1=================== 2ASoC Machine Driver 3=================== 4 5The ASoC machine (or board) driver is the code that glues together all the 6component drivers (e.g. codecs, platforms and DAIs). It also describes the 7relationships between each component which include audio paths, GPIOs, 8interrupts, clocking, jacks and voltage regulators. 9 10The machine driver can contain codec and platform specific code. It registers 11the audio subsystem with the kernel as a platform device and is represented by 12the following struct:- 13:: 14 15 /* SoC machine */ 16 struct snd_soc_card { 17 char *name; 18 19 ... 20 21 int (*probe)(struct platform_device *pdev); 22 int (*remove)(struct platform_device *pdev); 23 24 /* the pre and post PM functions are used to do any PM work before and 25 * after the codec and DAIs do any PM work. */ 26 int (*suspend_pre)(struct platform_device *pdev, pm_message_t state); 27 int (*suspend_post)(struct platform_device *pdev, pm_message_t state); 28 int (*resume_pre)(struct platform_device *pdev); 29 int (*resume_post)(struct platform_device *pdev); 30 31 ... 32 33 /* CPU <--> Codec DAI links */ 34 struct snd_soc_dai_link *dai_link; 35 int num_links; 36 37 ... 38 }; 39 40probe()/remove() 41---------------- 42probe/remove are optional. Do any machine specific probe here. 43 44 45suspend()/resume() 46------------------ 47The machine driver has pre and post versions of suspend and resume to take care 48of any machine audio tasks that have to be done before or after the codec, DAIs 49and DMA is suspended and resumed. Optional. 50 51 52Machine DAI Configuration 53------------------------- 54The machine DAI configuration glues all the codec and CPU DAIs together. It can 55also be used to set up the DAI system clock and for any machine related DAI 56initialisation e.g. the machine audio map can be connected to the codec audio 57map, unconnected codec pins can be set as such. 58 59struct snd_soc_dai_link is used to set up each DAI in your machine. e.g. 60:: 61 62 /* corgi digital audio interface glue - connects codec <--> CPU */ 63 static struct snd_soc_dai_link corgi_dai = { 64 .name = "WM8731", 65 .stream_name = "WM8731", 66 .cpu_dai_name = "pxa-is2-dai", 67 .codec_dai_name = "wm8731-hifi", 68 .platform_name = "pxa-pcm-audio", 69 .codec_name = "wm8713-codec.0-001a", 70 .init = corgi_wm8731_init, 71 .ops = &corgi_ops, 72 }; 73 74struct snd_soc_card then sets up the machine with its DAIs. e.g. 75:: 76 77 /* corgi audio machine driver */ 78 static struct snd_soc_card snd_soc_corgi = { 79 .name = "Corgi", 80 .dai_link = &corgi_dai, 81 .num_links = 1, 82 }; 83 84 85Machine Power Map 86----------------- 87 88The machine driver can optionally extend the codec power map and to become an 89audio power map of the audio subsystem. This allows for automatic power up/down 90of speaker/HP amplifiers, etc. Codec pins can be connected to the machines jack 91sockets in the machine init function. 92 93 94Machine Controls 95---------------- 96 97Machine specific audio mixer controls can be added in the DAI init function. 98