接下来我们看看codec的probe函数吧
static int wm8960_probe(struct snd_soc_codec *codec)
{
struct wm8960_priv *wm8960 = snd_soc_codec_get_drvdata(codec);
struct wm8960_data *pdata = dev_get_platdata(codec->dev);
int ret;
u16 reg;
wm8960->set_bias_level = wm8960_set_bias_level_out3;
codec->control_data = wm8960->control_data;
先看第一个snd_soc_codec_get_drvdata(codec);
static inline void *snd_soc_codec_get_drvdata(struct snd_soc_codec *codec)
{
return dev_get_drvdata(codec->dev);
}
void *dev_get_drvdata(const struct device *dev)
{
if (dev && dev->p)
return dev->p->driver_data;
return NULL;
}
由上面可知，最终得到的结构为codec->dev->p->driver_data，这个结构在哪呢，i2c_set_clientdata(i2c, wm8960) -> ret = snd_soc_register_codec(&i2c->dev,
&soc_codec_dev_wm8960, &wm8960_dai, 1); -> codec->dev = dev;，由此可知，这个driver_data为班级配置中定义的平台设备的driver_data
然后看第二个 dev_get_platdata(codec->dev);
static inline void *dev_get_platdata(const struct device *dev)
{
return dev->platform_data;
}
在板级配置中
#ifdef CONFIG_SND_SOC_WM8960_MINI210
{
I2C_BOARD_INFO("wm8960", 0x1a),
.platform_data = &wm8960_pdata,
},
#endif
#ifdef CONFIG_SND_SOC_WM8960_MINI210
#include
static struct wm8960_data wm8960_pdata = {
.capless = 0,
.dres = WM8960_DRES_400R,
};
#endif
////////////////////////////////////////////////////////////////////////////////////////////接着进行probe函数分析
wm8960->set_bias_level = wm8960_set_bias_level_out3;
codec->control_data = wm8960->control_data;这个地方的值为i2c
if (!pdata) {进行pdata的判断
dev_warn(codec->dev, "No platform data supplied
");
} else {
if (pdata->dres > WM8960_DRES_MAX) {
dev_err(codec->dev, "Invalid DRES: %d
", pdata->dres);
pdata->dres = 0;
}
if (pdata->capless)
wm8960->set_bias_level = wm8960_set_bias_level_capless;
}
ret = snd_soc_codec_set_cache_io(codec, 7, 9, wm8960->control_type);这个函数值得研究
if (ret < 0) {
dev_err(codec->dev, "Failed to set cache I/O: %d
", ret);
return ret;
}查看snd_soc_codec_set_cache_io函数/**建立标准io功能
* snd_soc_codec_set_cache_io: Set up standard I/O functions.
*
* @codec: CODEC to configure.
* @addr_bits: Number of bits of register address data. * @data_bits: Number of bits of data per register.
* @control: Control bus used.使用的控制总线
*寄存器格式被频繁的分享在i2c和spi设备间，为了提高代码的重用率，ASOC核心提供了标准的codec read 和write操作
* Register formats are frequently shared between many I2C and SPI
* devices. In order to promote code reuse the ASoC core provides
* some standard implementations of CODEC read and write operations
* which can be set up using this function.
*
* The caller is responsible for allocating and initialising the
* actual cache.
*
* Note that at present this code cannot be used by CODECs with
* volatile registers.
