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dummy.c

/*
 *  Dummy soundcard
 *  Copyright (c) by Jaroslav Kysela <perex@suse.cz>
 *
 *   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 <sound/driver.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/wait.h>
#include <linux/moduleparam.h>
#include <sound/core.h>
#include <sound/control.h>
#include <sound/pcm.h>
#include <sound/rawmidi.h>
#include <sound/initval.h>

MODULE_AUTHOR("Jaroslav Kysela <perex@suse.cz>");
MODULE_DESCRIPTION("Dummy soundcard (/dev/null)");
MODULE_LICENSE("GPL");
MODULE_SUPPORTED_DEVICE("{{ALSA,Dummy soundcard}}");

#define MAX_PCM_DEVICES       4
#define MAX_PCM_SUBSTREAMS    16
#define MAX_MIDI_DEVICES      2

#if 0 /* emu10k1 emulation */
#define MAX_BUFFER_SIZE       (128 * 1024)
static int emu10k1_playback_constraints(snd_pcm_runtime_t *runtime)
{
      int err;
      if ((err = snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS)) < 0)
            return err;
      if ((err = snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_BUFFER_BYTES, 256, UINT_MAX)) < 0)
            return err;
      return 0;
}
#define add_playback_constraints emu10k1_playback_constraints
#endif

#if 0 /* RME9652 emulation */
#define MAX_BUFFER_SIZE       (26 * 64 * 1024)
#define USE_FORMATS           SNDRV_PCM_FMTBIT_S32_LE
#define USE_CHANNELS_MIN      26
#define USE_CHANNELS_MAX      26
#define USE_PERIODS_MIN       2
#define USE_PERIODS_MAX       2
#endif

#if 0 /* ICE1712 emulation */
#define MAX_BUFFER_SIZE       (256 * 1024)
#define USE_FORMATS           SNDRV_PCM_FMTBIT_S32_LE
#define USE_CHANNELS_MIN      10
#define USE_CHANNELS_MAX      10
#define USE_PERIODS_MIN       1
#define USE_PERIODS_MAX       1024
#endif

#if 0 /* UDA1341 emulation */
#define MAX_BUFFER_SIZE       (16380)
#define USE_FORMATS           SNDRV_PCM_FMTBIT_S16_LE
#define USE_CHANNELS_MIN      2
#define USE_CHANNELS_MAX      2
#define USE_PERIODS_MIN       2
#define USE_PERIODS_MAX       255
#endif

#if 0 /* simple AC97 bridge (intel8x0) with 48kHz AC97 only codec */
#define USE_FORMATS           SNDRV_PCM_FMTBIT_S16_LE
#define USE_CHANNELS_MIN      2
#define USE_CHANNELS_MAX      2
#define USE_RATE        SNDRV_PCM_RATE_48000
#define USE_RATE_MIN          48000
#define USE_RATE_MAX          48000
#endif


/* defaults */
#ifndef MAX_BUFFER_SIZE
#define MAX_BUFFER_SIZE       (64*1024)
#endif
#ifndef USE_FORMATS
#define USE_FORMATS           (SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S16_LE)
#endif
#ifndef USE_RATE
#define USE_RATE        SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_48000
#define USE_RATE_MIN          5500
#define USE_RATE_MAX          48000
#endif
#ifndef USE_CHANNELS_MIN
#define USE_CHANNELS_MIN      1
#endif
#ifndef USE_CHANNELS_MAX
#define USE_CHANNELS_MAX      2
#endif
#ifndef USE_PERIODS_MIN
#define USE_PERIODS_MIN       1
#endif
#ifndef USE_PERIODS_MAX
#define USE_PERIODS_MAX       1024
#endif
#ifndef add_playback_constraints
#define add_playback_constraints(x) 0
#endif
#ifndef add_capture_constraints
#define add_capture_constraints(x) 0
#endif

static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;    /* Index 0-MAX */
static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;     /* ID for this card */
static int enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
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};

