1 files changed, 1190 insertions, 0 deletions

diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c
new file mode 100644
index 0000000000..4317677ba2
--- /dev/null
+++ b/sound/drivers/dummy.c
@@ -0,0 +1,1190 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Dummy soundcard
+ *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
+ */
+
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/jiffies.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+#include <linux/wait.h>
+#include <linux/hrtimer.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <sound/core.h>
+#include <sound/control.h>
+#include <sound/tlv.h>
+#include <sound/pcm.h>
+#include <sound/rawmidi.h>
+#include <sound/info.h>
+#include <sound/initval.h>
+
+MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
+MODULE_DESCRIPTION("Dummy soundcard (/dev/null)");
+MODULE_LICENSE("GPL");
+
+#define MAX_PCM_DEVICES		4
+#define MAX_PCM_SUBSTREAMS	128
+#define MAX_MIDI_DEVICES	2
+
+/* defaults */
+#define MAX_BUFFER_SIZE		(64*1024)
+#define MIN_PERIOD_SIZE		64
+#define MAX_PERIOD_SIZE		MAX_BUFFER_SIZE
+#define USE_FORMATS 		(SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S16_LE)
+#define USE_RATE		SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_48000
+#define USE_RATE_MIN		5500
+#define USE_RATE_MAX		48000
+#define USE_CHANNELS_MIN 	1
+#define USE_CHANNELS_MAX 	2
+#define USE_PERIODS_MIN 	1
+#define USE_PERIODS_MAX 	1024
+#define USE_MIXER_VOLUME_LEVEL_MIN	-50
+#define USE_MIXER_VOLUME_LEVEL_MAX	100
+
+static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;	/* Index 0-MAX */
+static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;	/* ID for this card */
+static bool enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
+static char *model[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = NULL};
+static int pcm_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 1};
+static int pcm_substreams[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 8};
+//static int midi_devs[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = 2};
+static int mixer_volume_level_min = USE_MIXER_VOLUME_LEVEL_MIN;
+static int mixer_volume_level_max = USE_MIXER_VOLUME_LEVEL_MAX;
+#ifdef CONFIG_HIGH_RES_TIMERS
+static bool hrtimer = 1;
+#endif
+static bool fake_buffer = 1;
+
+module_param_array(index, int, NULL, 0444);
+MODULE_PARM_DESC(index, "Index value for dummy soundcard.");
+module_param_array(id, charp, NULL, 0444);
+MODULE_PARM_DESC(id, "ID string for dummy soundcard.");
+module_param_array(enable, bool, NULL, 0444);
+MODULE_PARM_DESC(enable, "Enable this dummy soundcard.");
+module_param_array(model, charp, NULL, 0444);
+MODULE_PARM_DESC(model, "Soundcard model.");
+module_param_array(pcm_devs, int, NULL, 0444);
+MODULE_PARM_DESC(pcm_devs, "PCM devices # (0-4) for dummy driver.");
+module_param_array(pcm_substreams, int, NULL, 0444);
+MODULE_PARM_DESC(pcm_substreams, "PCM substreams # (1-128) for dummy driver.");
+//module_param_array(midi_devs, int, NULL, 0444);
+//MODULE_PARM_DESC(midi_devs, "MIDI devices # (0-2) for dummy driver.");
+module_param(mixer_volume_level_min, int, 0444);
+MODULE_PARM_DESC(mixer_volume_level_min, "Minimum mixer volume level for dummy driver. Default: -50");
+module_param(mixer_volume_level_max, int, 0444);
+MODULE_PARM_DESC(mixer_volume_level_max, "Maximum mixer volume level for dummy driver. Default: 100");
+module_param(fake_buffer, bool, 0444);
+MODULE_PARM_DESC(fake_buffer, "Fake buffer allocations.");
+#ifdef CONFIG_HIGH_RES_TIMERS
+module_param(hrtimer, bool, 0644);
+MODULE_PARM_DESC(hrtimer, "Use hrtimer as the timer source.");
+#endif
+
+static struct platform_device *devices[SNDRV_CARDS];
+
+#define MIXER_ADDR_MASTER	0
+#define MIXER_ADDR_LINE		1
+#define MIXER_ADDR_MIC		2
+#define MIXER_ADDR_SYNTH	3
+#define MIXER_ADDR_CD		4
+#define MIXER_ADDR_LAST		4
+
+struct dummy_timer_ops {
+	int (*create)(struct snd_pcm_substream *);
+	void (*free)(struct snd_pcm_substream *);
+	int (*prepare)(struct snd_pcm_substream *);
+	int (*start)(struct snd_pcm_substream *);
+	int (*stop)(struct snd_pcm_substream *);
+	snd_pcm_uframes_t (*pointer)(struct snd_pcm_substream *);
+};
+
+#define get_dummy_ops(substream) \
