asoc 音频驱动学习笔记3

Asoc 驱动中的platform 部分的dai部分
在sound/soc/s5pv2xx目录下，有关于处理器方面的asoc驱动部分，包括dma相关的和i2s部分，先看i2s部分吧，dma部分貌似简单，好找
在s5pc1xx-i2s.c文件中，这里驱动名为s3c64xx，应该是210的i2s部分和6410差不多吧
static struct platform_driver s3c64xx_iis_driver = {
 .probe  = s3c64xx_iis_dev_probe,
 .remove = s3c64xx_iis_dev_remove,
 .driver = {
  .name = "samsung-i2s",
  .owner = THIS_MODULE,
 },
};
static int __init s3c64xx_i2s_init(void)
{
 return platform_driver_register(&s3c64xx_iis_driver);
}
static __devinit int s3c64xx_iis_dev_probe(struct platform_device *pdev)
{
 struct s3c_audio_pdata *i2s_pdata;
 struct s3c_i2sv2_info *i2s;
 struct snd_soc_dai_driver *dai;
 struct resource *res;
 struct clk *fout_epll, *mout_epll;
 struct clk *mout_audss = NULL;
 unsigned long base;
 unsigned int  iismod;定义了一些结构，下面会用
 int ret = 0;
 if (pdev->id >= MAX_I2SV3) {
  dev_err(&pdev->dev, "id %d out of range\n", pdev->id);
  return -EINVAL;
 }
 i2s = &s3c64xx_i2s[pdev->id];根据平台驱动的id号选择结构
 i2s->dev = &pdev->dev;
 dai = &s3c64xx_i2s_dai_driver[pdev->id];根据平台驱动的id号选择结构
 //dai->dev = &pdev->dev;
 dai->id = pdev->id;
 s3c64xx_iis_dai_init(dai);初始化dai driver
 i2s->dma_capture = &s3c64xx_i2s_pcm_stereo_in[pdev->id];
 i2s->dma_playback = &s3c64xx_i2s_pcm_stereo_out[pdev->id];
 res = platform_get_resource(pdev, IORESOURCE_DMA, 0);得到i2s平台驱动DMA tx资源
 if (!res) {
  dev_err(&pdev->dev, "Unable to get I2S-TX dma resource\n");
  return -ENXIO;
 }
 i2s->dma_playback->channel = res->start;
 res = platform_get_resource(pdev, IORESOURCE_DMA, 1);得到i2s平台驱动DMA rx资源
 if (!res) {
  dev_err(&pdev->dev, "Unable to get I2S-RX dma resource\n");
  return -ENXIO;
 }
 i2s->dma_capture->channel = res->start;capture 采集，
 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);得到I2S寄存器地址资源
 if (!res) {
  dev_err(&pdev->dev, "Unable to get I2S SFR address\n");
  return -ENXIO;
 }
 if (!request_mem_region(res->start, resource_size(res),向系统申请一块寄存器资源区
    "s3c64xx-i2s")) {
  dev_err(&pdev->dev, "Unable to request SFR region\n");
  return -EBUSY;
 }
    为i2s结构赋值
 i2s->dma_capture->dma_addr = res->start + S3C2412_IISRXD;
 i2s->dma_playback->dma_addr = res->start + S3C2412_IISTXD;
 i2s->dma_capture->client = &s3c64xx_dma_client_in;
 i2s->dma_capture->dma_size = 4;
 i2s->dma_playback->client = &s3c64xx_dma_client_out;
 i2s->dma_playback->dma_size = 4;
 i2s_pdata = pdev->dev.platform_data;
 //dai->private_data = i2s;
 dev_set_drvdata(&pdev->dev, i2s);设置i2s结构到平台设备中，方便其他函数使用i2s结构中的信息
 base = i2s->dma_playback->dma_addr - S3C2412_IISTXD;
 i2s->regs = ioremap(base, 0x100);内存映射为虚拟地址
 if (i2s->regs == NULL) {
  dev_err(&pdev->dev, "cannot ioremap registers\n");
  return -ENXIO;
 }
 /* Configure the I2S pins if MUX'ed */
 if (i2s_pdata && i2s_pdata->cfg_gpio && i2s_pdata->cfg_gpio(pdev)) {
  dev_err(&pdev->dev, "Unable to configure gpio\n");
  return -EINVAL;
 }
 /* Get i2s power domain regulator */
 i2s->regulator = regulator_get(&pdev->dev, "pd");得到一个叫pd的i2s校准器
 if (IS_ERR(i2s->regulator)) {
  dev_err(&pdev->dev, "%s: failed to get resource %s\n",
    __func__, "i2s");
