xref: /linux/sound/drivers/dummy.c (revision 8a79db5e83a5d52c74e6f3c40d6f312cf899213e)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Dummy soundcard
4  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
5  */
6 
7 #include <linux/init.h>
8 #include <linux/err.h>
9 #include <linux/platform_device.h>
10 #include <linux/jiffies.h>
11 #include <linux/slab.h>
12 #include <linux/time.h>
13 #include <linux/wait.h>
14 #include <linux/hrtimer.h>
15 #include <linux/math64.h>
16 #include <linux/module.h>
17 #include <sound/core.h>
18 #include <sound/control.h>
19 #include <sound/tlv.h>
20 #include <sound/pcm.h>
21 #include <sound/rawmidi.h>
22 #include <sound/info.h>
23 #include <sound/initval.h>
24 
25 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
26 MODULE_DESCRIPTION("Dummy soundcard (/dev/null)");
27 MODULE_LICENSE("GPL");
28 MODULE_SUPPORTED_DEVICE("{{ALSA,Dummy soundcard}}");
29 
30 #define MAX_PCM_DEVICES		4
31 #define MAX_PCM_SUBSTREAMS	128
32 #define MAX_MIDI_DEVICES	2
33 
34 /* defaults */
35 #define MAX_BUFFER_SIZE		(64*1024)
36 #define MIN_PERIOD_SIZE		64
37 #define MAX_PERIOD_SIZE		MAX_BUFFER_SIZE
38 #define USE_FORMATS 		(SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S16_LE)
39 #define USE_RATE		SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_48000
40 #define USE_RATE_MIN		5500
41 #define USE_RATE_MAX		48000
42 #define USE_CHANNELS_MIN 	1
43 #define USE_CHANNELS_MAX 	2
44 #define USE_PERIODS_MIN 	1
45 #define USE_PERIODS_MAX 	1024
46 
47 static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;	/* Index 0-MAX */
48 static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;	/* ID for this card */
49 static bool enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
50 static char *model[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = NULL};
51 static int pcm_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};
52 static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
53 //static int midi_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 2};
54 #ifdef CONFIG_HIGH_RES_TIMERS
55 static bool hrtimer = 1;
56 #endif
57 static bool fake_buffer = 1;
58 
59 module_param_array(index, int, NULL, 0444);
60 MODULE_PARM_DESC(index, "Index value for dummy soundcard.");
61 module_param_array(id, charp, NULL, 0444);
62 MODULE_PARM_DESC(id, "ID string for dummy soundcard.");
63 module_param_array(enable, bool, NULL, 0444);
64 MODULE_PARM_DESC(enable, "Enable this dummy soundcard.");
65 module_param_array(model, charp, NULL, 0444);
66 MODULE_PARM_DESC(model, "Soundcard model.");
67 module_param_array(pcm_devs, int, NULL, 0444);
68 MODULE_PARM_DESC(pcm_devs, "PCM devices # (0-4) for dummy driver.");
69 module_param_array(pcm_substreams, int, NULL, 0444);
70 MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-128) for dummy driver.");
71 //module_param_array(midi_devs, int, NULL, 0444);
72 //MODULE_PARM_DESC(midi_devs, "MIDI devices # (0-2) for dummy driver.");
73 module_param(fake_buffer, bool, 0444);
74 MODULE_PARM_DESC(fake_buffer, "Fake buffer allocations.");
75 #ifdef CONFIG_HIGH_RES_TIMERS
76 module_param(hrtimer, bool, 0644);
77 MODULE_PARM_DESC(hrtimer, "Use hrtimer as the timer source.");
78 #endif
79 
80 static struct platform_device *devices[SNDRV_CARDS];
81 
82 #define MIXER_ADDR_MASTER	0
83 #define MIXER_ADDR_LINE		1
84 #define MIXER_ADDR_MIC		2
85 #define MIXER_ADDR_SYNTH	3
86 #define MIXER_ADDR_CD		4
87 #define MIXER_ADDR_LAST		4
88 
89 struct dummy_timer_ops {
90 	int (*create)(struct snd_pcm_substream *);
91 	void (*free)(struct snd_pcm_substream *);
92 	int (*prepare)(struct snd_pcm_substream *);
93 	int (*start)(struct snd_pcm_substream *);
94 	int (*stop)(struct snd_pcm_substream *);
95 	snd_pcm_uframes_t (*pointer)(struct snd_pcm_substream *);
96 };
97 
98 #define get_dummy_ops(substream) \
99 	(*(const struct dummy_timer_ops **)(substream)->runtime->private_data)
100 
101 struct dummy_model {
102 	const char *name;
103 	int (*playback_constraints)(struct snd_pcm_runtime *runtime);
104 	int (*capture_constraints)(struct snd_pcm_runtime *runtime);
105 	u64 formats;
106 	size_t buffer_bytes_max;
107 	size_t period_bytes_min;
108 	size_t period_bytes_max;
109 	unsigned int periods_min;
110 	unsigned int periods_max;
111 	unsigned int rates;
112 	unsigned int rate_min;
113 	unsigned int rate_max;
114 	unsigned int channels_min;
115 	unsigned int channels_max;
116 };
117 
118 struct snd_dummy {
119 	struct snd_card *card;
120 	struct dummy_model *model;
121 	struct snd_pcm *pcm;
122 	struct snd_pcm_hardware pcm_hw;
123 	spinlock_t mixer_lock;
124 	int mixer_volume[MIXER_ADDR_LAST+1][2];