+	(*(const struct dummy_timer_ops **)(substream)->runtime->private_data)
+
+struct dummy_model {
+	const char *name;
+	int (*playback_constraints)(struct snd_pcm_runtime *runtime);
+	int (*capture_constraints)(struct snd_pcm_runtime *runtime);
+	u64 formats;
+	size_t buffer_bytes_max;
+	size_t period_bytes_min;
+	size_t period_bytes_max;
+	unsigned int periods_min;
+	unsigned int periods_max;
+	unsigned int rates;
+	unsigned int rate_min;
+	unsigned int rate_max;
+	unsigned int channels_min;
+	unsigned int channels_max;
+};
+
+struct snd_dummy {
+	struct snd_card *card;
+	const struct dummy_model *model;
+	struct snd_pcm *pcm;
+	struct snd_pcm_hardware pcm_hw;
+	spinlock_t mixer_lock;
+	int mixer_volume[MIXER_ADDR_LAST+1][2];
+	int capture_source[MIXER_ADDR_LAST+1][2];
+	int iobox;
+	struct snd_kcontrol *cd_volume_ctl;
+	struct snd_kcontrol *cd_switch_ctl;
+};
+
+/*
+ * card models
+ */
+
+static int emu10k1_playback_constraints(struct snd_pcm_runtime *runtime)
+{
+	int err;
+	err = snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
+	if (err < 0)
+		return err;
+	err = snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_BUFFER_BYTES, 256, UINT_MAX);
+	if (err < 0)
+		return err;
+	return 0;
+}
+
+static const struct dummy_model model_emu10k1 = {
+	.name = "emu10k1",
+	.playback_constraints = emu10k1_playback_constraints,
+	.buffer_bytes_max = 128 * 1024,
+};
+
+static const struct dummy_model model_rme9652 = {
+	.name = "rme9652",
+	.buffer_bytes_max = 26 * 64 * 1024,
+	.formats = SNDRV_PCM_FMTBIT_S32_LE,
+	.channels_min = 26,
+	.channels_max = 26,
+	.periods_min = 2,
+	.periods_max = 2,
+};
+
+static const struct dummy_model model_ice1712 = {
+	.name = "ice1712",
+	.buffer_bytes_max = 256 * 1024,
+	.formats = SNDRV_PCM_FMTBIT_S32_LE,
+	.channels_min = 10,
+	.channels_max = 10,
+	.periods_min = 1,
+	.periods_max = 1024,
+};
+
+static const struct dummy_model model_uda1341 = {
+	.name = "uda1341",
+	.buffer_bytes_max = 16380,
+	.formats = SNDRV_PCM_FMTBIT_S16_LE,
+	.channels_min = 2,
+	.channels_max = 2,
+	.periods_min = 2,
+	.periods_max = 255,
+};
+
+static const struct dummy_model model_ac97 = {
+	.name = "ac97",
+	.formats = SNDRV_PCM_FMTBIT_S16_LE,
+	.channels_min = 2,
+	.channels_max = 2,
+	.rates = SNDRV_PCM_RATE_48000,
+	.rate_min = 48000,
+	.rate_max = 48000,
+};
+
+static const struct dummy_model model_ca0106 = {
+	.name = "ca0106",
+	.formats = SNDRV_PCM_FMTBIT_S16_LE,
+	.buffer_bytes_max = ((65536-64)*8),
+	.period_bytes_max = (65536-64),
+	.periods_min = 2,
+	.periods_max = 8,
+	.channels_min = 2,
+	.channels_max = 2,
+	.rates = SNDRV_PCM_RATE_48000|SNDRV_PCM_RATE_96000|SNDRV_PCM_RATE_192000,
+	.rate_min = 48000,
+	.rate_max = 192000,
+};
+
+static const struct dummy_model *dummy_models[] = {
+	&model_emu10k1,
+	&model_rme9652,
+	&model_ice1712,
+	&model_uda1341,
+	&model_ac97,
+	&model_ca0106,
+	NULL
+};
+
+/*
+ * system timer interface
+ */
+
+struct dummy_systimer_pcm {
+	/* ops must be the first item */
+	const struct dummy_timer_ops *timer_ops;
+	spinlock_t lock;
+	struct timer_list timer;
+	unsigned long base_time;
+	unsigned int frac_pos;	/* fractional sample position (based HZ) */
+	unsigned int frac_period_rest;
+	unsigned int frac_buffer_size;	/* buffer_size * HZ */
+	unsigned int frac_period_size;	/* period_size * HZ */
+	unsigned int rate;
+	int elapsed;
+	struct snd_pcm_substream *substream;
+};
+
+static void dummy_systimer_rearm(struct dummy_systimer_pcm *dpcm)
+{
+	mod_timer(&dpcm->timer, jiffies +
+		DIV_ROUND_UP(dpcm->frac_period_rest, dpcm->rate));
+}
+
+static void dummy_systimer_update(struct dummy_systimer_pcm *dpcm)
+{
+	unsigned long delta;
+
+	delta = jiffies - dpcm->base_time;
+	if (!delta)
+		return;
+	dpcm->base_time += delta;
+	delta *= dpcm->rate;
+	dpcm->frac_pos += delta;
+	while (dpcm->frac_pos >= dpcm->frac_buffer_size)
+		dpcm->frac_pos -= dpcm->frac_buffer_size;
+	while (dpcm->frac_period_rest <= delta) {
+		dpcm->elapsed++;
+		dpcm->frac_period_rest += dpcm->frac_period_size;
+	}
+	dpcm->frac_period_rest -= delta;
+}
+
+static int dummy_systimer_start(struct snd_pcm_substream *substream)
+{
+	struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
+	spin_lock(&dpcm->lock);
