soc_codec_dev_uda134x
==> uda134x_soc_probe
==> snd_soc_new_pcms 为DAI建立对应的pcm实例,1路dai对应1路pcm,1路pcm可以有多条放音和录音流通道
==> snd_soc_init_card 注册声卡
==> snd_card_register
==> snd_device_register_all 调用dev->ops->dev_register注册card->devices链表上的所有pcm实例[luther.gliethttp]
==> 比如在snd_pcm_new中设置dev->ops->dev_register其值为snd_pcm_dev_register
这个snd_pcm_dev_register函数最终会调用下面挂到snd_pcm_notify_list设备通知链表上的所有期望添加pcm时得到通知的函数
list_for_each_entry(notify, &snd_pcm_notify_list, list)
notify->n_register(pcm);
其中就包括alsa_pcm_oss_init中snd_pcm_notify(&snd_pcm_oss_notify, 0)添加的方法snd_pcm_oss_notify其内部实现如下：[luther.gliethttp]
static struct snd_pcm_notify snd_pcm_oss_notify =
{
.n_register = snd_pcm_oss_register_minor,
.n_disconnect = snd_pcm_oss_disconnect_minor,
.n_unregister = snd_pcm_oss_unregister_minor,
};
文件：sound/soc/s3c24xx/s3c24xx_uda134x.c
static int __init s3c24xx_uda134x_init(void)
{
return platform_driver_register(&s3c24xx_uda134x_driver); // 驱动arch/arm/mach-xx下注册的名为"s3c24xx_uda134x"的设备.
}
static struct platform_driver s3c24xx_uda134x_driver = {
.probe = s3c24xx_uda134x_probe, // 执行该probe进一步创建
.remove = s3c24xx_uda134x_remove,
.driver = {
.name = "s3c24xx_uda134x",
.owner = THIS_MODULE,
},
};
下面是s3c24xx_uda134x_probe的具体实现代码:
static int s3c24xx_uda134x_probe(struct platform_device *pdev)
{
int ret;
printk(KERN_INFO "S3C24XX_UDA134X SoC Audio driver\n");
s3c24xx_uda134x_l3_pins = pdev->dev.platform_data; // 由platform设备传进来的l3的3个控制io口
if (s3c24xx_uda134x_l3_pins == NULL) {
printk(KERN_ERR "S3C24XX_UDA134X SoC Audio: "
"unable to find platform data\n");
return -ENODEV;
}
s3c24xx_uda134x.power = s3c24xx_uda134x_l3_pins->power;
s3c24xx_uda134x.model = s3c24xx_uda134x_l3_pins->model;
if (s3c24xx_uda134x_setup_pin(s3c24xx_uda134x_l3_pins->l3_data, // 调用gpio_request申请io
"data") < 0)
return -EBUSY;
if (s3c24xx_uda134x_setup_pin(s3c24xx_uda134x_l3_pins->l3_clk, // 调用gpio_request申请io
"clk") < 0) {
gpio_free(s3c24xx_uda134x_l3_pins->l3_data);
return -EBUSY;
}
if (s3c24xx_uda134x_setup_pin(s3c24xx_uda134x_l3_pins->l3_mode, // 调用gpio_request申请io
"mode") < 0) {
gpio_free(s3c24xx_uda134x_l3_pins->l3_data);
gpio_free(s3c24xx_uda134x_l3_pins->l3_clk);
return -EBUSY;
}
s3c24xx_uda134x_snd_device = platform_device_alloc("soc-audio", -1); // 申请名为"soc-audio"设备
if (!s3c24xx_uda134x_snd_device) { // 该设备将由soc_driver声卡驱动管理
printk(KERN_ERR "S3C24XX_UDA134X SoC Audio: "
"Unable to register\n");
return -ENOMEM;
}
platform_set_drvdata(s3c24xx_uda134x_snd_device,
&s3c24xx_uda134x_snd_devdata); // s3c24xx_uda134x_snd_devdata声卡驱动soc_driver使用到的结构体
s3c24xx_uda134x_snd_devdata.dev = &s3c24xx_uda134x_snd_device->dev;
ret = platform_device_add(s3c24xx_uda134x_snd_device); // 将申请的"soc-audio"设备注册到
if (ret) { // platform总线,由soc_driver声卡驱动进一步管理