125 	int capture_source[MIXER_ADDR_LAST+1][2];
126 	int iobox;
127 	struct snd_kcontrol *cd_volume_ctl;
128 	struct snd_kcontrol *cd_switch_ctl;
129 };
130 
131 /*
132  * card models
133  */
134 
135 static int emu10k1_playback_constraints(struct snd_pcm_runtime *runtime)
136 {
137 	int err;
138 	err = snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
139 	if (err < 0)
140 		return err;
141 	err = snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_BUFFER_BYTES, 256, UINT_MAX);
142 	if (err < 0)
143 		return err;
144 	return 0;
145 }
146 
147 static struct dummy_model model_emu10k1 = {
148 	.name = "emu10k1",
149 	.playback_constraints = emu10k1_playback_constraints,
150 	.buffer_bytes_max = 128 * 1024,
151 };
152 
153 static struct dummy_model model_rme9652 = {
154 	.name = "rme9652",
155 	.buffer_bytes_max = 26 * 64 * 1024,
156 	.formats = SNDRV_PCM_FMTBIT_S32_LE,
157 	.channels_min = 26,
158 	.channels_max = 26,
159 	.periods_min = 2,
160 	.periods_max = 2,
161 };
162 
163 static struct dummy_model model_ice1712 = {
164 	.name = "ice1712",
165 	.buffer_bytes_max = 256 * 1024,
166 	.formats = SNDRV_PCM_FMTBIT_S32_LE,
167 	.channels_min = 10,
168 	.channels_max = 10,
169 	.periods_min = 1,
170 	.periods_max = 1024,
171 };
172 
173 static struct dummy_model model_uda1341 = {
174 	.name = "uda1341",
175 	.buffer_bytes_max = 16380,
176 	.formats = SNDRV_PCM_FMTBIT_S16_LE,
177 	.channels_min = 2,
178 	.channels_max = 2,
179 	.periods_min = 2,
180 	.periods_max = 255,
181 };
182 
183 static struct dummy_model model_ac97 = {
184 	.name = "ac97",
185 	.formats = SNDRV_PCM_FMTBIT_S16_LE,
186 	.channels_min = 2,
187 	.channels_max = 2,
188 	.rates = SNDRV_PCM_RATE_48000,
189 	.rate_min = 48000,
190 	.rate_max = 48000,
191 };
192 
193 static struct dummy_model model_ca0106 = {
194 	.name = "ca0106",
195 	.formats = SNDRV_PCM_FMTBIT_S16_LE,
196 	.buffer_bytes_max = ((65536-64)*8),
197 	.period_bytes_max = (65536-64),
198 	.periods_min = 2,
199 	.periods_max = 8,
200 	.channels_min = 2,
201 	.channels_max = 2,
202 	.rates = SNDRV_PCM_RATE_48000|SNDRV_PCM_RATE_96000|SNDRV_PCM_RATE_192000,
203 	.rate_min = 48000,
204 	.rate_max = 192000,
205 };
206 
207 static struct dummy_model *dummy_models[] = {
208 	&model_emu10k1,
209 	&model_rme9652,
210 	&model_ice1712,
211 	&model_uda1341,
212 	&model_ac97,
213 	&model_ca0106,
214 	NULL
215 };
216 
217 /*
218  * system timer interface
219  */
220 
221 struct dummy_systimer_pcm {
222 	/* ops must be the first item */
223 	const struct dummy_timer_ops *timer_ops;
224 	spinlock_t lock;
225 	struct timer_list timer;
226 	unsigned long base_time;
227 	unsigned int frac_pos;	/* fractional sample position (based HZ) */
228 	unsigned int frac_period_rest;
229 	unsigned int frac_buffer_size;	/* buffer_size * HZ */
230 	unsigned int frac_period_size;	/* period_size * HZ */
231 	unsigned int rate;
232 	int elapsed;
233 	struct snd_pcm_substream *substream;
234 };
235 
236 static void dummy_systimer_rearm(struct dummy_systimer_pcm *dpcm)
237 {
238 	mod_timer(&dpcm->timer, jiffies +
239 		(dpcm->frac_period_rest + dpcm->rate - 1) / dpcm->rate);
240 }
241 
242 static void dummy_systimer_update(struct dummy_systimer_pcm *dpcm)
243 {
244 	unsigned long delta;
245 
246 	delta = jiffies - dpcm->base_time;
247 	if (!delta)
248 		return;
249 	dpcm->base_time += delta;
250 	delta *= dpcm->rate;
251 	dpcm->frac_pos += delta;
252 	while (dpcm->frac_pos >= dpcm->frac_buffer_size)
253 		dpcm->frac_pos -= dpcm->frac_buffer_size;
254 	while (dpcm->frac_period_rest <= delta) {
255 		dpcm->elapsed++;
256 		dpcm->frac_period_rest += dpcm->frac_period_size;
257 	}
258 	dpcm->frac_period_rest -= delta;
259 }
260 
261 static int dummy_systimer_start(struct snd_pcm_substream *substream)
262 {
263 	struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
264 	spin_lock(&dpcm->lock);
265 	dpcm->base_time = jiffies;
266 	dummy_systimer_rearm(dpcm);
267 	spin_unlock(&dpcm->lock);
268 	return 0;
269 }
270 
271 static int dummy_systimer_stop(struct snd_pcm_substream *substream)
272 {
273 	struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
274 	spin_lock(&dpcm->lock);
275 	del_timer(&dpcm->timer);
276 	spin_unlock(&dpcm->lock);
277 	return 0;
278 }
279 
280 static int dummy_systimer_prepare(struct snd_pcm_substream *substream)
281 {
282 	struct snd_pcm_runtime *runtime = substream->runtime;
283 	struct dummy_systimer_pcm *dpcm = runtime->private_data;
284 
285 	dpcm->frac_pos = 0;
286 	dpcm->rate = runtime->rate;
287 	dpcm->frac_buffer_size = runtime->buffer_size * HZ;
288 	dpcm->frac_period_size = runtime->period_size * HZ;