+	dpcm->base_time = jiffies;
+	dummy_systimer_rearm(dpcm);
+	spin_unlock(&dpcm->lock);
+	return 0;
+}
+
+static int dummy_systimer_stop(struct snd_pcm_substream *substream)
+{
+	struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
+	spin_lock(&dpcm->lock);
+	del_timer(&dpcm->timer);
+	spin_unlock(&dpcm->lock);
+	return 0;
+}
+
+static int dummy_systimer_prepare(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct dummy_systimer_pcm *dpcm = runtime->private_data;
+
+	dpcm->frac_pos = 0;
+	dpcm->rate = runtime->rate;
+	dpcm->frac_buffer_size = runtime->buffer_size * HZ;
+	dpcm->frac_period_size = runtime->period_size * HZ;
+	dpcm->frac_period_rest = dpcm->frac_period_size;
+	dpcm->elapsed = 0;
+
+	return 0;
+}
+
+static void dummy_systimer_callback(struct timer_list *t)
+{
+	struct dummy_systimer_pcm *dpcm = from_timer(dpcm, t, timer);
+	unsigned long flags;
+	int elapsed = 0;
+
+	spin_lock_irqsave(&dpcm->lock, flags);
+	dummy_systimer_update(dpcm);
+	dummy_systimer_rearm(dpcm);
+	elapsed = dpcm->elapsed;
+	dpcm->elapsed = 0;
+	spin_unlock_irqrestore(&dpcm->lock, flags);
+	if (elapsed)
+		snd_pcm_period_elapsed(dpcm->substream);
+}
+
+static snd_pcm_uframes_t
+dummy_systimer_pointer(struct snd_pcm_substream *substream)
+{
+	struct dummy_systimer_pcm *dpcm = substream->runtime->private_data;
+	snd_pcm_uframes_t pos;
+
+	spin_lock(&dpcm->lock);
+	dummy_systimer_update(dpcm);
+	pos = dpcm->frac_pos / HZ;
+	spin_unlock(&dpcm->lock);
+	return pos;
+}
+
+static int dummy_systimer_create(struct snd_pcm_substream *substream)
+{
+	struct dummy_systimer_pcm *dpcm;
+
+	dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
+	if (!dpcm)
+		return -ENOMEM;
+	substream->runtime->private_data = dpcm;
+	timer_setup(&dpcm->timer, dummy_systimer_callback, 0);
+	spin_lock_init(&dpcm->lock);
+	dpcm->substream = substream;
+	return 0;
+}
+
+static void dummy_systimer_free(struct snd_pcm_substream *substream)
+{
+	kfree(substream->runtime->private_data);
+}
+
+static const struct dummy_timer_ops dummy_systimer_ops = {
+	.create =	dummy_systimer_create,
+	.free =		dummy_systimer_free,
+	.prepare =	dummy_systimer_prepare,
+	.start =	dummy_systimer_start,
+	.stop =		dummy_systimer_stop,
+	.pointer =	dummy_systimer_pointer,
+};
+
+#ifdef CONFIG_HIGH_RES_TIMERS
+/*
+ * hrtimer interface
+ */
+
+struct dummy_hrtimer_pcm {
+	/* ops must be the first item */
+	const struct dummy_timer_ops *timer_ops;
+	ktime_t base_time;
+	ktime_t period_time;
+	atomic_t running;
+	struct hrtimer timer;
+	struct snd_pcm_substream *substream;
+};
+
+static enum hrtimer_restart dummy_hrtimer_callback(struct hrtimer *timer)
+{
+	struct dummy_hrtimer_pcm *dpcm;
+
+	dpcm = container_of(timer, struct dummy_hrtimer_pcm, timer);
+	if (!atomic_read(&dpcm->running))
+		return HRTIMER_NORESTART;
+	/*
+	 * In cases of XRUN and draining, this calls .trigger to stop PCM
+	 * substream.
+	 */
+	snd_pcm_period_elapsed(dpcm->substream);
+	if (!atomic_read(&dpcm->running))
+		return HRTIMER_NORESTART;
+
+	hrtimer_forward_now(timer, dpcm->period_time);
+	return HRTIMER_RESTART;
+}
+
+static int dummy_hrtimer_start(struct snd_pcm_substream *substream)
+{
+	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
+
+	dpcm->base_time = hrtimer_cb_get_time(&dpcm->timer);
+	hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL_SOFT);
+	atomic_set(&dpcm->running, 1);
+	return 0;
+}
+
+static int dummy_hrtimer_stop(struct snd_pcm_substream *substream)
+{
+	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
+
+	atomic_set(&dpcm->running, 0);
+	if (!hrtimer_callback_running(&dpcm->timer))
+		hrtimer_cancel(&dpcm->timer);
+	return 0;
+}
+
+static inline void dummy_hrtimer_sync(struct dummy_hrtimer_pcm *dpcm)
+{
+	hrtimer_cancel(&dpcm->timer);
+}
+
+static snd_pcm_uframes_t
+dummy_hrtimer_pointer(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct dummy_hrtimer_pcm *dpcm = runtime->private_data;
+	u64 delta;
+	u32 pos;
+
+	delta = ktime_us_delta(hrtimer_cb_get_time(&dpcm->timer),
+			       dpcm->base_time);
+	delta = div_u64(delta * runtime->rate + 999999, 1000000);
+	div_u64_rem(delta, runtime->buffer_size, &pos);
+	return pos;
+}
+