  return PTR_ERR(i2s->regulator);
 }
 /* Enable Power domain */
 regulator_enable(i2s->regulator);使能这个电源校准器
 /* Audio Clock
  * fout_epll >> mout_epll >> sclk_audio
  * fout_epll >> mout_audss >> audio-bus(iis_clk)
  * fout_epll >> dout_audio_bus_clk_i2s(iis_busclk)
  */
 fout_epll = clk_get(&pdev->dev, "fout_epll");得到时钟
 if (IS_ERR(fout_epll)) {
  dev_err(&pdev->dev, "failed to get fout_epll\n");
  goto err;
 }
 mout_epll = clk_get(&pdev->dev, "mout_epll");
 if (IS_ERR(mout_epll)) {
  dev_err(&pdev->dev, "failed to get mout_epll\n");
  clk_put(fout_epll);
  goto err;
 }
 clk_set_parent(mout_epll, fout_epll);
 i2s->sclk_audio = clk_get(&pdev->dev, "sclk_audio");
 if (IS_ERR(i2s->sclk_audio)) {
  dev_err(&pdev->dev, "failed to get sclk_audio\n");
  ret = PTR_ERR(i2s->sclk_audio);
  clk_put(i2s->sclk_audio);
  goto err;
 }
 clk_set_parent(i2s->sclk_audio, mout_epll);
 /* Need not to enable in general */
 clk_enable(i2s->sclk_audio);
 /* When I2S V5.1 used, initialize audio subsystem clock */
 /* CLKMUX_ASS */
 if (pdev->id == 0) {
  mout_audss = clk_get(NULL, "mout_audss");
  if (IS_ERR(mout_audss)) {
   dev_err(&pdev->dev, "failed to get mout_audss\n");
   goto err1;
  }
  clk_set_parent(mout_audss, fout_epll);
  /*MUX-I2SA*/
  i2s->iis_clk = clk_get(&pdev->dev, "audio-bus");
  if (IS_ERR(i2s->iis_clk)) {
   dev_err(&pdev->dev, "failed to get audio-bus\n");
   clk_put(mout_audss);
   goto err2;
  }
  clk_set_parent(i2s->iis_clk, mout_audss);
  /*getting AUDIO BUS CLK*/
  i2s->iis_busclk = clk_get(NULL, "dout_audio_bus_clk_i2s");
  if (IS_ERR(i2s->iis_busclk)) {
   printk(KERN_ERR "failed to get audss_hclk\n");
   goto err3;
  }
  i2s->iis_ipclk = clk_get(&pdev->dev, "i2s_v50");
  if (IS_ERR(i2s->iis_ipclk)) {
   dev_err(&pdev->dev, "failed to get i2s_v50_clock\n");
   goto err4;
  }
 }
#if defined(CONFIG_PLAT_S5P)
 writel(((1<<0)|(1<<31)), i2s->regs + S3C2412_IISCON);
#endif
设置i2s模式。为txrx
 /* Mark ourselves as in TXRX mode so we can run through our cleanup
  * process without warnings. */
 iismod = readl(i2s->regs + S3C2412_IISMOD);
 iismod |= S3C2412_IISMOD_MODE_TXRX;
 writel(iismod, i2s->regs + S3C2412_IISMOD);
#ifdef CONFIG_S5P_INTERNAL_DMA
 s5p_i2s_sec_init(i2s->regs, base);
#endif
 ret = s5p_i2sv5_register_dai(&pdev->dev, dai);
 if (ret != 0)
  goto err_i2sv5;
 clk_put(i2s->iis_ipclk);
 clk_put(i2s->iis_busclk);
 clk_put(i2s->iis_clk);
 clk_put(mout_audss);
 clk_put(mout_epll);
 clk_put(fout_epll);
 return 0;
err4:
 clk_put(i2s->iis_busclk);
err3:
 clk_put(i2s->iis_clk);
err2:
 clk_put(mout_audss);
err1:
 clk_put(mout_epll);
 clk_put(fout_epll);
err_i2sv5:
 /* Not implemented for I2Sv5 core yet */
err:
 iounmap(i2s->regs);
 return ret;
}
进入s5p_i2sv5_register_dai
int s5p_i2sv5_register_dai(struct device *dev, struct snd_soc_dai_driver *dai)
{
 struct snd_soc_dai_ops *ops = dai->ops;
 ops->trigger = s5p_i2s_wr_trigger;
 ops->hw_params = s5p_i2s_wr_hw_params;
 ops->set_fmt = s5p_i2s_set_fmt;
 ops->set_clkdiv = s5p_i2s_set_clkdiv;
 ops->set_sysclk = s5p_i2s_set_sysclk;
 ops->startup   = s5p_i2s_wr_startup;
