linux uda1341驱动

分析：
1.板级描述文件是
linux-2.6.32.2/arch/arm/mach-s3c2440/mach-mini2440.c 第383行开始

static struct s3c24xx_uda134x_platform_data s3c24xx_uda134x_data = {
	.l3_clk = S3C2410_GPB(4),
	.l3_data = S3C2410_GPB(3),
	.l3_mode = S3C2410_GPB(2),
	.model = UDA134X_UDA1341,
};

static struct platform_device s3c24xx_uda134x = {
	.name = "s3c24xx_uda134x",
	.dev = {
		.platform_data    = &s3c24xx_uda134x_data,
	}
};

板级描述用于定义引脚

2.驱动文件路径：
linux-2.6.32.2/sound/soc/codecs/uda134x.c
a.首先是在linux系统中注册了一个platform驱动，用于匹配设备
这里得nama和板级描述文件一致，让驱动能匹配上

static struct platform_driver s3c24xx_uda134x_driver = {
	.probe  = s3c24xx_uda134x_probe,
	.remove = s3c24xx_uda134x_remove,
	.driver = {
		.name = "s3c24xx_uda134x",
		.owner = THIS_MODULE,
	},
};

static int __init s3c24xx_uda134x_init(void)
{
	return platform_driver_register(&s3c24xx_uda134x_driver);
}

static void __exit s3c24xx_uda134x_exit(void)
{
	platform_driver_unregister(&s3c24xx_uda134x_driver);
}

在这一层中，将三个要使用得引脚.l3_clk = S3C2410_GPB(4), .l3_data = S3C2410_GPB(3), .l3_mode = S3C2410_GPB(2),资源拿到。

static int s3c24xx_uda134x_setup_pin(int pin, char *fun)
{
	if (gpio_request(pin, "s3c24xx_uda134x") < 0) {
		printk(KERN_ERR "S3C24XX_UDA134X SoC Audio: "
		       "l3 %s pin already in use", fun);
		return -EBUSY;
	}
	gpio_direction_output(pin, 0);
	return 0;
}

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;
	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,
				      "data") < 0)
		return -EBUSY;
	if (s3c24xx_uda134x_setup_pin(s3c24xx_uda134x_l3_pins->l3_clk,
				      "clk") < 0) {
		gpio_free(s3c24xx_uda134x_l3_pins->l3_data);
		return -EBUSY;
	}
	if (s3c24xx_uda134x_setup_pin(s3c24xx_uda134x_l3_pins->l3_mode,
				      "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);//在这里申请一个soc-audio设备
	if (!s3c24xx_uda134x_snd_device) {
		printk(KERN_ERR "S3C24XX_UDA134X SoC Audio: "
		       "Unable to register\n");
		return -ENOMEM;
	}//为上层驱动做准备

//这里就厉害了，s3c24xx_uda134x_snd_devdata这个结构体中包含了
//上层结构操作芯片的所有资源（三个引脚，操作引脚的函数都在），
//将核心操作都留到了上层SoC Device - the audio subsystem，由系统统一使用
	platform_set_drvdata(s3c24xx_uda134x_snd_device,
			     &s3c24xx_uda134x_snd_devdata);

	s3c24xx_uda134x_snd_devdata.dev = &s3c24xx_uda134x_snd_device->dev;
	
//将刚刚申请的设备添加到系统，这里将由上层的驱动（SoC audio driver）来匹配	
//到这里底层的硬件资源就完成了
//上层将会配置uda1341芯片的寄存器
	ret = platform_device_add(s3c24xx_uda134x_snd_device);
	if (ret) {
		printk(KERN_ERR "S3C24XX_UDA134X SoC Audio: Unable to add\n");
		platform_device_put(s3c24xx_uda134x_snd_device);
	}

	return ret;
}