+static int dummy_hrtimer_prepare(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct dummy_hrtimer_pcm *dpcm = runtime->private_data;
+	unsigned int period, rate;
+	long sec;
+	unsigned long nsecs;
+
+	dummy_hrtimer_sync(dpcm);
+	period = runtime->period_size;
+	rate = runtime->rate;
+	sec = period / rate;
+	period %= rate;
+	nsecs = div_u64((u64)period * 1000000000UL + rate - 1, rate);
+	dpcm->period_time = ktime_set(sec, nsecs);
+
+	return 0;
+}
+
+static int dummy_hrtimer_create(struct snd_pcm_substream *substream)
+{
+	struct dummy_hrtimer_pcm *dpcm;
+
+	dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
+	if (!dpcm)
+		return -ENOMEM;
+	substream->runtime->private_data = dpcm;
+	hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_SOFT);
+	dpcm->timer.function = dummy_hrtimer_callback;
+	dpcm->substream = substream;
+	atomic_set(&dpcm->running, 0);
+	return 0;
+}
+
+static void dummy_hrtimer_free(struct snd_pcm_substream *substream)
+{
+	struct dummy_hrtimer_pcm *dpcm = substream->runtime->private_data;
+	dummy_hrtimer_sync(dpcm);
+	kfree(dpcm);
+}
+
+static const struct dummy_timer_ops dummy_hrtimer_ops = {
+	.create =	dummy_hrtimer_create,
+	.free =		dummy_hrtimer_free,
+	.prepare =	dummy_hrtimer_prepare,
+	.start =	dummy_hrtimer_start,
+	.stop =		dummy_hrtimer_stop,
+	.pointer =	dummy_hrtimer_pointer,
+};
+
+#endif /* CONFIG_HIGH_RES_TIMERS */
+
+/*
+ * PCM interface
+ */
+
+static int dummy_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
+{
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+	case SNDRV_PCM_TRIGGER_RESUME:
+		return get_dummy_ops(substream)->start(substream);
+	case SNDRV_PCM_TRIGGER_STOP:
+	case SNDRV_PCM_TRIGGER_SUSPEND:
+		return get_dummy_ops(substream)->stop(substream);
+	}
+	return -EINVAL;
+}
+
+static int dummy_pcm_prepare(struct snd_pcm_substream *substream)
+{
+	return get_dummy_ops(substream)->prepare(substream);
+}
+
+static snd_pcm_uframes_t dummy_pcm_pointer(struct snd_pcm_substream *substream)
+{
+	return get_dummy_ops(substream)->pointer(substream);
+}
+
+static const struct snd_pcm_hardware dummy_pcm_hardware = {
+	.info =			(SNDRV_PCM_INFO_MMAP |
+				 SNDRV_PCM_INFO_INTERLEAVED |
+				 SNDRV_PCM_INFO_RESUME |
+				 SNDRV_PCM_INFO_MMAP_VALID),
+	.formats =		USE_FORMATS,
+	.rates =		USE_RATE,
+	.rate_min =		USE_RATE_MIN,
+	.rate_max =		USE_RATE_MAX,
+	.channels_min =		USE_CHANNELS_MIN,
+	.channels_max =		USE_CHANNELS_MAX,
+	.buffer_bytes_max =	MAX_BUFFER_SIZE,
+	.period_bytes_min =	MIN_PERIOD_SIZE,
+	.period_bytes_max =	MAX_PERIOD_SIZE,
+	.periods_min =		USE_PERIODS_MIN,
+	.periods_max =		USE_PERIODS_MAX,
+	.fifo_size =		0,
+};
+
+static int dummy_pcm_hw_params(struct snd_pcm_substream *substream,
+			       struct snd_pcm_hw_params *hw_params)
+{
+	if (fake_buffer) {
+		/* runtime->dma_bytes has to be set manually to allow mmap */
+		substream->runtime->dma_bytes = params_buffer_bytes(hw_params);
+		return 0;
+	}
+	return 0;
+}
+
+static int dummy_pcm_open(struct snd_pcm_substream *substream)
+{
+	struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
+	const struct dummy_model *model = dummy->model;
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	const struct dummy_timer_ops *ops;
+	int err;
+
+	ops = &dummy_systimer_ops;
+#ifdef CONFIG_HIGH_RES_TIMERS
+	if (hrtimer)
+		ops = &dummy_hrtimer_ops;
+#endif
+
+	err = ops->create(substream);
+	if (err < 0)
+		return err;
+	get_dummy_ops(substream) = ops;
+
+	runtime->hw = dummy->pcm_hw;
+	if (substream->pcm->device & 1) {
+		runtime->hw.info &= ~SNDRV_PCM_INFO_INTERLEAVED;
+		runtime->hw.info |= SNDRV_PCM_INFO_NONINTERLEAVED;
+	}
+	if (substream->pcm->device & 2)
+		runtime->hw.info &= ~(SNDRV_PCM_INFO_MMAP |
+				      SNDRV_PCM_INFO_MMAP_VALID);
+
+	if (model == NULL)
+		return 0;
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		if (model->playback_constraints)
+			err = model->playback_constraints(substream->runtime);
+	} else {
+		if (model->capture_constraints)
+			err = model->capture_constraints(substream->runtime);
+	}
+	if (err < 0) {
+		get_dummy_ops(substream)->free(substream);
+		return err;
+	}
+	return 0;
+}
+
+static int dummy_pcm_close(struct snd_pcm_substream *substream)
+{
+	get_dummy_ops(substream)->free(substream);
+	return 0;
+}
