(struct snd_kcontrol *kcontrol,
1484	struct snd_ctl_elem_value *ucontrol)
1485	{
1486	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1487
1488	ucontrol->value.integer.value[0] =
1489	(__force int)loopback->setup[kcontrol->id.subdevice]
1490	[kcontrol->id.device].format;
1491	return 0;
1492	}
1493
1494	static int loopback_rate_info(struct snd_kcontrol *kcontrol,
1495	struct snd_ctl_elem_info *uinfo)
1496	{
1497	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1498	uinfo->count = 1;
1499	uinfo->value.integer.min = 0;
1500	uinfo->value.integer.max = 192000;
1501	uinfo->value.integer.step = 1;
1502	return 0;
1503	}
1504
1505	static int loopback_rate_get(struct snd_kcontrol *kcontrol,
1506	struct snd_ctl_elem_value *ucontrol)
1507	{
1508	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1509
1510	mutex_lock(&loopback->cable_lock);
1511	ucontrol->value.integer.value[0] =
1512	loopback->setup[kcontrol->id.subdevice]
1513	[kcontrol->id.device].rate;
1514	mutex_unlock(lock: &loopback->cable_lock);
1515	return 0;
1516	}
1517
1518	static int loopback_channels_info(struct snd_kcontrol *kcontrol,
1519	struct snd_ctl_elem_info *uinfo)
1520	{
1521	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1522	uinfo->count = 1;
1523	uinfo->value.integer.min = 1;
1524	uinfo->value.integer.max = 1024;
1525	uinfo->value.integer.step = 1;
1526	return 0;
1527	}
1528
1529	static int loopback_channels_get(struct snd_kcontrol *kcontrol,
1530	struct snd_ctl_elem_value *ucontrol)
1531	{
1532	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1533
1534	mutex_lock(&loopback->cable_lock);
1535	ucontrol->value.integer.value[0] =
1536	loopback->setup[kcontrol->id.subdevice]
1537	[kcontrol->id.device].channels;
1538	mutex_unlock(lock: &loopback->cable_lock);
1539	return 0;
1540	}
1541
1542	static int loopback_access_info(struct snd_kcontrol *kcontrol,
1543	struct snd_ctl_elem_info *uinfo)
1544	{
1545	const char * const texts[] = {"Interleaved", "Non-interleaved"};
1546
1547	return snd_ctl_enum_info(info: uinfo, channels: 1, ARRAY_SIZE(texts), names: texts);
1548	}
1549
1550	static int loopback_access_get(struct snd_kcontrol *kcontrol,
1551	struct snd_ctl_elem_value *ucontrol)
1552	{
1553	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1554	snd_pcm_access_t access;
1555
1556	mutex_lock(&loopback->cable_lock);
1557	access = loopback->setup[kcontrol->id.subdevice][kcontrol->id.device].access;
1558
1559	ucontrol->value.enumerated.item[0] = !is_access_interleaved(access);
1560
1561	mutex_unlock(lock: &loopback->cable_lock);
1562	return 0;
1563	}
1564
1565	static const struct snd_kcontrol_new loopback_controls[] = {
1566	{
1567	.iface = SNDRV_CTL_ELEM_IFACE_PCM,
1568	.name = "PCM Rate Shift 100000",
1569	.info = loopback_rate_shift_info,
1570	.get = loopback_rate_shift_get,
1571	.put = loopback_rate_shift_put,
1572	},
1573	{
1574	.iface = SNDRV_CTL_ELEM_IFACE_PCM,
1575	.name = "PCM Notify",
1576	.info = snd_ctl_boolean_mono_info,
1577	.get = loopback_notify_get,
1578	.put = loopback_notify_put,
1579	},
1580	#define ACTIVE_IDX 2
1581	{
1582	.access = SNDRV_CTL_ELEM_ACCESS_READ,
1583	.iface = SNDRV_CTL_ELEM_IFACE_PCM,
1584	.name = "PCM Slave Active",
1585	.info = snd_ctl_boolean_mono_info,
1586	.get = loopback_active_get,
1587	},
