ALSA声卡驱动详解(8)

{ .id = snd_soc_dapm_aif_out, .name = wname, .sname = stname, \\

.reg = wreg, .shift = wshift, .invert = winvert, \\ .event = wevent, .event_flags = wflags }

#define SND_SOC_DAPM_DAC(wname, stname, wreg, wshift, winvert) \\

{ .id = snd_soc_dapm_dac, .name = wname, .sname = stname, .reg = wreg, \\

.shift = wshift, .invert = winvert}

#define SND_SOC_DAPM_DAC_E(wname, stname, wreg, wshift, winvert, \\

wevent, wflags) \\

{ .id = snd_soc_dapm_dac, .name = wname, .sname = stname, .reg = wreg, \\

.shift = wshift, .invert = winvert, \\ .event = wevent, .event_flags = wflags}

#define SND_SOC_DAPM_ADC(wname, stname, wreg, wshift, winvert) \\

{ .id = snd_soc_dapm_adc, .name = wname, .sname = stname, .reg = wreg, \\

.shift = wshift, .invert = winvert}

#define SND_SOC_DAPM_ADC_E(wname, stname, wreg, wshift, winvert, \\

wevent, wflags) \\

{ .id = snd_soc_dapm_adc, .name = wname, .sname = stname, .reg = wreg, \\

.shift = wshift, .invert = winvert, \\ .event = wevent, .event_flags = wflags} #define SND_SOC_DAPM_CLOCK_SUPPLY(wname) \\

{ .id = snd_soc_dapm_clock_supply, .name = wname, \\ .reg = SND_SOC_NOPM, .event = dapm_clock_event, \\

.event_flags = SND_SOC_DAPM_PRE_PMU | SND_SOC_DAPM_POST_PMD }

除了上面这些widget，还有另外三种widget没有提供显示的定义方法，它们的种类id分别是：

snd_soc_dapm_dai_in

snd_soc_dapm_dai_out snd_soc_dapm_dai_link

还记得我们在Linux ALSA声卡驱动之七：ASoC架构中的Codec中的

snd_soc_dai结构吗？每个codec有多个dai，而cpu（通常就是指某个soc cpu芯片）也会有多个dai，dai注册时，dapm系统会为每个dai创建一个

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snd_soc_dapm_dai_in或snd_soc_dapm_dai_out类型的widget，通常，这两种widget会和codec中具有相同的stream name的widget进行连接。另外一种情况，当系统中具有多个音频处理器（比如多个codec）时，他们之间可能会通过某两个dai进行连接，当machine驱动确认有这种配置时（通过判断dai_links结构中的param字段），会为他们建立一个dai link把他们绑定在一起，因为有连接关系，两个音频处理器之间的widget的电源状态就可以互相传递。 除了还有几个通用的widget，他们的定义方法如下： [cpp] view plaincopy

#define SND_SOC_DAPM_REG(wid, wname, wreg, wshift, wmask, won_val, woff_val) \\

{ .id = wid, .name = wname, .kcontrol_news = NULL, .num_kcontrols = 0, \\

.reg = -((wreg) + 1), .shift = wshift, .mask = wmask, \\ .on_val = won_val, .off_val = woff_val, .event = dapm_reg_event, \\

.event_flags = SND_SOC_DAPM_PRE_PMU | SND_SOC_DAPM_POST_PMD}

#define SND_SOC_DAPM_SUPPLY(wname, wreg, wshift, winvert, wevent, wflags) \\

{ .id = snd_soc_dapm_supply, .name = wname, .reg = wreg, \\

.shift = wshift, .invert = winvert, .event = wevent, \\ .event_flags = wflags}

#define SND_SOC_DAPM_REGULATOR_SUPPLY(wname, wdelay, wflags) \\ …… 此处隐藏：417字，全部文档内容请下载后查看。喜欢就下载吧 ……