sound/usb/line6/pcm.c - kernel/common - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Line 6 Linux USB driver
  *
  * Copyright (C) 2004-2010 Markus Grabner ([email protected])
  */

 #include <linux/slab.h>
 #include <linux/export.h>
 #include <sound/core.h>
 #include <sound/control.h>
 #include <sound/pcm.h>
 #include <sound/pcm_params.h>

 #include "capture.h"
 #include "driver.h"
 #include "playback.h"

 /* impulse response volume controls */
 static int snd_line6_impulse_volume_info(struct snd_kcontrol *kcontrol,
 					 struct snd_ctl_elem_info *uinfo)
 {
 	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
 	uinfo->count = 1;
 	uinfo->value.integer.min = 0;
 	uinfo->value.integer.max = 255;
 	return 0;
 }

 static int snd_line6_impulse_volume_get(struct snd_kcontrol *kcontrol,
 					struct snd_ctl_elem_value *ucontrol)
 {
 	struct snd_line6_pcm *line6pcm = snd_kcontrol_chip(kcontrol);

 	ucontrol->value.integer.value[0] = line6pcm->impulse_volume;
 	return 0;
 }

 static int snd_line6_impulse_volume_put(struct snd_kcontrol *kcontrol,
 					struct snd_ctl_elem_value *ucontrol)
 {
 	struct snd_line6_pcm *line6pcm = snd_kcontrol_chip(kcontrol);
 	int value = ucontrol->value.integer.value[0];
 	int err;

 	if (line6pcm->impulse_volume == value)
 		return 0;

 	line6pcm->impulse_volume = value;
 	if (value > 0) {
 		err = line6_pcm_acquire(line6pcm, LINE6_STREAM_IMPULSE, true);
 		if (err < 0) {
 			line6pcm->impulse_volume = 0;
 			return err;
 		}
 	} else {
 		line6_pcm_release(line6pcm, LINE6_STREAM_IMPULSE);
 	}
 	return 1;
 }

 /* impulse response period controls */
 static int snd_line6_impulse_period_info(struct snd_kcontrol *kcontrol,
 					 struct snd_ctl_elem_info *uinfo)
 {
 	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
 	uinfo->count = 1;
 	uinfo->value.integer.min = 0;
 	uinfo->value.integer.max = 2000;
 	return 0;
 }

 static int snd_line6_impulse_period_get(struct snd_kcontrol *kcontrol,
 					struct snd_ctl_elem_value *ucontrol)
 {
 	struct snd_line6_pcm *line6pcm = snd_kcontrol_chip(kcontrol);

 	ucontrol->value.integer.value[0] = line6pcm->impulse_period;
 	return 0;
 }

 static int snd_line6_impulse_period_put(struct snd_kcontrol *kcontrol,
 					struct snd_ctl_elem_value *ucontrol)
 {
 	struct snd_line6_pcm *line6pcm = snd_kcontrol_chip(kcontrol);
 	int value = ucontrol->value.integer.value[0];

 	if (line6pcm->impulse_period == value)
 		return 0;

 	line6pcm->impulse_period = value;
 	return 1;
 }

 /*
 	Unlink all currently active URBs.
 */
 static void line6_unlink_audio_urbs(struct snd_line6_pcm *line6pcm,
 				    struct line6_pcm_stream *pcms)
 {
 	int i;

 	for (i = 0; i < line6pcm->line6->iso_buffers; i++) {
 		if (test_bit(i, &pcms->active_urbs)) {
 			if (!test_and_set_bit(i, &pcms->unlink_urbs))
 				usb_unlink_urb(pcms->urbs[i]);
 		}
 	}
 }

 /*
 	Wait until unlinking of all currently active URBs has been finished.
 */
 static void line6_wait_clear_audio_urbs(struct snd_line6_pcm *line6pcm,
 					struct line6_pcm_stream *pcms)
 {
 	int timeout = HZ;
 	int i;
 	int alive;

 	do {
 		alive = 0;
 		for (i = 0; i < line6pcm->line6->iso_buffers; i++) {
 			if (test_bit(i, &pcms->active_urbs))
 				alive++;
 		}
 		if (!alive)
 			break;
 		set_current_state(TASK_UNINTERRUPTIBLE);
 		schedule_timeout(1);
 	} while (--timeout > 0);
 	if (alive)
 		dev_err(line6pcm->line6->ifcdev,
 			"timeout: still %d active urbs..\n", alive);
 }

 static inline struct line6_pcm_stream *
 get_stream(struct snd_line6_pcm *line6pcm, int direction)
 {
 	return (direction == SNDRV_PCM_STREAM_PLAYBACK) ?
 		&line6pcm->out : &line6pcm->in;
 }

 /* allocate a buffer if not opened yet;
  * call this in line6pcm.state_mutex
  */
 static int line6_buffer_acquire(struct snd_line6_pcm *line6pcm,
 				struct line6_pcm_stream *pstr, int direction, int type)
 {
 	const int pkt_size =
 		(direction == SNDRV_PCM_STREAM_PLAYBACK) ?
 			line6pcm->max_packet_size_out :
 			line6pcm->max_packet_size_in;

