ALSA: core: add support for compress_offload
Vinod Koul [Fri, 23 Dec 2011 05:06:39 +0000 (10:06 +0530)]
This patch adds core.c, the file which implements the ioctls and
registers the devices

Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/compress_offload.c [new file with mode: 0644]

diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
new file mode 100644 (file)
index 0000000..dac3633
--- /dev/null
@@ -0,0 +1,765 @@
+/*
+ *  compress_core.c - compress offload core
+ *
+ *  Copyright (C) 2011 Intel Corporation
+ *  Authors:   Vinod Koul <vinod.koul@linux.intel.com>
+ *             Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
+ *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ *  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 <linux/file.h>
+#include <linux/fs.h>
+#include <linux/list.h>
+#include <linux/mm.h>
+#include <linux/mutex.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/uio.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include <sound/core.h>
+#include <sound/initval.h>
+#include <sound/compress_params.h>
+#include <sound/compress_offload.h>
+#include <sound/compress_driver.h>
+
+/* 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_WRONLY)
+               dirn = SND_COMPRESS_PLAYBACK;
+       else if (f->f_flags & O_RDONLY)
+               dirn = SND_COMPRESS_CAPTURE;
+       else {
+               pr_err("invalid direction\n");
+               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");
+               return -EINVAL;
+       }
+
+       data = kzalloc(sizeof(*data), GFP_KERNEL);
+       if (!data)
+               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);
+               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);
+       }
+       return ret;
+}
+
+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 void snd_compr_update_tstamp(struct snd_compr_stream *stream,
+               struct snd_compr_tstamp *tstamp)
+{
+       if (!stream->ops->pointer)
+               return;
+       stream->ops->pointer(stream, tstamp);
+       pr_debug("dsp consumed till %d total %d bytes\n",
+               tstamp->byte_offset, tstamp->copied_total);
+       stream->runtime->hw_pointer = tstamp->byte_offset;
+       stream->runtime->total_bytes_transferred = tstamp->copied_total;
+}
+
+static size_t snd_compr_calc_avail(struct snd_compr_stream *stream,
+               struct snd_compr_avail *avail)
+{
+       long avail_calc; /*this needs to be signed variable */
+
+       snd_compr_update_tstamp(stream, &avail->tstamp);
+
+       /* FIXME: This needs to be different for capture stream,
+          available is # of compressed data, for playback it's
+          remainder of buffer */
+
+       if (stream->runtime->total_bytes_available == 0 &&
+                       stream->runtime->state == SNDRV_PCM_STATE_SETUP) {
+               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) {
+               pr_debug("both pointers are same, returning full avail\n");
+               return stream->runtime->buffer_size;
+       }
+
+       /* FIXME: this routine isn't consistent, in one test we use
+        * cumulative values and in the other byte offsets. Do we
+        * really need the byte offsets if the cumulative values have
+        * been updated? In the PCM interface app_ptr and hw_ptr are
+        * already cumulative */
+
+       avail_calc = stream->runtime->buffer_size -
+               (stream->runtime->app_pointer - stream->runtime->hw_pointer);
+       pr_debug("calc avail as %ld, app_ptr %lld, hw+ptr %lld\n", avail_calc,
+                       stream->runtime->app_pointer,
+                       stream->runtime->hw_pointer);
+       if (avail_calc >= stream->runtime->buffer_size)
+               avail_calc -= stream->runtime->buffer_size;
+       pr_debug("ret avail as %ld\n", avail_calc);
+       avail->avail = avail_calc;
+       return avail_calc;
+}
+
+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;
+
+       dstn = runtime->buffer + runtime->app_pointer;
+       pr_debug("copying %ld at %lld\n",
+                       (unsigned long)count, runtime->app_pointer);
+       if (count < runtime->buffer_size - runtime->app_pointer) {
+               if (copy_from_user(dstn, buf, count))
+                       return -EFAULT;
+               runtime->app_pointer += count;
+       } else {
+               copy = runtime->buffer_size - runtime->app_pointer;
+               if (copy_from_user(dstn, buf, copy))
+                       return -EFAULT;
+               if (copy_from_user(runtime->buffer, buf + copy, count - copy))
+                       return -EFAULT;
+               runtime->app_pointer = count - copy;
+       }
+       /* 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)
+               retval = stream->ops->copy(stream, buf, 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)
+{
+       return -ENXIO;
+}
+
+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;
+
+       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 = kmalloc(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_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)))
+                       return -EFAULT;
+               retval = snd_compr_allocate_buffer(stream, params);
+               if (retval) {
+                       kfree(params);
+                       return -ENOMEM;
+               }
+               retval = stream->ops->set_params(stream, params);
+               if (retval)
+                       goto out;
+               stream->runtime->state = SNDRV_PCM_STATE_SETUP;
+       } 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 = kmalloc(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 inline int
+snd_compr_tstamp(struct snd_compr_stream *stream, unsigned long arg)
+{
+       struct snd_compr_tstamp tstamp;
+
+       snd_compr_update_tstamp(stream, &tstamp);
+       return copy_to_user((struct snd_compr_tstamp __user *)arg,
+               &tstamp, sizeof(tstamp)) ? -EFAULT : 0;
+}
+
+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;
+               wake_up(&stream->runtime->sleep);
+       }
+       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);
+       }
+       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 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_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;
+       }
+       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 <vinod.koul@linux.intel.com>");
+MODULE_LICENSE("GPL v2");