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
  33MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
  34MODULE_DESCRIPTION("A loopback soundcard");
  35MODULE_LICENSE("GPL");
  36
  37#define MAX_PCM_SUBSTREAMS	8
  38
  39static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;	/* Index 0-MAX */
  40static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;	/* ID for this card */
  41static bool enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
  42static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
  43static int pcm_notify[SNDRV_CARDS];
  44static char *timer_source[SNDRV_CARDS];
  45
  46module_param_array(index, int, NULL, 0444);
  47MODULE_PARM_DESC(index, "Index value for loopback soundcard.");
  48module_param_array(id, charp, NULL, 0444);
  49MODULE_PARM_DESC(id, "ID string for loopback soundcard.");
  50module_param_array(enable, bool, NULL, 0444);
  51MODULE_PARM_DESC(enable, "Enable this loopback soundcard.");
  52module_param_array(pcm_substreams, int, NULL, 0444);
  53MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-8) for loopback driver.");
  54module_param_array(pcm_notify, int, NULL, 0444);
  55MODULE_PARM_DESC(pcm_notify, "Break capture when PCM format/rate/channels changes.");
  56module_param_array(timer_source, charp, NULL, 0444);
  57MODULE_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
  65struct loopback_cable;
  66struct loopback_pcm;
  67
  68struct 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
  98struct 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
 117struct loopback_setup {
 118	unsigned int notify: 1;
 119	unsigned int rate_shift;
 120	snd_pcm_format_t format;
 121	unsigned int rate;
 
 122	unsigned int channels;
 123	struct snd_ctl_elem_id active_id;
 124	struct snd_ctl_elem_id format_id;
 125	struct snd_ctl_elem_id rate_id;
 126	struct snd_ctl_elem_id channels_id;
 
 127};
 128
 129struct loopback {
 130	struct snd_card *card;
 131	struct mutex cable_lock;
 132	struct loopback_cable *cables[MAX_PCM_SUBSTREAMS][2];
 133	struct snd_pcm *pcm[2];
 134	struct loopback_setup setup[MAX_PCM_SUBSTREAMS][2];
 135	const char *timer_source;
 136};
 137
 138struct loopback_pcm {
 139	struct loopback *loopback;
 140	struct snd_pcm_substream *substream;
 141	struct loopback_cable *cable;
 142	unsigned int pcm_buffer_size;
 143	unsigned int buf_pos;	/* position in buffer */
 144	unsigned int silent_size;
 145	/* PCM parameters */
 146	unsigned int pcm_period_size;
 147	unsigned int pcm_bps;		/* bytes per second */
 148	unsigned int pcm_salign;	/* bytes per sample * channels */
 149	unsigned int pcm_rate_shift;	/* rate shift value */
 150	/* flags */
 151	unsigned int period_update_pending :1;
 152	/* timer stuff */
 153	unsigned int irq_pos;		/* fractional IRQ position in jiffies
 154					 * ticks
 155					 */
 156	unsigned int period_size_frac;	/* period size in jiffies ticks */
 157	unsigned int last_drift;
 158	unsigned long last_jiffies;
 159	/* If jiffies timer is used */
 160	struct timer_list timer;
 
 
 
 161};
 162
 163static struct platform_device *devices[SNDRV_CARDS];
 164
 165static inline unsigned int byte_pos(struct loopback_pcm *dpcm, unsigned int x)
 166{
 167	if (dpcm->pcm_rate_shift == NO_PITCH) {
 168		x /= HZ;
 169	} else {
 170		x = div_u64(NO_PITCH * (unsigned long long)x,
 171			    HZ * (unsigned long long)dpcm->pcm_rate_shift);
 172	}
 173	return x - (x % dpcm->pcm_salign);
 174}
 175
 176static inline unsigned int frac_pos(struct loopback_pcm *dpcm, unsigned int x)
 177{
 178	if (dpcm->pcm_rate_shift == NO_PITCH) {	/* no pitch */
 179		return x * HZ;
 180	} else {
 181		x = div_u64(dpcm->pcm_rate_shift * (unsigned long long)x * HZ,
 182			    NO_PITCH);
 183	}
 184	return x;
 185}
 186
 187static inline struct loopback_setup *get_setup(struct loopback_pcm *dpcm)
 188{
 189	int device = dpcm->substream->pstr->pcm->device;
 190	
 191	if (dpcm->substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 192		device ^= 1;
 193	return &dpcm->loopback->setup[dpcm->substream->number][device];
 194}
 195
 196static inline unsigned int get_notify(struct loopback_pcm *dpcm)
 197{
 198	return get_setup(dpcm)->notify;
 199}
 200
 201static inline unsigned int get_rate_shift(struct loopback_pcm *dpcm)
 202{
 203	return get_setup(dpcm)->rate_shift;
 204}
 205
 206/* call in cable->lock */
 207static int loopback_jiffies_timer_start(struct loopback_pcm *dpcm)
 208{
 209	unsigned long tick;
 210	unsigned int rate_shift = get_rate_shift(dpcm);
 211
 212	if (rate_shift != dpcm->pcm_rate_shift) {
 213		dpcm->pcm_rate_shift = rate_shift;
 214		dpcm->period_size_frac = frac_pos(dpcm, dpcm->pcm_period_size);
 215	}
 216	if (dpcm->period_size_frac <= dpcm->irq_pos) {
 217		dpcm->irq_pos %= dpcm->period_size_frac;
 218		dpcm->period_update_pending = 1;
 219	}
 220	tick = dpcm->period_size_frac - dpcm->irq_pos;
 221	tick = DIV_ROUND_UP(tick, dpcm->pcm_bps);
 222	mod_timer(&dpcm->timer, jiffies + tick);
 223
 224	return 0;
 225}
 226
 227/* call in cable->lock */
 228static int loopback_snd_timer_start(struct loopback_pcm *dpcm)
 229{
 230	struct loopback_cable *cable = dpcm->cable;
 231	int err;
 232
 233	/* Loopback device has to use same period as timer card. Therefore
 234	 * wake up for each snd_pcm_period_elapsed() call of timer card.
 235	 */
 236	err = snd_timer_start(cable->snd_timer.instance, 1);
 237	if (err < 0) {
 238		/* do not report error if trying to start but already
 239		 * running. For example called by opposite substream
 240		 * of the same cable
 241		 */
 242		if (err == -EBUSY)
 243			return 0;
 244
 245		pcm_err(dpcm->substream->pcm,
 246			"snd_timer_start(%d,%d,%d) failed with %d",
 247			cable->snd_timer.id.card,
 248			cable->snd_timer.id.device,
 249			cable->snd_timer.id.subdevice,
 250			err);
 251	}
 252
 253	return err;
 254}
 255
 256/* call in cable->lock */
 257static inline int loopback_jiffies_timer_stop(struct loopback_pcm *dpcm)
 258{
 259	del_timer(&dpcm->timer);
 260	dpcm->timer.expires = 0;
 261
 262	return 0;
 263}
 264
 265/* call in cable->lock */
 266static int loopback_snd_timer_stop(struct loopback_pcm *dpcm)
 267{
 268	struct loopback_cable *cable = dpcm->cable;
 269	int err;
 270
 271	/* only stop if both devices (playback and capture) are not running */
 272	if (cable->running ^ cable->pause)
 273		return 0;
 274
 275	err = snd_timer_stop(cable->snd_timer.instance);
 276	if (err < 0) {
 277		pcm_err(dpcm->substream->pcm,
 278			"snd_timer_stop(%d,%d,%d) failed with %d",
 279			cable->snd_timer.id.card,
 280			cable->snd_timer.id.device,
 281			cable->snd_timer.id.subdevice,
 282			err);
 283	}
 284
 285	return err;
 286}
 287
 288static inline int loopback_jiffies_timer_stop_sync(struct loopback_pcm *dpcm)
 289{
 290	del_timer_sync(&dpcm->timer);
 291
 292	return 0;
 293}
 294
 295/* call in loopback->cable_lock */
 296static int loopback_snd_timer_close_cable(struct loopback_pcm *dpcm)
 297{
 298	struct loopback_cable *cable = dpcm->cable;
 299
 300	/* snd_timer was not opened */
 301	if (!cable->snd_timer.instance)
 302		return 0;
 303
 304	/* will only be called from free_cable() when other stream was
 305	 * already closed. Other stream cannot be reopened as long as
 306	 * loopback->cable_lock is locked. Therefore no need to lock
 307	 * cable->lock;
 308	 */
 309	snd_timer_close(cable->snd_timer.instance);
 310
 311	/* wait till drain work has finished if requested */
 312	cancel_work_sync(&cable->snd_timer.event_work);
 313
 314	snd_timer_instance_free(cable->snd_timer.instance);
 315	memset(&cable->snd_timer, 0, sizeof(cable->snd_timer));
 316
 317	return 0;
 318}
 319
 
