al5623.c内核代码框架分析(2)

我们先来看看数字音频接口做了什么？
以下具体的就是就是音频接口的操作，根据PCM音频和playback来进行设置
同时，也加载了alc5623_dai_ops这个操作集合

static struct snd_soc_dai_driver alc5623_dai = {
 .name = "alc5623-hifi",
 .playback = {
  .stream_name = "Playback",
  .channels_min = 1,
  .channels_max = 2,
  .rate_min = 8000,
  .rate_max = 48000,
  .rates = SNDRV_PCM_RATE_8000_48000,
  .formats = ALC5623_FORMATS,},
 .capture = {
  .stream_name = "Capture",
  .channels_min = 1,
  .channels_max = 2,
  .rate_min = 8000,
  .rate_max = 48000,
  .rates = SNDRV_PCM_RATE_8000_48000,
  .formats = ALC5623_FORMATS,},

.ops = &alc5623_dai_ops,
};

(1)alc5623_dai_ops操作集合的实现
以下这些得找具体的调音频的工程师才知道怎么设置相应的操作,具体我也不是特别懂，有兴趣可以看看函数的实现，对着数据手册的寄存器一个个看

static struct snd_soc_dai_ops alc5623_dai_ops = {
  .hw_params = alc5623_pcm_hw_params,
  .digital_mute = alc5623_mute,
  .set_fmt = alc5623_set_dai_fmt,
  .set_sysclk = alc5623_set_dai_sysclk,
  .set_pll = alc5623_set_dai_pll,
};

(2)soc_codec_device_alc5623

static struct snd_soc_codec_driver soc_codec_device_alc5623 = {
 .probe = alc5623_probe,
 .remove = alc5623_remove,
 .suspend = alc5623_suspend,  //  1
 .resume = alc5623_resume,    //  2  1和2是电源管理的回调函数,分别在声卡加载和卸载的时候被调用
 .set_bias_level = alc5623_set_bias_level, //设置偏置电压配置函数
 .reg_cache_size = ALC5623_VENDOR_ID2+2,
 .reg_word_size = sizeof(u16),
 .reg_cache_step = 2,
};

<1> alc5623_probe函数分析

//这部分我们不详细进行分析，拿出最主要的东西来讲，比如后面的snd_soc_add_codec_controls,主要说说它的作用
static int alc5623_probe(struct snd_soc_codec *codec)
{
 struct alc5623_priv *alc5623 = snd_soc_codec_get_drvdata(codec); //获取数据
 struct snd_soc_dapm_context *dapm = &codec->dapm;                //dapm相当于音频的一个组件
 int ret;
 
 ret = snd_soc_codec_set_cache_io(codec, 8, 16, alc5623->control_type);
 if (ret < 0) {
  dev_err(codec->dev, "Failed to set cache I/O: %d\n", ret);
  return ret;
 }

alc5623_reset(codec);  //复位芯片
 alc5623_fill_cache(codec);

/* power on device */
 alc5623_set_bias_level(codec, SND_SOC_BIAS_STANDBY);

if (alc5623->add_ctrl) {
  snd_soc_write(codec, ALC5623_ADD_CTRL_REG,
    alc5623->add_ctrl);
 }

if (alc5623->jack_det_ctrl) {
  snd_soc_write(codec, ALC5623_JACK_DET_CTRL,
    alc5623->jack_det_ctrl);
 }
 //根据芯片的id执行对应的snd_soc_add_codec_controls，这个controls就是给上层提供相应的操作接口
 //比如调节音量，耳机模式等等。
 //这里是alc5621，我们找到了这个controls的集合
 switch (alc5623->id) {
 case 0x21:
  snd_soc_add_codec_controls(codec, alc5621_vol_snd_controls,
   ARRAY_SIZE(alc5621_vol_snd_controls));
  break;
 case 0x22:
  snd_soc_add_codec_controls(codec, alc5622_vol_snd_controls,
   ARRAY_SIZE(alc5622_vol_snd_controls));
  break;
 case 0x23:
  snd_soc_add_codec_controls(codec, alc5623_vol_snd_controls,
   ARRAY_SIZE(alc5623_vol_snd_controls));
  break;
 default:
  return -EINVAL;
 }

snd_soc_add_codec_controls(codec, alc5623_snd_controls,
   ARRAY_SIZE(alc5623_snd_controls));

snd_soc_dapm_new_controls(dapm, alc5623_dapm_widgets,
     ARRAY_SIZE(alc5623_dapm_widgets));

/* set up audio path interconnects */
 snd_soc_dapm_add_routes(dapm, intercon, ARRAY_SIZE(intercon));