linux/sound/usb/line6/pcm.h

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

/*
	PCM interface to POD series devices.
*/

#ifndef PCM_H
#define PCM_H

#include <sound/pcm.h>

#include "driver.h"

/*
	number of USB frames per URB
	The Line 6 Windows driver always transmits two frames per packet, but
	the Linux driver performs significantly better (i.e., lower latency)
	with only one frame per packet.
*/
#define LINE6_ISO_PACKETS …

/* in a "full speed" device (such as the PODxt Pro) this means 1ms,
 *  for "high speed" it's 1/8ms
 */
#define LINE6_ISO_INTERVAL …

#define LINE6_IMPULSE_DEFAULT_PERIOD …

/*
	Get substream from Line 6 PCM data structure
*/
#define get_substream(line6pcm, stream) …

/*
	PCM mode bits.

	There are several features of the Line 6 USB driver which require PCM
	data to be exchanged with the device:
	*) PCM playback and capture via ALSA
	*) software monitoring (for devices without hardware monitoring)
	*) optional impulse response measurement
	However, from the device's point of view, there is just a single
	capture and playback stream, which must be shared between these
	subsystems. It is therefore necessary to maintain the state of the
	subsystems with respect to PCM usage.

	We define two bit flags, "opened" and "running", for each playback
	or capture stream.  Both can contain the bit flag corresponding to
	LINE6_STREAM_* type,
	  LINE6_STREAM_PCM = ALSA PCM playback or capture
	  LINE6_STREAM_MONITOR = software monitoring
	  IMPULSE = optional impulse response measurement
	The opened flag indicates whether the buffer is allocated while
	the running flag indicates whether the stream is running.

	For monitor or impulse operations, the driver needs to call
	line6_pcm_acquire() or line6_pcm_release() with the appropriate
	LINE6_STREAM_* flag.
*/

/* stream types */
enum { … };

/* misc bit flags for PCM operation */
enum { … };

struct line6_pcm_properties { … };

struct line6_pcm_stream { … };

struct snd_line6_pcm { … };

extern int line6_init_pcm(struct usb_line6 *line6,
			  struct line6_pcm_properties *properties);
extern int snd_line6_trigger(struct snd_pcm_substream *substream, int cmd);
extern int snd_line6_prepare(struct snd_pcm_substream *substream);
extern int snd_line6_hw_params(struct snd_pcm_substream *substream,
			       struct snd_pcm_hw_params *hw_params);
extern int snd_line6_hw_free(struct snd_pcm_substream *substream);
extern snd_pcm_uframes_t snd_line6_pointer(struct snd_pcm_substream *substream);
extern void line6_pcm_disconnect(struct snd_line6_pcm *line6pcm);
extern int line6_pcm_acquire(struct snd_line6_pcm *line6pcm, int type,
			       bool start);
extern void line6_pcm_release(struct snd_line6_pcm *line6pcm, int type);

#endif