drivers/media/usb/usbtv/usbtv-audio.c - linux - Git at Google

 /*
  * Copyright (c) 2013 Federico Simoncelli
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions, and the following disclaimer,
  *    without modification.
  * 2. The name of the author may not be used to endorse or promote products
  *    derived from this software without specific prior written permission.
  *
  * Alternatively, this software may be distributed under the terms of the
  * GNU General Public License ("GPL").
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 /*
  * Fushicai USBTV007 Audio-Video Grabber Driver
  *
  * Product web site:
  * http://www.fushicai.com/products_detail/&productId=d05449ee-b690-42f9-a661-aa7353894bed.html
  *
  * No physical hardware was harmed running Windows during the
  * reverse-engineering activity
  */

 #include <sound/core.h>
 #include <sound/initval.h>
 #include <sound/ac97_codec.h>
 #include <sound/pcm_params.h>

 #include "usbtv.h"

 static const struct snd_pcm_hardware snd_usbtv_digital_hw = {
 	.info = SNDRV_PCM_INFO_BATCH |
 		SNDRV_PCM_INFO_MMAP |
 		SNDRV_PCM_INFO_INTERLEAVED |
 		SNDRV_PCM_INFO_BLOCK_TRANSFER |
 		SNDRV_PCM_INFO_MMAP_VALID,
 	.formats = SNDRV_PCM_FMTBIT_S16_LE,
 	.rates = SNDRV_PCM_RATE_48000,
 	.rate_min = 48000,
 	.rate_max = 48000,
 	.channels_min = 2,
 	.channels_max = 2,
 	.period_bytes_min = 11059,
 	.period_bytes_max = 13516,
 	.periods_min = 2,
 	.periods_max = 98,
 	.buffer_bytes_max = 62720 * 8, /* value in usbaudio.c */
 };

 static int snd_usbtv_pcm_open(struct snd_pcm_substream *substream)
 {
 	struct usbtv *chip = snd_pcm_substream_chip(substream);
 	struct snd_pcm_runtime *runtime = substream->runtime;

 	chip->snd_substream = substream;
 	runtime->hw = snd_usbtv_digital_hw;

 	return 0;
 }

 static int snd_usbtv_pcm_close(struct snd_pcm_substream *substream)
 {
 	struct usbtv *chip = snd_pcm_substream_chip(substream);

 	if (atomic_read(&chip->snd_stream)) {
 		atomic_set(&chip->snd_stream, 0);
 		schedule_work(&chip->snd_trigger);
 	}

 	return 0;
 }

 static int snd_usbtv_prepare(struct snd_pcm_substream *substream)
 {
 	struct usbtv *chip = snd_pcm_substream_chip(substream);

 	chip->snd_buffer_pos = 0;
 	chip->snd_period_pos = 0;

 	return 0;
 }

 static void usbtv_audio_urb_received(struct urb *urb)
 {
 	struct usbtv *chip = urb->context;
 	struct snd_pcm_substream *substream = chip->snd_substream;
 	struct snd_pcm_runtime *runtime = substream->runtime;
 	size_t i, frame_bytes, chunk_length, buffer_pos, period_pos;
 	int period_elapsed;
 	unsigned long flags;
 	void *urb_current;

 	switch (urb->status) {
 	case 0:
 	case -ETIMEDOUT:
 		break;
 	case -ENOENT:
 	case -EPROTO:
 	case -ECONNRESET:
 	case -ESHUTDOWN:
 		return;
 	default:
 		dev_warn(chip->dev, "unknown audio urb status %i\n",
 			urb->status);
 	}

 	if (!atomic_read(&chip->snd_stream))
 		return;

 	frame_bytes = runtime->frame_bits >> 3;
 	chunk_length = USBTV_CHUNK / frame_bytes;

 	buffer_pos = chip->snd_buffer_pos;
 	period_pos = chip->snd_period_pos;
 	period_elapsed = 0;

 	for (i = 0; i < urb->actual_length; i += USBTV_CHUNK_SIZE) {
 		urb_current = urb->transfer_buffer + i + USBTV_AUDIO_HDRSIZE;

