[PATCH v4 5/6] core: add support for compress_offload

[Vinod Koul <vinod.koul@linux.intel.com>]

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: Vinod Koul <vinod.koul@linux.intel.com>
---
 sound/core/compress_offload.c |  705 +++++++++++++++++++++++++++++++++++++++++
 1 files changed, 705 insertions(+), 0 deletions(-)
 create mode 100644 sound/core/compress_offload.c

diff --git a/sound/core/compress_offload.c b/sound/core/compress_offload.c
new file mode 100644
index 0000000..d2345c2
--- /dev/null
+++ b/sound/core/compress_offload.c
@@ -0,0 +1,705 @@
+/*
+ *  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/snd_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;
+};
+
+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;
+	int ret, type;
+	int maj = imajor(inode);
+
+	if (f->f_flags & O_WRONLY)
+		type = SNDRV_DEVICE_TYPE_COMPR_PLAYBACK;
+	else if (f->f_flags & O_RDONLY)
+		type = SNDRV_DEVICE_TYPE_COMPR_CAPTURE;
+	else {
+		pr_err("invalid direction\n");
+		return -EINVAL;
+	}
+
+	if (maj == snd_major)
+		compr = snd_lookup_minor_data(iminor(inode), type);
+	else
+		return -ENXIO;
+
+	if (compr == NULL) {
+		pr_err("no device data!!!\n");
+		return -ENODEV;
+	}
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+	data->stream.ops = compr->ops;
+	data->stream.direction = type;
+	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 %ld total %ld bytes\n",
+		(long)tstamp->copied_bytes, (long)tstamp->copied_total);
+	stream->runtime->hw_pointer = tstamp->copied_bytes;
+	stream->runtime->bytes_copied = 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);
+
+	if (stream->runtime->bytes_written == 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 %ld, DSP consumed %ld\n",
+			(long)stream->runtime->bytes_written,
+			(long)stream->runtime->bytes_copied);
+	if (stream->runtime->bytes_written == stream->runtime->bytes_copied) {
+		pr_debug("both pointers are same, returning full avail\n");
+		return stream->runtime->buffer_size;
+	}
+
+	avail_calc = stream->runtime->buffer_size -
+		(stream->runtime->app_pointer - stream->runtime->hw_pointer);
+	pr_debug("calc avail as %ld, app_ptr %ld, hw+ptr %ld\n", avail_calc,
+			(long)stream->runtime->app_pointer,
+			(long)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((unsigned long __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 %ld\n",
+			(long)count, (long)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;
+
+	BUG_ON(!data);
+	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 -EPERM;
+	}
+
+	avail = snd_compr_get_avail(stream);
+	pr_debug("avail returned %ld\n", (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->bytes_written += 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 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;
+
+	BUG_ON(!data);
+	stream = &data->stream;
+
+	mutex_lock(&stream->device->lock);
+	if (stream->runtime->state != SNDRV_PCM_STATE_RUNNING) {
+		retval = -ENXIO;
+		goto out;
+	}
+	poll_wait(f, &stream->runtime->sleep, wait);
+
+	avail = snd_compr_get_avail(stream);
+	pr_debug("avail is %ld\n", (long)avail);
+	/* check if we have at least one fragment to fill */
+	switch (stream->runtime->state) {
+	case SNDRV_PCM_STATE_RUNNING:
+	case SNDRV_PCM_STATE_PREPARED:
+	case SNDRV_PCM_STATE_PAUSED:
+		if (avail >= stream->runtime->fragment_size) {
+			if (stream->direction == SNDRV_DEVICE_TYPE_COMPR_PLAYBACK)
+				retval = POLLOUT | POLLWRNORM;
+			else
+				retval = POLLIN | POLLRDNORM;
+			break;
+		}
+		/* Fall through */
+	case SNDRV_PCM_STATE_DRAINING:
+		break;
+	default:
+		if (stream->direction == SNDRV_DEVICE_TYPE_COMPR_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 -ENXIO;
+
+	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_SETUP;
+		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;
+
+	BUG_ON(!data);
+	stream = &data->stream;
+	BUG_ON(!stream);
+	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 -ENXIO;
+	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(compr->direction, 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;
+}
+
+int snd_compress_new(struct snd_card *card, int device,
+			int type, 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 = type;
+	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);
+	BUG_ON(!device->ops->open);
+	BUG_ON(!device->ops->free);
+	BUG_ON(!device->ops->set_params);
+	BUG_ON(!device->ops->trigger);
+
+	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");
-- 
1.7.0.4