*/
int snd_soc_codec_set_cache_io(struct snd_soc_codec *codec,
int addr_bits, int data_bits,
enum snd_soc_control_type control)
{
int i;
寻找匹配的寄存器操作格式，8960为7位地址，9位数据
for (i = 0; i < ARRAY_SIZE(io_types); i++)
if (io_types[i].addr_bits == addr_bits &&
io_types[i].data_bits == data_bits)
break;
if (i == ARRAY_SIZE(io_types)) {如果循环完了还没找到合适的格式，那么打印信息
printk(KERN_ERR
"No I/O functions for %d bit address %d bit data
",
addr_bits, data_bits);
return -EINVAL;
}
函数赋值
codec->write = io_types[i].write;这个结构赋值后，最终会调用回codec->hw_write函数
codec->read = io_types[i].read;read和write的处理方法不太一样，不深究了吧
codec->bulk_write_raw = snd_soc_hw_bulk_write_raw;
switch (control) {
case SND_SOC_I2C:
#if defined(CONFIG_I2C) || (defined(CONFIG_I2C_MODULE) && defined(MODULE))
codec->hw_write = (hw_write_t)i2c_master_send;
#endif
if (io_types[i].i2c_read)
codec->hw_read = io_types[i].i2c_read; codec->control_data = container_of(codec->dev,
struct i2c_client,
dev);这个和函数的意思是根据codec->dev找到它属于的结构struct i2c_client的地址，codec->dev,为dev型的
break;
case SND_SOC_SPI:
#ifdef CONFIG_SPI_MASTER
codec->hw_write = do_spi_write;
#endif
codec->control_data = container_of(codec->dev,
struct spi_device,
dev);
break;
}
return 0;
}
接着进行wm8960_probe函数分析
ret = wm8960_reset(codec);
if (ret < 0) {
dev_err(codec->dev, "Failed to issue reset
");
return ret;
}
////////////////////////////////展开wm8960_reset()
对8960进行复位
#define wm8960_reset(c) snd_soc_write(c, WM8960_RESET, 0)
unsigned int snd_soc_write(struct snd_soc_codec *codec,
unsigned int reg, unsigned int val)
{
dev_dbg(codec->dev, "write %x = %x
", reg, val);
trace_snd_soc_reg_write(codec, reg, val);
return codec->write(codec, reg, val);
}
//////////////////////回到probe函数
if (ret < 0) {
dev_err(codec->dev, "Failed to issue reset
");
return ret;
}
wm8960->set_bias_level(codec, SND_SOC_BIAS_STANDBY);
/* Latch the update bits */
reg = snd_soc_read(codec, WM8960_LINVOL);
snd_soc_write(codec, WM8960_LINVOL, reg | 0x100);reg = snd_soc_read(codec, WM8960_RINVOL);
snd_soc_write(codec, WM8960_RINVOL, reg | 0x100);
reg = snd_soc_read(codec, WM8960_LADC);
snd_soc_write(codec, WM8960_LADC, reg | 0x100);
reg = snd_soc_read(codec, WM8960_RADC);
snd_soc_write(codec, WM8960_RADC, reg | 0x100);
reg = snd_soc_read(codec, WM8960_LDAC);
snd_soc_write(codec, WM8960_LDAC, reg | 0x100);
reg = snd_soc_read(codec, WM8960_RDAC);
snd_soc_write(codec, WM8960_RDAC, reg | 0x100);
reg = snd_soc_read(codec, WM8960_LOUT1);
snd_soc_write(codec, WM8960_LOUT1, reg | 0x100);
reg = snd_soc_read(codec, WM8960_ROUT1);
snd_soc_write(codec, WM8960_ROUT1, reg | 0x100);
reg = snd_soc_read(codec, WM8960_LOUT2);
snd_soc_write(codec, WM8960_LOUT2, reg | 0x100);
reg = snd_soc_read(codec, WM8960_ROUT2);
snd_soc_write(codec, WM8960_ROUT2, reg | 0x100);
以上是对9860进行初始化操作
nd_soc_add_controls(codec, wm8960_snd_controls,
ARRAY_SIZE(wm8960_snd_controls));
wm8960_add_widgets(codec);
展开snd_soc_add_controls，添加一个控制队列到一个codec
/**
* snd_soc_add_controls - add an array of controls to a codec.
* Convienience function to add a list of controls. Many codecs were
* duplicating this code.
*
* @codec: codec to add controls to
* @controls: array of controls to add
* @num_controls: number of elements in the array
*
* Return 0 for success, else error.
*/
int snd_soc_add_controls(struct snd_soc_codec *codec,
const struct snd_kcontrol_new *controls, int num_controls)
{
struct snd_card *card = codec->card->snd_card;
int err, i;
for (i = 0; i < num_controls; i++) {
const struct snd_kcontrol_new *control = &controls[i];新的control
err = snd_ctl_add(card, snd_soc_cnew(control, codec,
control->name,codec->name_prefix));if (err < 0) {
dev_err(codec->dev, "%s: Failed to add %s: %d
",
codec->name, control->name, err);
return err;
}
}
return 0;
}/**
* snd_ctl_add - add the control instance to the card
* @card: the card instance
* @kcontrol: the control instance to add
*
* Adds the control instance created via snd_ctl_new() or
* snd_ctl_new1() to the given card. Assigns also an unique
* numid used for fast search.
*
* Returns zero if successful, or a negative error code on failure.
*
* It frees automatically the control which cannot be added.
*/
int snd_ctl_add(struct snd_card *card, struct snd_kcontrol *kcontrol)
这个函数的作用是添加一个control 实例到声卡Adds the control instance created via snd_ctl_new() or snd_ctl_new1() to the given card.
snd_soc_cnew(control, codec,control->name,codec->name_prefix)
kcontrol = snd_ctl_new1(&template, data);
return snd_ctl_new(&kctl, access);
Codec的驱动大体看到这，挺乱的，都是看代码时的顺序乱记的，写博客应该总结总结，以后再总结吧
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