 ops->shutdown = s5p_i2s_wr_shutdown;
 /* suspend/resume are not necessary due to Clock/Pwer gating scheme */
 dai->suspend = s5p_i2s_suspend;
 dai->resume = s5p_i2s_resume;
 return snd_soc_register_dai(dev, dai);
}
注册soc dai
int snd_soc_register_dai(struct device *dev,
  struct snd_soc_dai_driver *dai_drv)
{
 struct snd_soc_dai *dai;
 dev_dbg(dev, "dai register %s\n", dev_name(dev));
 dai = kzalloc(sizeof(struct snd_soc_dai), GFP_KERNEL);
 if (dai == NULL)
  return -ENOMEM;
 /* create DAI component name */
 dai->name = fmt_single_name(dev, &dai->id);
 if (dai->name == NULL) {
  kfree(dai);
  return -ENOMEM;
 }
 dai->dev = dev;
 dai->driver = dai_drv;
 if (!dai->driver->ops)
  dai->driver->ops = &null_dai_ops;
 mutex_lock(&client_mutex);
 list_add(&dai->list, &dai_list);
 snd_soc_instantiate_cards();
 mutex_unlock(&client_mutex);
 pr_debug("Registered DAI '%s'\n", dai->name);
 return 0;
}
这样成功的加入了dai链表，然后会匹配链表中的名字，执行一些回调
再看看DMA怎么搞的吧
static struct platform_driver asoc_dma_driver = {
 .driver = {
  .name = "samsung-audio",
  .owner = THIS_MODULE,
 },
 .probe = samsung_asoc_platform_probe,
 .remove = __devexit_p(samsung_asoc_platform_remove),
};
static int __init samsung_asoc_init(void)
{
 return platform_driver_register(&asoc_dma_driver);
}
struct snd_soc_platform_driver samsung_asoc_platform = {
 .ops  = &dma_ops,
 .pcm_new = dma_new,
 .pcm_free = dma_free_dma_buffers,
};
EXPORT_SYMBOL_GPL(samsung_asoc_platform);
#ifndef CONFIG_S5P_INTERNAL_DMA
static int __devinit samsung_asoc_platform_probe(struct platform_device *pdev)
{
 return snd_soc_register_platform(&pdev->dev, &samsung_asoc_platform);
}
注册了一个平台类型的soc驱动，此平台不同于彼平台，
static struct snd_pcm_ops dma_ops = {
 .open  = dma_open,
 .close  = dma_close,
 .ioctl  = snd_pcm_lib_ioctl,
 .hw_params = dma_hw_params,
 .hw_free = dma_hw_free,
 .prepare = dma_prepare,
 .trigger = dma_trigger,
 .pointer = dma_pointer,
 .mmap  = dma_mmap,
};
这些函数需要一一实现，内核里都搞好了的，
static int dma_new(struct snd_card *card,
  struct snd_soc_dai *dai, struct snd_pcm *pcm)
{
 int ret = 0;
 pr_debug("Entered %s\n", __func__);
 if (!card->dev->dma_mask)
  card->dev->dma_mask = &dma_mask;
 if (!card->dev->coherent_dma_mask)
  card->dev->coherent_dma_mask = 0xffffffff;
#ifndef CONFIG_S5P_INTERNAL_DMA
 if (dai->driver->playback.channels_min) {
为PCM流分配dma buffer
ret = preallocate_dma_buffer(pcm, SNDRV_PCM_STREAM_PLAYBACK);
  if (ret)
   goto out;
 }
#endif
 if (dai->driver->capture.channels_min) {
  ret = preallocate_dma_buffer(pcm, SNDRV_PCM_STREAM_CAPTURE);
  if (ret)
   goto out;
 }
out:
 return ret;
}

static int soc_bind_dai_link(struct snd_soc_card *card, int num)分析
   Struct snd_soc_dai_link *dai_link = &card->dai_link[num];从card结构取出dai_link
   struct snd_soc_pcm_runtime *rtd = &card->rtd[num];从card取出rtd结构
 /* do we already have the CPU DAI for this link ? */
 if (rtd->cpu_dai) {
  goto find_codec;如果rtd中已经有cpu_dai，则直接跳转
 }
 /* no, then find CPU DAI from registered DAIs*/
 list_for_each_entry(cpu_dai, &dai_list, list) {遍历结构