+
+/*
+ * dummy buffer handling
+ */
+
+static void *dummy_page[2];
+
+static void free_fake_buffer(void)
+{
+	if (fake_buffer) {
+		int i;
+		for (i = 0; i < 2; i++)
+			if (dummy_page[i]) {
+				free_page((unsigned long)dummy_page[i]);
+				dummy_page[i] = NULL;
+			}
+	}
+}
+
+static int alloc_fake_buffer(void)
+{
+	int i;
+
+	if (!fake_buffer)
+		return 0;
+	for (i = 0; i < 2; i++) {
+		dummy_page[i] = (void *)get_zeroed_page(GFP_KERNEL);
+		if (!dummy_page[i]) {
+			free_fake_buffer();
+			return -ENOMEM;
+		}
+	}
+	return 0;
+}
+
+static int dummy_pcm_copy(struct snd_pcm_substream *substream,
+			  int channel, unsigned long pos,
+			  struct iov_iter *iter, unsigned long bytes)
+{
+	return 0; /* do nothing */
+}
+
+static int dummy_pcm_silence(struct snd_pcm_substream *substream,
+			     int channel, unsigned long pos,
+			     unsigned long bytes)
+{
+	return 0; /* do nothing */
+}
+
+static struct page *dummy_pcm_page(struct snd_pcm_substream *substream,
+				   unsigned long offset)
+{
+	return virt_to_page(dummy_page[substream->stream]); /* the same page */
+}
+
+static const struct snd_pcm_ops dummy_pcm_ops = {
+	.open =		dummy_pcm_open,
+	.close =	dummy_pcm_close,
+	.hw_params =	dummy_pcm_hw_params,
+	.prepare =	dummy_pcm_prepare,
+	.trigger =	dummy_pcm_trigger,
+	.pointer =	dummy_pcm_pointer,
+};
+
+static const struct snd_pcm_ops dummy_pcm_ops_no_buf = {
+	.open =		dummy_pcm_open,
+	.close =	dummy_pcm_close,
+	.hw_params =	dummy_pcm_hw_params,
+	.prepare =	dummy_pcm_prepare,
+	.trigger =	dummy_pcm_trigger,
+	.pointer =	dummy_pcm_pointer,
+	.copy =		dummy_pcm_copy,
+	.fill_silence =	dummy_pcm_silence,
+	.page =		dummy_pcm_page,
+};
+
+static int snd_card_dummy_pcm(struct snd_dummy *dummy, int device,
+			      int substreams)
+{
+	struct snd_pcm *pcm;
+	const struct snd_pcm_ops *ops;
+	int err;
+
+	err = snd_pcm_new(dummy->card, "Dummy PCM", device,
+			       substreams, substreams, &pcm);
+	if (err < 0)
+		return err;
+	dummy->pcm = pcm;
+	if (fake_buffer)
+		ops = &dummy_pcm_ops_no_buf;
+	else
+		ops = &dummy_pcm_ops;
+	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, ops);
+	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, ops);
+	pcm->private_data = dummy;
+	pcm->info_flags = 0;
+	strcpy(pcm->name, "Dummy PCM");
+	if (!fake_buffer) {
+		snd_pcm_set_managed_buffer_all(pcm,
+			SNDRV_DMA_TYPE_CONTINUOUS,
+			NULL,
+			0, 64*1024);
+	}
+	return 0;
+}
+
+/*
+ * mixer interface
+ */
+
+#define DUMMY_VOLUME(xname, xindex, addr) \
+{ .iface = SNDRV_CTL_ELEM_IFACE_MIXER, \
+  .access = SNDRV_CTL_ELEM_ACCESS_READWRITE | SNDRV_CTL_ELEM_ACCESS_TLV_READ, \
+  .name = xname, .index = xindex, \
+  .info = snd_dummy_volume_info, \
+  .get = snd_dummy_volume_get, .put = snd_dummy_volume_put, \
+  .private_value = addr, \
+  .tlv = { .p = db_scale_dummy } }
+
+static int snd_dummy_volume_info(struct snd_kcontrol *kcontrol,
+				 struct snd_ctl_elem_info *uinfo)
+{
+	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+	uinfo->count = 2;
+	uinfo->value.integer.min = mixer_volume_level_min;
+	uinfo->value.integer.max = mixer_volume_level_max;
+	return 0;
+}
+
+static int snd_dummy_volume_get(struct snd_kcontrol *kcontrol,
+				struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_dummy *dummy = snd_kcontrol_chip(kcontrol);
+	int addr = kcontrol->private_value;
+
+	spin_lock_irq(&dummy->mixer_lock);
+	ucontrol->value.integer.value[0] = dummy->mixer_volume[addr][0];
+	ucontrol->value.integer.value[1] = dummy->mixer_volume[addr][1];
+	spin_unlock_irq(&dummy->mixer_lock);
+	return 0;
+}
+
+static int snd_dummy_volume_put(struct snd_kcontrol *kcontrol,
+				struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_dummy *dummy = snd_kcontrol_chip(kcontrol);
+	int change, addr = kcontrol->private_value;
+	int left, right;
+
+	left = ucontrol->value.integer.value[0];
+	if (left < mixer_volume_level_min)
+		left = mixer_volume_level_min;
+	if (left > mixer_volume_level_max)
+		left = mixer_volume_level_max;
+	right = ucontrol->value.integer.value[1];
+	if (right < mixer_volume_level_min)
+		right = mixer_volume_level_min;
+	if (right > mixer_volume_level_max)
+		right = mixer_volume_level_max;
+	spin_lock_irq(&dummy->mixer_lock);