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(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 # (1-16) for dummy driver.");
//module_param_array(midi_devs, int, NULL, 0444);
//MODULE_PARM_DESC(midi_devs, "MIDI devices # (0-2) for dummy driver.");

#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

typedef struct snd_card_dummy {
      snd_card_t *card;
      spinlock_t mixer_lock;
      int mixer_volume[MIXER_ADDR_LAST+1][2];
      int capture_source[MIXER_ADDR_LAST+1][2];
} snd_card_dummy_t;

typedef struct snd_card_dummy_pcm {
      snd_card_dummy_t *dummy;
      spinlock_t lock;
      struct timer_list timer;
      unsigned int pcm_size;
      unsigned int pcm_count;
      unsigned int pcm_bps;         /* bytes per second */
      unsigned int pcm_jiffie;      /* bytes per one jiffie */
      unsigned int pcm_irq_pos;     /* IRQ position */
      unsigned int pcm_buf_pos;     /* position in buffer */
      snd_pcm_substream_t *substream;
} snd_card_dummy_pcm_t;

static snd_card_t *snd_dummy_cards[SNDRV_CARDS] = SNDRV_DEFAULT_PTR;


static void snd_card_dummy_pcm_timer_start(snd_pcm_substream_t * substream)
{
      snd_pcm_runtime_t *runtime = substream->runtime;
      snd_card_dummy_pcm_t *dpcm = runtime->private_data;

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

static void snd_card_dummy_pcm_timer_stop(snd_pcm_substream_t * substream)
{
      snd_pcm_runtime_t *runtime = substream->runtime;
      snd_card_dummy_pcm_t *dpcm = runtime->private_data;

      del_timer(&dpcm->timer);
}

static int snd_card_dummy_playback_trigger(snd_pcm_substream_t * substream,
                                 int cmd)
{
      if (cmd == SNDRV_PCM_TRIGGER_START) {
            snd_card_dummy_pcm_timer_start(substream);
      } else if (cmd == SNDRV_PCM_TRIGGER_STOP) {
            snd_card_dummy_pcm_timer_stop(substream);
      } else {
            return -EINVAL;
      }
      return 0;
}

static int snd_card_dummy_capture_trigger(snd_pcm_substream_t * substream,
                                int cmd)
{
      if (cmd == SNDRV_PCM_TRIGGER_START) {
            snd_card_dummy_pcm_timer_start(substream);
      } else if (cmd == SNDRV_PCM_TRIGGER_STOP) {
            snd_card_dummy_pcm_timer_stop(substream);
      } else {
            return -EINVAL;
      }
      return 0;
}

static int snd_card_dummy_pcm_prepare(snd_pcm_substream_t * substream)
{
      snd_pcm_runtime_t *runtime = substream->runtime;
      snd_card_dummy_pcm_t *dpcm = runtime->private_data;
      unsigned int bps;

      bps = runtime->rate * runtime->channels;
      bps *= snd_pcm_format_width(runtime->format);
      bps /= 8;
      if (bps <= 0)
            return -EINVAL;
      dpcm->pcm_bps = bps;
      dpcm->pcm_jiffie = bps / HZ;
      dpcm->pcm_size = snd_pcm_lib_buffer_bytes(substream);
      dpcm->pcm_count = snd_pcm_lib_period_bytes(substream);
      dpcm->pcm_irq_pos = 0;
      dpcm->pcm_buf_pos = 0;
      return 0;
}

static int snd_card_dummy_playback_prepare(snd_pcm_substream_t * substream)
{
      return snd_card_dummy_pcm_prepare(substream);
}

static int snd_card_dummy_capture_prepare(snd_pcm_substream_t * substream)
{
      return snd_card_dummy_pcm_prepare(substream);
}

static void snd_card_dummy_pcm_timer_function(unsigned long data)
{
      snd_card_dummy_pcm_t *dpcm = (snd_card_dummy_pcm_t *)data;
      
