/* The i2c_client structure which is handed to the @detect callback is
* not a real i2c_client. It is initialized just enough so that you can
* call i2c_smbus_read_byte_data and friends on it. Don't do anything
* else with it. In particular, calling dev_dbg and friends on it is
* not allowed.
*/
struct i2c_driver {
int id;
unsigned int class;
/* Notifies the driver that a new bus has appeared or is about to be
* removed. You should avoid using this if you can, it will probably
* be removed in a near future.
*/
int (*attach_adapter)(struct i2c_adapter *);
int (*detach_adapter)(struct i2c_adapter *);
/* 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 *);
/* 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 *, int kind, struct i2c_board_info *);
const struct i2c_client_address_data *address_data;
struct list_head clients;
};
I2C客户端结构体：
i2c_client对应于真实的物理设备，每个I2C设备都需要一个i2c_client来描述。
struct i2c_client {
unsigned short flags;/* div., see below*/
unsigned short addr;/* chip address - NOTE: 7bit*/
/* addresses are stored in the*/
/* _LOWER_ 7 bits*/
char name[I2C_NAME_SIZE];
struct i2c_adapter *adapter;/* the adapter we sit on*/
struct i2c_driver *driver;/* and our access routines*/
struct device dev;/* the device structure*/
int irq;/* irq issued by device*/
struct list_head detected;
};
这四个数据结构之间又有密切联系。一个I2C适配器需要i2c_algorithm中提供的通信函数来控制适配器上产生特定的访问周期。缺少i2c_algorithm的i2c_adapter什么也做不了，因此i2c_adapter中包含其使用的 i2c_algorithm的指针。i2c_driver与i2c_client的关系是一对多，一个i2c_driver上可以支持多个同类型的i2c_client。