 		if (buffer_pos + chunk_length >= runtime->buffer_size) {
 			size_t cnt = (runtime->buffer_size - buffer_pos) *
 				frame_bytes;
 			memcpy(runtime->dma_area + buffer_pos * frame_bytes,
 				urb_current, cnt);
 			memcpy(runtime->dma_area, urb_current + cnt,
 				chunk_length * frame_bytes - cnt);
 		} else {
 			memcpy(runtime->dma_area + buffer_pos * frame_bytes,
 				urb_current, chunk_length * frame_bytes);
 		}

 		buffer_pos += chunk_length;
 		period_pos += chunk_length;

 		if (buffer_pos >= runtime->buffer_size)
 			buffer_pos -= runtime->buffer_size;

 		if (period_pos >= runtime->period_size) {
 			period_pos -= runtime->period_size;
 			period_elapsed = 1;
 		}
 	}

 	snd_pcm_stream_lock_irqsave(substream, flags);

 	chip->snd_buffer_pos = buffer_pos;
 	chip->snd_period_pos = period_pos;

 	snd_pcm_stream_unlock_irqrestore(substream, flags);

 	if (period_elapsed)
 		snd_pcm_period_elapsed(substream);

 	usb_submit_urb(urb, GFP_ATOMIC);
 }

 static int usbtv_audio_start(struct usbtv *chip)
 {
 	unsigned int pipe;
 	static const u16 setup[][2] = {
 		/* These seem to enable the device. */
 		{ USBTV_BASE + 0x0008, 0x0001 },
 		{ USBTV_BASE + 0x01d0, 0x00ff },
 		{ USBTV_BASE + 0x01d9, 0x0002 },

 		{ USBTV_BASE + 0x01da, 0x0013 },
 		{ USBTV_BASE + 0x01db, 0x0012 },
 		{ USBTV_BASE + 0x01e9, 0x0002 },
 		{ USBTV_BASE + 0x01ec, 0x006c },
 		{ USBTV_BASE + 0x0294, 0x0020 },
 		{ USBTV_BASE + 0x0255, 0x00cf },
 		{ USBTV_BASE + 0x0256, 0x0020 },
 		{ USBTV_BASE + 0x01eb, 0x0030 },
 		{ USBTV_BASE + 0x027d, 0x00a6 },
 		{ USBTV_BASE + 0x0280, 0x0011 },
 		{ USBTV_BASE + 0x0281, 0x0040 },
 		{ USBTV_BASE + 0x0282, 0x0011 },
 		{ USBTV_BASE + 0x0283, 0x0040 },
 		{ 0xf891, 0x0010 },

 		/* this sets the input from composite */
 		{ USBTV_BASE + 0x0284, 0x00aa },
 	};

 	chip->snd_bulk_urb = usb_alloc_urb(0, GFP_KERNEL);
 	if (chip->snd_bulk_urb == NULL)
 		goto err_alloc_urb;

 	pipe = usb_rcvbulkpipe(chip->udev, USBTV_AUDIO_ENDP);

 	chip->snd_bulk_urb->transfer_buffer = kzalloc(
 		USBTV_AUDIO_URBSIZE, GFP_KERNEL);
 	if (chip->snd_bulk_urb->transfer_buffer == NULL)
 		goto err_transfer_buffer;

 	usb_fill_bulk_urb(chip->snd_bulk_urb, chip->udev, pipe,
 		chip->snd_bulk_urb->transfer_buffer, USBTV_AUDIO_URBSIZE,
 		usbtv_audio_urb_received, chip);

 	/* starting the stream */
 	usbtv_set_regs(chip, setup, ARRAY_SIZE(setup));

 	usb_clear_halt(chip->udev, pipe);
 	usb_submit_urb(chip->snd_bulk_urb, GFP_ATOMIC);

 	return 0;

 err_transfer_buffer:
 	usb_free_urb(chip->snd_bulk_urb);
 	chip->snd_bulk_urb = NULL;

 err_alloc_urb:
 	return -ENOMEM;
 }

 static int usbtv_audio_stop(struct usbtv *chip)
 {
 	static const u16 setup[][2] = {
 	/* The original windows driver sometimes sends also:
 	 *   { USBTV_BASE + 0x00a2, 0x0013 }
 	 * but it seems useless and its real effects are untested at
 	 * the moment.
 	 */
 		{ USBTV_BASE + 0x027d, 0x0000 },
 		{ USBTV_BASE + 0x0280, 0x0010 },
 		{ USBTV_BASE + 0x0282, 0x0010 },
 	};