 
 
 
 
 
 
 
 
 
 
 320static int loopback_check_format(struct loopback_cable *cable, int stream)
 321{
 322	struct snd_pcm_runtime *runtime, *cruntime;
 323	struct loopback_setup *setup;
 324	struct snd_card *card;
 325	int check;
 326
 327	if (cable->valid != CABLE_VALID_BOTH) {
 328		if (stream == SNDRV_PCM_STREAM_PLAYBACK)
 329			goto __notify;
 330		return 0;
 331	}
 332	runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->
 333							substream->runtime;
 334	cruntime = cable->streams[SNDRV_PCM_STREAM_CAPTURE]->
 335							substream->runtime;
 336	check = runtime->format != cruntime->format ||
 337		runtime->rate != cruntime->rate ||
 338		runtime->channels != cruntime->channels;
 
 
 339	if (!check)
 340		return 0;
 341	if (stream == SNDRV_PCM_STREAM_CAPTURE) {
 342		return -EIO;
 343	} else {
 344		snd_pcm_stop(cable->streams[SNDRV_PCM_STREAM_CAPTURE]->
 345					substream, SNDRV_PCM_STATE_DRAINING);
 346	      __notify:
 347		runtime = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->
 348							substream->runtime;
 349		setup = get_setup(cable->streams[SNDRV_PCM_STREAM_PLAYBACK]);
 350		card = cable->streams[SNDRV_PCM_STREAM_PLAYBACK]->loopback->card;
 351		if (setup->format != runtime->format) {
 352			snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
 353							&setup->format_id);
 354			setup->format = runtime->format;
 355		}
 356		if (setup->rate != runtime->rate) {
 357			snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
 358							&setup->rate_id);
 359			setup->rate = runtime->rate;
 360		}
 361		if (setup->channels != runtime->channels) {
 362			snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
 363							&setup->channels_id);
 364			setup->channels = runtime->channels;
 365		}
 
 
 
 
 
 
 366	}
 367	return 0;
 368}
 369
 370static void loopback_active_notify(struct loopback_pcm *dpcm)
 371{
 372	snd_ctl_notify(dpcm->loopback->card,
 373		       SNDRV_CTL_EVENT_MASK_VALUE,
 374		       &get_setup(dpcm)->active_id);
 375}
 376
 377static int loopback_trigger(struct snd_pcm_substream *substream, int cmd)
 378{
 379	struct snd_pcm_runtime *runtime = substream->runtime;
 380	struct loopback_pcm *dpcm = runtime->private_data;
 381	struct loopback_cable *cable = dpcm->cable;
 382	int err = 0, stream = 1 << substream->stream;
 383
 384	switch (cmd) {
 385	case SNDRV_PCM_TRIGGER_START:
 386		err = loopback_check_format(cable, substream->stream);
 387		if (err < 0)
 388			return err;
 389		dpcm->last_jiffies = jiffies;
 390		dpcm->pcm_rate_shift = 0;
 391		dpcm->last_drift = 0;
 392		spin_lock(&cable->lock);	
 393		cable->running |= stream;
 394		cable->pause &= ~stream;
 395		err = cable->ops->start(dpcm);
 396		spin_unlock(&cable->lock);
 397		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 398			loopback_active_notify(dpcm);
 399		break;
 400	case SNDRV_PCM_TRIGGER_STOP:
 401		spin_lock(&cable->lock);	
 402		cable->running &= ~stream;
 403		cable->pause &= ~stream;
 404		err = cable->ops->stop(dpcm);
 405		spin_unlock(&cable->lock);
 406		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 407			loopback_active_notify(dpcm);
 408		break;
 409	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
 410	case SNDRV_PCM_TRIGGER_SUSPEND:
 411		spin_lock(&cable->lock);	
 412		cable->pause |= stream;
 413		err = cable->ops->stop(dpcm);
 414		spin_unlock(&cable->lock);
 415		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 416			loopback_active_notify(dpcm);
 417		break;
 418	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
 419	case SNDRV_PCM_TRIGGER_RESUME:
 420		spin_lock(&cable->lock);
 421		dpcm->last_jiffies = jiffies;
 422		cable->pause &= ~stream;
 423		err = cable->ops->start(dpcm);
 424		spin_unlock(&cable->lock);
 425		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 426			loopback_active_notify(dpcm);
 427		break;
 428	default:
 429		return -EINVAL;
 430	}
 431	return err;
 432}
 433
 434static void params_change(struct snd_pcm_substream *substream)
 435{
 436	struct snd_pcm_runtime *runtime = substream->runtime;
 437	struct loopback_pcm *dpcm = runtime->private_data;
 438	struct loopback_cable *cable = dpcm->cable;
 439
 440	cable->hw.formats = pcm_format_to_bits(runtime->format);
 441	cable->hw.rate_min = runtime->rate;
 442	cable->hw.rate_max = runtime->rate;
 443	cable->hw.channels_min = runtime->channels;
 444	cable->hw.channels_max = runtime->channels;
 445
 446	if (cable->snd_timer.instance) {
 447		cable->hw.period_bytes_min =
 448				frames_to_bytes(runtime, runtime->period_size);
 449		cable->hw.period_bytes_max = cable->hw.period_bytes_min;
 450	}
 451
 452}
 453
 454static int loopback_prepare(struct snd_pcm_substream *substream)
 455{
 456	struct snd_pcm_runtime *runtime = substream->runtime;
 457	struct loopback_pcm *dpcm = runtime->private_data;
 458	struct loopback_cable *cable = dpcm->cable;
 459	int err, bps, salign;
 460
 461	if (cable->ops->stop_sync) {
 462		err = cable->ops->stop_sync(dpcm);
 463		if (err < 0)
 464			return err;
 465	}
 466
 467	salign = (snd_pcm_format_physical_width(runtime->format) *
 468						runtime->channels) / 8;
 469	bps = salign * runtime->rate;
 470	if (bps <= 0 || salign <= 0)
 471		return -EINVAL;
 472
 473	dpcm->buf_pos = 0;
 474	dpcm->pcm_buffer_size = frames_to_bytes(runtime, runtime->buffer_size);
 
 475	if (substream->stream == SNDRV_PCM_STREAM_CAPTURE) {
 476		/* clear capture buffer */
 477		dpcm->silent_size = dpcm->pcm_buffer_size;
 478		snd_pcm_format_set_silence(runtime->format, runtime->dma_area,
 479					   runtime->buffer_size * runtime->channels);
 480	}
 481
 482	dpcm->irq_pos = 0;
 483	dpcm->period_update_pending = 0;
 484	dpcm->pcm_bps = bps;
 485	dpcm->pcm_salign = salign;
 486	dpcm->pcm_period_size = frames_to_bytes(runtime, runtime->period_size);
 487
 488	mutex_lock(&dpcm->loopback->cable_lock);
 489	if (!(cable->valid & ~(1 << substream->stream)) ||
 490            (get_setup(dpcm)->notify &&
 491	     substream->stream == SNDRV_PCM_STREAM_PLAYBACK))
 492		params_change(substream);
 493	cable->valid |= 1 << substream->stream;
 494	mutex_unlock(&dpcm->loopback->cable_lock);
 495
 496	return 0;
 497}
 498
 499static void clear_capture_buf(struct loopback_pcm *dpcm, unsigned int bytes)
 500{
 501	struct snd_pcm_runtime *runtime = dpcm->substream->runtime;
 502	char *dst = runtime->dma_area;
 503	unsigned int dst_off = dpcm->buf_pos;
 504
 505	if (dpcm->silent_size >= dpcm->pcm_buffer_size)
 506		return;
 507	if (dpcm->silent_size + bytes > dpcm->pcm_buffer_size)
 508		bytes = dpcm->pcm_buffer_size - dpcm->silent_size;
 509
 510	for (;;) {
 511		unsigned int size = bytes;
 512		if (dst_off + size > dpcm->pcm_buffer_size)
 513			size = dpcm->pcm_buffer_size - dst_off;
 514		snd_pcm_format_set_silence(runtime->format, dst + dst_off,
 515					   bytes_to_frames(runtime, size) *
 516					   	runtime->channels);
 517		dpcm->silent_size += size;
 518		bytes -= size;
 519		if (!bytes)
 520			break;
 521		dst_off = 0;
 522	}
 523}
 524
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 525static void copy_play_buf(struct loopback_pcm *play,
 526			  struct loopback_pcm *capt,
 527			  unsigned int bytes)
 528{
 529	struct snd_pcm_runtime *runtime = play->substream->runtime;
 530	char *src = runtime->dma_area;
 531	char *dst = capt->substream->runtime->dma_area;
 532	unsigned int src_off = play->buf_pos;
 533	unsigned int dst_off = capt->buf_pos;
 534	unsigned int clear_bytes = 0;
 535
 536	/* check if playback is draining, trim the capture copy size
 537	 * when our pointer is at the end of playback ring buffer */
 538	if (runtime->status->state == SNDRV_PCM_STATE_DRAINING &&
 539	    snd_pcm_playback_hw_avail(runtime) < runtime->buffer_size) { 
 540	    	snd_pcm_uframes_t appl_ptr, appl_ptr1, diff;
 541		appl_ptr = appl_ptr1 = runtime->control->appl_ptr;
 542		appl_ptr1 -= appl_ptr1 % runtime->buffer_size;
 543		appl_ptr1 += play->buf_pos / play->pcm_salign;
 544		if (appl_ptr < appl_ptr1)
 545			appl_ptr1 -= runtime->buffer_size;
 546		diff = (appl_ptr - appl_ptr1) * play->pcm_salign;
 547		if (diff < bytes) {
 548			clear_bytes = bytes - diff;
 549			bytes = diff;
 550		}
 551	}
 552
 553	for (;;) {
 554		unsigned int size = bytes;
 555		if (src_off + size > play->pcm_buffer_size)
 556			size = play->pcm_buffer_size - src_off;
 557		if (dst_off + size > capt->pcm_buffer_size)
 558			size = capt->pcm_buffer_size - dst_off;
 559		memcpy(dst + dst_off, src + src_off, size);
 