      dpcm->timer.expires = 1 + jiffies;
      add_timer(&dpcm->timer);
      spin_lock_irq(&dpcm->lock);
      dpcm->pcm_irq_pos += dpcm->pcm_jiffie;
      dpcm->pcm_buf_pos += dpcm->pcm_jiffie;
      dpcm->pcm_buf_pos %= dpcm->pcm_size;
      if (dpcm->pcm_irq_pos >= dpcm->pcm_count) {
            dpcm->pcm_irq_pos %= dpcm->pcm_count;
            snd_pcm_period_elapsed(dpcm->substream);
      }
      spin_unlock_irq(&dpcm->lock); 
}

static snd_pcm_uframes_t snd_card_dummy_playback_pointer(snd_pcm_substream_t * substream)
{
      snd_pcm_runtime_t *runtime = substream->runtime;
      snd_card_dummy_pcm_t *dpcm = runtime->private_data;

      return bytes_to_frames(runtime, dpcm->pcm_buf_pos);
}

static snd_pcm_uframes_t snd_card_dummy_capture_pointer(snd_pcm_substream_t * substream)
{
      snd_pcm_runtime_t *runtime = substream->runtime;
      snd_card_dummy_pcm_t *dpcm = runtime->private_data;

      return bytes_to_frames(runtime, dpcm->pcm_buf_pos);
}

static snd_pcm_hardware_t snd_card_dummy_playback =
{
      .info =                 (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
                         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 =     64,
      .period_bytes_max =     MAX_BUFFER_SIZE,
      .periods_min =          USE_PERIODS_MIN,
      .periods_max =          USE_PERIODS_MAX,
      .fifo_size =            0,
};

static snd_pcm_hardware_t snd_card_dummy_capture =
{
      .info =                 (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
                         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 =     64,
      .period_bytes_max =     MAX_BUFFER_SIZE,
      .periods_min =          USE_PERIODS_MIN,
      .periods_max =          USE_PERIODS_MAX,
      .fifo_size =            0,
};

static void snd_card_dummy_runtime_free(snd_pcm_runtime_t *runtime)
{
      snd_card_dummy_pcm_t *dpcm = runtime->private_data;
      kfree(dpcm);
}

static int snd_card_dummy_hw_params(snd_pcm_substream_t * substream,
                            snd_pcm_hw_params_t * hw_params)
{
      return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params));
}

static int snd_card_dummy_hw_free(snd_pcm_substream_t * substream)
{
      return snd_pcm_lib_free_pages(substream);
}

static int snd_card_dummy_playback_open(snd_pcm_substream_t * substream)
{
      snd_pcm_runtime_t *runtime = substream->runtime;
      snd_card_dummy_pcm_t *dpcm;
      int err;

      dpcm = kcalloc(1, sizeof(*dpcm), GFP_KERNEL);
      if (dpcm == NULL)
            return -ENOMEM;
      init_timer(&dpcm->timer);
      dpcm->timer.data = (unsigned long) dpcm;
      dpcm->timer.function = snd_card_dummy_pcm_timer_function;
      spin_lock_init(&dpcm->lock);
      dpcm->substream = substream;
      runtime->private_data = dpcm;
      runtime->private_free = snd_card_dummy_runtime_free;
      runtime->hw = snd_card_dummy_playback;
      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 ((err = add_playback_constraints(runtime)) < 0) {
            kfree(dpcm);
            return err;
      }

      return 0;
}

static int snd_card_dummy_capture_open(snd_pcm_substream_t * substream)
{
      snd_pcm_runtime_t *runtime = substream->runtime;
      snd_card_dummy_pcm_t *dpcm;
      int err;

      dpcm = kcalloc(1, sizeof(*dpcm), GFP_KERNEL);
      if (dpcm == NULL)
            return -ENOMEM;
      init_timer(&dpcm->timer);
      dpcm->timer.data = (unsigned long) dpcm;
      dpcm->timer.function = snd_card_dummy_pcm_timer_function;
      spin_lock_init(&dpcm->lock);
      dpcm->substream = substream;
      runtime->private_data = dpcm;
      runtime->private_free = snd_card_dummy_runtime_free;
      runtime->hw = snd_card_dummy_capture;
      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 ((err = add_capture_constraints(runtime)) < 0) {
            kfree(dpcm);
            return err;
      }