 	if (chip->snd_bulk_urb) {
 		usb_kill_urb(chip->snd_bulk_urb);
 		kfree(chip->snd_bulk_urb->transfer_buffer);
 		usb_free_urb(chip->snd_bulk_urb);
 		chip->snd_bulk_urb = NULL;
 	}

 	usbtv_set_regs(chip, setup, ARRAY_SIZE(setup));

 	return 0;
 }

 void usbtv_audio_suspend(struct usbtv *usbtv)
 {
 	if (atomic_read(&usbtv->snd_stream) && usbtv->snd_bulk_urb)
 		usb_kill_urb(usbtv->snd_bulk_urb);
 }

 void usbtv_audio_resume(struct usbtv *usbtv)
 {
 	if (atomic_read(&usbtv->snd_stream) && usbtv->snd_bulk_urb)
 		usb_submit_urb(usbtv->snd_bulk_urb, GFP_ATOMIC);
 }

 static void snd_usbtv_trigger(struct work_struct *work)
 {
 	struct usbtv *chip = container_of(work, struct usbtv, snd_trigger);

 	if (!chip->snd)
 		return;

 	if (atomic_read(&chip->snd_stream))
 		usbtv_audio_start(chip);
 	else
 		usbtv_audio_stop(chip);
 }

 static int snd_usbtv_card_trigger(struct snd_pcm_substream *substream, int cmd)
 {
 	struct usbtv *chip = snd_pcm_substream_chip(substream);

 	switch (cmd) {
 	case SNDRV_PCM_TRIGGER_START:
 	case SNDRV_PCM_TRIGGER_RESUME:
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
 		atomic_set(&chip->snd_stream, 1);
 		break;
 	case SNDRV_PCM_TRIGGER_STOP:
 	case SNDRV_PCM_TRIGGER_SUSPEND:
 	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
 		atomic_set(&chip->snd_stream, 0);
 		break;
 	default:
 		return -EINVAL;
 	}

 	schedule_work(&chip->snd_trigger);

 	return 0;
 }

 static snd_pcm_uframes_t snd_usbtv_pointer(struct snd_pcm_substream *substream)
 {
 	struct usbtv *chip = snd_pcm_substream_chip(substream);

 	return chip->snd_buffer_pos;
 }

 static const struct snd_pcm_ops snd_usbtv_pcm_ops = {
 	.open = snd_usbtv_pcm_open,
 	.close = snd_usbtv_pcm_close,
 	.prepare = snd_usbtv_prepare,
 	.trigger = snd_usbtv_card_trigger,
 	.pointer = snd_usbtv_pointer,
 };

 int usbtv_audio_init(struct usbtv *usbtv)
 {
 	int rv;
 	struct snd_card *card;
 	struct snd_pcm *pcm;

 	INIT_WORK(&usbtv->snd_trigger, snd_usbtv_trigger);
 	atomic_set(&usbtv->snd_stream, 0);

 	rv = snd_card_new(&usbtv->udev->dev, SNDRV_DEFAULT_IDX1, "usbtv",
 		THIS_MODULE, 0, &card);
 	if (rv < 0)
 		return rv;

 	strscpy(card->driver, usbtv->dev->driver->name, sizeof(card->driver));
 	strscpy(card->shortname, "usbtv", sizeof(card->shortname));
 	snprintf(card->longname, sizeof(card->longname),
 		"USBTV Audio at bus %d device %d", usbtv->udev->bus->busnum,
 		usbtv->udev->devnum);

 	snd_card_set_dev(card, usbtv->dev);

 	usbtv->snd = card;

 	rv = snd_pcm_new(card, "USBTV Audio", 0, 0, 1, &pcm);
 	if (rv < 0)
 		goto err;

 	strscpy(pcm->name, "USBTV Audio Input", sizeof(pcm->name));
 	pcm->info_flags = 0;
 	pcm->private_data = usbtv;