 
 
 560		capt->silent_size = 0;
 561		bytes -= size;
 562		if (!bytes)
 563			break;
 564		src_off = (src_off + size) % play->pcm_buffer_size;
 565		dst_off = (dst_off + size) % capt->pcm_buffer_size;
 566	}
 567
 568	if (clear_bytes > 0) {
 569		clear_capture_buf(capt, clear_bytes);
 570		capt->silent_size = 0;
 571	}
 572}
 573
 574static inline unsigned int bytepos_delta(struct loopback_pcm *dpcm,
 575					 unsigned int jiffies_delta)
 576{
 577	unsigned long last_pos;
 578	unsigned int delta;
 579
 580	last_pos = byte_pos(dpcm, dpcm->irq_pos);
 581	dpcm->irq_pos += jiffies_delta * dpcm->pcm_bps;
 582	delta = byte_pos(dpcm, dpcm->irq_pos) - last_pos;
 583	if (delta >= dpcm->last_drift)
 584		delta -= dpcm->last_drift;
 585	dpcm->last_drift = 0;
 586	if (dpcm->irq_pos >= dpcm->period_size_frac) {
 587		dpcm->irq_pos %= dpcm->period_size_frac;
 588		dpcm->period_update_pending = 1;
 589	}
 590	return delta;
 591}
 592
 593static inline void bytepos_finish(struct loopback_pcm *dpcm,
 594				  unsigned int delta)
 595{
 596	dpcm->buf_pos += delta;
 597	dpcm->buf_pos %= dpcm->pcm_buffer_size;
 598}
 599
 600/* call in cable->lock */
 601static unsigned int loopback_jiffies_timer_pos_update
 602		(struct loopback_cable *cable)
 603{
 604	struct loopback_pcm *dpcm_play =
 605			cable->streams[SNDRV_PCM_STREAM_PLAYBACK];
 606	struct loopback_pcm *dpcm_capt =
 607			cable->streams[SNDRV_PCM_STREAM_CAPTURE];
 608	unsigned long delta_play = 0, delta_capt = 0;
 609	unsigned int running, count1, count2;
 610
 