      return 0;
}

static int snd_card_dummy_playback_close(snd_pcm_substream_t * substream)
{
      return 0;
}

static int snd_card_dummy_capture_close(snd_pcm_substream_t * substream)
{
      return 0;
}

static snd_pcm_ops_t snd_card_dummy_playback_ops = {
      .open =                 snd_card_dummy_playback_open,
      .close =          snd_card_dummy_playback_close,
      .ioctl =          snd_pcm_lib_ioctl,
      .hw_params =            snd_card_dummy_hw_params,
      .hw_free =        snd_card_dummy_hw_free,
      .prepare =        snd_card_dummy_playback_prepare,
      .trigger =        snd_card_dummy_playback_trigger,
      .pointer =        snd_card_dummy_playback_pointer,
};

static snd_pcm_ops_t snd_card_dummy_capture_ops = {
      .open =                 snd_card_dummy_capture_open,
      .close =          snd_card_dummy_capture_close,
      .ioctl =          snd_pcm_lib_ioctl,
      .hw_params =            snd_card_dummy_hw_params,
      .hw_free =        snd_card_dummy_hw_free,
      .prepare =        snd_card_dummy_capture_prepare,
      .trigger =        snd_card_dummy_capture_trigger,
      .pointer =        snd_card_dummy_capture_pointer,
};

static int __init snd_card_dummy_pcm(snd_card_dummy_t *dummy, int device, int substreams)
{
      snd_pcm_t *pcm;
      int err;

      if ((err = snd_pcm_new(dummy->card, "Dummy PCM", device, substreams, substreams, &pcm)) < 0)
            return err;
      snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &snd_card_dummy_playback_ops);
      snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_card_dummy_capture_ops);
      pcm->private_data = dummy;
      pcm->info_flags = 0;
      strcpy(pcm->name, "Dummy PCM");
      snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
                                    snd_dma_continuous_data(GFP_KERNEL),
                                    0, 64*1024);
      return 0;
}

#define DUMMY_VOLUME(xname, xindex, addr) \
{ .iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = xname, .index = xindex, \
  .info = snd_dummy_volume_info, \
  .get = snd_dummy_volume_get, .put = snd_dummy_volume_put, \
  .private_value = addr }

static int snd_dummy_volume_info(snd_kcontrol_t * kcontrol, snd_ctl_elem_info_t * 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(snd_kcontrol_t * kcontrol, snd_ctl_elem_value_t * ucontrol)
{
      snd_card_dummy_t *dummy = snd_kcontrol_chip(kcontrol);
      unsigned long flags;
      int addr = kcontrol->private_value;

      spin_lock_irqsave(&dummy->mixer_lock, flags);
      ucontrol->value.integer.value[0] = dummy->mixer_volume[addr][0];
      ucontrol->value.integer.value[1] = dummy->mixer_volume[addr][1];
      spin_unlock_irqrestore(&dummy->mixer_lock, flags);
      return 0;
}

static int snd_dummy_volume_put(snd_kcontrol_t * kcontrol, snd_ctl_elem_value_t * ucontrol)
{
      snd_card_dummy_t *dummy = snd_kcontrol_chip(kcontrol);
      unsigned long flags;
      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_irqsave(&dummy->mixer_lock, flags);
      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_irqrestore(&dummy->mixer_lock, flags);
      return change;
}

