git://bbs.cooldavid.org / net-next-2.6.git / blame
| Commit | Line | Data |
|---|---|---|
| eb1a6af3 LG |
1 | ASoC Platform Driver |
| 2 | ==================== | |
| 3 | ||
| 4 | An ASoC platform driver can be divided into audio DMA and SoC DAI configuration | |
| 5 | and control. The platform drivers only target the SoC CPU and must have no board | |
| 6 | specific code. | |
| 7 | ||
| 8 | Audio DMA | |
| 9 | ========= | |
| 10 | ||
| 7c4dbbd8 | 11 | The platform DMA driver optionally supports the following ALSA operations:- |
| eb1a6af3 LG |
12 | |
| 13 | /* SoC audio ops */ | |
| 14 | struct snd_soc_ops { | |
| 5b78efd2 TI |
15 | int (*startup)(struct snd_pcm_substream *); |
| 16 | void (*shutdown)(struct snd_pcm_substream *); | |
| 17 | int (*hw_params)(struct snd_pcm_substream *, struct snd_pcm_hw_params *); | |
| 18 | int (*hw_free)(struct snd_pcm_substream *); | |
| 19 | int (*prepare)(struct snd_pcm_substream *); | |
| 20 | int (*trigger)(struct snd_pcm_substream *, int); | |
| eb1a6af3 LG |
21 | }; |
| 22 | ||
| 01dd2fbf | 23 | The platform driver exports its DMA functionality via struct snd_soc_platform:- |
| eb1a6af3 LG |
24 | |
| 25 | struct snd_soc_platform { | |
| 26 | char *name; | |
| 27 | ||
| 28 | int (*probe)(struct platform_device *pdev); | |
| 29 | int (*remove)(struct platform_device *pdev); | |
| 30 | int (*suspend)(struct platform_device *pdev, struct snd_soc_cpu_dai *cpu_dai); | |
| 31 | int (*resume)(struct platform_device *pdev, struct snd_soc_cpu_dai *cpu_dai); | |
| 32 | ||
| 33 | /* pcm creation and destruction */ | |
| 5b78efd2 TI |
34 | int (*pcm_new)(struct snd_card *, struct snd_soc_codec_dai *, struct snd_pcm *); |
| 35 | void (*pcm_free)(struct snd_pcm *); | |
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36 | |
| 37 | /* platform stream ops */ | |
| 5b78efd2 | 38 | struct snd_pcm_ops *pcm_ops; |
| eb1a6af3 LG |
39 | }; |
| 40 | ||
| 7c4dbbd8 | 41 | Please refer to the ALSA driver documentation for details of audio DMA. |
| 0ea6e611 | 42 | http://www.alsa-project.org/~iwai/writing-an-alsa-driver/ |
| eb1a6af3 LG |
43 | |
| 44 | An example DMA driver is soc/pxa/pxa2xx-pcm.c | |
| 45 | ||
| 46 | ||
| 47 | SoC DAI Drivers | |
| 48 | =============== | |
| 49 | ||
| 50 | Each SoC DAI driver must provide the following features:- | |
| 51 | ||
| 52 | 1) Digital audio interface (DAI) description | |
| 53 | 2) Digital audio interface configuration | |
| 54 | 3) PCM's description | |
| 7c4dbbd8 | 55 | 4) SYSCLK configuration |
| eb1a6af3 LG |
56 | 5) Suspend and resume (optional) |
| 57 | ||
| 58 | Please see codec.txt for a description of items 1 - 4. |