  if (!strcmp(cpu_dai->name, dai_link->cpu_dai_name)) {如果遍历出来的cpu_dai的名字和dai_link 中的名字一样，那么就把遍历出来的结构赋到rtd结构中
   rtd->cpu_dai = cpu_dai;
   goto find_codec;
  }
 }
find_codec:
 /* do we already have the CODEC for this link ? */
 if (rtd->codec) {
  goto find_platform;
 }
 /* no, then find CODEC from registered CODECs*/
 list_for_each_entry(codec, &codec_list, list) {遍历codec链表，
  if (!strcmp(codec->name, dai_link->codec_name)) {与dai_link中的codec_name做比较
   rtd->codec = codec;
   /* CODEC found, so find CODEC DAI from registered DAIs from this CODEC*/
   list_for_each_entry(codec_dai, &dai_list, list) {如果发现了codec,然后就再查找codec_dai
    if (codec->dev == codec_dai->dev &&如果codec的dev和codec_dai的dev相等，同时dai_link的名字也相等，就把codec_dai结构赋给rtd的codec_dai
      !strcmp(codec_dai->name, dai_link->codec_dai_name)) {
     rtd->codec_dai = codec_dai;
     goto find_platform;
    }
   }
   dev_dbg(card->dev, "CODEC DAI %s not registered\n",
     dai_link->codec_dai_name);
   goto find_platform;
  }
 }
 dev_dbg(card->dev, "CODEC %s not registered\n",
   dai_link->codec_name);

find_platform:
 /* do we need a platform? */
 if (rtd->platform)如果rtd的platform不为空，就跳转到out
  goto out;
 /* if there's no platform we match on the empty platform */
 platform_name = dai_link->platform_name;把dai_link的platform_name赋给platform
 if (!platform_name)
  platform_name = "snd-soc-dummy";
 /* no, then find one from the set of registered platforms */
 list_for_each_entry(platform, &platform_list, list) {遍历platform链表，
  if (!strcmp(platform->name, platform_name)) {名字比较，相同的话复制到rtd结构
   rtd->platform = platform;
   goto out;
  }
 }
 dev_dbg(card->dev, "platform %s not registered\n",
   dai_link->platform_name);
 return 0;
out:
 /* mark rtd as complete if we found all 4 of our client devices */
 if (rtd->codec && rtd->codec_dai && rtd->platform && rtd->cpu_dai) {如果上面所有的都匹配成功，那么rtd的complete字段赋值1
  rtd->complete = 1;
  card->num_rtd++;card的rtd数加1
 }
 return 1;
上面的分析中到处都是dai_link->，那么dai_link是哪来的，它的各种名字是从哪来的，
Asoc驱动分为codec ,platform,machine三部分，codec负责声卡芯片那端，platform负责处理器那端的dma数据传输以及与codec的数据接口部分，而machine负责把两部分绑定起来，
dai_link的各种name就是在machine部分定义的，以machine驱动smdk_wm8580.c为例
static struct snd_soc_card smdk = {
 .name = "SMDK-I2S",
 .dai_link = smdk_dai,
 .num_links = 2,
};
static struct snd_soc_dai_link smdk_dai[] = {
 [PRI_PLAYBACK] = { /* Primary Playback i/f */
  .name = "WM8580 PAIF RX",
  .stream_name = "Playback",
  .cpu_dai_name = "samsung-i2s.0",
  .codec_dai_name = "wm8580-hifi-playback",
  .platform_name = "samsung-audio",
  .codec_name = "wm8580-codec.0-001b",
  .init = smdk_wm8580_init_paifrx,
  .ops = &smdk_ops,
 },
 [PRI_CAPTURE] = { /* Primary Capture i/f */
  .name = "WM8580 PAIF TX",
  .stream_name = "Capture",
  .cpu_dai_name = "samsung-i2s.0",
  .codec_dai_name = "wm8580-hifi-capture",
  .platform_name = "samsung-audio",
  .codec_name = "wm8580-codec.0-001b",
  .init = smdk_wm8580_init_paiftx,
  .ops = &smdk_ops,
 },
这里有各种名字，就是根据这些名字进行了匹配
///////////////////////////////////////////////////完毕////////////////////////////////////////////////////////////