1588	#define FORMAT_IDX 3
1589	{
1590	.access = SNDRV_CTL_ELEM_ACCESS_READ,
1591	.iface = SNDRV_CTL_ELEM_IFACE_PCM,
1592	.name = "PCM Slave Format",
1593	.info = loopback_format_info,
1594	.get = loopback_format_get
1595	},
1596	#define RATE_IDX 4
1597	{
1598	.access = SNDRV_CTL_ELEM_ACCESS_READ,
1599	.iface = SNDRV_CTL_ELEM_IFACE_PCM,
1600	.name = "PCM Slave Rate",
1601	.info = loopback_rate_info,
1602	.get = loopback_rate_get
1603	},
1604	#define CHANNELS_IDX 5
1605	{
1606	.access = SNDRV_CTL_ELEM_ACCESS_READ,
1607	.iface = SNDRV_CTL_ELEM_IFACE_PCM,
1608	.name = "PCM Slave Channels",
1609	.info = loopback_channels_info,
1610	.get = loopback_channels_get
1611	},
1612	#define ACCESS_IDX 6
1613	{
1614	.access = SNDRV_CTL_ELEM_ACCESS_READ,
1615	.iface = SNDRV_CTL_ELEM_IFACE_PCM,
1616	.name = "PCM Slave Access Mode",
1617	.info = loopback_access_info,
1618	.get = loopback_access_get,
1619	},
1620	};
1621
1622	static int loopback_mixer_new(struct loopback *loopback, int notify)
1623	{
1624	struct snd_card *card = loopback->card;
1625	struct snd_pcm *pcm;
1626	struct snd_kcontrol *kctl;
1627	struct loopback_setup *setup;
1628	int err, dev, substr, substr_count, idx;
1629
1630	strcpy(p: card->mixername, q: "Loopback Mixer");
1631	for (dev = 0; dev < 2; dev++) {
1632	pcm = loopback->pcm[dev];
1633	substr_count =
1634	pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream_count;
1635	for (substr = 0; substr < substr_count; substr++) {
1636	setup = &loopback->setup[substr][dev];
1637	setup->notify = notify;
1638	setup->rate_shift = NO_PITCH;
1639	setup->format = SNDRV_PCM_FORMAT_S16_LE;
1640	setup->access = SNDRV_PCM_ACCESS_RW_INTERLEAVED;
1641	setup->rate = 48000;
1642	setup->channels = 2;
1643	for (idx = 0; idx < ARRAY_SIZE(loopback_controls);
1644	idx++) {
1645	kctl = snd_ctl_new1(kcontrolnew: &loopback_controls[idx],
1646	private_data: loopback);
1647	if (!kctl)
1648	return -ENOMEM;
1649	kctl->id.device = dev;
1650	kctl->id.subdevice = substr;
1651
1652	/* Add the control before copying the id so that
1653	* the numid field of the id is set in the copy.
1654	*/
1655	err = snd_ctl_add(card, kcontrol: kctl);
1656	if (err < 0)
1657	return err;
1658
1659	switch (idx) {
1660	case ACTIVE_IDX:
1661	setup->active_id = kctl->id;
1662	break;
1663	case FORMAT_IDX:
1664	setup->format_id = kctl->id;
1665	break;
1666	case RATE_IDX:
1667	setup->rate_id = kctl->id;
1668	break;
1669	case CHANNELS_IDX:
1670	setup->channels_id = kctl->id;
1671	break;
1672	case ACCESS_IDX:
1673	setup->access_id = kctl->id;
1674	break;
1675	default:
1676	break;
1677	}
1678	}
1679	}
1680	}
1681	return 0;
1682	}
1683
1684	static void print_dpcm_info(struct snd_info_buffer *buffer,
1685	struct loopback_pcm *dpcm,
1686	const char *id)
1687	{
1688	snd_iprintf(buffer, " %s\n", id);
1689	if (dpcm == NULL) {
1690	snd_iprintf(buffer, " inactive\n");
1691	return;
1692	}
1693	snd_iprintf(buffer, " buffer_size:\t%u\n", dpcm->pcm_buffer_size);
1694	snd_iprintf(buffer, " buffer_pos:\t\t%u\n", dpcm->buf_pos);
1695	snd_iprintf(buffer, " silent_size:\t%u\n", dpcm->silent_size);
1696	snd_iprintf(buffer, " period_size:\t%u\n", dpcm->pcm_period_size);
1697	snd_iprintf(buffer, " bytes_per_sec:\t%u\n", dpcm->pcm_bps);
1698	snd_iprintf(buffer, " sample_align:\t%u\n", dpcm->pcm_salign);
