linux/sound/virtio/virtio_pcm.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * virtio-snd: Virtio sound device
 * Copyright (C) 2021 OpenSynergy GmbH
 */
#include <linux/moduleparam.h>
#include <linux/virtio_config.h>

#include "virtio_card.h"

static u32 pcm_buffer_ms = …;
module_param(pcm_buffer_ms, uint, 0644);
MODULE_PARM_DESC(…) …;

static u32 pcm_periods_min = …;
module_param(pcm_periods_min, uint, 0644);
MODULE_PARM_DESC(…) …;

static u32 pcm_periods_max = …;
module_param(pcm_periods_max, uint, 0644);
MODULE_PARM_DESC(…) …;

static u32 pcm_period_ms_min = …;
module_param(pcm_period_ms_min, uint, 0644);
MODULE_PARM_DESC(…) …;

static u32 pcm_period_ms_max = …;
module_param(pcm_period_ms_max, uint, 0644);
MODULE_PARM_DESC(…) …;

/* Map for converting VirtIO format to ALSA format. */
static const snd_pcm_format_t g_v2a_format_map[] = …;

/* Map for converting VirtIO frame rate to ALSA frame rate. */
struct virtsnd_v2a_rate { … };

static const struct virtsnd_v2a_rate g_v2a_rate_map[] = …;

/**
 * virtsnd_pcm_build_hw() - Parse substream config and build HW descriptor.
 * @vss: VirtIO substream.
 * @info: VirtIO substream information entry.
 *
 * Context: Any context.
 * Return: 0 on success, -EINVAL if configuration is invalid.
 */
static int virtsnd_pcm_build_hw(struct virtio_pcm_substream *vss,
				struct virtio_snd_pcm_info *info)
{ … }

/**
 * virtsnd_pcm_find() - Find the PCM device for the specified node ID.
 * @snd: VirtIO sound device.
 * @nid: Function node ID.
 *
 * Context: Any context.
 * Return: a pointer to the PCM device or ERR_PTR(-ENOENT).
 */
struct virtio_pcm *virtsnd_pcm_find(struct virtio_snd *snd, u32 nid)
{ … }

/**
 * virtsnd_pcm_find_or_create() - Find or create the PCM device for the
 *                                specified node ID.
 * @snd: VirtIO sound device.
 * @nid: Function node ID.
 *
 * Context: Any context that permits to sleep.
 * Return: a pointer to the PCM device or ERR_PTR(-errno).
 */
struct virtio_pcm *virtsnd_pcm_find_or_create(struct virtio_snd *snd, u32 nid)
{ … }

/**
 * virtsnd_pcm_validate() - Validate if the device can be started.
 * @vdev: VirtIO parent device.
 *
 * Context: Any context.
 * Return: 0 on success, -EINVAL on failure.
 */
int virtsnd_pcm_validate(struct virtio_device *vdev)
{ … }

/**
 * virtsnd_pcm_period_elapsed() - Kernel work function to handle the elapsed
 *                                period state.
 * @work: Elapsed period work.
 *
 * The main purpose of this function is to call snd_pcm_period_elapsed() in
 * a process context, not in an interrupt context. This is necessary because PCM
 * devices operate in non-atomic mode.
 *
 * Context: Process context.
 */
static void virtsnd_pcm_period_elapsed(struct work_struct *work)
{ … }

/**
 * virtsnd_pcm_parse_cfg() - Parse the stream configuration.
 * @snd: VirtIO sound device.
 *
 * This function is called during initial device initialization.
 *
 * Context: Any context that permits to sleep.
 * Return: 0 on success, -errno on failure.
 */
int virtsnd_pcm_parse_cfg(struct virtio_snd *snd)
{ … }

/**
 * virtsnd_pcm_build_devs() - Build ALSA PCM devices.
 * @snd: VirtIO sound device.
 *
 * Context: Any context that permits to sleep.
 * Return: 0 on success, -errno on failure.
 */
int virtsnd_pcm_build_devs(struct virtio_snd *snd)
{ … }

/**
 * virtsnd_pcm_event() - Handle the PCM device event notification.
 * @snd: VirtIO sound device.
 * @event: VirtIO sound event.
 *
 * Context: Interrupt context.
 */
void virtsnd_pcm_event(struct virtio_snd *snd, struct virtio_snd_event *event)
{ … }