289 	dpcm->frac_period_rest = dpcm->frac_period_size;
290 	dpcm->elapsed = 0;
291 
292 	return 0;
293 }
294 
295 static void dummy_systimer_callback(struct timer_list *t)
296 {
297 	struct dummy_systimer_pcm *dpcm = from_timer(dpcm, t, timer);
298 	unsigned long flags;
299 	int elapsed = 0;
300 
301 	spin_lock_irqsave(&dpcm->lock, flags);
302 	dummy_systimer_update(dpcm);
303 	dummy_systimer_rearm(dpcm);
304 	elapsed = dpcm->elapsed;
305 	dpcm->elapsed = 0;
306 	spin_unlock_irqrestore(&dpcm->lock, flags);
307 	if (elapsed)
308 		snd_pcm_period_elapsed(dpcm->substream);
309 }
310 
311 static snd_pcm_uframes_t
312 dummy_systimer_pointer(struct snd_pcm_substream *substream)
313 {
314 	struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
315 	snd_pcm_uframes_t pos;
316 
317 	spin_lock(&dpcm->lock);
318 	dummy_systimer_update(dpcm);
319 	pos = dpcm->frac_pos / HZ;
320 	spin_unlock(&dpcm->lock);
321 	return pos;
322 }
323 
324 static int dummy_systimer_create(struct snd_pcm_substream *substream)
325 {
326 	struct dummy_systimer_pcm *dpcm;
327 
328 	dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
329 	if (!dpcm)
330 		return -ENOMEM;
331 	substream->runtime->private_data = dpcm;
332 	timer_setup(&dpcm->timer, dummy_systimer_callback, 0);
333 	spin_lock_init(&dpcm->lock);
334 	dpcm->substream = substream;
335 	return 0;
336 }
337 
338 static void dummy_systimer_free(struct snd_pcm_substream *substream)
339 {
340 	kfree(substream->runtime->private_data);
341 }
342 
343 static const struct dummy_timer_ops dummy_systimer_ops = {
344 	.create =	dummy_systimer_create,
345 	.free =		dummy_systimer_free,
346 	.prepare =	dummy_systimer_prepare,
347 	.start =	dummy_systimer_start,
348 	.stop =		dummy_systimer_stop,
349 	.pointer =	dummy_systimer_pointer,
350 };
351 
352 #ifdef CONFIG_HIGH_RES_TIMERS
353 /*
354  * hrtimer interface
355  */
356 
357 struct dummy_hrtimer_pcm {
358 	/* ops must be the first item */
359 	const struct dummy_timer_ops *timer_ops;
360 	ktime_t base_time;
361 	ktime_t period_time;
362 	atomic_t running;
363 	struct hrtimer timer;
364 	struct snd_pcm_substream *substream;
365 };
366 
367 static enum hrtimer_restart dummy_hrtimer_callback(struct hrtimer *timer)
368 {
369 	struct dummy_hrtimer_pcm *dpcm;
370 
371 	dpcm = container_of(timer, struct dummy_hrtimer_pcm, timer);
372 	if (!atomic_read(&dpcm->running))
373 		return HRTIMER_NORESTART;
374 	/*
375 	 * In cases of XRUN and draining, this calls .trigger to stop PCM
376 	 * substream.
377 	 */
378 	snd_pcm_period_elapsed(dpcm->substream);
379 	if (!atomic_read(&dpcm->running))
380 		return HRTIMER_NORESTART;
381 
382 	hrtimer_forward_now(timer, dpcm->period_time);
383 	return HRTIMER_RESTART;
384 }
385 
386 static int dummy_hrtimer_start(struct snd_pcm_substream *substream)
387 {
388 	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
389 
390 	dpcm->base_time = hrtimer_cb_get_time(&dpcm->timer);
391 	hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL_SOFT);
392 	atomic_set(&dpcm->running, 1);
393 	return 0;
394 }
395 
396 static int dummy_hrtimer_stop(struct snd_pcm_substream *substream)
397 {
398 	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
399 
400 	atomic_set(&dpcm->running, 0);
401 	if (!hrtimer_callback_running(&dpcm->timer))
402 		hrtimer_cancel(&dpcm->timer);
403 	return 0;
404 }
405 
406 static inline void dummy_hrtimer_sync(struct dummy_hrtimer_pcm *dpcm)
407 {
408 	hrtimer_cancel(&dpcm->timer);
409 }
410 
411 static snd_pcm_uframes_t
412 dummy_hrtimer_pointer(struct snd_pcm_substream *substream)
413 {
414 	struct snd_pcm_runtime *runtime = substream->runtime;
415 	struct dummy_hrtimer_pcm *dpcm = runtime->private_data;
416 	u64 delta;
417 	u32 pos;
418 
419 	delta = ktime_us_delta(hrtimer_cb_get_time(&dpcm->timer),
420 			       dpcm->base_time);
421 	delta = div_u64(delta * runtime->rate + 999999, 1000000);
422 	div_u64_rem(delta, runtime->buffer_size, &pos);
423 	return pos;
424 }
425 
426 static int dummy_hrtimer_prepare(struct snd_pcm_substream *substream)
427 {
428 	struct snd_pcm_runtime *runtime = substream->runtime;
429 	struct dummy_hrtimer_pcm *dpcm = runtime->private_data;
430 	unsigned int period, rate;
431 	long sec;
432 	unsigned long nsecs;
433 
434 	dummy_hrtimer_sync(dpcm);
435 	period = runtime->period_size;
436 	rate = runtime->rate;
437 	sec = period / rate;
438 	period %= rate;
439 	nsecs = div_u64((u64)period * 1000000000UL + rate - 1, rate);
440 	dpcm->period_time = ktime_set(sec, nsecs);
441 
442 	return 0;
443 }
444 
445 static int dummy_hrtimer_create(struct snd_pcm_substream *substream)
446 {
447 	struct dummy_hrtimer_pcm *dpcm;
448 