 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_usbtv_pcm_ops);
 	snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
 		NULL, USBTV_AUDIO_BUFFER, USBTV_AUDIO_BUFFER);

 	rv = snd_card_register(card);
 	if (rv)
 		goto err;

 	return 0;

 err:
 	usbtv->snd = NULL;
 	snd_card_free(card);

 	return rv;
 }

 void usbtv_audio_free(struct usbtv *usbtv)
 {
 	cancel_work_sync(&usbtv->snd_trigger);

 	if (usbtv->snd && usbtv->udev) {
 		snd_card_free(usbtv->snd);
 		usbtv->snd = NULL;
 	}
 }
	/*
	* Copyright (c) 2013 Federico Simoncelli
	* All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions, and the following disclaimer,
	* without modification.
	* 2. The name of the author may not be used to endorse or promote products
	* derived from this software without specific prior written permission.
	*
	* Alternatively, this software may be distributed under the terms of the
	* GNU General Public License ("GPL").
	*
	* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*/
	/*
	* Fushicai USBTV007 Audio-Video Grabber Driver
	*
	* Product web site:
	* http://www.fushicai.com/products_detail/&productId=d05449ee-b690-42f9-a661-aa7353894bed.html
	*
	* No physical hardware was harmed running Windows during the
	* reverse-engineering activity
	*/

	#include <sound/core.h>
	#include <sound/initval.h>
	#include <sound/ac97_codec.h>
	#include <sound/pcm_params.h>

	#include "usbtv.h"

	static const struct snd_pcm_hardware snd_usbtv_digital_hw = {
	.info = SNDRV_PCM_INFO_BATCH \|
	SNDRV_PCM_INFO_MMAP \|
	SNDRV_PCM_INFO_INTERLEAVED \|
	SNDRV_PCM_INFO_BLOCK_TRANSFER \|
	SNDRV_PCM_INFO_MMAP_VALID,
	.formats = SNDRV_PCM_FMTBIT_S16_LE,
	.rates = SNDRV_PCM_RATE_48000,
	.rate_min = 48000,
	.rate_max = 48000,
	.channels_min = 2,
	.channels_max = 2,
	.period_bytes_min = 11059,
	.period_bytes_max = 13516,
	.periods_min = 2,
	.periods_max = 98,
	.buffer_bytes_max = 62720 * 8, /* value in usbaudio.c */
	};

	static int snd_usbtv_pcm_open(struct snd_pcm_substream *substream)
	{
	struct usbtv *chip = snd_pcm_substream_chip(substream);
	struct snd_pcm_runtime *runtime = substream->runtime;

	chip->snd_substream = substream;
	runtime->hw = snd_usbtv_digital_hw;

	return 0;
	}

	static int snd_usbtv_pcm_close(struct snd_pcm_substream *substream)
	{
	struct usbtv *chip = snd_pcm_substream_chip(substream);

	if (atomic_read(&chip->snd_stream)) {
	atomic_set(&chip->snd_stream, 0);
	schedule_work(&chip->snd_trigger);
	}

	return 0;
	}

	static int snd_usbtv_prepare(struct snd_pcm_substream *substream)
	{
	struct usbtv *chip = snd_pcm_substream_chip(substream);

	chip->snd_buffer_pos = 0;
	chip->snd_period_pos = 0;

	return 0;
	}

	static void usbtv_audio_urb_received(struct urb *urb)
	{
	struct usbtv *chip = urb->context;
	struct snd_pcm_substream *substream = chip->snd_substream;
	struct snd_pcm_runtime *runtime = substream->runtime;
	size_t i, frame_bytes, chunk_length, buffer_pos, period_pos;
	int period_elapsed;
	unsigned long flags;
	void *urb_current;

	switch (urb->status) {
	case 0:
	case -ETIMEDOUT:
	break;
	case -ENOENT:
	case -EPROTO:
	case -ECONNRESET:
	case -ESHUTDOWN:
	return;
	default:
	dev_warn(chip->dev, "unknown audio urb status %i\n",
	urb->status);
	}

	if (!atomic_read(&chip->snd_stream))
	return;

	frame_bytes = runtime->frame_bits >> 3;
	chunk_length = USBTV_CHUNK / frame_bytes;

	buffer_pos = chip->snd_buffer_pos;
	period_pos = chip->snd_period_pos;
	period_elapsed = 0;

	for (i = 0; i < urb->actual_length; i += USBTV_CHUNK_SIZE) {
	urb_current = urb->transfer_buffer + i + USBTV_AUDIO_HDRSIZE;