 611	running = cable->running ^ cable->pause;
 612	if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {
 613		delta_play = jiffies - dpcm_play->last_jiffies;
 614		dpcm_play->last_jiffies += delta_play;
 615	}
 616
 617	if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {
 618		delta_capt = jiffies - dpcm_capt->last_jiffies;
 619		dpcm_capt->last_jiffies += delta_capt;
 620	}
 621
 622	if (delta_play == 0 && delta_capt == 0)
 623		goto unlock;
 624		
 625	if (delta_play > delta_capt) {
 626		count1 = bytepos_delta(dpcm_play, delta_play - delta_capt);
 627		bytepos_finish(dpcm_play, count1);
 628		delta_play = delta_capt;
 629	} else if (delta_play < delta_capt) {
 630		count1 = bytepos_delta(dpcm_capt, delta_capt - delta_play);
 631		clear_capture_buf(dpcm_capt, count1);
 632		bytepos_finish(dpcm_capt, count1);
 633		delta_capt = delta_play;
 634	}
 635
 636	if (delta_play == 0 && delta_capt == 0)
 637		goto unlock;
 638
 639	/* note delta_capt == delta_play at this moment */
 640	count1 = bytepos_delta(dpcm_play, delta_play);
 641	count2 = bytepos_delta(dpcm_capt, delta_capt);
 642	if (count1 < count2) {
 643		dpcm_capt->last_drift = count2 - count1;
 644		count1 = count2;
 645	} else if (count1 > count2) {
 646		dpcm_play->last_drift = count1 - count2;
 647	}
 648	copy_play_buf(dpcm_play, dpcm_capt, count1);
 649	bytepos_finish(dpcm_play, count1);
 650	bytepos_finish(dpcm_capt, count1);
 651 unlock:
 652	return running;
 653}
 654
 655static void loopback_jiffies_timer_function(struct timer_list *t)
 656{
 657	struct loopback_pcm *dpcm = from_timer(dpcm, t, timer);
 658	unsigned long flags;
 659
 660	spin_lock_irqsave(&dpcm->cable->lock, flags);
 661	if (loopback_jiffies_timer_pos_update(dpcm->cable) &
 662			(1 << dpcm->substream->stream)) {
 663		loopback_jiffies_timer_start(dpcm);
 664		if (dpcm->period_update_pending) {
 665			dpcm->period_update_pending = 0;
 666			spin_unlock_irqrestore(&dpcm->cable->lock, flags);
 667			/* need to unlock before calling below */
 668			snd_pcm_period_elapsed(dpcm->substream);
 669			return;
 670		}
 671	}
 672	spin_unlock_irqrestore(&dpcm->cable->lock, flags);
 673}
 674
 675/* call in cable->lock */
 676static int loopback_snd_timer_check_resolution(struct snd_pcm_runtime *runtime,
 677					       unsigned long resolution)
 678{
 679	if (resolution != runtime->timer_resolution) {
 680		struct loopback_pcm *dpcm = runtime->private_data;
 681		struct loopback_cable *cable = dpcm->cable;
 682		/* Worst case estimation of possible values for resolution
 683		 * resolution <= (512 * 1024) frames / 8kHz in nsec
 684		 * resolution <= 65.536.000.000 nsec
 685		 *
 686		 * period_size <= 65.536.000.000 nsec / 1000nsec/usec * 192kHz +
 687		 *  500.000
 688		 * period_size <= 12.582.912.000.000  <64bit
 689		 *  / 1.000.000 usec/sec
 690		 */
 691		snd_pcm_uframes_t period_size_usec =
 692				resolution / 1000 * runtime->rate;
 693		/* round to nearest sample rate */
 694		snd_pcm_uframes_t period_size =
 695				(period_size_usec + 500 * 1000) / (1000 * 1000);
 696
 697		pcm_err(dpcm->substream->pcm,
 698			"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.",
 699			runtime->period_size, resolution, period_size,
 700			cable->snd_timer.id.card,
 701			cable->snd_timer.id.device,
 702			cable->snd_timer.id.subdevice,
 703			period_size);
 704		return -EINVAL;
 705	}
 706	return 0;
 707}
 708
 709static void loopback_snd_timer_period_elapsed(struct loopback_cable *cable,
 710					      int event,
 711					      unsigned long resolution)
 712{
 713	struct loopback_pcm *dpcm_play, *dpcm_capt;
 714	struct snd_pcm_substream *substream_play, *substream_capt;
 715	struct snd_pcm_runtime *valid_runtime;
 716	unsigned int running, elapsed_bytes;
 717	unsigned long flags;
 718
 719	spin_lock_irqsave(&cable->lock, flags);
 720	running = cable->running ^ cable->pause;
 721	/* no need to do anything if no stream is running */
 722	if (!running) {
 723		spin_unlock_irqrestore(&cable->lock, flags);
 724		return;
 725	}
 726
 727	dpcm_play = cable->streams[SNDRV_PCM_STREAM_PLAYBACK];
 728	dpcm_capt = cable->streams[SNDRV_PCM_STREAM_CAPTURE];
 729
 730	if (event == SNDRV_TIMER_EVENT_MSTOP) {
 731		if (!dpcm_play ||
 732		    dpcm_play->substream->runtime->status->state !=
 733				SNDRV_PCM_STATE_DRAINING) {
 734			spin_unlock_irqrestore(&cable->lock, flags);
 735			return;
 736		}
 737	}
 738
 739	substream_play = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?
 740			dpcm_play->substream : NULL;
 741	substream_capt = (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) ?
 742			dpcm_capt->substream : NULL;
 743	valid_runtime = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ?
 744				dpcm_play->substream->runtime :
 745				dpcm_capt->substream->runtime;
 746
 747	/* resolution is only valid for SNDRV_TIMER_EVENT_TICK events */
 748	if (event == SNDRV_TIMER_EVENT_TICK) {
 749		/* The hardware rules guarantee that playback and capture period
 750		 * are the same. Therefore only one device has to be checked
 751		 * here.
 752		 */
 753		if (loopback_snd_timer_check_resolution(valid_runtime,
 754							resolution) < 0) {
 755			spin_unlock_irqrestore(&cable->lock, flags);
 756			if (substream_play)
 757				snd_pcm_stop_xrun(substream_play);
 758			if (substream_capt)
 759				snd_pcm_stop_xrun(substream_capt);
 760			return;
 761		}
 762	}
 763
 764	elapsed_bytes = frames_to_bytes(valid_runtime,
 765					valid_runtime->period_size);
 766	/* The same timer interrupt is used for playback and capture device */
 767	if ((running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) &&
 768	    (running & (1 << SNDRV_PCM_STREAM_CAPTURE))) {
 769		copy_play_buf(dpcm_play, dpcm_capt, elapsed_bytes);
 770		bytepos_finish(dpcm_play, elapsed_bytes);
 771		bytepos_finish(dpcm_capt, elapsed_bytes);
 772	} else if (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) {
 773		bytepos_finish(dpcm_play, elapsed_bytes);
 774	} else if (running & (1 << SNDRV_PCM_STREAM_CAPTURE)) {
 775		clear_capture_buf(dpcm_capt, elapsed_bytes);
 776		bytepos_finish(dpcm_capt, elapsed_bytes);
 777	}
 778	spin_unlock_irqrestore(&cable->lock, flags);
 779
 780	if (substream_play)
 781		snd_pcm_period_elapsed(substream_play);
 782	if (substream_capt)
 783		snd_pcm_period_elapsed(substream_capt);
 784}
 785
 786static void loopback_snd_timer_function(struct snd_timer_instance *timeri,
 787					unsigned long resolution,
 788					unsigned long ticks)
 789{
 790	struct loopback_cable *cable = timeri->callback_data;
 791
 792	loopback_snd_timer_period_elapsed(cable, SNDRV_TIMER_EVENT_TICK,
 793					  resolution);
 794}
 795
 796static void loopback_snd_timer_work(struct work_struct *work)
 797{
 798	struct loopback_cable *cable;
 799
 800	cable = container_of(work, struct loopback_cable, snd_timer.event_work);
 801	loopback_snd_timer_period_elapsed(cable, SNDRV_TIMER_EVENT_MSTOP, 0);
 802}
 803
 804static void loopback_snd_timer_event(struct snd_timer_instance *timeri,
 805				     int event,
 806				     struct timespec64 *tstamp,
 807				     unsigned long resolution)
 808{
 809	/* Do not lock cable->lock here because timer->lock is already hold.
 810	 * There are other functions which first lock cable->lock and than
 811	 * timer->lock e.g.
 812	 * loopback_trigger()
 813	 * spin_lock(&cable->lock)
 814	 * loopback_snd_timer_start()
 815	 * snd_timer_start()
 816	 * spin_lock(&timer->lock)
 817	 * Therefore when using the oposit order of locks here it could result
 818	 * in a deadlock.
 819	 */
 820
 821	if (event == SNDRV_TIMER_EVENT_MSTOP) {
 822		struct loopback_cable *cable = timeri->callback_data;
 823
 824		/* sound card of the timer was stopped. Therefore there will not
 825		 * be any further timer callbacks. Due to this forward audio
 826		 * data from here if in draining state. When still in running
 827		 * state the streaming will be aborted by the usual timeout. It
 828		 * should not be aborted here because may be the timer sound
 829		 * card does only a recovery and the timer is back soon.
 830		 * This work triggers loopback_snd_timer_work()
 831		 */
 832		schedule_work(&cable->snd_timer.event_work);
 833	}
 834}
 835
 836static void loopback_jiffies_timer_dpcm_info(struct loopback_pcm *dpcm,
 837					     struct snd_info_buffer *buffer)
 838{
 839	snd_iprintf(buffer, "    update_pending:\t%u\n",
 840		    dpcm->period_update_pending);
 841	snd_iprintf(buffer, "    irq_pos:\t\t%u\n", dpcm->irq_pos);
 842	snd_iprintf(buffer, "    period_frac:\t%u\n", dpcm->period_size_frac);
 843	snd_iprintf(buffer, "    last_jiffies:\t%lu (%lu)\n",
 844		    dpcm->last_jiffies, jiffies);
 845	snd_iprintf(buffer, "    timer_expires:\t%lu\n", dpcm->timer.expires);
 846}
 847
 848static void loopback_snd_timer_dpcm_info(struct loopback_pcm *dpcm,
 849					 struct snd_info_buffer *buffer)
 850{
 851	struct loopback_cable *cable = dpcm->cable;
 852
 853	snd_iprintf(buffer, "    sound timer:\thw:%d,%d,%d\n",
 854		    cable->snd_timer.id.card,
 855		    cable->snd_timer.id.device,
 856		    cable->snd_timer.id.subdevice);
 857	snd_iprintf(buffer, "    timer open:\t\t%s\n",
 858		    (cable->snd_timer.stream == SNDRV_PCM_STREAM_CAPTURE) ?
 859			    "capture" : "playback");
 860}
 861
 862static snd_pcm_uframes_t loopback_pointer(struct snd_pcm_substream *substream)
 863{
 864	struct snd_pcm_runtime *runtime = substream->runtime;
 865	struct loopback_pcm *dpcm = runtime->private_data;
 866	snd_pcm_uframes_t pos;
 867
 868	spin_lock(&dpcm->cable->lock);
 869	if (dpcm->cable->ops->pos_update)
 870		dpcm->cable->ops->pos_update(dpcm->cable);
 871	pos = dpcm->buf_pos;
 872	spin_unlock(&dpcm->cable->lock);
 873	return bytes_to_frames(runtime, pos);
 874}
 875
 876static const struct snd_pcm_hardware loopback_pcm_hardware =
 877{
 878	.info =		(SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_MMAP |
 879			 SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_PAUSE |
 880			 SNDRV_PCM_INFO_RESUME),
 881	.formats =	(SNDRV_PCM_FMTBIT_S16_LE | SNDRV_PCM_FMTBIT_S16_BE |
 882			 SNDRV_PCM_FMTBIT_S24_LE | SNDRV_PCM_FMTBIT_S24_BE |
 883			 SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S24_3BE |
 884			 SNDRV_PCM_FMTBIT_S32_LE | SNDRV_PCM_FMTBIT_S32_BE |
 885			 SNDRV_PCM_FMTBIT_FLOAT_LE | SNDRV_PCM_FMTBIT_FLOAT_BE),
 886	.rates =	SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_192000,
 887	.rate_min =		8000,
 888	.rate_max =		192000,
 889	.channels_min =		1,
 890	.channels_max =		32,
 891	.buffer_bytes_max =	2 * 1024 * 1024,
