/* * compress_core.c - compress offload core * * Copyright (C) 2011 Intel Corporation * Authors: Vinod Koul * Pierre-Louis Bossart * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * * 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; version 2 of the License. * * 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. * * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * */ #define FORMAT(fmt) "%s: %d: " fmt, __func__, __LINE__ #define pr_fmt(fmt) KBUILD_MODNAME ": " FORMAT(fmt) #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* TODO: * - add substream support for multiple devices in case of * SND_DYNAMIC_MINORS is not used * - Multiple node representation * driver should be able to register multiple nodes */ static DEFINE_MUTEX(device_mutex); struct snd_compr_file { unsigned long caps; struct snd_compr_stream stream; }; /* * a note on stream states used: * we use follwing states in the compressed core * SNDRV_PCM_STATE_OPEN: When stream has been opened. * SNDRV_PCM_STATE_SETUP: When stream has been initialized. This is done by * calling SNDRV_COMPRESS_SET_PARAMS. running streams will come to this * state at stop by calling SNDRV_COMPRESS_STOP, or at end of drain. * SNDRV_PCM_STATE_RUNNING: When stream has been started and is * decoding/encoding and rendering/capturing data. * SNDRV_PCM_STATE_DRAINING: When stream is draining current data. This is done * by calling SNDRV_COMPRESS_DRAIN. * SNDRV_PCM_STATE_PAUSED: When stream is paused. This is done by calling * SNDRV_COMPRESS_PAUSE. It can be stopped or resumed by calling * SNDRV_COMPRESS_STOP or SNDRV_COMPRESS_RESUME respectively. */ static int snd_compr_open(struct inode *inode, struct file *f) { struct snd_compr *compr; struct snd_compr_file *data; struct snd_compr_runtime *runtime; enum snd_compr_direction dirn; int maj = imajor(inode); int ret; if ((f->f_flags & O_ACCMODE) == O_WRONLY) dirn = SND_COMPRESS_PLAYBACK; else if ((f->f_flags & O_ACCMODE) == O_RDONLY) dirn = SND_COMPRESS_CAPTURE; else return -EINVAL; if (maj == snd_major) compr = snd_lookup_minor_data(iminor(inode), SNDRV_DEVICE_TYPE_COMPRESS); else return -EBADFD; if (compr == NULL) { pr_err("no device data!!!\n"); return -ENODEV; } if (dirn != compr->direction) { pr_err("this device doesn't support this direction\n"); snd_card_unref(compr->card); return -EINVAL; } data = kzalloc(sizeof(*data), GFP_KERNEL); if (!data) { snd_card_unref(compr->card); return -ENOMEM; } data->stream.ops = compr->ops; data->stream.direction = dirn; data->stream.private_data = compr->private_data; data->stream.device = compr; runtime = kzalloc(sizeof(*runtime), GFP_KERNEL); if (!runtime) { kfree(data); snd_card_unref(compr->card); return -ENOMEM; } runtime->state = SNDRV_PCM_STATE_OPEN; init_waitqueue_head(&runtime->sleep); data->stream.runtime = runtime; f->private_data = (void *)data; mutex_lock(&compr->lock); ret = compr->ops->open(&data->stream); mutex_unlock(&compr->lock); if (ret) { kfree(runtime); kfree(data); } snd_card_unref(compr->card); return 0; } static int snd_compr_free(struct inode *inode, struct file *f) { struct snd_compr_file *data = f->private_data; data->stream.ops->free(&data->stream); kfree(data->stream.runtime->buffer); kfree(data->stream.runtime); kfree(data); return 0; } static int snd_compr_update_tstamp(struct snd_compr_stream *stream, struct snd_compr_tstamp *tstamp) { if (!stream->ops->pointer) return -ENOTSUPP; stream->ops->pointer(stream, tstamp); pr_debug("dsp consumed till %d total %d bytes\n", tstamp->byte_offset, tstamp->copied_total); if (stream->direction == SND_COMPRESS_PLAYBACK) stream->runtime->total_bytes_transferred = tstamp->copied_total; else stream->runtime->total_bytes_available = tstamp->copied_total; return 0; } static size_t