 	/* Invoked multiple times in a row so allocate once only */
 	if (!test_and_set_bit(type, &pstr->opened) && !pstr->buffer) {
 		pstr->buffer =
 			kmalloc(array3_size(line6pcm->line6->iso_buffers,
 					    LINE6_ISO_PACKETS, pkt_size),
 				GFP_KERNEL);
 		if (!pstr->buffer)
 			return -ENOMEM;
 	}
 	return 0;
 }

 /* free a buffer if all streams are closed;
  * call this in line6pcm.state_mutex
  */
 static void line6_buffer_release(struct snd_line6_pcm *line6pcm,
 				 struct line6_pcm_stream *pstr, int type)
 {
 	clear_bit(type, &pstr->opened);
 	if (!pstr->opened) {
 		line6_wait_clear_audio_urbs(line6pcm, pstr);
 		kfree(pstr->buffer);
 		pstr->buffer = NULL;
 	}
 }

 /* start a PCM stream */
 static int line6_stream_start(struct snd_line6_pcm *line6pcm, int direction,
 			      int type)
 {
 	unsigned long flags;
 	struct line6_pcm_stream *pstr = get_stream(line6pcm, direction);
 	int ret = 0;

 	spin_lock_irqsave(&pstr->lock, flags);
 	if (!test_and_set_bit(type, &pstr->running) &&
 	    !(pstr->active_urbs || pstr->unlink_urbs)) {
 		pstr->count = 0;
 		/* Submit all currently available URBs */
 		if (direction == SNDRV_PCM_STREAM_PLAYBACK)
 			ret = line6_submit_audio_out_all_urbs(line6pcm);
 		else
 			ret = line6_submit_audio_in_all_urbs(line6pcm);
 	}

 	if (ret < 0)
 		clear_bit(type, &pstr->running);
 	spin_unlock_irqrestore(&pstr->lock, flags);
 	return ret;
 }

 /* stop a PCM stream; this doesn't sync with the unlinked URBs */
 static void line6_stream_stop(struct snd_line6_pcm *line6pcm, int direction,
 			  int type)
 {
 	unsigned long flags;
 	struct line6_pcm_stream *pstr = get_stream(line6pcm, direction);

 	spin_lock_irqsave(&pstr->lock, flags);
 	clear_bit(type, &pstr->running);
 	if (!pstr->running) {
 		spin_unlock_irqrestore(&pstr->lock, flags);
 		line6_unlink_audio_urbs(line6pcm, pstr);
 		spin_lock_irqsave(&pstr->lock, flags);
 		if (direction == SNDRV_PCM_STREAM_CAPTURE) {
 			line6pcm->prev_fbuf = NULL;
 			line6pcm->prev_fsize = 0;
 		}
 	}
 	spin_unlock_irqrestore(&pstr->lock, flags);
 }

 /* common PCM trigger callback */
 int snd_line6_trigger(struct snd_pcm_substream *substream, int cmd)
 {
 	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
 	struct snd_pcm_substream *s;
 	int err;

 	clear_bit(LINE6_FLAG_PREPARED, &line6pcm->flags);

 	snd_pcm_group_for_each_entry(s, substream) {
 		if (s->pcm->card != substream->pcm->card)
 			continue;

 		switch (cmd) {
 		case SNDRV_PCM_TRIGGER_START:
 		case SNDRV_PCM_TRIGGER_RESUME:
 			if (s->stream == SNDRV_PCM_STREAM_CAPTURE &&
 				(line6pcm->line6->properties->capabilities &
 					LINE6_CAP_IN_NEEDS_OUT)) {
 				err = line6_stream_start(line6pcm, SNDRV_PCM_STREAM_PLAYBACK,
 						 LINE6_STREAM_CAPTURE_HELPER);
 				if (err < 0)
 					return err;
 			}
 			err = line6_stream_start(line6pcm, s->stream,
 						 LINE6_STREAM_PCM);
 			if (err < 0)
 				return err;
 			break;

 		case SNDRV_PCM_TRIGGER_STOP:
 		case SNDRV_PCM_TRIGGER_SUSPEND:
 			if (s->stream == SNDRV_PCM_STREAM_CAPTURE &&
 				(line6pcm->line6->properties->capabilities &
 					LINE6_CAP_IN_NEEDS_OUT)) {
 				line6_stream_stop(line6pcm, SNDRV_PCM_STREAM_PLAYBACK,
 					  LINE6_STREAM_CAPTURE_HELPER);
 			}
 			line6_stream_stop(line6pcm, s->stream,
 					  LINE6_STREAM_PCM);
 			break;

 		case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
 			if (s->stream != SNDRV_PCM_STREAM_PLAYBACK)
 				return -EINVAL;
 			set_bit(LINE6_FLAG_PAUSE_PLAYBACK, &line6pcm->flags);
 			break;

 		case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
 			if (s->stream != SNDRV_PCM_STREAM_PLAYBACK)
 				return -EINVAL;
 			clear_bit(LINE6_FLAG_PAUSE_PLAYBACK, &line6pcm->flags);
 			break;

 		default:
 			return -EINVAL;
 		}
 	}

 	return 0;
 }

 /* common PCM pointer callback */
 snd_pcm_uframes_t snd_line6_pointer(struct snd_pcm_substream *substream)
 {
 	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
 	struct line6_pcm_stream *pstr = get_stream(line6pcm, substream->stream);

 	return pstr->pos_done;
 }

 /* Acquire and optionally start duplex streams:
  * type is either LINE6_STREAM_IMPULSE or LINE6_STREAM_MONITOR
  */
 int line6_pcm_acquire(struct snd_line6_pcm *line6pcm, int type, bool start)
 {
 	struct line6_pcm_stream *pstr;
 	int ret = 0, dir;