printk(KERN_ERR "S3C24XX_UDA134X SoC Audio: Unable to add\n");
platform_device_put(s3c24xx_uda134x_snd_device);
}
return ret;
}
// 下面是soc_driver声卡驱动将要使用到的结构体定义
static struct snd_soc_device s3c24xx_uda134x_snd_devdata = {
.card = &snd_soc_s3c24xx_uda134x, // 定义的card声卡
.codec_dev = &soc_codec_dev_uda134x,
.codec_data = &s3c24xx_uda134x,
};
struct snd_soc_codec_device soc_codec_dev_uda134x = {
.probe = uda134x_soc_probe,
.remove = uda134x_soc_remove,
.suspend = uda134x_soc_suspend,
.resume = uda134x_soc_resume,
};
EXPORT_SYMBOL_GPL(soc_codec_dev_uda134x);
static struct uda134x_platform_data s3c24xx_uda134x = {
.l3 = {
.setdat = setdat,
.setclk = setclk,
.setmode = setmode,
.data_hold = 1,
.data_setup = 1,
.clock_high = 1,
.mode_hold = 1,
.mode = 1,
.mode_setup = 1,
},
};
static struct snd_soc_card snd_soc_s3c24xx_uda134x = {// card声卡的结构体
.name = "S3C24XX_UDA134X",
.platform = &s3c24xx_soc_platform, // 使用s3c24xx_soc_platform平台
.dai_link = &s3c24xx_uda134x_dai_link, // 使用s3c24xx_uda134x_dai_link中的cpu_dai和codec_dai解码流通道,他们将生成一个pcm实例,然后对声音流数据进行发送和接收处理.
.num_links = 1,
};
static struct snd_soc_dai_link s3c24xx_uda134x_dai_link = {
.name = "UDA134X", // 一个pcm实例将要对应的所有CPU <-> DAI信息.
.stream_name = "UDA134X",
.codec_dai = &uda134x_dai, // codec芯片接口控制结构体
.cpu_dai = &s3c24xx_i2s_dai, // cpu内置的音频控制单元
.ops = &s3c24xx_uda134x_ops, // pcm实例使用到自定义操作方法集
};
struct snd_soc_dai uda134x_dai = { // codec芯片接口音频控制结构体
.name = "UDA134X",
/* playback capabilities */
.playback = { // 放音通道
.stream_name = "Playback",
.channels_min = 1,
.channels_max = 2,
.rates = UDA134X_RATES,
.formats = UDA134X_FORMATS,
},
/* capture capabilities */
.capture = { // 录音通道
.stream_name = "Capture",
.channels_min = 1,
.channels_max = 2,
.rates = UDA134X_RATES,
.formats = UDA134X_FORMATS,
},
/* pcm operations */
.ops = &uda134x_dai_ops,
};
EXPORT_SYMBOL(uda134x_dai);
static int __init uda134x_init(void)
{
return snd_soc_register_dai(&uda134x_dai); // 注册codec芯片音频驱动模块codec_dai到dai_list链表上[luther.gliethttp].
}
module_init(uda134x_init);
struct snd_soc_dai s3c24xx_i2s_dai = { // cpu内置的音频控制单元
.name = "s3c24xx-i2s",
.id = 0,
.probe = s3c24xx_i2s_probe,
.suspend = s3c24xx_i2s_suspend,
.resume = s3c24xx_i2s_resume,
.playback = { // cpu对放音通道的控制
.channels_min = 2,
.channels_max = 2,
.rates = S3C24XX_I2S_RATES,
.formats = SNDRV_PCM_FMTBIT_S8 | SNDRV_PCM_FMTBIT_S16_LE,},
.capture = { // cpu对录音通道的控制
.channels_min = 2,
.channels_max = 2,
.rates = S3C24XX_I2S_RATES,
.formats = SNDRV_PCM_FMTBIT_S8 | SNDRV_PCM_FMTBIT_S16_LE,},
.ops = &s3c24xx_i2s_dai_ops,
};
static int __init s3c24xx_i2s_init(void)
{
return snd_soc_register_dai(&s3c24xx_i2s_dai); // 注册cpun内部音频驱动模块cpu_dai到dai_list链表上[luther.gliethttp].