snd_compr_calc_avail(struct snd_compr_stream *stream, struct snd_compr_avail *avail) { memset(avail, 0, sizeof(*avail)); snd_compr_update_tstamp(stream, &avail->tstamp); /* Still need to return avail even if tstamp can't be filled in */ if (stream->runtime->total_bytes_available == 0 && stream->runtime->state == SNDRV_PCM_STATE_SETUP && stream->direction == SND_COMPRESS_PLAYBACK) { pr_debug("detected init and someone forgot to do a write\n"); return stream->runtime->buffer_size; } pr_debug("app wrote %lld, DSP consumed %lld\n", stream->runtime->total_bytes_available, stream->runtime->total_bytes_transferred); if (stream->runtime->total_bytes_available == stream->runtime->total_bytes_transferred) { if (stream->direction == SND_COMPRESS_PLAYBACK) { pr_debug("both pointers are same, returning full avail\n"); return stream->runtime->buffer_size; } else { pr_debug("both pointers are same, returning no avail\n"); return 0; } } avail->avail = stream->runtime->total_bytes_available - stream->runtime->total_bytes_transferred; if (stream->direction == SND_COMPRESS_PLAYBACK) avail->avail = stream->runtime->buffer_size - avail->avail; pr_debug("ret avail as %lld\n", avail->avail); return avail->avail; } static inline size_t snd_compr_get_avail(struct snd_compr_stream *stream) { struct snd_compr_avail avail; return snd_compr_calc_avail(stream, &avail); } static int snd_compr_ioctl_avail(struct snd_compr_stream *stream, unsigned long arg) { struct snd_compr_avail ioctl_avail; size_t avail; avail = snd_compr_calc_avail(stream, &ioctl_avail); ioctl_avail.avail = avail; if (copy_to_user((__u64 __user *)arg, &ioctl_avail, sizeof(ioctl_avail))) return -EFAULT; return 0; } static int snd_compr_write_data(struct snd_compr_stream *stream, const char __user *buf, size_t count) { void *dstn; size_t copy; struct snd_compr_runtime *runtime = stream->runtime; /* 64-bit Modulus */ u64 app_pointer = div64_u64(runtime->total_bytes_available, runtime->buffer_size); app_pointer = runtime->total_bytes_available - (app_pointer * runtime->buffer_size); dstn = runtime->buffer + app_pointer; pr_debug("copying %ld at %lld\n", (unsigned long)count, app_pointer); if (count < runtime->buffer_size - app_pointer) { if (copy_from_user(dstn, buf, count)) return -EFAULT; } else { copy = runtime->buffer_size - app_pointer; if (copy_from_user(dstn, buf, copy)) return -EFAULT; if (copy_from_user(runtime->buffer, buf + copy, count - copy)) return -EFAULT; } /* if DSP cares, let it know data has been written */ if (stream->ops->ack) stream->ops->ack(stream, count); return count; } static ssize_t snd_compr_write(struct file *f, const char __user *buf, size_t count, loff_t *offset) { struct snd_compr_file *data = f->private_data; struct snd_compr_stream *stream; size_t avail; int retval; if (snd_BUG_ON(!data)) return -EFAULT; stream = &data->stream; mutex_lock(&stream->device->lock); /* write is allowed when stream is running or has been steup */ if (stream->runtime->state != SNDRV_PCM_STATE_SETUP && stream->runtime->state != SNDRV_PCM_STATE_RUNNING) { mutex_unlock(&stream->device->lock); return -EBADFD; } avail = snd_compr_get_avail(stream); pr_debug("avail returned %ld\n", (unsigned long)avail); /* calculate how much we can write to buffer */ if (avail > count) avail = count; if (stream->ops->copy) { char __user* cbuf = (char __user*)buf; retval = stream->ops->copy(stream, cbuf, avail); } else { retval = snd_compr_write_data(stream, buf, avail); } if (retval > 0) stream->runtime->total_bytes_available += retval; /* while initiating the stream, write should be called before START * call, so in setup move state */ if (stream->runtime->state == SNDRV_PCM_STATE_SETUP) { stream->runtime->state = SNDRV_PCM_STATE_PREPARED; pr_debug("stream