 	/* TODO: We should assert SNDRV_PCM_STREAM_PLAYBACK/CAPTURE == 0/1 */
 	mutex_lock(&line6pcm->state_mutex);
 	for (dir = 0; dir < 2; dir++) {
 		pstr = get_stream(line6pcm, dir);
 		ret = line6_buffer_acquire(line6pcm, pstr, dir, type);
 		if (ret < 0)
 			goto error;
 		if (!pstr->running)
 			line6_wait_clear_audio_urbs(line6pcm, pstr);
 	}
 	if (start) {
 		for (dir = 0; dir < 2; dir++) {
 			ret = line6_stream_start(line6pcm, dir, type);
 			if (ret < 0)
 				goto error;
 		}
 	}
  error:
 	mutex_unlock(&line6pcm->state_mutex);
 	if (ret < 0)
 		line6_pcm_release(line6pcm, type);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(line6_pcm_acquire);

 /* Stop and release duplex streams */
 void line6_pcm_release(struct snd_line6_pcm *line6pcm, int type)
 {
 	struct line6_pcm_stream *pstr;
 	int dir;

 	mutex_lock(&line6pcm->state_mutex);
 	for (dir = 0; dir < 2; dir++)
 		line6_stream_stop(line6pcm, dir, type);
 	for (dir = 0; dir < 2; dir++) {
 		pstr = get_stream(line6pcm, dir);
 		line6_buffer_release(line6pcm, pstr, type);
 	}
 	mutex_unlock(&line6pcm->state_mutex);
 }
 EXPORT_SYMBOL_GPL(line6_pcm_release);

 /* common PCM hw_params callback */
 int snd_line6_hw_params(struct snd_pcm_substream *substream,
 			struct snd_pcm_hw_params *hw_params)
 {
 	int ret;
 	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
 	struct line6_pcm_stream *pstr = get_stream(line6pcm, substream->stream);

 	mutex_lock(&line6pcm->state_mutex);
 	ret = line6_buffer_acquire(line6pcm, pstr, substream->stream,
 	                           LINE6_STREAM_PCM);
 	if (ret < 0)
 		goto error;

 	ret = snd_pcm_lib_malloc_pages(substream,
 				       params_buffer_bytes(hw_params));
 	if (ret < 0) {
 		line6_buffer_release(line6pcm, pstr, LINE6_STREAM_PCM);
 		goto error;
 	}

 	pstr->period = params_period_bytes(hw_params);
  error:
 	mutex_unlock(&line6pcm->state_mutex);
 	return ret;
 }

 /* common PCM hw_free callback */
 int snd_line6_hw_free(struct snd_pcm_substream *substream)
 {
 	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
 	struct line6_pcm_stream *pstr = get_stream(line6pcm, substream->stream);

 	mutex_lock(&line6pcm->state_mutex);
 	line6_buffer_release(line6pcm, pstr, LINE6_STREAM_PCM);
 	mutex_unlock(&line6pcm->state_mutex);
 	return snd_pcm_lib_free_pages(substream);
 }


 /* control info callback */
 static int snd_line6_control_playback_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 = 0;
 	uinfo->value.integer.max = 256;
 	return 0;
 }

 /* control get callback */
 static int snd_line6_control_playback_get(struct snd_kcontrol *kcontrol,
 					  struct snd_ctl_elem_value *ucontrol)
 {
 	int i;
 	struct snd_line6_pcm *line6pcm = snd_kcontrol_chip(kcontrol);

 	for (i = 0; i < 2; i++)
 		ucontrol->value.integer.value[i] = line6pcm->volume_playback[i];

 	return 0;
 }

 /* control put callback */
 static int snd_line6_control_playback_put(struct snd_kcontrol *kcontrol,
 					  struct snd_ctl_elem_value *ucontrol)
 {
 	int i, changed = 0;
 	struct snd_line6_pcm *line6pcm = snd_kcontrol_chip(kcontrol);

 	for (i = 0; i < 2; i++)
 		if (line6pcm->volume_playback[i] !=
 		    ucontrol->value.integer.value[i]) {
 			line6pcm->volume_playback[i] =
 			    ucontrol->value.integer.value[i];
 			changed = 1;
 		}

 	return changed;
 }

 /* control definition */
 static const struct snd_kcontrol_new line6_controls[] = {
 	{
 		.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 		.name = "PCM Playback Volume",
 		.info = snd_line6_control_playback_info,
 		.get = snd_line6_control_playback_get,
 		.put = snd_line6_control_playback_put
 	},
 	{
 		.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 		.name = "Impulse Response Volume",
 		.info = snd_line6_impulse_volume_info,
 		.get = snd_line6_impulse_volume_get,
 		.put = snd_line6_impulse_volume_put
 	},
 	{
 		.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 		.name = "Impulse Response Period",
 		.info = snd_line6_impulse_period_info,
 		.get = snd_line6_impulse_period_get,
 		.put = snd_line6_impulse_period_put
 	},
 };

