dummy.c

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/*
 *  Dummy soundcard
 *  Copyright (c) by Jaroslav Kysela <[email protected]>
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#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 <[email protected]>");
MODULE_DESCRIPTION("Dummy soundcard (/dev/null)");
MODULE_LICENSE("GPL");
MODULE_SUPPORTED_DEVICE("{{ALSA,Dummy soundcard}}");

#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

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};
#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(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 *);
};

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;
    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];
    const struct dummy_timer_ops *timer_ops;
};

/*
 * 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;
}

struct dummy_model model_emu10k1 = {
    .name = "emu10k1",
    .playback_constraints = emu10k1_playback_constraints,
    .buffer_bytes_max = 128 * 1024,
};

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,
};

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,
};

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,
};

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,
};

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,
};

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 {
    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)
{
    dpcm->timer.expires = jiffies +
        (dpcm->frac_period_rest + dpcm->rate - 1) / dpcm->rate;
    add_timer(&dpcm->timer);
}

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(unsigned long data)
{
    struct dummy_systimer_pcm *dpcm = (struct dummy_systimer_pcm *)data;
    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;
    init_timer(&dpcm->timer);
    dpcm->timer.data = (unsigned long) dpcm;
    dpcm->timer.function = dummy_systimer_callback;
    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 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 {
    ktime_t base_time;
    ktime_t period_time;
    atomic_t running;
    struct hrtimer timer;
    struct tasklet_struct tasklet;
    struct snd_pcm_substream *substream;
};

static void dummy_hrtimer_pcm_elapsed(unsigned long priv)
{
    struct dummy_hrtimer_pcm *dpcm = (struct dummy_hrtimer_pcm *)priv;
    if (atomic_read(&dpcm->running))
        snd_pcm_period_elapsed(dpcm->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;
    tasklet_schedule(&dpcm->tasklet);
    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);
    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);
    hrtimer_cancel(&dpcm->timer);
    return 0;
}

static inline void dummy_hrtimer_sync(struct dummy_hrtimer_pcm *dpcm)
{
    tasklet_kill(&dpcm->tasklet);
}

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);
    dpcm->timer.function = dummy_hrtimer_callback;
    dpcm->substream = substream;
    atomic_set(&dpcm->running, 0);
    tasklet_init(&dpcm->tasklet, dummy_hrtimer_pcm_elapsed,
             (unsigned long)dpcm);
    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 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)
{
    struct snd_dummy *dummy = snd_pcm_substream_chip(substream);

    switch (cmd) {
    case SNDRV_PCM_TRIGGER_START:
    case SNDRV_PCM_TRIGGER_RESUME:
        return dummy->timer_ops->start(substream);
    case SNDRV_PCM_TRIGGER_STOP:
    case SNDRV_PCM_TRIGGER_SUSPEND:
        return dummy->timer_ops->stop(substream);
    }
    return -EINVAL;
}

static int dummy_pcm_prepare(struct snd_pcm_substream *substream)
{
    struct snd_dummy *dummy = snd_pcm_substream_chip(substream);

    return dummy->timer_ops->prepare(substream);
}

static snd_pcm_uframes_t dummy_pcm_pointer(struct snd_pcm_substream *substream)
{
    struct snd_dummy *dummy = snd_pcm_substream_chip(substream);

    return dummy->timer_ops->pointer(substream);
}

static 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 snd_pcm_lib_malloc_pages(substream,
                    params_buffer_bytes(hw_params));
}

static int dummy_pcm_hw_free(struct snd_pcm_substream *substream)
{
    if (fake_buffer)
        return 0;
    return snd_pcm_lib_free_pages(substream);
}

static int dummy_pcm_open(struct snd_pcm_substream *substream)
{
    struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
    struct dummy_model *model = dummy->model;
    struct snd_pcm_runtime *runtime = substream->runtime;
    int err;

    dummy->timer_ops = &dummy_systimer_ops;
#ifdef CONFIG_HIGH_RES_TIMERS
    if (hrtimer)
        dummy->timer_ops = &dummy_hrtimer_ops;
#endif

    err = dummy->timer_ops->create(substream);
    if (err < 0)
        return err;

