[mirror_ubuntu-jammy-kernel.git] / Documentation / sound / alsa / soc / machine.txt

ASoC Machine Driver
===================

The ASoC machine (or board) driver is the code that glues together the platform
and codec drivers.

The machine driver can contain codec and platform specific code. It registers
the audio subsystem with the kernel as a platform device and is represented by
the following struct:-

/* SoC machine */
struct snd_soc_card {
	char *name;

	...

	int (*probe)(struct platform_device *pdev);
	int (*remove)(struct platform_device *pdev);

	/* the pre and post PM functions are used to do any PM work before and
	 * after the codec and DAIs do any PM work. */
	int (*suspend_pre)(struct platform_device *pdev, pm_message_t state);
	int (*suspend_post)(struct platform_device *pdev, pm_message_t state);
	int (*resume_pre)(struct platform_device *pdev);
	int (*resume_post)(struct platform_device *pdev);

	...

	/* CPU <--> Codec DAI links  */
	struct snd_soc_dai_link *dai_link;
	int num_links;

	...
};

probe()/remove()
----------------
probe/remove are optional. Do any machine specific probe here.


suspend()/resume()
------------------
The machine driver has pre and post versions of suspend and resume to take care
of any machine audio tasks that have to be done before or after the codec, DAIs
and DMA is suspended and resumed. Optional.


Machine DAI Configuration
-------------------------
The machine DAI configuration glues all the codec and CPU DAIs together. It can
also be used to set up the DAI system clock and for any machine related DAI
initialisation e.g. the machine audio map can be connected to the codec audio
map, unconnected codec pins can be set as such.

struct snd_soc_dai_link is used to set up each DAI in your machine. e.g.

/* corgi digital audio interface glue - connects codec <--> CPU */
static struct snd_soc_dai_link corgi_dai = {
	.name = "WM8731",
	.stream_name = "WM8731",
	.cpu_dai_name = "pxa-is2-dai",
	.codec_dai_name = "wm8731-hifi",
	.platform_name = "pxa-pcm-audio",
	.codec_name = "wm8713-codec.0-001a",
	.init = corgi_wm8731_init,
	.ops = &corgi_ops,
};

struct snd_soc_card then sets up the machine with its DAIs. e.g.

/* corgi audio machine driver */
static struct snd_soc_card snd_soc_corgi = {
	.name = "Corgi",
	.dai_link = &corgi_dai,
	.num_links = 1,
};


Machine Power Map
-----------------

The machine driver can optionally extend the codec power map and to become an
audio power map of the audio subsystem. This allows for automatic power up/down
of speaker/HP amplifiers, etc. Codec pins can be connected to the machines jack
sockets in the machine init function.


Machine Controls
----------------

Machine specific audio mixer controls can be added in the DAI init function.
Commit	Line	Data
eb1a6af3 LG	1	ASoC Machine Driver
	2	===================
	3
	4	The ASoC machine (or board) driver is the code that glues together the platform
	5	and codec drivers.
	6
	7	The machine driver can contain codec and platform specific code. It registers
	8	the audio subsystem with the kernel as a platform device and is represented by
	9	the following struct:-
	10
	11	/* SoC machine */
4f904735	12	struct snd_soc_card {
eb1a6af3 LG	13	char *name;
eb1a6af3 LG	14
379c4bf1 SY	15	...
379c4bf1 SY	16
eb1a6af3 LG	17	int (probe)(struct platform_device pdev);
	18	int (remove)(struct platform_device pdev);
	19
	20	/* the pre and post PM functions are used to do any PM work before and
7c4dbbd8	21	* after the codec and DAIs do any PM work. */
eb1a6af3 LG	22	int (suspend_pre)(struct platform_device pdev, pm_message_t state);
	23	int (suspend_post)(struct platform_device pdev, pm_message_t state);
	24	int (resume_pre)(struct platform_device pdev);
	25	int (resume_post)(struct platform_device pdev);
	26
379c4bf1	27	...
eb1a6af3 LG	28
	29	/* CPU <--> Codec DAI links */
	30	struct snd_soc_dai_link *dai_link;
	31	int num_links;
379c4bf1 SY	32
379c4bf1 SY	33	...
eb1a6af3 LG	34	};
	35
	36	probe()/remove()
	37	----------------
	38	probe/remove are optional. Do any machine specific probe here.
	39
	40
	41	suspend()/resume()
	42	------------------
	43	The machine driver has pre and post versions of suspend and resume to take care
7c4dbbd8	44	of any machine audio tasks that have to be done before or after the codec, DAIs
eb1a6af3 LG	45	and DMA is suspended and resumed. Optional.
	46
	47
eb1a6af3 LG	48	Machine DAI Configuration
eb1a6af3 LG	49	-------------------------
7c4dbbd8	50	The machine DAI configuration glues all the codec and CPU DAIs together. It can
eb1a6af3 LG	51	also be used to set up the DAI system clock and for any machine related DAI
eb1a6af3 LG	52	initialisation e.g. the machine audio map can be connected to the codec audio
145294c3	53	map, unconnected codec pins can be set as such.
eb1a6af3 LG	54
	55	struct snd_soc_dai_link is used to set up each DAI in your machine. e.g.
	56
	57	/* corgi digital audio interface glue - connects codec <--> CPU */
	58	static struct snd_soc_dai_link corgi_dai = {
	59	.name = "WM8731",
	60	.stream_name = "WM8731",
379c4bf1 SY	61	.cpu_dai_name = "pxa-is2-dai",
	62	.codec_dai_name = "wm8731-hifi",
	63	.platform_name = "pxa-pcm-audio",
	64	.codec_name = "wm8713-codec.0-001a",
eb1a6af3	65	.init = corgi_wm8731_init,
10b98527	66	.ops = &corgi_ops,
eb1a6af3 LG	67	};
eb1a6af3 LG	68
a33f3224	69	struct snd_soc_card then sets up the machine with its DAIs. e.g.
eb1a6af3 LG	70
eb1a6af3 LG	71	/* corgi audio machine driver */
87506549	72	static struct snd_soc_card snd_soc_corgi = {
eb1a6af3 LG	73	.name = "Corgi",
	74	.dai_link = &corgi_dai,
	75	.num_links = 1,
eb1a6af3 LG	76	};
	77
	78
eb1a6af3 LG	79	Machine Power Map
	80	-----------------
	81
	82	The machine driver can optionally extend the codec power map and to become an
	83	audio power map of the audio subsystem. This allows for automatic power up/down
	84	of speaker/HP amplifiers, etc. Codec pins can be connected to the machines jack
145294c3	85	sockets in the machine init function.
eb1a6af3 LG	86
	87
	88	Machine Controls
	89	----------------
	90
7c4dbbd8	91	Machine specific audio mixer controls can be added in the DAI init function.