 /*
 	Cleanup the PCM device.
 */
 static void cleanup_urbs(struct line6_pcm_stream *pcms, int iso_buffers)
 {
 	int i;

 	/* Most likely impossible in current code... */
 	if (pcms->urbs == NULL)
 		return;

 	for (i = 0; i < iso_buffers; i++) {
 		if (pcms->urbs[i]) {
 			usb_kill_urb(pcms->urbs[i]);
 			usb_free_urb(pcms->urbs[i]);
 		}
 	}
 	kfree(pcms->urbs);
 	pcms->urbs = NULL;
 }

 static void line6_cleanup_pcm(struct snd_pcm *pcm)
 {
 	struct snd_line6_pcm *line6pcm = snd_pcm_chip(pcm);

 	cleanup_urbs(&line6pcm->out, line6pcm->line6->iso_buffers);
 	cleanup_urbs(&line6pcm->in, line6pcm->line6->iso_buffers);
 	kfree(line6pcm);
 }

 /* create a PCM device */
 static int snd_line6_new_pcm(struct usb_line6 *line6, struct snd_pcm **pcm_ret)
 {
 	struct snd_pcm *pcm;
 	int err;

 	err = snd_pcm_new(line6->card, (char *)line6->properties->name,
 			  0, 1, 1, pcm_ret);
 	if (err < 0)
 		return err;
 	pcm = *pcm_ret;
 	strcpy(pcm->name, line6->properties->name);

 	/* set operators */
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK,
 			&snd_line6_playback_ops);
 	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_line6_capture_ops);

 	/* pre-allocation of buffers */
 	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
 					      snd_dma_continuous_data
 					      (GFP_KERNEL), 64 * 1024,
 					      128 * 1024);
 	return 0;
 }

 /*
 	Sync with PCM stream stops.
 */
 void line6_pcm_disconnect(struct snd_line6_pcm *line6pcm)
 {
 	line6_unlink_audio_urbs(line6pcm, &line6pcm->out);
 	line6_unlink_audio_urbs(line6pcm, &line6pcm->in);
 	line6_wait_clear_audio_urbs(line6pcm, &line6pcm->out);
 	line6_wait_clear_audio_urbs(line6pcm, &line6pcm->in);
 }

 /*
 	Create and register the PCM device and mixer entries.
 	Create URBs for playback and capture.
 */
 int line6_init_pcm(struct usb_line6 *line6,
 		   struct line6_pcm_properties *properties)
 {
 	int i, err;
 	unsigned ep_read = line6->properties->ep_audio_r;
 	unsigned ep_write = line6->properties->ep_audio_w;
 	struct snd_pcm *pcm;
 	struct snd_line6_pcm *line6pcm;

 	if (!(line6->properties->capabilities & LINE6_CAP_PCM))
 		return 0;	/* skip PCM initialization and report success */

 	err = snd_line6_new_pcm(line6, &pcm);
 	if (err < 0)
 		return err;

 	line6pcm = kzalloc(sizeof(*line6pcm), GFP_KERNEL);
 	if (!line6pcm)
 		return -ENOMEM;

 	mutex_init(&line6pcm->state_mutex);
 	line6pcm->pcm = pcm;
 	line6pcm->properties = properties;
 	line6pcm->volume_playback[0] = line6pcm->volume_playback[1] = 255;
 	line6pcm->volume_monitor = 255;
 	line6pcm->line6 = line6;

 	line6pcm->max_packet_size_in =
 		usb_maxpacket(line6->usbdev,
 			usb_rcvisocpipe(line6->usbdev, ep_read), 0);
 	line6pcm->max_packet_size_out =
 		usb_maxpacket(line6->usbdev,
 			usb_sndisocpipe(line6->usbdev, ep_write), 1);

 	spin_lock_init(&line6pcm->out.lock);
 	spin_lock_init(&line6pcm->in.lock);
 	line6pcm->impulse_period = LINE6_IMPULSE_DEFAULT_PERIOD;

 	line6->line6pcm = line6pcm;

 	pcm->private_data = line6pcm;
 	pcm->private_free = line6_cleanup_pcm;

 	err = line6_create_audio_out_urbs(line6pcm);
 	if (err < 0)
 		return err;

 	err = line6_create_audio_in_urbs(line6pcm);
 	if (err < 0)
 		return err;

 	/* mixer: */
 	for (i = 0; i < ARRAY_SIZE(line6_controls); i++) {
 		err = snd_ctl_add(line6->card,
 				  snd_ctl_new1(&line6_controls[i], line6pcm));
 		if (err < 0)
 			return err;
 	}

 	return 0;
 }
 EXPORT_SYMBOL_GPL(line6_init_pcm);