 892	.period_bytes_min =	64,
 893	/* note check overflow in frac_pos() using pcm_rate_shift before
 894	   changing period_bytes_max value */
 895	.period_bytes_max =	1024 * 1024,
 896	.periods_min =		1,
 897	.periods_max =		1024,
 898	.fifo_size =		0,
 899};
 900
 901static void loopback_runtime_free(struct snd_pcm_runtime *runtime)
 902{
 903	struct loopback_pcm *dpcm = runtime->private_data;
 904	kfree(dpcm);
 905}
 906
 907static int loopback_hw_free(struct snd_pcm_substream *substream)
 908{
 909	struct snd_pcm_runtime *runtime = substream->runtime;
 910	struct loopback_pcm *dpcm = runtime->private_data;
 911	struct loopback_cable *cable = dpcm->cable;
 912
 913	mutex_lock(&dpcm->loopback->cable_lock);
 914	cable->valid &= ~(1 << substream->stream);
 915	mutex_unlock(&dpcm->loopback->cable_lock);
 916	return 0;
 917}
 918
 919static unsigned int get_cable_index(struct snd_pcm_substream *substream)
 920{
 921	if (!substream->pcm->device)
 922		return substream->stream;
 923	else
 924		return !substream->stream;
 925}
 926
 927static int rule_format(struct snd_pcm_hw_params *params,
 928		       struct snd_pcm_hw_rule *rule)
 929{
 930	struct loopback_pcm *dpcm = rule->private;
 931	struct loopback_cable *cable = dpcm->cable;
 932	struct snd_mask m;
 933
 934	snd_mask_none(&m);
 935	mutex_lock(&dpcm->loopback->cable_lock);
 936	m.bits[0] = (u_int32_t)cable->hw.formats;
 937	m.bits[1] = (u_int32_t)(cable->hw.formats >> 32);
 938	mutex_unlock(&dpcm->loopback->cable_lock);
 939	return snd_mask_refine(hw_param_mask(params, rule->var), &m);
 940}
 941
 942static int rule_rate(struct snd_pcm_hw_params *params,
 943		     struct snd_pcm_hw_rule *rule)
 944{
 945	struct loopback_pcm *dpcm = rule->private;
 946	struct loopback_cable *cable = dpcm->cable;
 947	struct snd_interval t;
 948
 949	mutex_lock(&dpcm->loopback->cable_lock);
 950	t.min = cable->hw.rate_min;
 951	t.max = cable->hw.rate_max;
 952	mutex_unlock(&dpcm->loopback->cable_lock);
 953        t.openmin = t.openmax = 0;
 954        t.integer = 0;
 955	return snd_interval_refine(hw_param_interval(params, rule->var), &t);
 956}
 957
 958static int rule_channels(struct snd_pcm_hw_params *params,
 959			 struct snd_pcm_hw_rule *rule)
 960{
 961	struct loopback_pcm *dpcm = rule->private;
 962	struct loopback_cable *cable = dpcm->cable;
 963	struct snd_interval t;
 964
 965	mutex_lock(&dpcm->loopback->cable_lock);
 966	t.min = cable->hw.channels_min;
 967	t.max = cable->hw.channels_max;
 968	mutex_unlock(&dpcm->loopback->cable_lock);
 969        t.openmin = t.openmax = 0;
 970        t.integer = 0;
 971	return snd_interval_refine(hw_param_interval(params, rule->var), &t);
 972}
 973
 974static int rule_period_bytes(struct snd_pcm_hw_params *params,
 975			     struct snd_pcm_hw_rule *rule)
 976{
 977	struct loopback_pcm *dpcm = rule->private;
 978	struct loopback_cable *cable = dpcm->cable;
 979	struct snd_interval t;
 980
 981	mutex_lock(&dpcm->loopback->cable_lock);
 982	t.min = cable->hw.period_bytes_min;
 983	t.max = cable->hw.period_bytes_max;
 984	mutex_unlock(&dpcm->loopback->cable_lock);
 985	t.openmin = 0;
 986	t.openmax = 0;
 987	t.integer = 0;
 988	return snd_interval_refine(hw_param_interval(params, rule->var), &t);
 989}
 990
 991static void free_cable(struct snd_pcm_substream *substream)
 992{
 993	struct loopback *loopback = substream->private_data;
 994	int dev = get_cable_index(substream);
 995	struct loopback_cable *cable;
 996
 997	cable = loopback->cables[substream->number][dev];
 998	if (!cable)
 999		return;
1000	if (cable->streams[!substream->stream]) {
1001		/* other stream is still alive */
1002		spin_lock_irq(&cable->lock);
1003		cable->streams[substream->stream] = NULL;
1004		spin_unlock_irq(&cable->lock);
1005	} else {
1006		struct loopback_pcm *dpcm = substream->runtime->private_data;
1007
1008		if (cable->ops && cable->ops->close_cable && dpcm)
1009			cable->ops->close_cable(dpcm);
1010		/* free the cable */
1011		loopback->cables[substream->number][dev] = NULL;
1012		kfree(cable);
1013	}
1014}
1015
1016static int loopback_jiffies_timer_open(struct loopback_pcm *dpcm)
1017{
1018	timer_setup(&dpcm->timer, loopback_jiffies_timer_function, 0);
1019
1020	return 0;
1021}
1022
1023static const struct loopback_ops loopback_jiffies_timer_ops = {
1024	.open = loopback_jiffies_timer_open,
1025	.start = loopback_jiffies_timer_start,
1026	.stop = loopback_jiffies_timer_stop,
1027	.stop_sync = loopback_jiffies_timer_stop_sync,
1028	.close_substream = loopback_jiffies_timer_stop_sync,
1029	.pos_update = loopback_jiffies_timer_pos_update,
1030	.dpcm_info = loopback_jiffies_timer_dpcm_info,
1031};
1032
1033static int loopback_parse_timer_id(const char *str,
1034				   struct snd_timer_id *tid)
1035{
1036	/* [<pref>:](<card name>|<card idx>)[{.,}<dev idx>[{.,}<subdev idx>]] */
1037	const char * const sep_dev = ".,";
1038	const char * const sep_pref = ":";
1039	const char *name = str;
1040	char *sep, save = '\0';
1041	int card_idx = 0, dev = 0, subdev = 0;
1042	int err;
1043
1044	sep = strpbrk(str, sep_pref);
1045	if (sep)
1046		name = sep + 1;
1047	sep = strpbrk(name, sep_dev);
1048	if (sep) {
1049		save = *sep;
1050		*sep = '\0';
1051	}
1052	err = kstrtoint(name, 0, &card_idx);
1053	if (err == -EINVAL) {
1054		/* Must be the name, not number */
1055		for (card_idx = 0; card_idx < snd_ecards_limit; card_idx++) {
1056			struct snd_card *card = snd_card_ref(card_idx);
1057
1058			if (card) {
1059				if (!strcmp(card->id, name))
1060					err = 0;
1061				snd_card_unref(card);
1062			}
1063			if (!err)
1064				break;
1065		}
1066	}
1067	if (sep) {
1068		*sep = save;
1069		if (!err) {
1070			char *sep2, save2 = '\0';
1071
1072			sep2 = strpbrk(sep + 1, sep_dev);
1073			if (sep2) {
1074				save2 = *sep2;
1075				*sep2 = '\0';
1076			}
1077			err = kstrtoint(sep + 1, 0, &dev);
1078			if (sep2) {
1079				*sep2 = save2;
1080				if (!err)
1081					err = kstrtoint(sep2 + 1, 0, &subdev);
1082			}
1083		}
1084	}
1085	if (!err && tid) {
1086		tid->card = card_idx;
1087		tid->device = dev;
1088		tid->subdevice = subdev;
1089	}
1090	return err;
1091}
1092
1093/* call in loopback->cable_lock */
1094static int loopback_snd_timer_open(struct loopback_pcm *dpcm)
1095{
1096	int err = 0;
1097	struct snd_timer_id tid = {
1098		.dev_class = SNDRV_TIMER_CLASS_PCM,
1099		.dev_sclass = SNDRV_TIMER_SCLASS_APPLICATION,
1100	};
1101	struct snd_timer_instance *timeri;
1102	struct loopback_cable *cable = dpcm->cable;
1103
1104	/* check if timer was already opened. It is only opened once
1105	 * per playback and capture subdevice (aka cable).
1106	 */
1107	if (cable->snd_timer.instance)
1108		goto exit;
1109
1110	err = loopback_parse_timer_id(dpcm->loopback->timer_source, &tid);
1111	if (err < 0) {
1112		pcm_err(dpcm->substream->pcm,
1113			"Parsing timer source \'%s\' failed with %d",
1114			dpcm->loopback->timer_source, err);
1115		goto exit;
1116	}
1117
1118	cable->snd_timer.stream = dpcm->substream->stream;
1119	cable->snd_timer.id = tid;
1120
1121	timeri = snd_timer_instance_new(dpcm->loopback->card->id);
1122	if (!timeri) {
1123		err = -ENOMEM;
1124		goto exit;
1125	}
1126	/* The callback has to be called from another work. If
1127	 * SNDRV_TIMER_IFLG_FAST is specified it will be called from the
1128	 * snd_pcm_period_elapsed() call of the selected sound card.
1129	 * snd_pcm_period_elapsed() helds snd_pcm_stream_lock_irqsave().
1130	 * Due to our callback loopback_snd_timer_function() also calls
1131	 * snd_pcm_period_elapsed() which calls snd_pcm_stream_lock_irqsave().
1132	 * This would end up in a dead lock.
1133	 */
1134	timeri->flags |= SNDRV_TIMER_IFLG_AUTO;
1135	timeri->callback = loopback_snd_timer_function;
1136	timeri->callback_data = (void *)cable;
1137	timeri->ccallback = loopback_snd_timer_event;
1138
1139	/* initialise a work used for draining */
1140	INIT_WORK(&cable->snd_timer.event_work, loopback_snd_timer_work);
1141
1142	/* The mutex loopback->cable_lock is kept locked.
1143	 * Therefore snd_timer_open() cannot be called a second time
1144	 * by the other device of the same cable.
1145	 * Therefore the following issue cannot happen:
1146	 * [proc1] Call loopback_timer_open() ->
1147	 *	   Unlock cable->lock for snd_timer_close/open() call
1148	 * [proc2] Call loopback_timer_open() -> snd_timer_open(),
1149	 *	   snd_timer_start()
1150	 * [proc1] Call snd_timer_open() and overwrite running timer
1151	 *	   instance
1152	 */
1153	err = snd_timer_open(timeri, &cable->snd_timer.id, current->pid);
1154	if (err < 0) {
1155		pcm_err(dpcm->substream->pcm,
1156			"snd_timer_open (%d,%d,%d) failed with %d",
1157			cable->snd_timer.id.card,
1158			cable->snd_timer.id.device,
1159			cable->snd_timer.id.subdevice,
1160			err);
1161		snd_timer_instance_free(timeri);
1162		goto exit;
1163	}
1164
1165	cable->snd_timer.instance = timeri;
1166
1167exit:
1168	return err;
1169}
1170
1171/* stop_sync() is not required for sound timer because it does not need to be
1172 * restarted in loopback_prepare() on Xrun recovery
1173 */
1174static const struct loopback_ops loopback_snd_timer_ops = {
1175	.open = loopback_snd_timer_open,
1176	.start = loopback_snd_timer_start,
1177	.stop = loopback_snd_timer_stop,
1178	.close_cable = loopback_snd_timer_close_cable,
1179	.dpcm_info = loopback_snd_timer_dpcm_info,
1180};
1181
1182static int loopback_open(struct snd_pcm_substream *substream)
1183{
1184	struct snd_pcm_runtime *runtime = substream->runtime;
1185	struct loopback *loopback = substream->private_data;
1186	struct loopback_pcm *dpcm;
1187	struct loopback_cable *cable = NULL;
1188	int err = 0;
1189	int dev = get_cable_index(substream);
1190
1191	mutex_lock(&loopback->cable_lock);
1192	dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
1193	if (!dpcm) {
1194		err = -ENOMEM;
1195		goto unlock;
1196	}
1197	dpcm->loopback = loopback;
1198	dpcm->substream = substream;
1199
1200	cable = loopback->cables[substream->number][dev];
1201	if (!cable) {
1202		cable = kzalloc(sizeof(*cable), GFP_KERNEL);
1203		if (!cable) {
1204			err = -ENOMEM;
1205			goto unlock;
1206		}
1207		spin_lock_init(&cable->lock);
1208		cable->hw = loopback_pcm_hardware;
1209		if (loopback->timer_source)
1210			cable->ops = &loopback_snd_timer_ops;
1211		else
1212			cable->ops = &loopback_jiffies_timer_ops;
1213		loopback->cables[substream->number][dev] = cable;
1214	}
1215	dpcm->cable = cable;
1216	runtime->private_data = dpcm;
1217
1218	if (cable->ops->open) {
1219		err = cable->ops->open(dpcm);
1220		if (err < 0)