}
module_init(s3c24xx_i2s_init);
static int __init s3c24xx_soc_platform_init(void)
{
return snd_soc_register_platform(&s3c24xx_soc_platform); // 登记注册24xx的声卡设备到声卡驱动专用的platform_list链表上
}
module_init(s3c24xx_soc_platform_init);
struct snd_soc_platform s3c24xx_soc_platform = {
.name = "s3c24xx-audio",
.pcm_ops = &s3c24xx_pcm_ops, // 本platform平台提供的pcm操作方法
.pcm_new = s3c24xx_pcm_new,
.pcm_free = s3c24xx_pcm_free_dma_buffers,
};
EXPORT_SYMBOL_GPL(s3c24xx_soc_platform);
文件：sound/soc/soc-core.c
// 上面s3c24xx_uda134x_probe==>platform_device_add(s3c24xx_uda134x_snd_device);将直接触发
// 此处soc_probe检测函数的进一步执行[luther.gliethttp].
/* ASoC platform driver */
static struct platform_driver soc_driver = {
.driver = {
.name = "soc-audio",
.owner = THIS_MODULE,
},
.probe = soc_probe,
.remove = soc_remove,
.suspend = soc_suspend,
.resume = soc_resume,
};
/* probes a new socdev */
static int soc_probe(struct platform_device *pdev)
{
int ret = 0;
struct snd_soc_device *socdev = platform_get_drvdata(pdev); // 对应上面的s3c24xx_uda134x_snd_devdata结构体[luther.gliethttp].
struct snd_soc_card *card = socdev->card; // 对应上面的snd_soc_s3c24xx_uda134x
/* Bodge while we push things out of socdev */
card->socdev = socdev;
/* Bodge while we unpick instantiation */
card->dev = &pdev->dev;
ret = snd_soc_register_card(card); // 注册生成声卡
if (ret != 0) {
dev_err(&pdev->dev, "Failed to register card\n");
return ret;
}
return 0;
}
static int snd_soc_register_card(struct snd_soc_card *card) // 注册生成声卡
{
if (!card->name || !card->dev)
return -EINVAL;
INIT_LIST_HEAD(&card->list);
card->instantiated = 0; // 标识未初始化该声卡,因为该函数只在soc_probe中调用,所以可以保证确实是第1次创建
mutex_lock(&client_mutex);
list_add(&card->list, &card_list); // 所有注册的声卡都要添加到声卡设备链表card_list[luther.gliethttp].
snd_soc_instantiate_cards(); // 对声卡进行实例化,生成pcm.
mutex_unlock(&client_mutex);
dev_dbg(card->dev, "Registered card '%s'\n", card->name);
return 0;
}
static void snd_soc_instantiate_cards(void) // 对声卡进行实例化,生成pcm.
{
struct snd_soc_card *card;
list_for_each_entry(card, &card_list, list) // 遍历声卡链表card_list上所有声卡,如果该声卡的instantiated等于0,那么将被执行实例化,生成该声卡描述的所有pcm流通道.
snd_soc_instantiate_card(card); // 实例化声卡内部所有stream流通道为pcm.
}
static void snd_soc_instantiate_card(struct snd_soc_card *card) // 作声卡实例化
{
struct platform_device *pdev = container_of(card->dev,
struct platform_device,
dev);
struct snd_soc_codec_device *codec_dev = card->socdev->codec_dev;
struct snd_soc_platform *platform;
struct snd_soc_dai *dai;
int i, found, ret, ac97;
if (card->instantiated) // 该card声卡已经完成实例化,简单的返回[luther.gliethttp].
return;
found = 0;
list_for_each_entry(platform, &platform_list, list) // 搜索platform_list上登记的s3c24xx_soc_platform平台驱动,
if (card->platform == platform) { // 因为s3c24xx_soc_platform在module_init(s3c24xx_soc_platform_init);中
found = 1; // 被登记,所以这就有一个模块加载顺序问题,s3c24xx_soc_platform_init必须先
break; // 先执行先被添加到platform_list链表中才能保证[luther.gliethttp].