 /* prepare pcm callback */
 int snd_line6_prepare(struct snd_pcm_substream *substream)
 {
 	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
 	struct line6_pcm_stream *pstr = get_stream(line6pcm, substream->stream);

 	mutex_lock(&line6pcm->state_mutex);
 	if (!pstr->running)
 		line6_wait_clear_audio_urbs(line6pcm, pstr);

 	if (!test_and_set_bit(LINE6_FLAG_PREPARED, &line6pcm->flags)) {
 		line6pcm->out.count = 0;
 		line6pcm->out.pos = 0;
 		line6pcm->out.pos_done = 0;
 		line6pcm->out.bytes = 0;
 		line6pcm->in.count = 0;
 		line6pcm->in.pos_done = 0;
 		line6pcm->in.bytes = 0;
 	}

 	mutex_unlock(&line6pcm->state_mutex);
 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Line 6 Linux USB driver
	*
	* Copyright (C) 2004-2010 Markus Grabner ([email protected])
	*/

	#include <linux/slab.h>
	#include <linux/export.h>
	#include <sound/core.h>
	#include <sound/control.h>
	#include <sound/pcm.h>
	#include <sound/pcm_params.h>

	#include "capture.h"
	#include "driver.h"
	#include "playback.h"

	/* impulse response volume controls */
	static int snd_line6_impulse_volume_info(struct snd_kcontrol *kcontrol,
	struct snd_ctl_elem_info *uinfo)
	{
	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
	uinfo->count = 1;
	uinfo->value.integer.min = 0;
	uinfo->value.integer.max = 255;
	return 0;
	}

	static int snd_line6_impulse_volume_get(struct snd_kcontrol *kcontrol,
	struct snd_ctl_elem_value *ucontrol)
	{
	struct snd_line6_pcm *line6pcm = snd_kcontrol_chip(kcontrol);

	ucontrol->value.integer.value[0] = line6pcm->impulse_volume;
	return 0;
	}

	static int snd_line6_impulse_volume_put(struct snd_kcontrol *kcontrol,
	struct snd_ctl_elem_value *ucontrol)
	{
	struct snd_line6_pcm *line6pcm = snd_kcontrol_chip(kcontrol);
	int value = ucontrol->value.integer.value[0];
	int err;

	if (line6pcm->impulse_volume == value)
	return 0;

	line6pcm->impulse_volume = value;
	if (value > 0) {
	err = line6_pcm_acquire(line6pcm, LINE6_STREAM_IMPULSE, true);
	if (err < 0) {
	line6pcm->impulse_volume = 0;
	return err;
	}
	} else {
	line6_pcm_release(line6pcm, LINE6_STREAM_IMPULSE);
	}
	return 1;
	}

	/* impulse response period controls */
	static int snd_line6_impulse_period_info(struct snd_kcontrol *kcontrol,
	struct snd_ctl_elem_info *uinfo)
	{
	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
	uinfo->count = 1;
	uinfo->value.integer.min = 0;
	uinfo->value.integer.max = 2000;
	return 0;
	}

	static int snd_line6_impulse_period_get(struct snd_kcontrol *kcontrol,
	struct snd_ctl_elem_value *ucontrol)
	{
	struct snd_line6_pcm *line6pcm = snd_kcontrol_chip(kcontrol);

	ucontrol->value.integer.value[0] = line6pcm->impulse_period;
	return 0;
	}

	static int snd_line6_impulse_period_put(struct snd_kcontrol *kcontrol,
	struct snd_ctl_elem_value *ucontrol)
	{
	struct snd_line6_pcm *line6pcm = snd_kcontrol_chip(kcontrol);
	int value = ucontrol->value.integer.value[0];

	if (line6pcm->impulse_period == value)
	return 0;

	line6pcm->impulse_period = value;
	return 1;
	}

	/*
	Unlink all currently active URBs.
	*/
	static void line6_unlink_audio_urbs(struct snd_line6_pcm *line6pcm,
	struct line6_pcm_stream *pcms)
	{
	int i;

	for (i = 0; i < line6pcm->line6->iso_buffers; i++) {
	if (test_bit(i, &pcms->active_urbs)) {
	if (!test_and_set_bit(i, &pcms->unlink_urbs))
	usb_unlink_urb(pcms->urbs[i]);
	}
	}
	}

	/*
	Wait until unlinking of all currently active URBs has been finished.
	*/
	static void line6_wait_clear_audio_urbs(struct snd_line6_pcm *line6pcm,
	struct line6_pcm_stream *pcms)
	{
	int timeout = HZ;
	int i;
	int alive;

	do {
	alive = 0;
	for (i = 0; i < line6pcm->line6->iso_buffers; i++) {
	if (test_bit(i, &pcms->active_urbs))
	alive++;
	}
	if (!alive)
	break;
	set_current_state(TASK_UNINTERRUPTIBLE);
	schedule_timeout(1);
	} while (--timeout > 0);
	if (alive)
	dev_err(line6pcm->line6->ifcdev,
	"timeout: still %d active urbs..\n", alive);
	}

	static inline struct line6_pcm_stream *
	get_stream(struct snd_line6_pcm *line6pcm, int direction)
	{
	return (direction == SNDRV_PCM_STREAM_PLAYBACK) ?
	&line6pcm->out : &line6pcm->in;
	}

	/* allocate a buffer if not opened yet;
	* call this in line6pcm.state_mutex
	*/
	static int line6_buffer_acquire(struct snd_line6_pcm *line6pcm,
	struct line6_pcm_stream *pstr, int direction, int type)
	{
	const int pkt_size =
	(direction == SNDRV_PCM_STREAM_PLAYBACK) ?
	line6pcm->max_packet_size_out :
	line6pcm->max_packet_size_in;