1221			goto unlock;
1222	}
1223
1224	snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
1225
1226	/* use dynamic rules based on actual runtime->hw values */
1227	/* note that the default rules created in the PCM midlevel code */
1228	/* are cached -> they do not reflect the actual state */
1229	err = snd_pcm_hw_rule_add(runtime, 0,
1230				  SNDRV_PCM_HW_PARAM_FORMAT,
1231				  rule_format, dpcm,
1232				  SNDRV_PCM_HW_PARAM_FORMAT, -1);
1233	if (err < 0)
1234		goto unlock;
1235	err = snd_pcm_hw_rule_add(runtime, 0,
1236				  SNDRV_PCM_HW_PARAM_RATE,
1237				  rule_rate, dpcm,
1238				  SNDRV_PCM_HW_PARAM_RATE, -1);
1239	if (err < 0)
1240		goto unlock;
1241	err = snd_pcm_hw_rule_add(runtime, 0,
1242				  SNDRV_PCM_HW_PARAM_CHANNELS,
1243				  rule_channels, dpcm,
1244				  SNDRV_PCM_HW_PARAM_CHANNELS, -1);
1245	if (err < 0)
1246		goto unlock;
1247
1248	/* In case of sound timer the period time of both devices of the same
1249	 * loop has to be the same.
1250	 * This rule only takes effect if a sound timer was chosen
1251	 */
1252	if (cable->snd_timer.instance) {
1253		err = snd_pcm_hw_rule_add(runtime, 0,
1254					  SNDRV_PCM_HW_PARAM_PERIOD_BYTES,
1255					  rule_period_bytes, dpcm,
1256					  SNDRV_PCM_HW_PARAM_PERIOD_BYTES, -1);
1257		if (err < 0)
1258			goto unlock;
1259	}
1260
1261	/* loopback_runtime_free() has not to be called if kfree(dpcm) was
1262	 * already called here. Otherwise it will end up with a double free.
1263	 */
1264	runtime->private_free = loopback_runtime_free;
1265	if (get_notify(dpcm))
1266		runtime->hw = loopback_pcm_hardware;
1267	else
1268		runtime->hw = cable->hw;
1269
1270	spin_lock_irq(&cable->lock);
1271	cable->streams[substream->stream] = dpcm;
1272	spin_unlock_irq(&cable->lock);
1273
1274 unlock:
1275	if (err < 0) {
1276		free_cable(substream);
1277		kfree(dpcm);
1278	}
1279	mutex_unlock(&loopback->cable_lock);
1280	return err;
1281}
1282
1283static int loopback_close(struct snd_pcm_substream *substream)
1284{
1285	struct loopback *loopback = substream->private_data;
1286	struct loopback_pcm *dpcm = substream->runtime->private_data;
1287	int err = 0;
1288
1289	if (dpcm->cable->ops->close_substream)
1290		err = dpcm->cable->ops->close_substream(dpcm);
1291	mutex_lock(&loopback->cable_lock);
1292	free_cable(substream);
1293	mutex_unlock(&loopback->cable_lock);
1294	return err;
1295}
1296
1297static const struct snd_pcm_ops loopback_pcm_ops = {
1298	.open =		loopback_open,
1299	.close =	loopback_close,
1300	.hw_free =	loopback_hw_free,
1301	.prepare =	loopback_prepare,
1302	.trigger =	loopback_trigger,
1303	.pointer =	loopback_pointer,
1304};
1305
1306static int loopback_pcm_new(struct loopback *loopback,
1307			    int device, int substreams)
1308{
1309	struct snd_pcm *pcm;
1310	int err;
1311
1312	err = snd_pcm_new(loopback->card, "Loopback PCM", device,
1313			  substreams, substreams, &pcm);
1314	if (err < 0)
1315		return err;
1316	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &loopback_pcm_ops);
1317	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &loopback_pcm_ops);
1318	snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, 0, 0);
1319
1320	pcm->private_data = loopback;
1321	pcm->info_flags = 0;
1322	strcpy(pcm->name, "Loopback PCM");
1323
1324	loopback->pcm[device] = pcm;
1325	return 0;
1326}
1327
1328static int loopback_rate_shift_info(struct snd_kcontrol *kcontrol,   
1329				    struct snd_ctl_elem_info *uinfo) 
1330{
1331	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1332	uinfo->count = 1;
1333	uinfo->value.integer.min = 80000;
1334	uinfo->value.integer.max = 120000;
1335	uinfo->value.integer.step = 1;
1336	return 0;
1337}                                  
1338
1339static int loopback_rate_shift_get(struct snd_kcontrol *kcontrol,
1340				   struct snd_ctl_elem_value *ucontrol)
1341{
1342	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1343	
1344	mutex_lock(&loopback->cable_lock);
1345	ucontrol->value.integer.value[0] =
1346		loopback->setup[kcontrol->id.subdevice]
1347			       [kcontrol->id.device].rate_shift;
1348	mutex_unlock(&loopback->cable_lock);
1349	return 0;
1350}
1351
1352static int loopback_rate_shift_put(struct snd_kcontrol *kcontrol,
1353				   struct snd_ctl_elem_value *ucontrol)
1354{
1355	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1356	unsigned int val;
1357	int change = 0;
1358
1359	val = ucontrol->value.integer.value[0];
1360	if (val < 80000)
1361		val = 80000;
1362	if (val > 120000)
1363		val = 120000;	
1364	mutex_lock(&loopback->cable_lock);
1365	if (val != loopback->setup[kcontrol->id.subdevice]
1366				  [kcontrol->id.device].rate_shift) {
1367		loopback->setup[kcontrol->id.subdevice]
1368			       [kcontrol->id.device].rate_shift = val;
1369		change = 1;
1370	}
1371	mutex_unlock(&loopback->cable_lock);
1372	return change;
1373}
1374
1375static int loopback_notify_get(struct snd_kcontrol *kcontrol,
1376			       struct snd_ctl_elem_value *ucontrol)
1377{
1378	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1379	
1380	mutex_lock(&loopback->cable_lock);
1381	ucontrol->value.integer.value[0] =
1382		loopback->setup[kcontrol->id.subdevice]
1383			       [kcontrol->id.device].notify;
1384	mutex_unlock(&loopback->cable_lock);
1385	return 0;
1386}
1387
1388static int loopback_notify_put(struct snd_kcontrol *kcontrol,
1389			       struct snd_ctl_elem_value *ucontrol)
1390{
1391	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1392	unsigned int val;
1393	int change = 0;
1394
1395	val = ucontrol->value.integer.value[0] ? 1 : 0;
1396	mutex_lock(&loopback->cable_lock);
1397	if (val != loopback->setup[kcontrol->id.subdevice]
1398				[kcontrol->id.device].notify) {
1399		loopback->setup[kcontrol->id.subdevice]
1400			[kcontrol->id.device].notify = val;
1401		change = 1;
1402	}
1403	mutex_unlock(&loopback->cable_lock);
1404	return change;
1405}
1406
1407static int loopback_active_get(struct snd_kcontrol *kcontrol,
1408			       struct snd_ctl_elem_value *ucontrol)
1409{
1410	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1411	struct loopback_cable *cable;
1412
1413	unsigned int val = 0;
1414
1415	mutex_lock(&loopback->cable_lock);
1416	cable = loopback->cables[kcontrol->id.subdevice][kcontrol->id.device ^ 1];
1417	if (cable != NULL) {
1418		unsigned int running = cable->running ^ cable->pause;
1419
1420		val = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ? 1 : 0;
1421	}
1422	mutex_unlock(&loopback->cable_lock);
1423	ucontrol->value.integer.value[0] = val;
1424	return 0;
1425}
1426
1427static int loopback_format_info(struct snd_kcontrol *kcontrol,   
1428				struct snd_ctl_elem_info *uinfo) 
1429{
1430	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1431	uinfo->count = 1;
1432	uinfo->value.integer.min = 0;
1433	uinfo->value.integer.max = (__force int)SNDRV_PCM_FORMAT_LAST;
1434	uinfo->value.integer.step = 1;
1435	return 0;
1436}                                  
1437
1438static int loopback_format_get(struct snd_kcontrol *kcontrol,
1439			       struct snd_ctl_elem_value *ucontrol)
1440{
1441	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1442	
1443	ucontrol->value.integer.value[0] =
1444		(__force int)loopback->setup[kcontrol->id.subdevice]
1445			       [kcontrol->id.device].format;
1446	return 0;
1447}
1448
1449static int loopback_rate_info(struct snd_kcontrol *kcontrol,   
1450			      struct snd_ctl_elem_info *uinfo) 
1451{
1452	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1453	uinfo->count = 1;
1454	uinfo->value.integer.min = 0;
1455	uinfo->value.integer.max = 192000;
1456	uinfo->value.integer.step = 1;
1457	return 0;
1458}                                  
1459
1460static int loopback_rate_get(struct snd_kcontrol *kcontrol,
1461			     struct snd_ctl_elem_value *ucontrol)
1462{
1463	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1464	
1465	mutex_lock(&loopback->cable_lock);
1466	ucontrol->value.integer.value[0] =
1467		loopback->setup[kcontrol->id.subdevice]
1468			       [kcontrol->id.device].rate;
1469	mutex_unlock(&loopback->cable_lock);
1470	return 0;
1471}
1472
1473static int loopback_channels_info(struct snd_kcontrol *kcontrol,   
1474				  struct snd_ctl_elem_info *uinfo) 
1475{
1476	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
1477	uinfo->count = 1;
1478	uinfo->value.integer.min = 1;
1479	uinfo->value.integer.max = 1024;
1480	uinfo->value.integer.step = 1;
1481	return 0;
1482}                                  
1483
1484static int loopback_channels_get(struct snd_kcontrol *kcontrol,
1485				 struct snd_ctl_elem_value *ucontrol)
1486{
1487	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
1488	
1489	mutex_lock(&loopback->cable_lock);
1490	ucontrol->value.integer.value[0] =
1491		loopback->setup[kcontrol->id.subdevice]
1492			       [kcontrol->id.device].channels;
1493	mutex_unlock(&loopback->cable_lock);
1494	return 0;
1495}
1496
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1497static const struct snd_kcontrol_new loopback_controls[]  = {
1498{
1499	.iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1500	.name =         "PCM Rate Shift 100000",
1501	.info =         loopback_rate_shift_info,
1502	.get =          loopback_rate_shift_get,
1503	.put =          loopback_rate_shift_put,
1504},
1505{
1506	.iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1507	.name =         "PCM Notify",
1508	.info =         snd_ctl_boolean_mono_info,
1509	.get =          loopback_notify_get,
1510	.put =          loopback_notify_put,
1511},
1512#define ACTIVE_IDX 2
1513{
1514	.access =	SNDRV_CTL_ELEM_ACCESS_READ,
1515	.iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1516	.name =         "PCM Slave Active",
1517	.info =         snd_ctl_boolean_mono_info,
1518	.get =          loopback_active_get,
1519},
1520#define FORMAT_IDX 3
1521{
1522	.access =	SNDRV_CTL_ELEM_ACCESS_READ,
1523	.iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1524	.name =         "PCM Slave Format",
1525	.info =         loopback_format_info,
1526	.get =          loopback_format_get
1527},
1528#define RATE_IDX 4
1529{
1530	.access =	SNDRV_CTL_ELEM_ACCESS_READ,
1531	.iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1532	.name =         "PCM Slave Rate",
1533	.info =         loopback_rate_info,
1534	.get =          loopback_rate_get
1535},
1536#define CHANNELS_IDX 5
1537{
1538	.access =	SNDRV_CTL_ELEM_ACCESS_READ,
1539	.iface =        SNDRV_CTL_ELEM_IFACE_PCM,
1540	.name =         "PCM Slave Channels",
1541	.info =         loopback_channels_info,
1542	.get =          loopback_channels_get
1543}
 
