linux/drivers/usb/gadget/function/u_uac1_legacy.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * u_uac1.c -- ALSA audio utilities for Gadget stack
 *
 * Copyright (C) 2008 Bryan Wu <[email protected]>
 * Copyright (C) 2008 Analog Devices, Inc
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/ctype.h>
#include <linux/random.h>
#include <linux/syscalls.h>

#include "u_uac1_legacy.h"

/*
 * This component encapsulates the ALSA devices for USB audio gadget
 */

/*-------------------------------------------------------------------------*/

/*
 * Some ALSA internal helper functions
 */
static int snd_interval_refine_set(struct snd_interval *i, unsigned int val)
{ … }

static int _snd_pcm_hw_param_set(struct snd_pcm_hw_params *params,
				 snd_pcm_hw_param_t var, unsigned int val,
				 int dir)
{ … }
/*-------------------------------------------------------------------------*/

/*
 * Set default hardware params
 */
static int playback_default_hw_params(struct gaudio_snd_dev *snd)
{ … }

/*
 * Playback audio buffer data by ALSA PCM device
 */
size_t u_audio_playback(struct gaudio *card, void *buf, size_t count)
{ … }

int u_audio_get_playback_channels(struct gaudio *card)
{ … }

int u_audio_get_playback_rate(struct gaudio *card)
{ … }

/*
 * Open ALSA PCM and control device files
 * Initial the PCM or control device
 */
static int gaudio_open_snd_dev(struct gaudio *card)
{ … }

/*
 * Close ALSA PCM and control device files
 */
static int gaudio_close_snd_dev(struct gaudio *gau)
{ … }

/*
 * gaudio_setup - setup ALSA interface and preparing for USB transfer
 *
 * This sets up PCM, mixer or MIDI ALSA devices fore USB gadget using.
 *
 * Returns negative errno, or zero on success
 */
int gaudio_setup(struct gaudio *card)
{ … }

/*
 * gaudio_cleanup - remove ALSA device interface
 *
 * This is called to free all resources allocated by @gaudio_setup().
 */
void gaudio_cleanup(struct gaudio *the_card)
{ … }