449 	dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
450 	if (!dpcm)
451 		return -ENOMEM;
452 	substream->runtime->private_data = dpcm;
453 	hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
454 	dpcm->timer.function = dummy_hrtimer_callback;
455 	dpcm->substream = substream;
456 	atomic_set(&dpcm->running, 0);
457 	return 0;
458 }
459 
460 static void dummy_hrtimer_free(struct snd_pcm_substream *substream)
461 {
462 	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
463 	dummy_hrtimer_sync(dpcm);
464 	kfree(dpcm);
465 }
466 
467 static const struct dummy_timer_ops dummy_hrtimer_ops = {
468 	.create =	dummy_hrtimer_create,
469 	.free =		dummy_hrtimer_free,
470 	.prepare =	dummy_hrtimer_prepare,
471 	.start =	dummy_hrtimer_start,
472 	.stop =		dummy_hrtimer_stop,
473 	.pointer =	dummy_hrtimer_pointer,
474 };
475 
476 #endif /* CONFIG_HIGH_RES_TIMERS */
477 
478 /*
479  * PCM interface
480  */
481 
482 static int dummy_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
483 {
484 	switch (cmd) {
485 	case SNDRV_PCM_TRIGGER_START:
486 	case SNDRV_PCM_TRIGGER_RESUME:
487 		return get_dummy_ops(substream)->start(substream);
488 	case SNDRV_PCM_TRIGGER_STOP:
489 	case SNDRV_PCM_TRIGGER_SUSPEND:
490 		return get_dummy_ops(substream)->stop(substream);
491 	}
492 	return -EINVAL;
493 }
494 
495 static int dummy_pcm_prepare(struct snd_pcm_substream *substream)
496 {
497 	return get_dummy_ops(substream)->prepare(substream);
498 }
499 
500 static snd_pcm_uframes_t dummy_pcm_pointer(struct snd_pcm_substream *substream)
501 {
502 	return get_dummy_ops(substream)->pointer(substream);
503 }
504 
505 static const struct snd_pcm_hardware dummy_pcm_hardware = {
506 	.info =			(SNDRV_PCM_INFO_MMAP |
507 				 SNDRV_PCM_INFO_INTERLEAVED |
508 				 SNDRV_PCM_INFO_RESUME |
509 				 SNDRV_PCM_INFO_MMAP_VALID),
510 	.formats =		USE_FORMATS,
511 	.rates =		USE_RATE,
512 	.rate_min =		USE_RATE_MIN,
513 	.rate_max =		USE_RATE_MAX,
514 	.channels_min =		USE_CHANNELS_MIN,
515 	.channels_max =		USE_CHANNELS_MAX,
516 	.buffer_bytes_max =	MAX_BUFFER_SIZE,
517 	.period_bytes_min =	MIN_PERIOD_SIZE,
518 	.period_bytes_max =	MAX_PERIOD_SIZE,
519 	.periods_min =		USE_PERIODS_MIN,
520 	.periods_max =		USE_PERIODS_MAX,
521 	.fifo_size =		0,
522 };
523 
524 static int dummy_pcm_hw_params(struct snd_pcm_substream *substream,
525 			       struct snd_pcm_hw_params *hw_params)
526 {
527 	if (fake_buffer) {
528 		/* runtime->dma_bytes has to be set manually to allow mmap */
529 		substream->runtime->dma_bytes = params_buffer_bytes(hw_params);
530 		return 0;
531 	}
532 	return snd_pcm_lib_malloc_pages(substream,
533 					params_buffer_bytes(hw_params));
534 }
535 
536 static int dummy_pcm_hw_free(struct snd_pcm_substream *substream)
537 {
538 	if (fake_buffer)
539 		return 0;
540 	return snd_pcm_lib_free_pages(substream);
541 }
542 
543 static int dummy_pcm_open(struct snd_pcm_substream *substream)
544 {
545 	struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
546 	struct dummy_model *model = dummy->model;
547 	struct snd_pcm_runtime *runtime = substream->runtime;
548 	const struct dummy_timer_ops *ops;
549 	int err;
550 
551 	ops = &dummy_systimer_ops;
552 #ifdef CONFIG_HIGH_RES_TIMERS
553 	if (hrtimer)
554 		ops = &dummy_hrtimer_ops;
555 #endif
556 
557 	err = ops->create(substream);
558 	if (err < 0)
559 		return err;
560 	get_dummy_ops(substream) = ops;
561 
562 	runtime->hw = dummy->pcm_hw;
563 	if (substream->pcm->device & 1) {
564 		runtime->hw.info &= ~SNDRV_PCM_INFO_INTERLEAVED;
565 		runtime->hw.info |= SNDRV_PCM_INFO_NONINTERLEAVED;
566 	}
567 	if (substream->pcm->device & 2)
568 		runtime->hw.info &= ~(SNDRV_PCM_INFO_MMAP |
569 				      SNDRV_PCM_INFO_MMAP_VALID);
570 
571 	if (model == NULL)
572 		return 0;
573 
574 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
575 		if (model->playback_constraints)
576 			err = model->playback_constraints(substream->runtime);
577 	} else {
578 		if (model->capture_constraints)
579 			err = model->capture_constraints(substream->runtime);
580 	}
581 	if (err < 0) {
582 		get_dummy_ops(substream)->free(substream);
583 		return err;
584 	}
585 	return 0;
586 }
587 
588 static int dummy_pcm_close(struct snd_pcm_substream *substream)
589 {
590 	get_dummy_ops(substream)->free(substream);
591 	return 0;
592 }
593 
594 /*
595  * dummy buffer handling
596  */
597 
598 static void *dummy_page[2];
599 
600 static void free_fake_buffer(void)
601 {
602 	if (fake_buffer) {
603 		int i;
604 		for (i = 0; i < 2; i++)
605 			if (dummy_page[i]) {
606 				free_page((unsigned long)dummy_page[i]);
607 				dummy_page[i] = NULL;
