关于i2c驱动配对时匹配的数据结构源码追踪

最新推荐文章于 2025-06-29 15:14:19 发布

KELLY_F2018

最新推荐文章于 2025-06-29 15:14:19 发布

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分类专栏：嵌入式驱动开发

本文链接：https://blog.youkuaiyun.com/qq_36109845/article/details/81292079

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本文详细介绍了Linux系统中I2C驱动的数据结构及其工作原理，包括i2c_driver和device_driver结构体的作用与关联，以及of_device_id在设备匹配过程中的作用。

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先来看看i2c驱动的数据结构

struct i2c_driver {
	unsigned int class;

	/* Notifies the driver that a new bus has appeared. You should avoid
	 * using this, it will be removed in a near future.
	 */
	int (*attach_adapter)(struct i2c_adapter *) __deprecated;

	/* Standard driver model interfaces */
	int (*probe)(struct i2c_client *, const struct i2c_device_id *);
	int (*remove)(struct i2c_client *);

	/* driver model interfaces that don't relate to enumeration  */
	void (*shutdown)(struct i2c_client *);
	int (*suspend)(struct i2c_client *, pm_message_t mesg);
	int (*resume)(struct i2c_client *);

	/* Alert callback, for example for the SMBus alert protocol.
	 * The format and meaning of the data value depends on the protocol.
	 * For the SMBus alert protocol, there is a single bit of data passed
	 * as the alert response's low bit ("event flag").
	 */
	void (*alert)(struct i2c_client *, unsigned int data);

	/* a ioctl like command that can be used to perform specific functions
	 * with the device.
	 */
	int (*command)(struct i2c_client *client, unsigned int cmd, void *arg);

	struct device_driver driver;
	const struct i2c_device_id *id_table;

	/* Device detection callback for automatic device creation */
	int (*detect)(struct i2c_client *, struct i2c_board_info *);
	const unsigned short *address_list;
	struct list_head clients;
}

我们都知道linux上的设备驱动都要与实际的设备配对，而完成这一工作的函数就是match函数。但是在i2c_driver结构体中并没有这一成员，而我们能在里面看到他是包含了一个 device_driver 结构体，展开这个结构体：

struct device_driver {
	const char		*name;
	struct bus_type		*bus;

	struct module		*owner;
	const char		*mod_name;	/* used for built-in modules */

	bool suppress_bind_attrs;	/* disables bind/unbind via sysfs */

	const struct of_device_id	*of_match_table;
	const struct acpi_device_id	*acpi_match_table;

	int (*probe) (struct device *dev);
	int (*remove) (struct device *dev);
	void (*shutdown) (struct device *dev);
	int (*suspend) (struct device *dev, pm_message_t state);
	int (*resume) (struct device *dev);
	const struct attribute_group **groups;

	const struct dev_pm_ops *pm;

	struct driver_private *p;
};

在这里面我们能看到一个成员叫做 of_match_table ，我们可以推测这个结构体指针和match有关，接下来展开 of_device_id 结构体：

/*
 * Struct used for matching a device
 */
struct of_device_id
{
	char	name[32];
	char	type[32];
	char	compatible[128];
	const void *data;
};

从注释就可以看出，这个结构体就是配对时匹配的内容。