	/* Invoked multiple times in a row so allocate once only */
	if (!test_and_set_bit(type, &pstr->opened) && !pstr->buffer) {
	pstr->buffer =
	kmalloc(array3_size(line6pcm->line6->iso_buffers,
	LINE6_ISO_PACKETS, pkt_size),
	GFP_KERNEL);
	if (!pstr->buffer)
	return -ENOMEM;
	}
	return 0;
	}

	/* free a buffer if all streams are closed;
	* call this in line6pcm.state_mutex
	*/
	static void line6_buffer_release(struct snd_line6_pcm *line6pcm,
	struct line6_pcm_stream *pstr, int type)
	{
	clear_bit(type, &pstr->opened);
	if (!pstr->opened) {
	line6_wait_clear_audio_urbs(line6pcm, pstr);
	kfree(pstr->buffer);
	pstr->buffer = NULL;
	}
	}

	/* start a PCM stream */
	static int line6_stream_start(struct snd_line6_pcm *line6pcm, int direction,
	int type)
	{
	unsigned long flags;
	struct line6_pcm_stream *pstr = get_stream(line6pcm, direction);
	int ret = 0;

	spin_lock_irqsave(&pstr->lock, flags);
	if (!test_and_set_bit(type, &pstr->running) &&
	!(pstr->active_urbs \|\| pstr->unlink_urbs)) {
	pstr->count = 0;
	/* Submit all currently available URBs */
	if (direction == SNDRV_PCM_STREAM_PLAYBACK)
	ret = line6_submit_audio_out_all_urbs(line6pcm);
	else
	ret = line6_submit_audio_in_all_urbs(line6pcm);
	}

	if (ret < 0)
	clear_bit(type, &pstr->running);
	spin_unlock_irqrestore(&pstr->lock, flags);
	return ret;
	}

	/* stop a PCM stream; this doesn't sync with the unlinked URBs */
	static void line6_stream_stop(struct snd_line6_pcm *line6pcm, int direction,
	int type)
	{
	unsigned long flags;
	struct line6_pcm_stream *pstr = get_stream(line6pcm, direction);

	spin_lock_irqsave(&pstr->lock, flags);
	clear_bit(type, &pstr->running);
	if (!pstr->running) {
	spin_unlock_irqrestore(&pstr->lock, flags);
	line6_unlink_audio_urbs(line6pcm, pstr);
	spin_lock_irqsave(&pstr->lock, flags);
	if (direction == SNDRV_PCM_STREAM_CAPTURE) {
	line6pcm->prev_fbuf = NULL;
	line6pcm->prev_fsize = 0;
	}
	}
	spin_unlock_irqrestore(&pstr->lock, flags);
	}

	/* common PCM trigger callback */
	int snd_line6_trigger(struct snd_pcm_substream *substream, int cmd)
	{
	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
	struct snd_pcm_substream *s;
	int err;

	clear_bit(LINE6_FLAG_PREPARED, &line6pcm->flags);

	snd_pcm_group_for_each_entry(s, substream) {
	if (s->pcm->card != substream->pcm->card)
	continue;

	switch (cmd) {
	case SNDRV_PCM_TRIGGER_START:
	case SNDRV_PCM_TRIGGER_RESUME:
	if (s->stream == SNDRV_PCM_STREAM_CAPTURE &&
	(line6pcm->line6->properties->capabilities &
	LINE6_CAP_IN_NEEDS_OUT)) {
	err = line6_stream_start(line6pcm, SNDRV_PCM_STREAM_PLAYBACK,
	LINE6_STREAM_CAPTURE_HELPER);
	if (err < 0)
	return err;
	}
	err = line6_stream_start(line6pcm, s->stream,
	LINE6_STREAM_PCM);
	if (err < 0)
	return err;
	break;

	case SNDRV_PCM_TRIGGER_STOP:
	case SNDRV_PCM_TRIGGER_SUSPEND:
	if (s->stream == SNDRV_PCM_STREAM_CAPTURE &&
	(line6pcm->line6->properties->capabilities &
	LINE6_CAP_IN_NEEDS_OUT)) {
	line6_stream_stop(line6pcm, SNDRV_PCM_STREAM_PLAYBACK,
	LINE6_STREAM_CAPTURE_HELPER);
	}
	line6_stream_stop(line6pcm, s->stream,
	LINE6_STREAM_PCM);
	break;

	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
	if (s->stream != SNDRV_PCM_STREAM_PLAYBACK)
	return -EINVAL;
	set_bit(LINE6_FLAG_PAUSE_PLAYBACK, &line6pcm->flags);
	break;

	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
	if (s->stream != SNDRV_PCM_STREAM_PLAYBACK)
	return -EINVAL;
	clear_bit(LINE6_FLAG_PAUSE_PLAYBACK, &line6pcm->flags);
	break;

	default:
	return -EINVAL;
	}
	}

	return 0;
	}

	/* common PCM pointer callback */
	snd_pcm_uframes_t snd_line6_pointer(struct snd_pcm_substream *substream)
	{
	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
	struct line6_pcm_stream *pstr = get_stream(line6pcm, substream->stream);

	return pstr->pos_done;
	}

	/* Acquire and optionally start duplex streams:
	* type is either LINE6_STREAM_IMPULSE or LINE6_STREAM_MONITOR
	*/
	int line6_pcm_acquire(struct snd_line6_pcm *line6pcm, int type, bool start)
	{
	struct line6_pcm_stream *pstr;
	int ret = 0, dir;