prepared, Houston we are good to go\n"); } mutex_unlock(&stream->device->lock); return retval; } static ssize_t snd_compr_read(struct file *f, char __user *buf, size_t count, loff_t *offset) { struct snd_compr_file *data = f->private_data; struct snd_compr_stream *stream; size_t avail; int retval; if (snd_BUG_ON(!data)) return -EFAULT; stream = &data->stream; mutex_lock(&stream->device->lock); /* read is allowed when stream is running */ if (stream->runtime->state != SNDRV_PCM_STATE_RUNNING) { retval = -EBADFD; goto out; } avail = snd_compr_get_avail(stream); pr_debug("avail returned %ld\n", (unsigned long)avail); /* calculate how much we can read from buffer */ if (avail > count) avail = count; if (stream->ops->copy) { retval = stream->ops->copy(stream, buf, avail); } else { retval = -ENXIO; goto out; } if (retval > 0) stream->runtime->total_bytes_transferred += retval; out: mutex_unlock(&stream->device->lock); return retval; } static int snd_compr_mmap(struct file *f, struct vm_area_struct *vma) { return -ENXIO; } static inline int snd_compr_get_poll(struct snd_compr_stream *stream) { if (stream->direction == SND_COMPRESS_PLAYBACK) return POLLOUT | POLLWRNORM; else return POLLIN | POLLRDNORM; } static unsigned int snd_compr_poll(struct file *f, poll_table *wait) { struct snd_compr_file *data = f->private_data; struct snd_compr_stream *stream; size_t avail; int retval = 0; if (snd_BUG_ON(!data)) return -EFAULT; stream = &data->stream; if (snd_BUG_ON(!stream)) return -EFAULT; mutex_lock(&stream->device->lock); if (stream->runtime->state == SNDRV_PCM_STATE_PAUSED || stream->runtime->state == SNDRV_PCM_STATE_OPEN) { retval = -EBADFD; goto out; } poll_wait(f, &stream->runtime->sleep, wait); avail = snd_compr_get_avail(stream); pr_debug("avail is %ld\n", (unsigned long)avail); /* check if we have at least one fragment to fill */ switch (stream->runtime->state) { case SNDRV_PCM_STATE_DRAINING: /* stream has been woken up after drain is complete * draining done so set stream state to stopped */ retval = snd_compr_get_poll(stream); stream->runtime->state = SNDRV_PCM_STATE_SETUP; break; case SNDRV_PCM_STATE_RUNNING: case SNDRV_PCM_STATE_PREPARED: case SNDRV_PCM_STATE_PAUSED: if (avail >= stream->runtime->fragment_size) retval = snd_compr_get_poll(stream); break; default: if (stream->direction == SND_COMPRESS_PLAYBACK) retval = POLLOUT | POLLWRNORM | POLLERR; else retval = POLLIN | POLLRDNORM | POLLERR; break; } out: mutex_unlock(&stream->device->lock); return retval; } static int snd_compr_get_caps(struct snd_compr_stream *stream, unsigned long arg) { int retval; struct snd_compr_caps caps; if (!stream->ops->get_caps) return -ENXIO; memset(&caps, 0, sizeof(caps)); retval = stream->ops->get_caps(stream, &caps); if (retval) goto out; if (copy_to_user((void __user *)arg, &caps, sizeof(caps))) retval = -EFAULT; out: return retval; } static int snd_compr_get_codec_caps(struct snd_compr_stream *stream, unsigned long arg) { int retval; struct snd_compr_codec_caps *caps; if (!stream->ops->get_codec_caps) return -ENXIO; caps = kzalloc(sizeof(*caps), GFP_KERNEL); if (!caps) return -ENOMEM; retval = stream->ops->get_codec_caps(stream, caps); if (retval) goto out; if (copy_to_user((void __user *)arg, caps, sizeof(*caps))) retval = -EFAULT; out: kfree(caps); return retval; } /* revisit this with snd_pcm_preallocate_xxx */ static int snd_compr_allocate_buffer(struct snd_compr_stream *stream, struct snd_compr_params *params) { unsigned int buffer_size; void *buffer; buffer_size = params->buffer.fragment_size * params->buffer.fragments; if (stream->ops->copy) { buffer = NULL; /* if copy is defined the driver will be required to copy * the data from core */ } else { buffer = kmalloc(buffer_size, GFP_KERNEL); if (!buffer) return -ENOMEM; } stream->runtime->fragment_size = params->buffer.fragment_size; stream->runtime->fragments = params->buffer.fragments; stream->runtime->buffer = buffer; stream->runtime->buffer_size = buffer_size; return 0; } static int snd_compress_check_input(struct snd_compr_params *params) { /* first let's check the buffer parameter's */ if (params->buffer.fragment_size == 0 || params->buffer.fragments > SIZE_MAX / params->buffer.fragment_size) return -EINVAL; /* now codec parameters */ if (params->codec.id == 0 || params->codec.id > SND_AUDIOCODEC_MAX) return -EINVAL; if (params->codec.ch_in == 0 || params->codec.ch_out == 0) return -EINVAL; if (!(params->codec.sample_rate & SNDRV_PCM_RATE_8000_192000)) return -EINVAL; return 0; } static int snd_compr_set_params(struct snd_compr_stream *stream, unsigned long arg) { struct snd_compr_params *params; int retval; if (stream->runtime->state == SNDRV_PCM_STATE_OPEN) { /* * we should allow parameter change only when stream has been * opened not in other cases */ params = kmalloc(sizeof(*params), GFP_KERNEL); if (!params) return -ENOMEM; if (copy_from_user(params, (void __user *)arg, sizeof(*params))) { retval = -EFAULT; goto out; } retval = snd_compress_check_input(params); if (retval) goto out; retval = snd_compr_allocate_buffer(stream, params); if (retval) { retval = -ENOMEM; goto out; } retval = stream->ops->set_params(stream, params); if (retval) goto out; stream->metadata_set = false; stream->next_track = false; if (stream->direction == SND_COMPRESS_PLAYBACK) stream->runtime->state = SNDRV_PCM_STATE_SETUP; else stream->runtime->state = SNDRV_PCM_STATE_PREPARED; } else { return -EPERM; } out: kfree(params); return retval; } static int snd_compr_get_params(struct snd_compr_stream *stream, unsigned long arg) { struct snd_codec *params; int retval; if (!stream->ops->get_params) return -EBADFD; params = kzalloc(sizeof(*params), GFP_KERNEL); if (!params) return -ENOMEM; retval = stream->ops->get_params(stream, params); if (retval) goto out; if (copy_to_user((char __user *)arg, params, sizeof(*params))) retval = -EFAULT; out: kfree(params); return retval; } static int snd_compr_get_metadata(struct snd_compr_stream *stream, unsigned long arg) { struct snd_compr_metadata metadata; int retval; if (!stream->ops->get_metadata) return -ENXIO; if (copy_from_user(&metadata, (void __user *)arg, sizeof(metadata))) return -EFAULT; retval = stream->ops->get_metadata(stream, &metadata); if (retval != 0) return retval; if (copy_to_user((void __user *)arg, &metadata, sizeof(metadata))) return -EFAULT; return 0; } static int snd_compr_set_metadata(struct snd_compr_stream *stream, unsigned long arg) { struct snd_compr_metadata metadata; int retval; if (!stream->ops->set_metadata) return -ENXIO; /* * we should allow parameter change only when stream has been * opened not in other cases */ if (copy_from_user(&metadata, (void __user *)arg, sizeof(metadata))) return -EFAULT; retval = stream->ops->set_metadata(stream, &metadata); stream->metadata_set = true; return retval; } static inline int snd_compr_tstamp(struct snd_compr_stream *stream, unsigned long arg) { struct snd_compr_tstamp tstamp = {0}; int ret; ret = snd_compr_update_tstamp(stream, &tstamp); if (ret == 0) ret = copy_to_user((struct snd_compr_tstamp __user *)arg, &tstamp, sizeof(tstamp)) ? -EFAULT : 0; return ret; } static int snd_compr_pause(struct snd_compr_stream *stream) { int retval; if (stream->runtime->state != SNDRV_PCM_STATE_RUNNING) return -EPERM; retval = stream->ops->trigger(stream, SNDRV_PCM_TRIGGER_PAUSE_PUSH); if (!retval) stream->runtime->state = SNDRV_PCM_STATE_PAUSED; return retval; } static int snd_compr_resume(struct snd_compr_stream *stream) { int retval; if (stream->runtime->state != SNDRV_PCM_STATE_PAUSED) return -EPERM; retval = stream->ops->trigger(stream, SNDRV_PCM_TRIGGER_PAUSE_RELEASE); if (!retval) stream->runtime->state = SNDRV_PCM_STATE_RUNNING; return retval; } static int snd_compr_start(struct snd_compr_stream *stream) { int retval; if (stream->runtime->state != SNDRV_PCM_STATE_PREPARED) return -EPERM; retval = stream->ops->trigger(stream, SNDRV_PCM_TRIGGER_START); if (!retval) stream->runtime->state = SNDRV_PCM_STATE_RUNNING; return retval; } static int snd_compr_stop(struct snd_compr_stream *stream) { int retval; if (stream->runtime->state == SNDRV_PCM_STATE_PREPARED || stream->runtime->state == SNDRV_PCM_STATE_SETUP) return -EPERM; retval = stream->ops->trigger(stream, SNDRV_PCM_TRIGGER_STOP); if (!retval) { stream->runtime->state = SNDRV_PCM_STATE_SETUP; wake_up(&stream->runtime->sleep); stream->runtime->total_bytes_available = 0; stream->runtime->total_bytes_transferred = 0; } return retval; } static int snd_compr_drain(struct snd_compr_stream *stream) { int retval; if (stream->runtime->state == SNDRV_PCM_STATE_PREPARED || stream->runtime->state == SNDRV_PCM_STATE_SETUP) return -EPERM; retval = stream->ops->trigger(stream, SND_COMPR_TRIGGER_DRAIN); if (!retval) { stream->runtime->state = SNDRV_PCM_STATE_DRAINING; wake_up(&stream->runtime->sleep); } return retval; } static int snd_compr_next_track(struct snd_compr_stream *stream) { int retval; /* only a running stream can transition to next track */ if (stream->runtime->state != SNDRV_PCM_STATE_RUNNING) return -EPERM; /* you can signal next track isf this is intended to be a gapless stream * and current track metadata is set */ if (stream->metadata_set == false) return -EPERM; retval = stream->ops->trigger(stream, SND_COMPR_TRIGGER_NEXT_TRACK); if (retval != 0) return retval; stream->metadata_set = false; stream->next_track = true; return 0; } static int snd_compr_partial_drain(struct snd_compr_stream *stream) { int retval; if (stream->runtime->state == SNDRV_PCM_STATE_PREPARED || stream->runtime->state == SNDRV_PCM_STATE_SETUP) return -EPERM; /* stream can be drained only when next track has been signalled */ if (stream->next_track == false) return -EPERM; retval = stream->ops->trigger(stream, SND_COMPR_TRIGGER_PARTIAL_DRAIN); stream->next_track = false; return retval; } static long snd_compr_ioctl(struct file *f, unsigned int cmd, unsigned long arg) { struct snd_compr_file *data = f->private_data; struct snd_compr_stream *stream; int retval = -ENOTTY; if (snd_BUG_ON(!data)) return -EFAULT; stream = &data->stream; if (snd_BUG_ON(!stream)) return -EFAULT; mutex_lock(&stream->device->lock); switch (_IOC_NR(cmd)) { case _IOC_NR(SNDRV_COMPRESS_IOCTL_VERSION): put_user(SNDRV_COMPRESS_VERSION, (int __user *)arg) ? -EFAULT : 0; break; case _IOC_NR(SNDRV_COMPRESS_GET_CAPS): retval = snd_compr_get_caps(stream, arg); break; case _IOC_NR(SNDRV_COMPRESS_GET_CODEC_CAPS): retval = snd_compr_get_codec_caps(stream, arg); break; case _IOC_NR(SNDRV_COMPRESS_SET_PARAMS): retval = snd_compr_set_params(stream, arg); break; case _IOC_NR(SNDRV_COMPRESS_GET_PARAMS): retval = snd_compr_get_params(stream, arg); break; case _IOC_NR(SNDRV_COMPRESS_SET_METADATA): retval = snd_compr_set_metadata(stream, arg); break; case _IOC_NR(SNDRV_COMPRESS_GET_METADATA): retval = snd_compr_get_metadata(stream, arg); break; case _IOC_NR(SNDRV_COMPRESS_TSTAMP): retval = snd_compr_tstamp(stream, arg); break; case _IOC_NR(SNDRV_COMPRESS_AVAIL): retval = snd_compr_ioctl_avail(stream, arg); break; case _IOC_NR(SNDRV_COMPRESS_PAUSE): retval = snd_compr_pause(stream); break; case _IOC_NR(SNDRV_COMPRESS_RESUME): retval = snd_compr_resume(stream); break; case _IOC_NR(SNDRV_COMPRESS_START): retval = snd_compr_start(stream); break; case _IOC_NR(SNDRV_COMPRESS_STOP): retval = snd_compr_stop(stream); break; case _IOC_NR(SNDRV_COMPRESS_DRAIN): retval = snd_compr_drain(stream); break; case _IOC_NR(SNDRV_COMPRESS_PARTIAL_DRAIN): retval = snd_compr_partial_drain(stream); break; case _IOC_NR(SNDRV_COMPRESS_NEXT_TRACK): retval = snd_compr_next_track(stream); break; } mutex_unlock(&stream->device->lock); return retval; } static const struct file_operations snd_compr_file_ops = { .owner = THIS_MODULE, .open = snd_compr_open, .release = snd_compr_free, .write = snd_compr_write, .read = snd_compr_read, .unlocked_ioctl = snd_compr_ioctl, .mmap = snd_compr_mmap, .poll = snd_compr_poll, }; static int snd_compress_dev_register(struct snd_device *device) { int ret = -EINVAL; char str[16]; struct snd_compr *compr; if (snd_BUG_ON(!device || !device->device_data)) return -EBADFD; compr = device->device_data; sprintf(str, "comprC%iD%i", compr->card->number, compr->device); pr_debug("reg %s for device %s, direction %d\n", str, compr->name, compr->direction); /* register compressed device */ ret = snd_register_device(SNDRV_DEVICE_TYPE_COMPRESS, compr->card, compr->device, &snd_compr_file_ops, compr, str); if (ret < 0) { pr_err("snd_register_device failed\n %d", ret); return ret; } return ret; } static int snd_compress_dev_disconnect(struct snd_device *device) { struct snd_compr *compr; compr = device->device_data; snd_unregister_device(compr->direction, compr->card, compr->device); return 0; } /* * snd_compress_new: create new compress device * @card: sound card pointer * @device: device number * @dirn: device direction, should be of type enum snd_compr_direction * @compr: compress device pointer */ int snd_compress_new(struct snd_card *card, int device, int dirn, struct snd_compr *compr) { static struct snd_device_ops ops = { .dev_free = NULL, .dev_register = snd_compress_dev_register, .dev_disconnect = snd_compress_dev_disconnect, }; compr->card = card; compr->device = device; compr->direction = dirn; return snd_device_new(card, SNDRV_DEV_COMPRESS, compr, &ops); } EXPORT_SYMBOL_GPL(snd_compress_new); static int snd_compress_add_device(struct snd_compr *device) { int ret; if (!device->card) return -EINVAL; /* register the card */ ret = snd_card_register(device->card); if (ret) goto out; return 0; out: pr_err("failed with %d\n", ret); return ret; } static int snd_compress_remove_device(struct snd_compr *device) { return snd_card_free(device->card); } /** * snd_compress_register - register compressed device * * @device: compressed device to register */ int snd_compress_register(struct snd_compr *device) { int retval; if (device->name == NULL || device->dev == NULL || device->ops == NULL) return -EINVAL; pr_debug("Registering compressed device %s\n", device->name); if (snd_BUG_ON(!device->ops->open)) return -EINVAL; if (snd_BUG_ON(!device->ops->free)) return -EINVAL; if (snd_BUG_ON(!device->ops->set_params)) return -EINVAL; if (snd_BUG_ON(!device->ops->trigger)) return -EINVAL; mutex_init(&device->lock); /* register a compressed card */ mutex_lock(&device_mutex); retval = snd_compress_add_device(device); mutex_unlock(&device_mutex); return retval; } EXPORT_SYMBOL_GPL(snd_compress_register); int snd_compress_deregister(struct snd_compr *device) { pr_debug("Removing compressed device %s\n", device->name); mutex_lock(&device_mutex); snd_compress_remove_device(device); mutex_unlock(&device_mutex); return 0; } EXPORT_SYMBOL_GPL(snd_compress_deregister); static int __init snd_compress_init(void) { return 0; } static void __exit snd_compress_exit(void) { } module_init(snd_compress_init); module_exit(snd_compress_exit); MODULE_DESCRIPTION("ALSA Compressed offload framework"); MODULE_AUTHOR("Vinod Koul "); MODULE_LICENSE("GPL v2");