+	change = dummy->mixer_volume[addr][0] != left ||
+	         dummy->mixer_volume[addr][1] != right;
+	dummy->mixer_volume[addr][0] = left;
+	dummy->mixer_volume[addr][1] = right;
+	spin_unlock_irq(&dummy->mixer_lock);
+	return change;
+}
+
+static const DECLARE_TLV_DB_SCALE(db_scale_dummy, -4500, 30, 0);
+
+#define DUMMY_CAPSRC(xname, xindex, addr) \
+{ .iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = xname, .index = xindex, \
+  .info = snd_dummy_capsrc_info, \
+  .get = snd_dummy_capsrc_get, .put = snd_dummy_capsrc_put, \
+  .private_value = addr }
+
+#define snd_dummy_capsrc_info	snd_ctl_boolean_stereo_info
+
+static int snd_dummy_capsrc_get(struct snd_kcontrol *kcontrol,
+				struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_dummy *dummy = snd_kcontrol_chip(kcontrol);
+	int addr = kcontrol->private_value;
+
+	spin_lock_irq(&dummy->mixer_lock);
+	ucontrol->value.integer.value[0] = dummy->capture_source[addr][0];
+	ucontrol->value.integer.value[1] = dummy->capture_source[addr][1];
+	spin_unlock_irq(&dummy->mixer_lock);
+	return 0;
+}
+
+static int snd_dummy_capsrc_put(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_value *ucontrol)
+{
+	struct snd_dummy *dummy = snd_kcontrol_chip(kcontrol);
+	int change, addr = kcontrol->private_value;
+	int left, right;
+
+	left = ucontrol->value.integer.value[0] & 1;
+	right = ucontrol->value.integer.value[1] & 1;
+	spin_lock_irq(&dummy->mixer_lock);
+	change = dummy->capture_source[addr][0] != left &&
+	         dummy->capture_source[addr][1] != right;
+	dummy->capture_source[addr][0] = left;
+	dummy->capture_source[addr][1] = right;
+	spin_unlock_irq(&dummy->mixer_lock);
+	return change;
+}
+
+static int snd_dummy_iobox_info(struct snd_kcontrol *kcontrol,
+				struct snd_ctl_elem_info *info)
+{
+	static const char *const names[] = { "None", "CD Player" };
+
+	return snd_ctl_enum_info(info, 1, 2, names);
+}
+
+static int snd_dummy_iobox_get(struct snd_kcontrol *kcontrol,
+			       struct snd_ctl_elem_value *value)
+{
+	struct snd_dummy *dummy = snd_kcontrol_chip(kcontrol);
+
+	value->value.enumerated.item[0] = dummy->iobox;
+	return 0;
+}
+
+static int snd_dummy_iobox_put(struct snd_kcontrol *kcontrol,
+			       struct snd_ctl_elem_value *value)
+{
+	struct snd_dummy *dummy = snd_kcontrol_chip(kcontrol);
+	int changed;
+
+	if (value->value.enumerated.item[0] > 1)
+		return -EINVAL;
+
+	changed = value->value.enumerated.item[0] != dummy->iobox;
+	if (changed) {
+		dummy->iobox = value->value.enumerated.item[0];
+
+		if (dummy->iobox) {
+			dummy->cd_volume_ctl->vd[0].access &=
+				~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
+			dummy->cd_switch_ctl->vd[0].access &=
+				~SNDRV_CTL_ELEM_ACCESS_INACTIVE;
+		} else {
+			dummy->cd_volume_ctl->vd[0].access |=
+				SNDRV_CTL_ELEM_ACCESS_INACTIVE;
+			dummy->cd_switch_ctl->vd[0].access |=
+				SNDRV_CTL_ELEM_ACCESS_INACTIVE;
+		}
+
+		snd_ctl_notify(dummy->card, SNDRV_CTL_EVENT_MASK_INFO,
+			       &dummy->cd_volume_ctl->id);
+		snd_ctl_notify(dummy->card, SNDRV_CTL_EVENT_MASK_INFO,
+			       &dummy->cd_switch_ctl->id);
+	}
+
+	return changed;
+}
+
+static const struct snd_kcontrol_new snd_dummy_controls[] = {
+DUMMY_VOLUME("Master Volume", 0, MIXER_ADDR_MASTER),
+DUMMY_CAPSRC("Master Capture Switch", 0, MIXER_ADDR_MASTER),
+DUMMY_VOLUME("Synth Volume", 0, MIXER_ADDR_SYNTH),
+DUMMY_CAPSRC("Synth Capture Switch", 0, MIXER_ADDR_SYNTH),
+DUMMY_VOLUME("Line Volume", 0, MIXER_ADDR_LINE),
+DUMMY_CAPSRC("Line Capture Switch", 0, MIXER_ADDR_LINE),
+DUMMY_VOLUME("Mic Volume", 0, MIXER_ADDR_MIC),
+DUMMY_CAPSRC("Mic Capture Switch", 0, MIXER_ADDR_MIC),
+DUMMY_VOLUME("CD Volume", 0, MIXER_ADDR_CD),
+DUMMY_CAPSRC("CD Capture Switch", 0, MIXER_ADDR_CD),
+{
+	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
+	.name  = "External I/O Box",
+	.info  = snd_dummy_iobox_info,
+	.get   = snd_dummy_iobox_get,
+	.put   = snd_dummy_iobox_put,
+},
+};
+
+static int snd_card_dummy_new_mixer(struct snd_dummy *dummy)
+{
+	struct snd_card *card = dummy->card;
+	struct snd_kcontrol *kcontrol;
+	unsigned int idx;
+	int err;
+
+	spin_lock_init(&dummy->mixer_lock);
+	strcpy(card->mixername, "Dummy Mixer");
+	dummy->iobox = 1;