608 			}
609 	}
610 }
611 
612 static int alloc_fake_buffer(void)
613 {
614 	int i;
615 
616 	if (!fake_buffer)
617 		return 0;
618 	for (i = 0; i < 2; i++) {
619 		dummy_page[i] = (void *)get_zeroed_page(GFP_KERNEL);
620 		if (!dummy_page[i]) {
621 			free_fake_buffer();
622 			return -ENOMEM;
623 		}
624 	}
625 	return 0;
626 }
627 
628 static int dummy_pcm_copy(struct snd_pcm_substream *substream,
629 			  int channel, unsigned long pos,
630 			  void __user *dst, unsigned long bytes)
631 {
632 	return 0; /* do nothing */
633 }
634 
635 static int dummy_pcm_copy_kernel(struct snd_pcm_substream *substream,
636 				 int channel, unsigned long pos,
637 				 void *dst, unsigned long bytes)
638 {
639 	return 0; /* do nothing */
640 }
641 
642 static int dummy_pcm_silence(struct snd_pcm_substream *substream,
643 			     int channel, unsigned long pos,
644 			     unsigned long bytes)
645 {
646 	return 0; /* do nothing */
647 }
648 
649 static struct page *dummy_pcm_page(struct snd_pcm_substream *substream,
650 				   unsigned long offset)
651 {
652 	return virt_to_page(dummy_page[substream->stream]); /* the same page */
653 }
654 
655 static struct snd_pcm_ops dummy_pcm_ops = {
656 	.open =		dummy_pcm_open,
657 	.close =	dummy_pcm_close,
658 	.ioctl =	snd_pcm_lib_ioctl,
659 	.hw_params =	dummy_pcm_hw_params,
660 	.hw_free =	dummy_pcm_hw_free,
661 	.prepare =	dummy_pcm_prepare,
662 	.trigger =	dummy_pcm_trigger,
663 	.pointer =	dummy_pcm_pointer,
664 };
665 
666 static struct snd_pcm_ops dummy_pcm_ops_no_buf = {
667 	.open =		dummy_pcm_open,
668 	.close =	dummy_pcm_close,
669 	.ioctl =	snd_pcm_lib_ioctl,
670 	.hw_params =	dummy_pcm_hw_params,
671 	.hw_free =	dummy_pcm_hw_free,
672 	.prepare =	dummy_pcm_prepare,
673 	.trigger =	dummy_pcm_trigger,
674 	.pointer =	dummy_pcm_pointer,
675 	.copy_user =	dummy_pcm_copy,
676 	.copy_kernel =	dummy_pcm_copy_kernel,
677 	.fill_silence =	dummy_pcm_silence,
678 	.page =		dummy_pcm_page,
679 };
680 
681 static int snd_card_dummy_pcm(struct snd_dummy *dummy, int device,
682 			      int substreams)
683 {
684 	struct snd_pcm *pcm;
685 	struct snd_pcm_ops *ops;
686 	int err;
687 
688 	err = snd_pcm_new(dummy->card, "Dummy PCM", device,
689 			       substreams, substreams, &pcm);
690 	if (err < 0)
691 		return err;
692 	dummy->pcm = pcm;
693 	if (fake_buffer)
694 		ops = &dummy_pcm_ops_no_buf;
695 	else
696 		ops = &dummy_pcm_ops;
697 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, ops);
698 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, ops);
699 	pcm->private_data = dummy;
700 	pcm->info_flags = 0;
701 	strcpy(pcm->name, "Dummy PCM");
702 	if (!fake_buffer) {
703 		snd_pcm_lib_preallocate_pages_for_all(pcm,
704 			SNDRV_DMA_TYPE_CONTINUOUS,
705 			NULL,
706 			0, 64*1024);
707 	}
708 	return 0;
709 }
710 
711 /*
712  * mixer interface
713  */
714 
715 #define DUMMY_VOLUME(xname, xindex, addr) \
716 { .iface = SNDRV_CTL_ELEM_IFACE_MIXER, \
717   .access = SNDRV_CTL_ELEM_ACCESS_READWRITE | SNDRV_CTL_ELEM_ACCESS_TLV_READ, \
718   .name = xname, .index = xindex, \
719   .info = snd_dummy_volume_info, \
720   .get = snd_dummy_volume_get, .put = snd_dummy_volume_put, \
721   .private_value = addr, \
722   .tlv = { .p = db_scale_dummy } }
723 
724 static int snd_dummy_volume_info(struct snd_kcontrol *kcontrol,
725 				 struct snd_ctl_elem_info *uinfo)
726 {
727 	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
728 	uinfo->count = 2;
729 	uinfo->value.integer.min = -50;
730 	uinfo->value.integer.max = 100;
731 	return 0;
732 }
733 
734 static int snd_dummy_volume_get(struct snd_kcontrol *kcontrol,
735 				struct snd_ctl_elem_value *ucontrol)
736 {
737 	struct snd_dummy *dummy = snd_kcontrol_chip(kcontrol);
738 	int addr = kcontrol->private_value;
739 
740 	spin_lock_irq(&dummy->mixer_lock);
741 	ucontrol->value.integer.value[0] = dummy->mixer_volume[addr][0];
742 	ucontrol->value.integer.value[1] = dummy->mixer_volume[addr][1];
743 	spin_unlock_irq(&dummy->mixer_lock);
744 	return 0;
745 }
746 
747 static int snd_dummy_volume_put(struct snd_kcontrol *kcontrol,
748 				struct snd_ctl_elem_value *ucontrol)
749 {
750 	struct snd_dummy *dummy = snd_kcontrol_chip(kcontrol);
751 	int change, addr = kcontrol->private_value;
752 	int left, right;
753 
754 	left = ucontrol->value.integer.value[0];
755 	if (left < -50)
756 		left = -50;
757 	if (left > 100)
758 		left = 100;
759 	right = ucontrol->value.integer.value[1];
760 	if (right < -50)
761 		right = -50;
762 	if (right > 100)
763 		right = 100;
764 	spin_lock_irq(&dummy->mixer_lock);
765 	change = dummy->mixer_volume[addr][0] != left ||