 
 
 
 
 
 
 
1544};
1545
1546static int loopback_mixer_new(struct loopback *loopback, int notify)
1547{
1548	struct snd_card *card = loopback->card;
1549	struct snd_pcm *pcm;
1550	struct snd_kcontrol *kctl;
1551	struct loopback_setup *setup;
1552	int err, dev, substr, substr_count, idx;
1553
1554	strcpy(card->mixername, "Loopback Mixer");
1555	for (dev = 0; dev < 2; dev++) {
1556		pcm = loopback->pcm[dev];
1557		substr_count =
1558		    pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream_count;
1559		for (substr = 0; substr < substr_count; substr++) {
1560			setup = &loopback->setup[substr][dev];
1561			setup->notify = notify;
1562			setup->rate_shift = NO_PITCH;
1563			setup->format = SNDRV_PCM_FORMAT_S16_LE;
 
1564			setup->rate = 48000;
1565			setup->channels = 2;
1566			for (idx = 0; idx < ARRAY_SIZE(loopback_controls);
1567									idx++) {
1568				kctl = snd_ctl_new1(&loopback_controls[idx],
1569						    loopback);
1570				if (!kctl)
1571					return -ENOMEM;
1572				kctl->id.device = dev;
1573				kctl->id.subdevice = substr;
1574
1575				/* Add the control before copying the id so that
1576				 * the numid field of the id is set in the copy.
1577				 */
1578				err = snd_ctl_add(card, kctl);
1579				if (err < 0)
1580					return err;
1581
1582				switch (idx) {
1583				case ACTIVE_IDX:
1584					setup->active_id = kctl->id;
1585					break;
1586				case FORMAT_IDX:
1587					setup->format_id = kctl->id;
1588					break;
1589				case RATE_IDX:
1590					setup->rate_id = kctl->id;
1591					break;
1592				case CHANNELS_IDX:
1593					setup->channels_id = kctl->id;
1594					break;
 
 
 