+
+	for (idx = 0; idx < ARRAY_SIZE(snd_dummy_controls); idx++) {
+		kcontrol = snd_ctl_new1(&snd_dummy_controls[idx], dummy);
+		err = snd_ctl_add(card, kcontrol);
+		if (err < 0)
+			return err;
+		if (!strcmp(kcontrol->id.name, "CD Volume"))
+			dummy->cd_volume_ctl = kcontrol;
+		else if (!strcmp(kcontrol->id.name, "CD Capture Switch"))
+			dummy->cd_switch_ctl = kcontrol;
+
+	}
+	return 0;
+}
+
+#if defined(CONFIG_SND_DEBUG) && defined(CONFIG_SND_PROC_FS)
+/*
+ * proc interface
+ */
+static void print_formats(struct snd_dummy *dummy,
+			  struct snd_info_buffer *buffer)
+{
+	snd_pcm_format_t i;
+
+	pcm_for_each_format(i) {
+		if (dummy->pcm_hw.formats & pcm_format_to_bits(i))
+			snd_iprintf(buffer, " %s", snd_pcm_format_name(i));
+	}
+}
+
+static void print_rates(struct snd_dummy *dummy,
+			struct snd_info_buffer *buffer)
+{
+	static const int rates[] = {
+		5512, 8000, 11025, 16000, 22050, 32000, 44100, 48000,
+		64000, 88200, 96000, 176400, 192000,
+	};
+	int i;
+
+	if (dummy->pcm_hw.rates & SNDRV_PCM_RATE_CONTINUOUS)
+		snd_iprintf(buffer, " continuous");
+	if (dummy->pcm_hw.rates & SNDRV_PCM_RATE_KNOT)
+		snd_iprintf(buffer, " knot");
+	for (i = 0; i < ARRAY_SIZE(rates); i++)
+		if (dummy->pcm_hw.rates & (1 << i))
+			snd_iprintf(buffer, " %d", rates[i]);
+}
+
+#define get_dummy_int_ptr(dummy, ofs) \
+	(unsigned int *)((char *)&((dummy)->pcm_hw) + (ofs))
+#define get_dummy_ll_ptr(dummy, ofs) \
+	(unsigned long long *)((char *)&((dummy)->pcm_hw) + (ofs))
+
+struct dummy_hw_field {
+	const char *name;
+	const char *format;
+	unsigned int offset;
+	unsigned int size;
+};
+#define FIELD_ENTRY(item, fmt) {		   \
+	.name = #item,				   \
+	.format = fmt,				   \
+	.offset = offsetof(struct snd_pcm_hardware, item), \
+	.size = sizeof(dummy_pcm_hardware.item) }
+
+static const struct dummy_hw_field fields[] = {
+	FIELD_ENTRY(formats, "%#llx"),
+	FIELD_ENTRY(rates, "%#x"),
+	FIELD_ENTRY(rate_min, "%d"),
+	FIELD_ENTRY(rate_max, "%d"),
+	FIELD_ENTRY(channels_min, "%d"),
+	FIELD_ENTRY(channels_max, "%d"),
+	FIELD_ENTRY(buffer_bytes_max, "%ld"),
+	FIELD_ENTRY(period_bytes_min, "%ld"),
+	FIELD_ENTRY(period_bytes_max, "%ld"),
+	FIELD_ENTRY(periods_min, "%d"),
+	FIELD_ENTRY(periods_max, "%d"),
+};
+
+static void dummy_proc_read(struct snd_info_entry *entry,
+			    struct snd_info_buffer *buffer)
+{
+	struct snd_dummy *dummy = entry->private_data;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(fields); i++) {
+		snd_iprintf(buffer, "%s ", fields[i].name);
+		if (fields[i].size == sizeof(int))
+			snd_iprintf(buffer, fields[i].format,
+				*get_dummy_int_ptr(dummy, fields[i].offset));
+		else
+			snd_iprintf(buffer, fields[i].format,
+				*get_dummy_ll_ptr(dummy, fields[i].offset));
+		if (!strcmp(fields[i].name, "formats"))
+			print_formats(dummy, buffer);
+		else if (!strcmp(fields[i].name, "rates"))
+			print_rates(dummy, buffer);
+		snd_iprintf(buffer, "\n");
+	}
+}
+
+static void dummy_proc_write(struct snd_info_entry *entry,
+			     struct snd_info_buffer *buffer)
+{
+	struct snd_dummy *dummy = entry->private_data;
+	char line[64];
+
+	while (!snd_info_get_line(buffer, line, sizeof(line))) {
+		char item[20];
+		const char *ptr;
+		unsigned long long val;
+		int i;
+
+		ptr = snd_info_get_str(item, line, sizeof(item));
+		for (i = 0; i < ARRAY_SIZE(fields); i++) {
+			if (!strcmp(item, fields[i].name))
+				break;
+		}
+		if (i >= ARRAY_SIZE(fields))
+			continue;
+		snd_info_get_str(item, ptr, sizeof(item));
+		if (kstrtoull(item, 0, &val))
+			continue;
+		if (fields[i].size == sizeof(int))
+			*get_dummy_int_ptr(dummy, fields[i].offset) = val;
+		else
+			*get_dummy_ll_ptr(dummy, fields[i].offset) = val;
+	}
+}
+
+static void dummy_proc_init(struct snd_dummy *chip)
+{
+	snd_card_rw_proc_new(chip->card, "dummy_pcm", chip,
+			     dummy_proc_read, dummy_proc_write);
+}
+#else
+#define dummy_proc_init(x)
+#endif /* CONFIG_SND_DEBUG && CONFIG_SND_PROC_FS */
+
+static int snd_dummy_probe(struct platform_device *devptr)
+{
+	struct snd_card *card;
+	struct snd_dummy *dummy;
+	const struct dummy_model *m = NULL, **mdl;
+	int idx, err;
+	int dev = devptr->id;
+
+	err = snd_devm_card_new(&devptr->dev, index[dev], id[dev], THIS_MODULE,