} // 但是从arch_initcall(customize_machine);可以发现,如果声卡built-in进内核
// 的话,MACHINE_START(EDB9312, "Cirrus Logic EDB9312 Evaluation Board")可能存在潜在危险.
// #define arch_initcall(fn) __define_initcall("3",fn,3)
// #define device_initcall(fn) __define_initcall("6",fn,6)
// #define __initcall(fn) device_initcall(fn)
// #define module_init(x) __initcall(x);
ac97 = 0;
for (i = 0; i < card->num_links; i++) {
found = 0;
list_for_each_entry(dai, &dai_list, list) // 检查dai_list是否已经注册登记了.cpu_dai引用到的驱动模块[luther.gliethttp].
if (card->dai_link[i].cpu_dai == dai) { // 这里就是s3c24xx_uda134x_dai_link中的.cpu_dai = &s3c24xx_i2s_dai
found = 1; // 他在s3c24xx_i2s_init中完成注册登记.
break;
}
if (!found) {
dev_dbg(card->dev, "DAI %s not registered\n",
card->dai_link[i].cpu_dai->name);
return;
}
if (card->dai_link[i].cpu_dai->ac97_control)
ac97 = 1;
}
if (!ac97) // 如果不是ac97设备
for (i = 0; i < card->num_links; i++) {
found = 0;
list_for_each_entry(dai, &dai_list, list)
if (card->dai_link[i].codec_dai == dai) { // 检查dai_list是否已经注册登记了.codec_dai引用到的驱动模块[luther.gliethttp].
found = 1; // 这里就是s3c24xx_uda134x_dai_link中的.codec_dai = &uda134x_dai
break; // 他在uda134x_init中完成注册登记.
}
if (!found) {
dev_dbg(card->dev, "DAI %s not registered\n",
card->dai_link[i].codec_dai->name);
return;
}
}
/* Found everything, bring it up */ // ok,所以依赖的模块都已经就位,那么下面开始创建card声卡.
if (card->probe) {
ret = card->probe(pdev); // 对于snd_soc_s3c24xx_uda134x没有定义probe
if (ret < 0)
return;
}
for (i = 0; i < card->num_links; i++) {
struct snd_soc_dai *cpu_dai = card->dai_link[i].cpu_dai;
if (cpu_dai->probe) {
ret = cpu_dai->probe(pdev, cpu_dai); // cpu集成的音频控制单元probe初始化,s3c24xx_i2s_dai.s3c24xx_i2s_probe
if (ret < 0) // 主要完成i2s控制器时钟启动和s3c24xx的i2s对应的io口配置初始化[luther.gliethttp].
goto cpu_dai_err;
}
}
// 这里将完成设备节点'/dev/dsp'和alsa节点的所有创建工作[luther.gliethttp].
if (codec_dev->probe) { // soc_codec_dev_uda134x.soc_codec_dev_uda134x.uda134x_soc_probe初始化
ret = codec_dev->probe(pdev); // 将执行snd_soc_new_pcms(socdev, SNDRV_DEFAULT_IDX1, SNDRV_DEFAULT_STR1);
if (ret < 0) // 生成声卡内存结构体和创建所有pcms流通道,最后调用snd_soc_init_card(socdev);
goto cpu_dai_err; // 根据dsp_map[]索引号选择一个默认pcm流通道生成"/dev/dsp"节点和alsa节点[luther.gliethttp].
}
if (platform->probe) { // s3c24xx_soc_platform没有提供probe来初始化
ret = platform->probe(pdev);
if (ret < 0)
goto platform_err;
}
/* DAPM stream work */
INIT_DELAYED_WORK(&card->delayed_work, close_delayed_work);
#ifdef CONFIG_PM
/* deferred resume work */
INIT_WORK(&card->deferred_resume_work, soc_resume_deferred);
#endif
card->instantiated = 1;
return;
}
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