linux/sound/usb/format.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 */

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/usb/audio.h>
#include <linux/usb/audio-v2.h>
#include <linux/usb/audio-v3.h>

#include <sound/core.h>
#include <sound/pcm.h>

#include "usbaudio.h"
#include "card.h"
#include "quirks.h"
#include "helper.h"
#include "clock.h"
#include "format.h"

/*
 * parse the audio format type I descriptor
 * and returns the corresponding pcm format
 *
 * @dev: usb device
 * @fp: audioformat record
 * @format: the format tag (wFormatTag)
 * @fmt: the format type descriptor (v1/v2) or AudioStreaming descriptor (v3)
 */
static u64 parse_audio_format_i_type(struct snd_usb_audio *chip,
				     struct audioformat *fp,
				     u64 format, void *_fmt)
{ … }

static int set_fixed_rate(struct audioformat *fp, int rate, int rate_bits)
{ … }

/* set up rate_min, rate_max and rates from the rate table */
static void set_rate_table_min_max(struct audioformat *fp)
{ … }

/*
 * parse the format descriptor and stores the possible sample rates
 * on the audioformat table (audio class v1).
 *
 * @dev: usb device
 * @fp: audioformat record
 * @fmt: the format descriptor
 * @offset: the start offset of descriptor pointing the rate type
 *          (7 for type I and II, 8 for type II)
 */
static int parse_audio_format_rates_v1(struct snd_usb_audio *chip, struct audioformat *fp,
				       unsigned char *fmt, int offset)
{ … }


/*
 * Presonus Studio 1810c supports a limited set of sampling
 * rates per altsetting but reports the full set each time.
 * If we don't filter out the unsupported rates and attempt
 * to configure the card, it will hang refusing to do any
 * further audio I/O until a hard reset is performed.
 *
 * The list of supported rates per altsetting (set of available
 * I/O channels) is described in the owner's manual, section 2.2.
 */
static bool s1810c_valid_sample_rate(struct audioformat *fp,
				     unsigned int rate)
{ … }

/*
 * Many Focusrite devices supports a limited set of sampling rates per
 * altsetting. Maximum rate is exposed in the last 4 bytes of Format Type
 * descriptor which has a non-standard bLength = 10.
 */
static bool focusrite_valid_sample_rate(struct snd_usb_audio *chip,
					struct audioformat *fp,
					unsigned int rate)
{ … }

/*
 * Helper function to walk the array of sample rate triplets reported by
 * the device. The problem is that we need to parse whole array first to
 * get to know how many sample rates we have to expect.
 * Then fp->rate_table can be allocated and filled.
 */
static int parse_uac2_sample_rate_range(struct snd_usb_audio *chip,
					struct audioformat *fp, int nr_triplets,
					const unsigned char *data)
{ … }

/* Line6 Helix series and the Rode Rodecaster Pro don't support the
 * UAC2_CS_RANGE usb function call. Return a static table of known
 * clock rates.
 */
static int line6_parse_audio_format_rates_quirk(struct snd_usb_audio *chip,
						struct audioformat *fp)
{ … }

/* check whether the given altsetting is supported for the already set rate */
static bool check_valid_altsetting_v2v3(struct snd_usb_audio *chip, int iface,
					int altsetting)
{ … }

/*
 * Validate each sample rate with the altsetting
 * Rebuild the rate table if only partial values are valid
 */
static int validate_sample_rate_table_v2v3(struct snd_usb_audio *chip,
					   struct audioformat *fp,
					   int clock)
{ … }

/*
 * parse the format descriptor and stores the possible sample rates
 * on the audioformat table (audio class v2 and v3).
 */
static int parse_audio_format_rates_v2v3(struct snd_usb_audio *chip,
				       struct audioformat *fp)
{ … }

/*
 * parse the format type I and III descriptors
 */
static int parse_audio_format_i(struct snd_usb_audio *chip,
				struct audioformat *fp, u64 format,
				void *_fmt)
{ … }

/*
 * parse the format type II descriptor
 */
static int parse_audio_format_ii(struct snd_usb_audio *chip,
				 struct audioformat *fp,
				 u64 format, void *_fmt)
{ … }

int snd_usb_parse_audio_format(struct snd_usb_audio *chip,
			       struct audioformat *fp, u64 format,
			       struct uac_format_type_i_continuous_descriptor *fmt,
			       int stream)
{ … }

int snd_usb_parse_audio_format_v3(struct snd_usb_audio *chip,
			       struct audioformat *fp,
			       struct uac3_as_header_descriptor *as,
			       int stream)
{ … }