766 	         dummy->mixer_volume[addr][1] != right;
767 	dummy->mixer_volume[addr][0] = left;
768 	dummy->mixer_volume[addr][1] = right;
769 	spin_unlock_irq(&dummy->mixer_lock);
770 	return change;
771 }
772 
773 static const DECLARE_TLV_DB_SCALE(db_scale_dummy, -4500, 30, 0);
774 
775 #define DUMMY_CAPSRC(xname, xindex, addr) \
776 { .iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = xname, .index = xindex, \
777   .info = snd_dummy_capsrc_info, \
778   .get = snd_dummy_capsrc_get, .put = snd_dummy_capsrc_put, \
779   .private_value = addr }
780 
781 #define snd_dummy_capsrc_info	snd_ctl_boolean_stereo_info
782 
783 static int snd_dummy_capsrc_get(struct snd_kcontrol *kcontrol,
784 				struct snd_ctl_elem_value *ucontrol)
785 {
786 	struct snd_dummy *dummy = snd_kcontrol_chip(kcontrol);
787 	int addr = kcontrol->private_value;
788 
789 	spin_lock_irq(&dummy->mixer_lock);
790 	ucontrol->value.integer.value[0] = dummy->capture_source[addr][0];
791 	ucontrol->value.integer.value[1] = dummy->capture_source[addr][1];
792 	spin_unlock_irq(&dummy->mixer_lock);
793 	return 0;
794 }
795 
796 static int snd_dummy_capsrc_put(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_value *ucontrol)
797 {
798 	struct snd_dummy *dummy = snd_kcontrol_chip(kcontrol);
799 	int change, addr = kcontrol->private_value;
800 	int left, right;
801 
802 	left = ucontrol->value.integer.value[0] & 1;
803 	right = ucontrol->value.integer.value[1] & 1;
804 	spin_lock_irq(&dummy->mixer_lock);
805 	change = dummy->capture_source[addr][0] != left &&
806 	         dummy->capture_source[addr][1] != right;
807 	dummy->capture_source[addr][0] = left;
808 	dummy->capture_source[addr][1] = right;
809 	spin_unlock_irq(&dummy->mixer_lock);
810 	return change;
811 }
812 
813 static int snd_dummy_iobox_info(struct snd_kcontrol *kcontrol,
814 				struct snd_ctl_elem_info *info)
815 {
816 	static const char *const names[] = { "None", "CD Player" };
817 
818 	return snd_ctl_enum_info(info, 1, 2, names);
819 }
820 
821 static int snd_dummy_iobox_get(struct snd_kcontrol *kcontrol,
822 			       struct snd_ctl_elem_value *value)
823 {
824 	struct snd_dummy *dummy = snd_kcontrol_chip(kcontrol);
825 
826 	value->value.enumerated.item[0] = dummy->iobox;
827 	return 0;
828 }
829 
830 static int snd_dummy_iobox_put(struct snd_kcontrol *kcontrol,
831 			       struct snd_ctl_elem_value *value)
832 {
833 	struct snd_dummy *dummy = snd_kcontrol_chip(kcontrol);
834 	int changed;
835 
836 	if (value->value.enumerated.item[0] > 1)
837 		return -EINVAL;
838 
839 	changed = value->value.enumerated.item[0] != dummy->iobox;
840 	if (changed) {
841 		dummy->iobox = value->value.enumerated.item[0];
842 
843 		if (dummy->iobox) {
844 			dummy->cd_volume_ctl->vd[0].access &=
845 				~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
846 			dummy->cd_switch_ctl->vd[0].access &=
847 				~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
848 		} else {
849 			dummy->cd_volume_ctl->vd[0].access |=
850 				SNDRV_CTL_ELEM_ACCESS_INACTIVE;
851 			dummy->cd_switch_ctl->vd[0].access |=
852 				SNDRV_CTL_ELEM_ACCESS_INACTIVE;
853 		}
854 
855 		snd_ctl_notify(dummy->card, SNDRV_CTL_EVENT_MASK_INFO,
856 			       &dummy->cd_volume_ctl->id);
857 		snd_ctl_notify(dummy->card, SNDRV_CTL_EVENT_MASK_INFO,
858 			       &dummy->cd_switch_ctl->id);
859 	}
860 
861 	return changed;
862 }
863 
864 static struct snd_kcontrol_new snd_dummy_controls[] = {
865 DUMMY_VOLUME("Master Volume", 0, MIXER_ADDR_MASTER),
866 DUMMY_CAPSRC("Master Capture Switch", 0, MIXER_ADDR_MASTER),
867 DUMMY_VOLUME("Synth Volume", 0, MIXER_ADDR_SYNTH),
868 DUMMY_CAPSRC("Synth Capture Switch", 0, MIXER_ADDR_SYNTH),
869 DUMMY_VOLUME("Line Volume", 0, MIXER_ADDR_LINE),
870 DUMMY_CAPSRC("Line Capture Switch", 0, MIXER_ADDR_LINE),
871 DUMMY_VOLUME("Mic Volume", 0, MIXER_ADDR_MIC),
872 DUMMY_CAPSRC("Mic Capture Switch", 0, MIXER_ADDR_MIC),
873 DUMMY_VOLUME("CD Volume", 0, MIXER_ADDR_CD),
874 DUMMY_CAPSRC("CD Capture Switch", 0, MIXER_ADDR_CD),
875 {
876 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
877 	.name  = "External I/O Box",
878 	.info  = snd_dummy_iobox_info,
879 	.get   = snd_dummy_iobox_get,
880 	.put   = snd_dummy_iobox_put,
881 },
882 };
883 
884 static int snd_card_dummy_new_mixer(struct snd_dummy *dummy)
885 {
886 	struct snd_card *card = dummy->card;
887 	struct snd_kcontrol *kcontrol;
888 	unsigned int idx;
889 	int err;
890 
891 	spin_lock_init(&dummy->mixer_lock);
892 	strcpy(card->mixername, "Dummy Mixer");
893 	dummy->iobox = 1;
894 
895 	for (idx = 0; idx < ARRAY_SIZE(snd_dummy_controls); idx++) {
896 		kcontrol = snd_ctl_new1(&snd_dummy_controls[idx], dummy);