1595				default:
1596					break;
1597				}
1598			}
1599		}
1600	}
1601	return 0;
1602}
1603
1604static void print_dpcm_info(struct snd_info_buffer *buffer,
1605			    struct loopback_pcm *dpcm,
1606			    const char *id)
1607{
1608	snd_iprintf(buffer, "  %s\n", id);
1609	if (dpcm == NULL) {
1610		snd_iprintf(buffer, "    inactive\n");
1611		return;
1612	}
1613	snd_iprintf(buffer, "    buffer_size:\t%u\n", dpcm->pcm_buffer_size);
1614	snd_iprintf(buffer, "    buffer_pos:\t\t%u\n", dpcm->buf_pos);
1615	snd_iprintf(buffer, "    silent_size:\t%u\n", dpcm->silent_size);
1616	snd_iprintf(buffer, "    period_size:\t%u\n", dpcm->pcm_period_size);
1617	snd_iprintf(buffer, "    bytes_per_sec:\t%u\n", dpcm->pcm_bps);
1618	snd_iprintf(buffer, "    sample_align:\t%u\n", dpcm->pcm_salign);
1619	snd_iprintf(buffer, "    rate_shift:\t\t%u\n", dpcm->pcm_rate_shift);
1620	if (dpcm->cable->ops->dpcm_info)
1621		dpcm->cable->ops->dpcm_info(dpcm, buffer);
1622}
1623
1624static void print_substream_info(struct snd_info_buffer *buffer,
1625				 struct loopback *loopback,
1626				 int sub,
1627				 int num)
1628{
1629	struct loopback_cable *cable = loopback->cables[sub][num];
1630
1631	snd_iprintf(buffer, "Cable %i substream %i:\n", num, sub);
1632	if (cable == NULL) {
1633		snd_iprintf(buffer, "  inactive\n");
1634		return;
1635	}
1636	snd_iprintf(buffer, "  valid: %u\n", cable->valid);
1637	snd_iprintf(buffer, "  running: %u\n", cable->running);
1638	snd_iprintf(buffer, "  pause: %u\n", cable->pause);
1639	print_dpcm_info(buffer, cable->streams[0], "Playback");
1640	print_dpcm_info(buffer, cable->streams[1], "Capture");
1641}
1642
1643static void print_cable_info(struct snd_info_entry *entry,
1644			     struct snd_info_buffer *buffer)
1645{
1646	struct loopback *loopback = entry->private_data;
1647	int sub, num;
1648
1649	mutex_lock(&loopback->cable_lock);
1650	num = entry->name[strlen(entry->name)-1];
1651	num = num == '0' ? 0 : 1;
1652	for (sub = 0; sub < MAX_PCM_SUBSTREAMS; sub++)
1653		print_substream_info(buffer, loopback, sub, num);
1654	mutex_unlock(&loopback->cable_lock);
1655}
1656
1657static int loopback_cable_proc_new(struct loopback *loopback, int cidx)
1658{
1659	char name[32];
1660
1661	snprintf(name, sizeof(name), "cable#%d", cidx);
1662	return snd_card_ro_proc_new(loopback->card, name, loopback,
1663				    print_cable_info);
1664}
1665
1666static void loopback_set_timer_source(struct loopback *loopback,
1667				      const char *value)
1668{
1669	if (loopback->timer_source) {
1670		devm_kfree(loopback->card->dev, loopback->timer_source);
1671		loopback->timer_source = NULL;
1672	}
1673	if (value && *value)
1674		loopback->timer_source = devm_kstrdup(loopback->card->dev,
1675						      value, GFP_KERNEL);
1676}
1677
1678static void print_timer_source_info(struct snd_info_entry *entry,
1679				    struct snd_info_buffer *buffer)
1680{
1681	struct loopback *loopback = entry->private_data;
1682
1683	mutex_lock(&loopback->cable_lock);
1684	snd_iprintf(buffer, "%s\n",
1685		    loopback->timer_source ? loopback->timer_source : "");
1686	mutex_unlock(&loopback->cable_lock);
1687}
1688
1689static void change_timer_source_info(struct snd_info_entry *entry,
1690				     struct snd_info_buffer *buffer)
1691{
1692	struct loopback *loopback = entry->private_data;
1693	char line[64];
1694
1695	mutex_lock(&loopback->cable_lock);
1696	if (!snd_info_get_line(buffer, line, sizeof(line)))
1697		loopback_set_timer_source(loopback, strim(line));
1698	mutex_unlock(&loopback->cable_lock);
1699}
1700
1701static int loopback_timer_source_proc_new(struct loopback *loopback)
1702{
1703	return snd_card_rw_proc_new(loopback->card, "timer_source", loopback,
1704				    print_timer_source_info,
1705				    change_timer_source_info);
1706}
1707
1708static int loopback_probe(struct platform_device *devptr)
1709{
1710	struct snd_card *card;
1711	struct loopback *loopback;
1712	int dev = devptr->id;
1713	int err;
1714
1715	err = snd_card_new(&devptr->dev, index[dev], id[dev], THIS_MODULE,
1716			   sizeof(struct loopback), &card);
1717	if (err < 0)
1718		return err;
1719	loopback = card->private_data;
1720
1721	if (pcm_substreams[dev] < 1)
1722		pcm_substreams[dev] = 1;
1723	if (pcm_substreams[dev] > MAX_PCM_SUBSTREAMS)
1724		pcm_substreams[dev] = MAX_PCM_SUBSTREAMS;
1725	
1726	loopback->card = card;
1727	loopback_set_timer_source(loopback, timer_source[dev]);
1728
1729	mutex_init(&loopback->cable_lock);
1730
1731	err = loopback_pcm_new(loopback, 0, pcm_substreams[dev]);
1732	if (err < 0)
1733		goto __nodev;
1734	err = loopback_pcm_new(loopback, 1, pcm_substreams[dev]);
1735	if (err < 0)
1736		goto __nodev;
1737	err = loopback_mixer_new(loopback, pcm_notify[dev] ? 1 : 0);
1738	if (err < 0)
1739		goto __nodev;
1740	loopback_cable_proc_new(loopback, 0);
1741	loopback_cable_proc_new(loopback, 1);
1742	loopback_timer_source_proc_new(loopback);
1743	strcpy(card->driver, "Loopback");
1744	strcpy(card->shortname, "Loopback");
1745	sprintf(card->longname, "Loopback %i", dev + 1);
1746	err = snd_card_register(card);
1747	if (!err) {
1748		platform_set_drvdata(devptr, card);
1749		return 0;
1750	}
1751      __nodev:
1752	snd_card_free(card);
1753	return err;
1754}
1755
1756static int loopback_remove(struct platform_device *devptr)
1757{
1758	snd_card_free(platform_get_drvdata(devptr));
1759	return 0;
1760}
1761
1762#ifdef CONFIG_PM_SLEEP
1763static int loopback_suspend(struct device *pdev)
1764{
1765	struct snd_card *card = dev_get_drvdata(pdev);
1766
1767	snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
1768	return 0;
1769}
1770	
1771static int loopback_resume(struct device *pdev)
1772{
1773	struct snd_card *card = dev_get_drvdata(pdev);
1774
1775	snd_power_change_state(card, SNDRV_CTL_POWER_D0);
1776	return 0;
1777}
1778
1779static SIMPLE_DEV_PM_OPS(loopback_pm, loopback_suspend, loopback_resume);
1780#define LOOPBACK_PM_OPS	&loopback_pm
1781#else
1782#define LOOPBACK_PM_OPS	NULL
1783#endif
1784
1785#define SND_LOOPBACK_DRIVER	"snd_aloop"
1786
1787static struct platform_driver loopback_driver = {
1788	.probe		= loopback_probe,
1789	.remove		= loopback_remove,
1790	.driver		= {
1791		.name	= SND_LOOPBACK_DRIVER,
1792		.pm	= LOOPBACK_PM_OPS,
1793	},
1794};
1795
1796static void loopback_unregister_all(void)
1797{
1798	int i;
1799
1800	for (i = 0; i < ARRAY_SIZE(devices); ++i)
1801		platform_device_unregister(devices[i]);
1802	platform_driver_unregister(&loopback_driver);
1803}
1804
1805static int __init alsa_card_loopback_init(void)
1806{
1807	int i, err, cards;
1808
1809	err = platform_driver_register(&loopback_driver);
1810	if (err < 0)
1811		return err;
1812
1813
1814	cards = 0;
1815	for (i = 0; i < SNDRV_CARDS; i++) {
1816		struct platform_device *device;
1817		if (!enable[i])
1818			continue;
1819		device = platform_device_register_simple(SND_LOOPBACK_DRIVER,
1820							 i, NULL, 0);
1821		if (IS_ERR(device))
1822			continue;
1823		if (!platform_get_drvdata(device)) {
1824			platform_device_unregister(device);
1825			continue;
1826		}
1827		devices[i] = device;
1828		cards++;
1829	}
1830	if (!cards) {
1831#ifdef MODULE
1832		printk(KERN_ERR "aloop: No loopback enabled\n");
1833#endif
1834		loopback_unregister_all();
1835		return -ENODEV;
1836	}
1837	return 0;
1838}
1839
1840static void __exit alsa_card_loopback_exit(void)
1841{
1842	loopback_unregister_all();
1843}
1844
1845module_init(alsa_card_loopback_init)
1846module_exit(alsa_card_loopback_exit)