| Liam Girdwood | eb1a6af | 2006-10-06 18:34:51 +0200 | [diff] [blame^] | 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 */ |
| 12 | struct snd_soc_machine { |
| 13 | char *name; |
| 14 | |
| 15 | int (*probe)(struct platform_device *pdev); |
| 16 | int (*remove)(struct platform_device *pdev); |
| 17 | |
| 18 | /* the pre and post PM functions are used to do any PM work before and |
| 19 | * after the codec and DAI's do any PM work. */ |
| 20 | int (*suspend_pre)(struct platform_device *pdev, pm_message_t state); |
| 21 | int (*suspend_post)(struct platform_device *pdev, pm_message_t state); |
| 22 | int (*resume_pre)(struct platform_device *pdev); |
| 23 | int (*resume_post)(struct platform_device *pdev); |
| 24 | |
| 25 | /* machine stream operations */ |
| 26 | struct snd_soc_ops *ops; |
| 27 | |
| 28 | /* CPU <--> Codec DAI links */ |
| 29 | struct snd_soc_dai_link *dai_link; |
| 30 | int num_links; |
| 31 | }; |
| 32 | |
| 33 | probe()/remove() |
| 34 | ---------------- |
| 35 | probe/remove are optional. Do any machine specific probe here. |
| 36 | |
| 37 | |
| 38 | suspend()/resume() |
| 39 | ------------------ |
| 40 | The machine driver has pre and post versions of suspend and resume to take care |
| 41 | of any machine audio tasks that have to be done before or after the codec, DAI's |
| 42 | and DMA is suspended and resumed. Optional. |
| 43 | |
| 44 | |
| 45 | Machine operations |
| 46 | ------------------ |
| 47 | The machine specific audio operations can be set here. Again this is optional. |
| 48 | |
| 49 | |
| 50 | Machine DAI Configuration |
| 51 | ------------------------- |
| 52 | The machine DAI configuration glues all the codec and CPU DAI's together. It can |
| 53 | also be used to set up the DAI system clock and for any machine related DAI |
| 54 | initialisation e.g. the machine audio map can be connected to the codec audio |
| 55 | map, unconnnected codec pins can be set as such. Please see corgi.c, spitz.c |
| 56 | for examples. |
| 57 | |
| 58 | struct snd_soc_dai_link is used to set up each DAI in your machine. e.g. |
| 59 | |
| 60 | /* corgi digital audio interface glue - connects codec <--> CPU */ |
| 61 | static struct snd_soc_dai_link corgi_dai = { |
| 62 | .name = "WM8731", |
| 63 | .stream_name = "WM8731", |
| 64 | .cpu_dai = &pxa_i2s_dai, |
| 65 | .codec_dai = &wm8731_dai, |
| 66 | .init = corgi_wm8731_init, |
| 67 | .config_sysclk = corgi_config_sysclk, |
| 68 | }; |
| 69 | |
| 70 | struct snd_soc_machine then sets up the machine with it's DAI's. e.g. |
| 71 | |
| 72 | /* corgi audio machine driver */ |
| 73 | static struct snd_soc_machine snd_soc_machine_corgi = { |
| 74 | .name = "Corgi", |
| 75 | .dai_link = &corgi_dai, |
| 76 | .num_links = 1, |
| 77 | .ops = &corgi_ops, |
| 78 | }; |
| 79 | |
| 80 | |
| 81 | Machine Audio Subsystem |
| 82 | ----------------------- |
| 83 | |
| 84 | The machine soc device glues the platform, machine and codec driver together. |
| 85 | Private data can also be set here. e.g. |
| 86 | |
| 87 | /* corgi audio private data */ |
| 88 | static struct wm8731_setup_data corgi_wm8731_setup = { |
| 89 | .i2c_address = 0x1b, |
| 90 | }; |
| 91 | |
| 92 | /* corgi audio subsystem */ |
| 93 | static struct snd_soc_device corgi_snd_devdata = { |
| 94 | .machine = &snd_soc_machine_corgi, |
| 95 | .platform = &pxa2xx_soc_platform, |
| 96 | .codec_dev = &soc_codec_dev_wm8731, |
| 97 | .codec_data = &corgi_wm8731_setup, |
| 98 | }; |
| 99 | |
| 100 | |
| 101 | Machine Power Map |
| 102 | ----------------- |
| 103 | |
| 104 | The machine driver can optionally extend the codec power map and to become an |
| 105 | audio power map of the audio subsystem. This allows for automatic power up/down |
| 106 | of speaker/HP amplifiers, etc. Codec pins can be connected to the machines jack |
| 107 | sockets in the machine init function. See soc/pxa/spitz.c and dapm.txt for |
| 108 | details. |
| 109 | |
| 110 | |
| 111 | Machine Controls |
| 112 | ---------------- |
| 113 | |
| 114 | Machine specific audio mixer controls can be added in the dai init function. |