897 		err = snd_ctl_add(card, kcontrol);
898 		if (err < 0)
899 			return err;
900 		if (!strcmp(kcontrol->id.name, "CD Volume"))
901 			dummy->cd_volume_ctl = kcontrol;
902 		else if (!strcmp(kcontrol->id.name, "CD Capture Switch"))
903 			dummy->cd_switch_ctl = kcontrol;
904 
905 	}
906 	return 0;
907 }
908 
909 #if defined(CONFIG_SND_DEBUG) && defined(CONFIG_SND_PROC_FS)
910 /*
911  * proc interface
912  */
913 static void print_formats(struct snd_dummy *dummy,
914 			  struct snd_info_buffer *buffer)
915 {
916 	int i;
917 
918 	for (i = 0; i < SNDRV_PCM_FORMAT_LAST; i++) {
919 		if (dummy->pcm_hw.formats & (1ULL << i))
920 			snd_iprintf(buffer, " %s", snd_pcm_format_name(i));
921 	}
922 }
923 
924 static void print_rates(struct snd_dummy *dummy,
925 			struct snd_info_buffer *buffer)
926 {
927 	static int rates[] = {
928 		5512, 8000, 11025, 16000, 22050, 32000, 44100, 48000,
929 		64000, 88200, 96000, 176400, 192000,
930 	};
931 	int i;
932 
933 	if (dummy->pcm_hw.rates & SNDRV_PCM_RATE_CONTINUOUS)
934 		snd_iprintf(buffer, " continuous");
935 	if (dummy->pcm_hw.rates & SNDRV_PCM_RATE_KNOT)
936 		snd_iprintf(buffer, " knot");
937 	for (i = 0; i < ARRAY_SIZE(rates); i++)
938 		if (dummy->pcm_hw.rates & (1 << i))
939 			snd_iprintf(buffer, " %d", rates[i]);
940 }
941 
942 #define get_dummy_int_ptr(dummy, ofs) \
943 	(unsigned int *)((char *)&((dummy)->pcm_hw) + (ofs))
944 #define get_dummy_ll_ptr(dummy, ofs) \
945 	(unsigned long long *)((char *)&((dummy)->pcm_hw) + (ofs))
946 
947 struct dummy_hw_field {
948 	const char *name;
949 	const char *format;
950 	unsigned int offset;
951 	unsigned int size;
952 };
953 #define FIELD_ENTRY(item, fmt) {		   \
954 	.name = #item,				   \
955 	.format = fmt,				   \
956 	.offset = offsetof(struct snd_pcm_hardware, item), \
957 	.size = sizeof(dummy_pcm_hardware.item) }
958 
959 static struct dummy_hw_field fields[] = {
960 	FIELD_ENTRY(formats, "%#llx"),
961 	FIELD_ENTRY(rates, "%#x"),
962 	FIELD_ENTRY(rate_min, "%d"),
963 	FIELD_ENTRY(rate_max, "%d"),
964 	FIELD_ENTRY(channels_min, "%d"),
965 	FIELD_ENTRY(channels_max, "%d"),
966 	FIELD_ENTRY(buffer_bytes_max, "%ld"),
967 	FIELD_ENTRY(period_bytes_min, "%ld"),
968 	FIELD_ENTRY(period_bytes_max, "%ld"),
969 	FIELD_ENTRY(periods_min, "%d"),
970 	FIELD_ENTRY(periods_max, "%d"),
971 };
972 
973 static void dummy_proc_read(struct snd_info_entry *entry,
974 			    struct snd_info_buffer *buffer)
975 {
976 	struct snd_dummy *dummy = entry->private_data;
977 	int i;
978 
979 	for (i = 0; i < ARRAY_SIZE(fields); i++) {
980 		snd_iprintf(buffer, "%s ", fields[i].name);
981 		if (fields[i].size == sizeof(int))
982 			snd_iprintf(buffer, fields[i].format,
983 				*get_dummy_int_ptr(dummy, fields[i].offset));
984 		else
985 			snd_iprintf(buffer, fields[i].format,
986 				*get_dummy_ll_ptr(dummy, fields[i].offset));
987 		if (!strcmp(fields[i].name, "formats"))
988 			print_formats(dummy, buffer);
989 		else if (!strcmp(fields[i].name, "rates"))
990 			print_rates(dummy, buffer);
991 		snd_iprintf(buffer, "\n");
992 	}
993 }
994 
995 static void dummy_proc_write(struct snd_info_entry *entry,
996 			     struct snd_info_buffer *buffer)
997 {
998 	struct snd_dummy *dummy = entry->private_data;
999 	char line[64];
1000 
1001 	while (!snd_info_get_line(buffer, line, sizeof(line))) {
1002 		char item[20];
1003 		const char *ptr;
1004 		unsigned long long val;
1005 		int i;
1006 
1007 		ptr = snd_info_get_str(item, line, sizeof(item));
1008 		for (i = 0; i < ARRAY_SIZE(fields); i++) {
1009 			if (!strcmp(item, fields[i].name))
1010 				break;
1011 		}
1012 		if (i >= ARRAY_SIZE(fields))
1013 			continue;
1014 		snd_info_get_str(item, ptr, sizeof(item));
1015 		if (kstrtoull(item, 0, &val))
1016 			continue;
1017 		if (fields[i].size == sizeof(int))
1018 			*get_dummy_int_ptr(dummy, fields[i].offset) = val;
1019 		else
1020 			*get_dummy_ll_ptr(dummy, fields[i].offset) = val;
1021 	}
1022 }
1023 
1024 static void dummy_proc_init(struct snd_dummy *chip)
1025 {
1026 	snd_card_rw_proc_new(chip->card, "dummy_pcm", chip,
1027 			     dummy_proc_read, dummy_proc_write);
1028 }
1029 #else
1030 #define dummy_proc_init(x)
1031 #endif /* CONFIG_SND_DEBUG && CONFIG_SND_PROC_FS */
1032 
1033 static int snd_dummy_probe(struct platform_device *devptr)
1034 {
1035 	struct snd_card *card;
1036 	struct snd_dummy *dummy;
1037 	struct dummy_model *m = NULL, **mdl;
1038 	int idx, err;
1039 	int dev = devptr->id;
1040 
1041 	err = snd_card_new(&devptr->dev, index[dev], id[dev], THIS_MODULE,
1042 			   sizeof(struct snd_dummy), &card);
1043 	if (err < 0)
1044 		return err;