	if (buffer_pos + chunk_length >= runtime->buffer_size) {
	size_t cnt = (runtime->buffer_size - buffer_pos) *
	frame_bytes;
	memcpy(runtime->dma_area + buffer_pos * frame_bytes,
	urb_current, cnt);
	memcpy(runtime->dma_area, urb_current + cnt,
	chunk_length * frame_bytes - cnt);
	} else {
	memcpy(runtime->dma_area + buffer_pos * frame_bytes,
	urb_current, chunk_length * frame_bytes);
	}

	buffer_pos += chunk_length;
	period_pos += chunk_length;

	if (buffer_pos >= runtime->buffer_size)
	buffer_pos -= runtime->buffer_size;

	if (period_pos >= runtime->period_size) {
	period_pos -= runtime->period_size;
	period_elapsed = 1;
	}
	}

	snd_pcm_stream_lock_irqsave(substream, flags);

	chip->snd_buffer_pos = buffer_pos;
	chip->snd_period_pos = period_pos;

	snd_pcm_stream_unlock_irqrestore(substream, flags);

	if (period_elapsed)
	snd_pcm_period_elapsed(substream);

	usb_submit_urb(urb, GFP_ATOMIC);
	}

	static int usbtv_audio_start(struct usbtv *chip)
	{
	unsigned int pipe;
	static const u16 setup[][2] = {
	/* These seem to enable the device. */
	{ USBTV_BASE + 0x0008, 0x0001 },
	{ USBTV_BASE + 0x01d0, 0x00ff },
	{ USBTV_BASE + 0x01d9, 0x0002 },

	{ USBTV_BASE + 0x01da, 0x0013 },
	{ USBTV_BASE + 0x01db, 0x0012 },
	{ USBTV_BASE + 0x01e9, 0x0002 },
	{ USBTV_BASE + 0x01ec, 0x006c },
	{ USBTV_BASE + 0x0294, 0x0020 },
	{ USBTV_BASE + 0x0255, 0x00cf },
	{ USBTV_BASE + 0x0256, 0x0020 },
	{ USBTV_BASE + 0x01eb, 0x0030 },
	{ USBTV_BASE + 0x027d, 0x00a6 },
	{ USBTV_BASE + 0x0280, 0x0011 },
	{ USBTV_BASE + 0x0281, 0x0040 },
	{ USBTV_BASE + 0x0282, 0x0011 },
	{ USBTV_BASE + 0x0283, 0x0040 },
	{ 0xf891, 0x0010 },

	/* this sets the input from composite */
	{ USBTV_BASE + 0x0284, 0x00aa },
	};

	chip->snd_bulk_urb = usb_alloc_urb(0, GFP_KERNEL);
	if (chip->snd_bulk_urb == NULL)
	goto err_alloc_urb;

	pipe = usb_rcvbulkpipe(chip->udev, USBTV_AUDIO_ENDP);

	chip->snd_bulk_urb->transfer_buffer = kzalloc(
	USBTV_AUDIO_URBSIZE, GFP_KERNEL);
	if (chip->snd_bulk_urb->transfer_buffer == NULL)
	goto err_transfer_buffer;

	usb_fill_bulk_urb(chip->snd_bulk_urb, chip->udev, pipe,
	chip->snd_bulk_urb->transfer_buffer, USBTV_AUDIO_URBSIZE,
	usbtv_audio_urb_received, chip);

	/* starting the stream */
	usbtv_set_regs(chip, setup, ARRAY_SIZE(setup));

	usb_clear_halt(chip->udev, pipe);
	usb_submit_urb(chip->snd_bulk_urb, GFP_ATOMIC);

	return 0;

	err_transfer_buffer:
	usb_free_urb(chip->snd_bulk_urb);
	chip->snd_bulk_urb = NULL;

	err_alloc_urb:
	return -ENOMEM;
	}

	static int usbtv_audio_stop(struct usbtv *chip)
	{
	static const u16 setup[][2] = {
	/* The original windows driver sometimes sends also:
	* { USBTV_BASE + 0x00a2, 0x0013 }
	* but it seems useless and its real effects are untested at
	* the moment.
	*/
	{ USBTV_BASE + 0x027d, 0x0000 },
	{ USBTV_BASE + 0x0280, 0x0010 },
	{ USBTV_BASE + 0x0282, 0x0010 },
	};

