Full ASoC stub driver · trace playback capability → DAPM route → platform probe. Source-aware explanations and edge cases.
// SPDX-License-Identifier: GPL-2.0-only
/*
* ALSA SoC SPDIF DIT driver
*
* This driver is used by controllers which can operate in DIT (SPDI/F) where
* no codec is needed. This file provides stub codec that can be used
* in these configurations. TI DaVinci Audio controller uses this driver.
* Author: Steve Chen, <schen@mvista.com>
* Copyright: (C) 2009 MontaVista Software, Inc., <source@mvista.com>
* Copyright: (C) 2009 Texas Instruments, India
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <sound/soc.h>
#include <sound/pcm.h>
#include <sound/initval.h>
#include <linux/of.h>
#define DRV_NAME "spdif-dit"
#define STUB_RATES (SNDRV_PCM_RATE_8000_768000 | \\
SNDRV_PCM_RATE_128000)
#define STUB_FORMATS (SNDRV_PCM_FMTBIT_S16_LE | \\
SNDRV_PCM_FMTBIT_S20_3LE | \\
SNDRV_PCM_FMTBIT_S24_LE | \\
SNDRV_PCM_FMTBIT_S32_LE)
static const struct snd_soc_dapm_widget dit_widgets[] = {
SND_SOC_DAPM_OUTPUT("spdif-out"),
};
static const struct snd_soc_dapm_route dit_routes[] = {
{ "spdif-out", NULL, "Playback" },
static const struct snd_soc_component_driver soc_codec_spdif_dit = {
.dapm_widgets = dit_widgets,
.num_dapm_widgets = ARRAY_SIZE(dit_widgets),
.dapm_routes = dit_routes,
.num_dapm_routes = ARRAY_SIZE(dit_routes),
.idle_bias_on = 1,
.use_pmdown_time = 1,
.endianness = 1,
static struct snd_soc_dai_driver dit_stub_dai = {
.name = "dit-hifi",
.playback = {
.stream_name = "Playback",
.channels_min = 1,
.channels_max = 384,
.rates = STUB_RATES,
.formats = STUB_FORMATS,
},
static int spdif_dit_probe(struct platform_device *pdev)
{
return devm_snd_soc_register_component(&pdev->dev,
&soc_codec_spdif_dit,
&dit_stub_dai, 1);
}
#ifdef CONFIG_OF
static const struct of_device_id spdif_dit_dt_ids[] = {
{ .compatible = "linux,spdif-dit", },
{ }
MODULE_DEVICE_TABLE(of, spdif_dit_dt_ids);
#endif
static struct platform_driver spdif_dit_driver = {
.probe = spdif_dit_probe,
.driver = {
.name = DRV_NAME,
.of_match_table = of_match_ptr(spdif_dit_dt_ids),
module_platform_driver(spdif_dit_driver);
MODULE_AUTHOR("Steve Chen <schen@mvista.com>");
MODULE_DESCRIPTION("SPDIF dummy codec driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" DRV_NAME);