1699	snd_iprintf(buffer, " rate_shift:\t\t%u\n", dpcm->pcm_rate_shift);
1700	if (dpcm->cable->ops->dpcm_info)
1701	dpcm->cable->ops->dpcm_info(dpcm, buffer);
1702	}
1703
1704	static void print_substream_info(struct snd_info_buffer *buffer,
1705	struct loopback *loopback,
1706	int sub,
1707	int num)
1708	{
1709	struct loopback_cable *cable = loopback->cables[sub][num];
1710
1711	snd_iprintf(buffer, "Cable %i substream %i:\n", num, sub);
1712	if (cable == NULL) {
1713	snd_iprintf(buffer, " inactive\n");
1714	return;
1715	}
1716	snd_iprintf(buffer, " valid: %u\n", cable->valid);
1717	snd_iprintf(buffer, " running: %u\n", cable->running);
1718	snd_iprintf(buffer, " pause: %u\n", cable->pause);
1719	print_dpcm_info(buffer, dpcm: cable->streams[0], id: "Playback");
1720	print_dpcm_info(buffer, dpcm: cable->streams[1], id: "Capture");
1721	}
1722
1723	static void print_cable_info(struct snd_info_entry *entry,
1724	struct snd_info_buffer *buffer)
1725	{
1726	struct loopback *loopback = entry->private_data;
1727	int sub, num;
1728
1729	mutex_lock(&loopback->cable_lock);
1730	num = entry->name[strlen(entry->name)-1];
1731	num = num == '0' ? 0 : 1;
1732	for (sub = 0; sub < MAX_PCM_SUBSTREAMS; sub++)
1733	print_substream_info(buffer, loopback, sub, num);
1734	mutex_unlock(lock: &loopback->cable_lock);
1735	}
1736
1737	static int loopback_cable_proc_new(struct loopback *loopback, int cidx)
1738	{
1739	char name[32];
1740
1741	snprintf(buf: name, size: sizeof(name), fmt: "cable#%d", cidx);
1742	return snd_card_ro_proc_new(card: loopback->card, name, private_data: loopback,
1743	read: print_cable_info);
1744	}
1745
1746	static void loopback_set_timer_source(struct loopback *loopback,
1747	const char *value)
1748	{
1749	if (loopback->timer_source) {
1750	devm_kfree(dev: loopback->card->dev, p: loopback->timer_source);
1751	loopback->timer_source = NULL;
1752	}
1753	if (value && *value)
1754	loopback->timer_source = devm_kstrdup(dev: loopback->card->dev,
1755	s: value, GFP_KERNEL);
1756	}
1757
1758	static void print_timer_source_info(struct snd_info_entry *entry,
1759	struct snd_info_buffer *buffer)
1760	{
1761	struct loopback *loopback = entry->private_data;
1762
1763	mutex_lock(&loopback->cable_lock);
1764	snd_iprintf(buffer, "%s\n",
1765	loopback->timer_source ? loopback->timer_source : "");
1766	mutex_unlock(lock: &loopback->cable_lock);
1767	}
1768
1769	static void change_timer_source_info(struct snd_info_entry *entry,
1770	struct snd_info_buffer *buffer)
1771	{
1772	struct loopback *loopback = entry->private_data;
1773	char line[64];
1774
1775	mutex_lock(&loopback->cable_lock);
1776	if (!snd_info_get_line(buffer, line, len: sizeof(line)))
1777	loopback_set_timer_source(loopback, value: strim(line));
1778	mutex_unlock(lock: &loopback->cable_lock);
1779	}
1780
1781	static int loopback_timer_source_proc_new(struct loopback *loopback)
1782	{
1783	return snd_card_rw_proc_new(card: loopback->card, name: "timer_source", private_data: loopback,
1784	read: print_timer_source_info,
1785	write: change_timer_source_info);
1786	}
1787
1788	static int loopback_probe(struct platform_device *devptr)
1789	{
1790	struct snd_card *card;
1791	struct loopback *loopback;
1792	int dev = devptr->id;
1793	int err;
1794