#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 }

static int snd_dummy_capsrc_info(snd_kcontrol_t * kcontrol, snd_ctl_elem_info_t * uinfo)
{
      uinfo->type = SNDRV_CTL_ELEM_TYPE_BOOLEAN;
      uinfo->count = 2;
      uinfo->value.integer.min = 0;
      uinfo->value.integer.max = 1;
      return 0;
}
 
static int snd_dummy_capsrc_get(snd_kcontrol_t * kcontrol, snd_ctl_elem_value_t * ucontrol)
{
      snd_card_dummy_t *dummy = snd_kcontrol_chip(kcontrol);
      unsigned long flags;
      int addr = kcontrol->private_value;

      spin_lock_irqsave(&dummy->mixer_lock, flags);
      ucontrol->value.integer.value[0] = dummy->capture_source[addr][0];
      ucontrol->value.integer.value[1] = dummy->capture_source[addr][1];
      spin_unlock_irqrestore(&dummy->mixer_lock, flags);
      return 0;
}

static int snd_dummy_capsrc_put(snd_kcontrol_t * kcontrol, snd_ctl_elem_value_t * ucontrol)
{
      snd_card_dummy_t *dummy = snd_kcontrol_chip(kcontrol);
      unsigned long flags;
      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_irqsave(&dummy->mixer_lock, flags);
      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_irqrestore(&dummy->mixer_lock, flags);
      return change;
}

static snd_kcontrol_new_t 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_MASTER),
DUMMY_VOLUME("Line Volume", 0, MIXER_ADDR_LINE),
DUMMY_CAPSRC("Line Capture Switch", 0, MIXER_ADDR_MASTER),
DUMMY_VOLUME("Mic Volume", 0, MIXER_ADDR_MIC),
DUMMY_CAPSRC("Mic Capture Switch", 0, MIXER_ADDR_MASTER),
DUMMY_VOLUME("CD Volume", 0, MIXER_ADDR_CD),
DUMMY_CAPSRC("CD Capture Switch", 0, MIXER_ADDR_MASTER)
};

static int __init snd_card_dummy_new_mixer(snd_card_dummy_t * dummy)
{
      snd_card_t *card = dummy->card;
      unsigned int idx;
      int err;

      snd_assert(dummy != NULL, return -EINVAL);
      spin_lock_init(&dummy->mixer_lock);
      strcpy(card->mixername, "Dummy Mixer");

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

static int __init snd_card_dummy_probe(int dev)
{
      snd_card_t *card;
      struct snd_card_dummy *dummy;
      int idx, err;

      if (!enable[dev])
            return -ENODEV;
      card = snd_card_new(index[dev], id[dev], THIS_MODULE,
                      sizeof(struct snd_card_dummy));
      if (card == NULL)
            return -ENOMEM;
      dummy = (struct snd_card_dummy *)card->private_data;
      dummy->card = card;
      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;
            if ((err = snd_card_dummy_pcm(dummy, idx, pcm_substreams[dev])) < 0)
                  goto __nodev;
      }
      if ((err = snd_card_dummy_new_mixer(dummy)) < 0)
            goto __nodev;
      strcpy(card->driver, "Dummy");
      strcpy(card->shortname, "Dummy");
      sprintf(card->longname, "Dummy %i", dev + 1);
      if ((err = snd_card_register(card)) == 0) {
            snd_dummy_cards[dev] = card;
            return 0;
      }
      __nodev:
      snd_card_free(card);
      return err;
}

static int __init alsa_card_dummy_init(void)
{
      int dev, cards;

      for (dev = cards = 0; dev < SNDRV_CARDS && enable[dev]; dev++) {
            if (snd_card_dummy_probe(dev) < 0) {
#ifdef MODULE
                  printk(KERN_ERR "Dummy soundcard #%i not found or device busy\n", dev + 1);
#endif
                  break;
            }
            cards++;
      }
      if (!cards) {
#ifdef MODULE
            printk(KERN_ERR "Dummy soundcard not found or device busy\n");
#endif
            return -ENODEV;
      }
      return 0;
}

static void __exit alsa_card_dummy_exit(void)
{
      int idx;

      for (idx = 0; idx < SNDRV_CARDS; idx++)
            snd_card_free(snd_dummy_cards[idx]);
}

module_init(alsa_card_dummy_init)
module_exit(alsa_card_dummy_exit)

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