	/* TODO: We should assert SNDRV_PCM_STREAM_PLAYBACK/CAPTURE == 0/1 */
	mutex_lock(&line6pcm->state_mutex);
	for (dir = 0; dir < 2; dir++) {
	pstr = get_stream(line6pcm, dir);
	ret = line6_buffer_acquire(line6pcm, pstr, dir, type);
	if (ret < 0)
	goto error;
	if (!pstr->running)
	line6_wait_clear_audio_urbs(line6pcm, pstr);
	}
	if (start) {
	for (dir = 0; dir < 2; dir++) {
	ret = line6_stream_start(line6pcm, dir, type);
	if (ret < 0)
	goto error;
	}
	}
	error:
	mutex_unlock(&line6pcm->state_mutex);
	if (ret < 0)
	line6_pcm_release(line6pcm, type);
	return ret;
	}
	EXPORT_SYMBOL_GPL(line6_pcm_acquire);

	/* Stop and release duplex streams */
	void line6_pcm_release(struct snd_line6_pcm *line6pcm, int type)
	{
	struct line6_pcm_stream *pstr;
	int dir;

	mutex_lock(&line6pcm->state_mutex);
	for (dir = 0; dir < 2; dir++)
	line6_stream_stop(line6pcm, dir, type);
	for (dir = 0; dir < 2; dir++) {
	pstr = get_stream(line6pcm, dir);
	line6_buffer_release(line6pcm, pstr, type);
	}
	mutex_unlock(&line6pcm->state_mutex);
	}
	EXPORT_SYMBOL_GPL(line6_pcm_release);

	/* common PCM hw_params callback */
	int snd_line6_hw_params(struct snd_pcm_substream *substream,
	struct snd_pcm_hw_params *hw_params)
	{
	int ret;
	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
	struct line6_pcm_stream *pstr = get_stream(line6pcm, substream->stream);

	mutex_lock(&line6pcm->state_mutex);
	ret = line6_buffer_acquire(line6pcm, pstr, substream->stream,
	LINE6_STREAM_PCM);
	if (ret < 0)
	goto error;

	ret = snd_pcm_lib_malloc_pages(substream,
	params_buffer_bytes(hw_params));
	if (ret < 0) {
	line6_buffer_release(line6pcm, pstr, LINE6_STREAM_PCM);
	goto error;
	}

	pstr->period = params_period_bytes(hw_params);
	error:
	mutex_unlock(&line6pcm->state_mutex);
	return ret;
	}

	/* common PCM hw_free callback */
	int snd_line6_hw_free(struct snd_pcm_substream *substream)
	{
	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
	struct line6_pcm_stream *pstr = get_stream(line6pcm, substream->stream);

	mutex_lock(&line6pcm->state_mutex);
	line6_buffer_release(line6pcm, pstr, LINE6_STREAM_PCM);
	mutex_unlock(&line6pcm->state_mutex);
	return snd_pcm_lib_free_pages(substream);
	}


	/* control info callback */
	static int snd_line6_control_playback_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 = 0;
	uinfo->value.integer.max = 256;
	return 0;
	}

	/* control get callback */
	static int snd_line6_control_playback_get(struct snd_kcontrol *kcontrol,
	struct snd_ctl_elem_value *ucontrol)
	{
	int i;
	struct snd_line6_pcm *line6pcm = snd_kcontrol_chip(kcontrol);

	for (i = 0; i < 2; i++)
	ucontrol->value.integer.value[i] = line6pcm->volume_playback[i];

	return 0;
	}

	/* control put callback */
	static int snd_line6_control_playback_put(struct snd_kcontrol *kcontrol,
	struct snd_ctl_elem_value *ucontrol)
	{
	int i, changed = 0;
	struct snd_line6_pcm *line6pcm = snd_kcontrol_chip(kcontrol);

	for (i = 0; i < 2; i++)
	if (line6pcm->volume_playback[i] !=
	ucontrol->value.integer.value[i]) {
	line6pcm->volume_playback[i] =
	ucontrol->value.integer.value[i];
	changed = 1;
	}

	return changed;
	}

	/* control definition */
	static const struct snd_kcontrol_new line6_controls[] = {
	{
	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
	.name = "PCM Playback Volume",
	.info = snd_line6_control_playback_info,
	.get = snd_line6_control_playback_get,
	.put = snd_line6_control_playback_put
	},
	{
	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
	.name = "Impulse Response Volume",
	.info = snd_line6_impulse_volume_info,
	.get = snd_line6_impulse_volume_get,
	.put = snd_line6_impulse_volume_put
	},
	{
	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
	.name = "Impulse Response Period",
	.info = snd_line6_impulse_period_info,
	.get = snd_line6_impulse_period_get,
	.put = snd_line6_impulse_period_put
	},
	};