1795	err = snd_devm_card_new(parent: &devptr->dev, idx: index[dev], xid: id[dev], THIS_MODULE,
1796	extra_size: sizeof(struct loopback), card_ret: &card);
1797	if (err < 0)
1798	return err;
1799	loopback = card->private_data;
1800
1801	if (pcm_substreams[dev] < 1)
1802	pcm_substreams[dev] = 1;
1803	if (pcm_substreams[dev] > MAX_PCM_SUBSTREAMS)
1804	pcm_substreams[dev] = MAX_PCM_SUBSTREAMS;
1805
1806	loopback->card = card;
1807	loopback_set_timer_source(loopback, value: timer_source[dev]);
1808
1809	mutex_init(&loopback->cable_lock);
1810
1811	err = loopback_pcm_new(loopback, device: 0, substreams: pcm_substreams[dev]);
1812	if (err < 0)
1813	return err;
1814	err = loopback_pcm_new(loopback, device: 1, substreams: pcm_substreams[dev]);
1815	if (err < 0)
1816	return err;
1817	err = loopback_mixer_new(loopback, notify: pcm_notify[dev] ? 1 : 0);
1818	if (err < 0)
1819	return err;
1820	loopback_cable_proc_new(loopback, cidx: 0);
1821	loopback_cable_proc_new(loopback, cidx: 1);
1822	loopback_timer_source_proc_new(loopback);
1823	strcpy(p: card->driver, q: "Loopback");
1824	strcpy(p: card->shortname, q: "Loopback");
1825	sprintf(buf: card->longname, fmt: "Loopback %i", dev + 1);
1826	err = snd_card_register(card);
1827	if (err < 0)
1828	return err;
1829	platform_set_drvdata(pdev: devptr, data: card);
1830	return 0;
1831	}
1832
1833	static int loopback_suspend(struct device *pdev)
1834	{
1835	struct snd_card *card = dev_get_drvdata(dev: pdev);
1836
1837	snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
1838	return 0;
1839	}
1840
1841	static int loopback_resume(struct device *pdev)
1842	{
1843	struct snd_card *card = dev_get_drvdata(dev: pdev);
1844
1845	snd_power_change_state(card, SNDRV_CTL_POWER_D0);
1846	return 0;
1847	}
1848
1849	static DEFINE_SIMPLE_DEV_PM_OPS(loopback_pm, loopback_suspend, loopback_resume);
1850
1851	#define SND_LOOPBACK_DRIVER "snd_aloop"
1852
1853	static struct platform_driver loopback_driver = {
1854	.probe = loopback_probe,
1855	.driver = {
1856	.name = SND_LOOPBACK_DRIVER,
1857	.pm = &loopback_pm,
1858	},
1859	};
1860
1861	static void loopback_unregister_all(void)
1862	{
1863	int i;
1864
1865	for (i = 0; i < ARRAY_SIZE(devices); ++i)
1866	platform_device_unregister(devices[i]);
1867	platform_driver_unregister(&loopback_driver);
1868	}
1869
1870	static int __init alsa_card_loopback_init(void)
1871	{
1872	int i, err, cards;
1873
1874	err = platform_driver_register(&loopback_driver);
1875	if (err < 0)
1876	return err;
1877
1878
1879	cards = 0;
1880	for (i = 0; i < SNDRV_CARDS; i++) {
1881	struct platform_device *device;
1882	if (!enable[i])
1883	continue;
1884	device = platform_device_register_simple(SND_LOOPBACK_DRIVER,
1885	id: i, NULL, num: 0);
1886	if (IS_ERR(ptr: device))
1887	continue;
1888	if (!platform_get_drvdata(pdev: device)) {
1889	platform_device_unregister(device);
1890	continue;
1891	}
1892	devices[i] = device;
1893	cards++;
1894	}
1895	if (!cards) {
1896	#ifdef MODULE
1897	printk(KERN_ERR "aloop: No loopback enabled\n");
1898	#endif
1899	loopback_unregister_all();
1900	return -ENODEV;
1901	}
1902	return 0;
1903	}
1904
1905	static void __exit alsa_card_loopback_exit(void)
1906	{
1907	loopback_unregister_all();
1908	}
1909
1910	module_init(alsa_card_loopback_init)
1911	module_exit(alsa_card_loopback_exit)
1912