	if (chip->snd_bulk_urb) {
	usb_kill_urb(chip->snd_bulk_urb);
	kfree(chip->snd_bulk_urb->transfer_buffer);
	usb_free_urb(chip->snd_bulk_urb);
	chip->snd_bulk_urb = NULL;
	}

	usbtv_set_regs(chip, setup, ARRAY_SIZE(setup));

	return 0;
	}

	void usbtv_audio_suspend(struct usbtv *usbtv)
	{
	if (atomic_read(&usbtv->snd_stream) && usbtv->snd_bulk_urb)
	usb_kill_urb(usbtv->snd_bulk_urb);
	}

	void usbtv_audio_resume(struct usbtv *usbtv)
	{
	if (atomic_read(&usbtv->snd_stream) && usbtv->snd_bulk_urb)
	usb_submit_urb(usbtv->snd_bulk_urb, GFP_ATOMIC);
	}

	static void snd_usbtv_trigger(struct work_struct *work)
	{
	struct usbtv *chip = container_of(work, struct usbtv, snd_trigger);

	if (!chip->snd)
	return;

	if (atomic_read(&chip->snd_stream))
	usbtv_audio_start(chip);
	else
	usbtv_audio_stop(chip);
	}

	static int snd_usbtv_card_trigger(struct snd_pcm_substream *substream, int cmd)
	{
	struct usbtv *chip = snd_pcm_substream_chip(substream);

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_START:
	case SNDRV_PCM_TRIGGER_RESUME:
	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
	atomic_set(&chip->snd_stream, 1);
	break;
	case SNDRV_PCM_TRIGGER_STOP:
	case SNDRV_PCM_TRIGGER_SUSPEND:
	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
	atomic_set(&chip->snd_stream, 0);
	break;
	default:
	return -EINVAL;
	}

	schedule_work(&chip->snd_trigger);

	return 0;
	}

	static snd_pcm_uframes_t snd_usbtv_pointer(struct snd_pcm_substream *substream)
	{
	struct usbtv *chip = snd_pcm_substream_chip(substream);

	return chip->snd_buffer_pos;
	}

	static const struct snd_pcm_ops snd_usbtv_pcm_ops = {
	.open = snd_usbtv_pcm_open,
	.close = snd_usbtv_pcm_close,
	.prepare = snd_usbtv_prepare,
	.trigger = snd_usbtv_card_trigger,
	.pointer = snd_usbtv_pointer,
	};

	int usbtv_audio_init(struct usbtv *usbtv)
	{
	int rv;
	struct snd_card *card;
	struct snd_pcm *pcm;

	INIT_WORK(&usbtv->snd_trigger, snd_usbtv_trigger);
	atomic_set(&usbtv->snd_stream, 0);

	rv = snd_card_new(&usbtv->udev->dev, SNDRV_DEFAULT_IDX1, "usbtv",
	THIS_MODULE, 0, &card);
	if (rv < 0)
	return rv;

	strscpy(card->driver, usbtv->dev->driver->name, sizeof(card->driver));
	strscpy(card->shortname, "usbtv", sizeof(card->shortname));
	snprintf(card->longname, sizeof(card->longname),
	"USBTV Audio at bus %d device %d", usbtv->udev->bus->busnum,
	usbtv->udev->devnum);

	snd_card_set_dev(card, usbtv->dev);

	usbtv->snd = card;

	rv = snd_pcm_new(card, "USBTV Audio", 0, 0, 1, &pcm);
	if (rv < 0)
	goto err;

	strscpy(pcm->name, "USBTV Audio Input", sizeof(pcm->name));
	pcm->info_flags = 0;
	pcm->private_data = usbtv;

	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_usbtv_pcm_ops);
	snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
	NULL, USBTV_AUDIO_BUFFER, USBTV_AUDIO_BUFFER);

	rv = snd_card_register(card);
	if (rv)
	goto err;

	return 0;

	err:
	usbtv->snd = NULL;
	snd_card_free(card);

	return rv;
	}

	void usbtv_audio_free(struct usbtv *usbtv)
	{
	cancel_work_sync(&usbtv->snd_trigger);

	if (usbtv->snd && usbtv->udev) {
	snd_card_free(usbtv->snd);
	usbtv->snd = NULL;
	}
	}