/* * Dummy soundcard * Copyright (c) by Jaroslav Kysela * * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include MODULE_AUTHOR("Jaroslav Kysela "); 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(struct snd_pcm_runtime *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 #if 0 /* CA0106 */ #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|SNDRV_PCM_RATE_96000|SNDRV_PCM_RATE_192000) #define USE_RATE_MIN 48000 #define USE_RATE_MAX 192000 #define MAX_BUFFER_SIZE ((65536-64)*8) #define MAX_PERIOD_SIZE (65536-64) #define USE_PERIODS_MIN 2 #define USE_PERIODS_MAX 8 #endif /* defaults */ #ifndef MAX_BUFFER_SIZE #define MAX_BUFFER_SIZE (64*1024) #endif #ifndef MAX_PERIOD_SIZE #define MAX_PERIOD_SIZE MAX_BUFFER_SIZE #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."); 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 snd_dummy { struct snd_card *card; struct snd_pcm *pcm; spinlock_t mixer_lock; int mixer_volume[MIXER_ADDR_LAST+1][2]; int capture_source[MIXER_ADDR_LAST+1][2]; }; struct snd_dummy_pcm { struct snd_dummy *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 */ struct snd_pcm_substream *substream; }; static inline void snd_card_dummy_pcm_timer_start(struct snd_dummy_pcm *dpcm) { dpcm->timer.expires = 1 + jiffies; add_timer(&dpcm->timer); } static inline void snd_card_dummy_pcm_timer_stop(struct snd_dummy_pcm *dpcm) { del_timer(&dpcm->timer); } static int snd_card_dummy_pcm_trigger(struct snd_pcm_substream *substream, int cmd) { struct snd_pcm_runtime *runtime = substream->runtime; struct snd_dummy_pcm *dpcm = runtime->private_data; int err = 0; spin_lock(&dpcm->lock); switch (cmd) { case SNDRV_PCM_TRIGGER_START: case SNDRV_PCM_TRIGGER_RESUME: snd_card_dummy_pcm_timer_start(dpcm); break; case SNDRV_PCM_TRIGGER_STOP: case SNDRV_PCM_TRIGGER_SUSPEND: snd_card_dummy_pcm_timer_stop(dpcm); break; default: err = -EINVAL; break; } spin_unlock(&dpcm->lock); return 0; } static int snd_card_dummy_pcm_prepare(struct snd_pcm_substream *substream) { struct snd_pcm_runtime *runtime = substream->runtime; struct snd_dummy_pcm *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 void snd_card_dummy_pcm_timer_function(unsigned long data) { struct snd_dummy_pcm *dpcm = (struct snd_dummy_pcm *)data; unsigned long flags; spin_lock_irqsave(&dpcm->lock, flags); dpcm->timer.expires = 1 + jiffies; add_timer(&dpcm->timer); 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; spin_unlock_irqrestore(&dpcm->lock, flags); snd_pcm_period_elapsed(dpcm->substream); } else spin_unlock_irqrestore(&dpcm->lock, flags); } static snd_pcm_uframes_t snd_card_dummy_pcm_pointer(struct snd_pcm_substream *substream) { struct snd_pcm_runtime *runtime = substream->runtime; struct snd_dummy_pcm *dpcm = runtime->private_data; return bytes_to_frames(runtime, dpcm->pcm_buf_pos); } static struct snd_pcm_hardware snd_card_dummy_playback = { .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 = 64, .period_bytes_max = MAX_BUFFER_SIZE, .periods_min = USE_PERIODS_MIN, .periods_max = USE_PERIODS_MAX, .fifo_size = 0, }; static struct snd_pcm_hardware snd_card_dummy_capture = { .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 = 64, .period_bytes_max = MAX_PERIOD_SIZE, .periods_min = USE_PERIODS_MIN, .periods_max = USE_PERIODS_MAX, .fifo_size = 0, }; static void snd_card_dummy_runtime_free(struct snd_pcm_runtime *runtime) { kfree(runtime->private_data); } static int snd_card_dummy_hw_params(struct snd_pcm_substream *substream, struct snd_pcm_hw_params *hw_params) { return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params)); } static int snd_card_dummy_hw_free(struct snd_pcm_substream *substream) { return snd_pcm_lib_free_pages(substream); } static struct snd_dummy_pcm *new_pcm_stream(struct snd_pcm_substream *substream) { struct snd_dummy_pcm *dpcm; dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL); if (! dpcm) return dpcm; 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; return dpcm; } static int snd_card_dummy_playback_open(struct snd_pcm_substream *substream) { struct snd_pcm_runtime *runtime = substream->runtime; struct snd_dummy_pcm *dpcm; int err; if ((dpcm = new_pcm_stream(substream)) == NULL) return -ENOMEM; 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(struct snd_pcm_substream *substream) { struct snd_pcm_runtime *runtime = substream->runtime; struct snd_dummy_pcm *dpcm; int err; if ((dpcm = new_pcm_stream(substream)) == NULL) return -ENOMEM; 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(struct snd_pcm_substream *substream) { return 0; } static int snd_card_dummy_capture_close(struct snd_pcm_substream *substream) { return 0; } static struct snd_pcm_ops 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_pcm_prepare, .trigger = snd_card_dummy_pcm_trigger, .pointer = snd_card_dummy_pcm_pointer, }; static struct snd_pcm_ops 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_pcm_prepare, .trigger = snd_card_dummy_pcm_trigger, .pointer = snd_card_dummy_pcm_pointer, }; static int __init snd_card_dummy_pcm(struct snd_dummy *dummy, int device, int substreams) { struct snd_pcm *pcm; int err; if ((err = snd_pcm_new(dummy->card, "Dummy PCM", device, substreams, substreams, &pcm)) < 0) return err; dummy->pcm = pcm; 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(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; } #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(struct snd_kcontrol *kcontrol, struct snd_ctl_elem_info *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(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_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(struct snd_dummy *dummy) { struct snd_card *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_dummy_probe(struct platform_device *devptr) { struct snd_card *card; struct snd_dummy *dummy; int idx, err; int dev = devptr->id; card = snd_card_new(index[dev], id[dev], THIS_MODULE, sizeof(struct snd_dummy)); if (card == NULL) return -ENOMEM; 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); snd_card_set_dev(card, &devptr->dev); if ((err = snd_card_register(card)) == 0) { platform_set_drvdata(devptr, card); return 0; } __nodev: snd_card_free(card); return err; } static int snd_dummy_remove(struct platform_device *devptr) { snd_card_free(platform_get_drvdata(devptr)); platform_set_drvdata(devptr, NULL); return 0; } #ifdef CONFIG_PM static int snd_dummy_suspend(struct platform_device *pdev, pm_message_t state) { struct snd_card *card = platform_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 platform_device *pdev) { struct snd_card *card = platform_get_drvdata(pdev); snd_power_change_state(card, SNDRV_CTL_POWER_D0); return 0; } #endif #define SND_DUMMY_DRIVER "snd_dummy" static struct platform_driver snd_dummy_driver = { .probe = snd_dummy_probe, .remove = snd_dummy_remove, #ifdef CONFIG_PM .suspend = snd_dummy_suspend, .resume = snd_dummy_resume, #endif .driver = { .name = SND_DUMMY_DRIVER }, }; static void __init_or_module 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); } static int __init alsa_card_dummy_init(void) { int i, cards, err; if ((err = platform_driver_register(&snd_dummy_driver)) < 0) return err; cards = 0; for (i = 0; i < SNDRV_CARDS && enable[i]; i++) { struct platform_device *device; device = platform_device_register_simple(SND_DUMMY_DRIVER, i, NULL, 0); if (IS_ERR(device)) { err = PTR_ERR(device); goto errout; } devices[i] = device; cards++; } if (!cards) { #ifdef MODULE printk(KERN_ERR "Dummy soundcard not found or device busy\n"); #endif err = -ENODEV; goto errout; } return 0; errout: snd_dummy_unregister_all(); return err; } static void __exit alsa_card_dummy_exit(void) { snd_dummy_unregister_all(); } module_init(alsa_card_dummy_init) module_exit(alsa_card_dummy_exit)