113 lines
3.3 KiB
Plaintext
113 lines
3.3 KiB
Plaintext
ASoC Machine Driver
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===================
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The ASoC machine (or board) driver is the code that glues together the platform
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and codec drivers.
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The machine driver can contain codec and platform specific code. It registers
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the audio subsystem with the kernel as a platform device and is represented by
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the following struct:-
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/* SoC machine */
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struct snd_soc_machine {
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char *name;
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int (*probe)(struct platform_device *pdev);
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int (*remove)(struct platform_device *pdev);
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/* the pre and post PM functions are used to do any PM work before and
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* after the codec and DAI's do any PM work. */
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int (*suspend_pre)(struct platform_device *pdev, pm_message_t state);
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int (*suspend_post)(struct platform_device *pdev, pm_message_t state);
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int (*resume_pre)(struct platform_device *pdev);
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int (*resume_post)(struct platform_device *pdev);
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/* machine stream operations */
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struct snd_soc_ops *ops;
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/* CPU <--> Codec DAI links */
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struct snd_soc_dai_link *dai_link;
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int num_links;
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};
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probe()/remove()
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----------------
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probe/remove are optional. Do any machine specific probe here.
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suspend()/resume()
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------------------
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The machine driver has pre and post versions of suspend and resume to take care
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of any machine audio tasks that have to be done before or after the codec, DAI's
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and DMA is suspended and resumed. Optional.
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Machine operations
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------------------
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The machine specific audio operations can be set here. Again this is optional.
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Machine DAI Configuration
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-------------------------
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The machine DAI configuration glues all the codec and CPU DAI's together. It can
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also be used to set up the DAI system clock and for any machine related DAI
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initialisation e.g. the machine audio map can be connected to the codec audio
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map, unconnnected codec pins can be set as such. Please see corgi.c, spitz.c
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for examples.
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struct snd_soc_dai_link is used to set up each DAI in your machine. e.g.
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/* corgi digital audio interface glue - connects codec <--> CPU */
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static struct snd_soc_dai_link corgi_dai = {
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.name = "WM8731",
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.stream_name = "WM8731",
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.cpu_dai = &pxa_i2s_dai,
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.codec_dai = &wm8731_dai,
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.init = corgi_wm8731_init,
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.ops = &corgi_ops,
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};
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struct snd_soc_machine then sets up the machine with it's DAI's. e.g.
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/* corgi audio machine driver */
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static struct snd_soc_machine snd_soc_machine_corgi = {
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.name = "Corgi",
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.dai_link = &corgi_dai,
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.num_links = 1,
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};
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Machine Audio Subsystem
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-----------------------
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The machine soc device glues the platform, machine and codec driver together.
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Private data can also be set here. e.g.
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/* corgi audio private data */
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static struct wm8731_setup_data corgi_wm8731_setup = {
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.i2c_address = 0x1b,
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};
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/* corgi audio subsystem */
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static struct snd_soc_device corgi_snd_devdata = {
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.machine = &snd_soc_machine_corgi,
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.platform = &pxa2xx_soc_platform,
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.codec_dev = &soc_codec_dev_wm8731,
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.codec_data = &corgi_wm8731_setup,
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};
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Machine Power Map
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-----------------
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The machine driver can optionally extend the codec power map and to become an
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audio power map of the audio subsystem. This allows for automatic power up/down
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of speaker/HP amplifiers, etc. Codec pins can be connected to the machines jack
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sockets in the machine init function. See soc/pxa/spitz.c and dapm.txt for
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details.
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Machine Controls
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----------------
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Machine specific audio mixer controls can be added in the dai init function. |