    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) {
        dummy->timer_ops->free(substream);
        return err;
    }
    return 0;
}

static int dummy_pcm_close(struct snd_pcm_substream *substream)
{
    struct snd_dummy *dummy = snd_pcm_substream_chip(substream);
    dummy->timer_ops->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, snd_pcm_uframes_t pos,
              void __user *dst, snd_pcm_uframes_t count)
{
    return 0; /* do nothing */
}

static int dummy_pcm_silence(struct snd_pcm_substream *substream,
                 int channel, snd_pcm_uframes_t pos,
                 snd_pcm_uframes_t count)
{
    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 struct snd_pcm_ops dummy_pcm_ops = {
    .open =     dummy_pcm_open,
    .close =    dummy_pcm_close,
    .ioctl =    snd_pcm_lib_ioctl,
    .hw_params =    dummy_pcm_hw_params,
    .hw_free =  dummy_pcm_hw_free,
    .prepare =  dummy_pcm_prepare,
    .trigger =  dummy_pcm_trigger,
    .pointer =  dummy_pcm_pointer,
};

static struct snd_pcm_ops dummy_pcm_ops_no_buf = {
    .open =     dummy_pcm_open,
    .close =    dummy_pcm_close,
    .ioctl =    snd_pcm_lib_ioctl,
    .hw_params =    dummy_pcm_hw_params,
    .hw_free =  dummy_pcm_hw_free,
    .prepare =  dummy_pcm_prepare,
    .trigger =  dummy_pcm_trigger,
    .pointer =  dummy_pcm_pointer,
    .copy =     dummy_pcm_copy,
    .silence =  dummy_pcm_silence,
    .page =     dummy_pcm_page,
};

static int __devinit snd_card_dummy_pcm(struct snd_dummy *dummy, int device,
                    int substreams)
{
    struct snd_pcm *pcm;
    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_lib_preallocate_pages_for_all(pcm,
            SNDRV_DMA_TYPE_CONTINUOUS,
            snd_dma_continuous_data(GFP_KERNEL),
            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 = -50;
    uinfo->value.integer.max = 100;
    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 < -50)
        left = -50;
    if (left > 100)
        left = 100;
    right = ucontrol->value.integer.value[1];
    if (right < -50)
        right = -50;
    if (right > 100)
        right = 100;
    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 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)
};

static int __devinit snd_card_dummy_new_mixer(struct snd_dummy *dummy)
{
    struct snd_card *card = dummy->card;
    unsigned int idx;
    int err;

    spin_lock_init(&dummy->mixer_lock);
    strcpy(card->mixername, "Dummy Mixer");

    for (idx = 0; idx < ARRAY_SIZE(snd_dummy_controls); idx++) {
        err = snd_ctl_add(card, snd_ctl_new1(&snd_dummy_controls[idx], dummy));
        if (err < 0)
            return err;
    }
    return 0;
}

#if defined(CONFIG_SND_DEBUG) && defined(CONFIG_PROC_FS)
/*
 * proc interface
 */
static void print_formats(struct snd_dummy *dummy,
              struct snd_info_buffer *buffer)
{
    int i;

    for (i = 0; i < SNDRV_PCM_FORMAT_LAST; i++) {
        if (dummy->pcm_hw.formats & (1ULL << i))
            snd_iprintf(buffer, " %s", snd_pcm_format_name(i));
    }
}

static void print_rates(struct snd_dummy *dummy,
            struct snd_info_buffer *buffer)
{
    static 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 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 (strict_strtoull(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 __devinit dummy_proc_init(struct snd_dummy *chip)
{
    struct snd_info_entry *entry;

    if (!snd_card_proc_new(chip->card, "dummy_pcm", &entry)) {
        snd_info_set_text_ops(entry, chip, dummy_proc_read);
        entry->c.text.write = dummy_proc_write;
        entry->mode |= S_IWUSR;
        entry->private_data = chip;
    }
}
#else
#define dummy_proc_init(x)
#endif /* CONFIG_SND_DEBUG && CONFIG_PROC_FS */

static int __devinit snd_dummy_probe(struct platform_device *devptr)
{
    struct snd_card *card;
    struct snd_dummy *dummy;
    struct dummy_model *m = NULL, **mdl;
    int idx, err;
    int dev = devptr->id;

    err = snd_card_create(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)
            goto __nodev;
    }

    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;
    }

    err = snd_card_dummy_new_mixer(dummy);
    if (err < 0)
        goto __nodev;
    strcpy(card->driver, "Dummy");
    strcpy(card->shortname, "Dummy");
    sprintf(card->longname, "Dummy %i", dev + 1);

    dummy_proc_init(dummy);

    snd_card_set_dev(card, &devptr->dev);

    err = snd_card_register(card);
    if (err == 0) {
        platform_set_drvdata(devptr, card);
        return 0;
    }
      __nodev:
    snd_card_free(card);
    return err;
}

static int __devexit snd_dummy_remove(struct platform_device *devptr)
{
    snd_card_free(platform_get_drvdata(devptr));
    platform_set_drvdata(devptr, NULL);
    return 0;
}

#ifdef CONFIG_PM_SLEEP
static int snd_dummy_suspend(struct device *pdev)
{
    struct snd_card *card = dev_get_drvdata(pdev);
    struct snd_dummy *dummy = card->private_data;

    snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
    snd_pcm_suspend_all(dummy->pcm);
    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,
    .remove     = __devexit_p(snd_dummy_remove),
    .driver     = {
        .name   = SND_DUMMY_DRIVER,
        .owner  = THIS_MODULE,
        .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)