1045 	dummy = card->private_data;
1046 	dummy->card = card;
1047 	for (mdl = dummy_models; *mdl && model[dev]; mdl++) {
1048 		if (strcmp(model[dev], (*mdl)->name) == 0) {
1049 			printk(KERN_INFO
1050 				"snd-dummy: Using model '%s' for card %i\n",
1051 				(*mdl)->name, card->number);
1052 			m = dummy->model = *mdl;
1053 			break;
1054 		}
1055 	}
1056 	for (idx = 0; idx < MAX_PCM_DEVICES && idx < pcm_devs[dev]; idx++) {
1057 		if (pcm_substreams[dev] < 1)
1058 			pcm_substreams[dev] = 1;
1059 		if (pcm_substreams[dev] > MAX_PCM_SUBSTREAMS)
1060 			pcm_substreams[dev] = MAX_PCM_SUBSTREAMS;
1061 		err = snd_card_dummy_pcm(dummy, idx, pcm_substreams[dev]);
1062 		if (err < 0)
1063 			goto __nodev;
1064 	}
1065 
1066 	dummy->pcm_hw = dummy_pcm_hardware;
1067 	if (m) {
1068 		if (m->formats)
1069 			dummy->pcm_hw.formats = m->formats;
1070 		if (m->buffer_bytes_max)
1071 			dummy->pcm_hw.buffer_bytes_max = m->buffer_bytes_max;
1072 		if (m->period_bytes_min)
1073 			dummy->pcm_hw.period_bytes_min = m->period_bytes_min;
1074 		if (m->period_bytes_max)
1075 			dummy->pcm_hw.period_bytes_max = m->period_bytes_max;
1076 		if (m->periods_min)
1077 			dummy->pcm_hw.periods_min = m->periods_min;
1078 		if (m->periods_max)
1079 			dummy->pcm_hw.periods_max = m->periods_max;
1080 		if (m->rates)
1081 			dummy->pcm_hw.rates = m->rates;
1082 		if (m->rate_min)
1083 			dummy->pcm_hw.rate_min = m->rate_min;
1084 		if (m->rate_max)
1085 			dummy->pcm_hw.rate_max = m->rate_max;
1086 		if (m->channels_min)
1087 			dummy->pcm_hw.channels_min = m->channels_min;
1088 		if (m->channels_max)
1089 			dummy->pcm_hw.channels_max = m->channels_max;
1090 	}
1091 
1092 	err = snd_card_dummy_new_mixer(dummy);
1093 	if (err < 0)
1094 		goto __nodev;
1095 	strcpy(card->driver, "Dummy");
1096 	strcpy(card->shortname, "Dummy");
1097 	sprintf(card->longname, "Dummy %i", dev + 1);
1098 
1099 	dummy_proc_init(dummy);
1100 
1101 	err = snd_card_register(card);
1102 	if (err == 0) {
1103 		platform_set_drvdata(devptr, card);
1104 		return 0;
1105 	}
1106       __nodev:
1107 	snd_card_free(card);
1108 	return err;
1109 }
1110 
1111 static int snd_dummy_remove(struct platform_device *devptr)
1112 {
1113 	snd_card_free(platform_get_drvdata(devptr));
1114 	return 0;
1115 }
1116 
1117 #ifdef CONFIG_PM_SLEEP
1118 static int snd_dummy_suspend(struct device *pdev)
1119 {
1120 	struct snd_card *card = dev_get_drvdata(pdev);
1121 
1122 	snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
1123 	return 0;
1124 }
1125 
1126 static int snd_dummy_resume(struct device *pdev)
1127 {
1128 	struct snd_card *card = dev_get_drvdata(pdev);
1129 
1130 	snd_power_change_state(card, SNDRV_CTL_POWER_D0);
1131 	return 0;
1132 }
1133 
1134 static SIMPLE_DEV_PM_OPS(snd_dummy_pm, snd_dummy_suspend, snd_dummy_resume);
1135 #define SND_DUMMY_PM_OPS	&snd_dummy_pm
1136 #else
1137 #define SND_DUMMY_PM_OPS	NULL
1138 #endif
1139 
1140 #define SND_DUMMY_DRIVER	"snd_dummy"
1141 
1142 static struct platform_driver snd_dummy_driver = {
1143 	.probe		= snd_dummy_probe,
1144 	.remove		= snd_dummy_remove,
1145 	.driver		= {
1146 		.name	= SND_DUMMY_DRIVER,
1147 		.pm	= SND_DUMMY_PM_OPS,
1148 	},
1149 };
1150 
1151 static void snd_dummy_unregister_all(void)
1152 {
1153 	int i;
1154 
1155 	for (i = 0; i < ARRAY_SIZE(devices); ++i)
1156 		platform_device_unregister(devices[i]);
1157 	platform_driver_unregister(&snd_dummy_driver);
1158 	free_fake_buffer();
1159 }
1160 
1161 static int __init alsa_card_dummy_init(void)
1162 {
1163 	int i, cards, err;
1164 
1165 	err = platform_driver_register(&snd_dummy_driver);
1166 	if (err < 0)
1167 		return err;
1168 
1169 	err = alloc_fake_buffer();
1170 	if (err < 0) {
1171 		platform_driver_unregister(&snd_dummy_driver);
1172 		return err;
1173 	}
1174 
1175 	cards = 0;
1176 	for (i = 0; i < SNDRV_CARDS; i++) {
1177 		struct platform_device *device;
1178 		if (! enable[i])
1179 			continue;
1180 		device = platform_device_register_simple(SND_DUMMY_DRIVER,
1181 							 i, NULL, 0);
1182 		if (IS_ERR(device))
1183 			continue;
1184 		if (!platform_get_drvdata(device)) {
1185 			platform_device_unregister(device);
1186 			continue;
1187 		}
1188 		devices[i] = device;
1189 		cards++;
1190 	}
1191 	if (!cards) {
1192 #ifdef MODULE
1193 		printk(KERN_ERR "Dummy soundcard not found or device busy\n");
1194 #endif
1195 		snd_dummy_unregister_all();
1196 		return -ENODEV;
1197 	}
1198 	return 0;
1199 }
1200 
1201 static void __exit alsa_card_dummy_exit(void)
1202 {
1203 	snd_dummy_unregister_all();
1204 }
1205 
1206 module_init(alsa_card_dummy_init)
1207 module_exit(alsa_card_dummy_exit)
1208