+				sizeof(struct snd_dummy), &card);
+	if (err < 0)
+		return err;
+	dummy = card->private_data;
+	dummy->card = card;
+	for (mdl = dummy_models; *mdl && model[dev]; mdl++) {
+		if (strcmp(model[dev], (*mdl)->name) == 0) {
+			printk(KERN_INFO
+				"snd-dummy: Using model '%s' for card %i\n",
+				(*mdl)->name, card->number);
+			m = dummy->model = *mdl;
+			break;
+		}
+	}
+	for (idx = 0; idx < MAX_PCM_DEVICES && idx < pcm_devs[dev]; idx++) {
+		if (pcm_substreams[dev] < 1)
+			pcm_substreams[dev] = 1;
+		if (pcm_substreams[dev] > MAX_PCM_SUBSTREAMS)
+			pcm_substreams[dev] = MAX_PCM_SUBSTREAMS;
+		err = snd_card_dummy_pcm(dummy, idx, pcm_substreams[dev]);
+		if (err < 0)
+			return err;
+	}
+
+	dummy->pcm_hw = dummy_pcm_hardware;
+	if (m) {
+		if (m->formats)
+			dummy->pcm_hw.formats = m->formats;
+		if (m->buffer_bytes_max)
+			dummy->pcm_hw.buffer_bytes_max = m->buffer_bytes_max;
+		if (m->period_bytes_min)
+			dummy->pcm_hw.period_bytes_min = m->period_bytes_min;
+		if (m->period_bytes_max)
+			dummy->pcm_hw.period_bytes_max = m->period_bytes_max;
+		if (m->periods_min)
+			dummy->pcm_hw.periods_min = m->periods_min;
+		if (m->periods_max)
+			dummy->pcm_hw.periods_max = m->periods_max;
+		if (m->rates)
+			dummy->pcm_hw.rates = m->rates;
+		if (m->rate_min)
+			dummy->pcm_hw.rate_min = m->rate_min;
+		if (m->rate_max)
+			dummy->pcm_hw.rate_max = m->rate_max;
+		if (m->channels_min)
+			dummy->pcm_hw.channels_min = m->channels_min;
+		if (m->channels_max)
+			dummy->pcm_hw.channels_max = m->channels_max;
+	}
+
+	if (mixer_volume_level_min > mixer_volume_level_max) {
+		pr_warn("snd-dummy: Invalid mixer volume level: min=%d, max=%d. Fall back to default value.\n",
+		mixer_volume_level_min, mixer_volume_level_max);
+		mixer_volume_level_min = USE_MIXER_VOLUME_LEVEL_MIN;
+		mixer_volume_level_max = USE_MIXER_VOLUME_LEVEL_MAX;
+	}
+	err = snd_card_dummy_new_mixer(dummy);
+	if (err < 0)
+		return err;
+	strcpy(card->driver, "Dummy");
+	strcpy(card->shortname, "Dummy");
+	sprintf(card->longname, "Dummy %i", dev + 1);
+
+	dummy_proc_init(dummy);
+
+	err = snd_card_register(card);
+	if (err < 0)
+		return err;
+	platform_set_drvdata(devptr, card);
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int snd_dummy_suspend(struct device *pdev)
+{
+	struct snd_card *card = dev_get_drvdata(pdev);
+
+	snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
+	return 0;
+}
+
+static int snd_dummy_resume(struct device *pdev)
+{
+	struct snd_card *card = dev_get_drvdata(pdev);
+
+	snd_power_change_state(card, SNDRV_CTL_POWER_D0);
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(snd_dummy_pm, snd_dummy_suspend, snd_dummy_resume);
+#define SND_DUMMY_PM_OPS	&snd_dummy_pm
+#else
+#define SND_DUMMY_PM_OPS	NULL
+#endif
+
+#define SND_DUMMY_DRIVER	"snd_dummy"
+
+static struct platform_driver snd_dummy_driver = {
+	.probe		= snd_dummy_probe,
+	.driver		= {
+		.name	= SND_DUMMY_DRIVER,
+		.pm	= SND_DUMMY_PM_OPS,
+	},
+};
+
+static void snd_dummy_unregister_all(void)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(devices); ++i)
+		platform_device_unregister(devices[i]);
+	platform_driver_unregister(&snd_dummy_driver);
+	free_fake_buffer();
+}
+
+static int __init alsa_card_dummy_init(void)
+{
+	int i, cards, err;
+
+	err = platform_driver_register(&snd_dummy_driver);
+	if (err < 0)
+		return err;
+
+	err = alloc_fake_buffer();
+	if (err < 0) {
+		platform_driver_unregister(&snd_dummy_driver);
+		return err;
+	}
+
+	cards = 0;
+	for (i = 0; i < SNDRV_CARDS; i++) {
+		struct platform_device *device;
+		if (! enable[i])
+			continue;
+		device = platform_device_register_simple(SND_DUMMY_DRIVER,
+							 i, NULL, 0);
+		if (IS_ERR(device))
+			continue;
+		if (!platform_get_drvdata(device)) {
+			platform_device_unregister(device);
+			continue;
+		}
+		devices[i] = device;
+		cards++;
+	}
+	if (!cards) {
+#ifdef MODULE
+		printk(KERN_ERR "Dummy soundcard not found or device busy\n");
+#endif
+		snd_dummy_unregister_all();
+		return -ENODEV;
+	}
+	return 0;
+}
+
+static void __exit alsa_card_dummy_exit(void)
+{
+	snd_dummy_unregister_all();
+}
+
+module_init(alsa_card_dummy_init)
+module_exit(alsa_card_dummy_exit)