	/*
	Cleanup the PCM device.
	*/
	static void cleanup_urbs(struct line6_pcm_stream *pcms, int iso_buffers)
	{
	int i;

	/* Most likely impossible in current code... */
	if (pcms->urbs == NULL)
	return;

	for (i = 0; i < iso_buffers; i++) {
	if (pcms->urbs[i]) {
	usb_kill_urb(pcms->urbs[i]);
	usb_free_urb(pcms->urbs[i]);
	}
	}
	kfree(pcms->urbs);
	pcms->urbs = NULL;
	}

	static void line6_cleanup_pcm(struct snd_pcm *pcm)
	{
	struct snd_line6_pcm *line6pcm = snd_pcm_chip(pcm);

	cleanup_urbs(&line6pcm->out, line6pcm->line6->iso_buffers);
	cleanup_urbs(&line6pcm->in, line6pcm->line6->iso_buffers);
	kfree(line6pcm);
	}

	/* create a PCM device */
	static int snd_line6_new_pcm(struct usb_line6 line6, struct snd_pcm *pcm_ret)
	{
	struct snd_pcm *pcm;
	int err;

	err = snd_pcm_new(line6->card, (char *)line6->properties->name,
	0, 1, 1, pcm_ret);
	if (err < 0)
	return err;
	pcm = *pcm_ret;
	strcpy(pcm->name, line6->properties->name);

	/* set operators */
	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK,
	&snd_line6_playback_ops);
	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &snd_line6_capture_ops);

	/* pre-allocation of buffers */
	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
	snd_dma_continuous_data
	(GFP_KERNEL), 64 * 1024,
	128 * 1024);
	return 0;
	}

	/*
	Sync with PCM stream stops.
	*/
	void line6_pcm_disconnect(struct snd_line6_pcm *line6pcm)
	{
	line6_unlink_audio_urbs(line6pcm, &line6pcm->out);
	line6_unlink_audio_urbs(line6pcm, &line6pcm->in);
	line6_wait_clear_audio_urbs(line6pcm, &line6pcm->out);
	line6_wait_clear_audio_urbs(line6pcm, &line6pcm->in);
	}

	/*
	Create and register the PCM device and mixer entries.
	Create URBs for playback and capture.
	*/
	int line6_init_pcm(struct usb_line6 *line6,
	struct line6_pcm_properties *properties)
	{
	int i, err;
	unsigned ep_read = line6->properties->ep_audio_r;
	unsigned ep_write = line6->properties->ep_audio_w;
	struct snd_pcm *pcm;
	struct snd_line6_pcm *line6pcm;

	if (!(line6->properties->capabilities & LINE6_CAP_PCM))
	return 0; /* skip PCM initialization and report success */

	err = snd_line6_new_pcm(line6, &pcm);
	if (err < 0)
	return err;

	line6pcm = kzalloc(sizeof(*line6pcm), GFP_KERNEL);
	if (!line6pcm)
	return -ENOMEM;

	mutex_init(&line6pcm->state_mutex);
	line6pcm->pcm = pcm;
	line6pcm->properties = properties;
	line6pcm->volume_playback[0] = line6pcm->volume_playback[1] = 255;
	line6pcm->volume_monitor = 255;
	line6pcm->line6 = line6;

	line6pcm->max_packet_size_in =
	usb_maxpacket(line6->usbdev,
	usb_rcvisocpipe(line6->usbdev, ep_read), 0);
	line6pcm->max_packet_size_out =
	usb_maxpacket(line6->usbdev,
	usb_sndisocpipe(line6->usbdev, ep_write), 1);

	spin_lock_init(&line6pcm->out.lock);
	spin_lock_init(&line6pcm->in.lock);
	line6pcm->impulse_period = LINE6_IMPULSE_DEFAULT_PERIOD;

	line6->line6pcm = line6pcm;

	pcm->private_data = line6pcm;
	pcm->private_free = line6_cleanup_pcm;

	err = line6_create_audio_out_urbs(line6pcm);
	if (err < 0)
	return err;

	err = line6_create_audio_in_urbs(line6pcm);
	if (err < 0)
	return err;

	/* mixer: */
	for (i = 0; i < ARRAY_SIZE(line6_controls); i++) {
	err = snd_ctl_add(line6->card,
	snd_ctl_new1(&line6_controls[i], line6pcm));
	if (err < 0)
	return err;
	}

	return 0;
	}
	EXPORT_SYMBOL_GPL(line6_init_pcm);

	/* prepare pcm callback */
	int snd_line6_prepare(struct snd_pcm_substream *substream)
	{
	struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);
	struct line6_pcm_stream *pstr = get_stream(line6pcm, substream->stream);

	mutex_lock(&line6pcm->state_mutex);
	if (!pstr->running)
	line6_wait_clear_audio_urbs(line6pcm, pstr);

	if (!test_and_set_bit(LINE6_FLAG_PREPARED, &line6pcm->flags)) {
	line6pcm->out.count = 0;
	line6pcm->out.pos = 0;
	line6pcm->out.pos_done = 0;
	line6pcm->out.bytes = 0;
	line6pcm->in.count = 0;
	line6pcm->in.pos_done = 0;
	line6pcm->in.bytes = 0;
	}

	mutex_unlock(&line6pcm->state_mutex);
	return 0;
	}