Linux I2C 驱动结构
i2c体系结构由三部分组成
- i2C core
i2c core提供了i2c 总线驱动 和 设备驱动的注册，注销方法
i2C and SMBus protocol 实现 - i2C “bus” driver
algorithm driver
adapter driver - i2c device driver
chip drivers, 包括多种类型，如RTC, EEPROM, I/O expander, hardware monitoring, sound, video等
i2c adapter 和 i2C algorithm
i2c adapter对应于物理上的适配器。 i2C algorithm对应一套通信方法。
i2c 设备驱动
i2c 设备驱动要使用i2c_driver 和i2c_client数据结构并填充i2c_driver中的成员函数
/**
* struct i2c_driver - represent an I2C device driver
* @class: What kind of i2c device we instantiate (for detect)
* @attach_adapter: Callback for bus addition (deprecated)
* @probe: Callback for device binding - soon to be deprecated
* @probe_new: New callback for device binding
* @remove: Callback for device unbinding
* @shutdown: Callback for device shutdown
* @alert: Alert callback, for example for the SMBus alert protocol
* @command: Callback for bus-wide signaling (optional)
* @driver: Device driver model driver
* @id_table: List of I2C devices supported by this driver
* @detect: Callback for device detection
* @address_list: The I2C addresses to probe (for detect)
* @clients: List of detected clients we created (for i2c-core use only)
* @disable_i2c_core_irq_mapping: Tell the i2c-core to not do irq-mapping
*
* The driver.owner field should be set to the module owner of this driver.
* The driver.name field should be set to the name of this driver.
*
* For automatic device detection, both @detect and @address_list must
* be defined. @class should also be set, otherwise only devices forced
* with module parameters will be created. The detect function must
* fill at least the name field of the i2c_board_info structure it is
* handed upon successful detection, and possibly also the flags field.
*
* If @detect is missing, the driver will still work fine for enumerated
* devices. Detected devices simply won't be supported. This is expected
* for the many I2C/SMBus devices which can't be detected reliably, and
* the ones which can always be enumerated in practice.
*
* 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 {
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 *);
/* New driver model interface to aid the seamless removal of the
* current probe()'s, more commonly unused than used second parameter.
*/
int (*probe_new)(struct i2c_client *);
/* driver model interfaces that don't relate to enumeration */
void (*shutdown)(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").
* For the SMBus Host Notify protocol, the data corresponds to the
* 16-bit payload data reported by the slave device acting as master.
*/
void (*alert)(struct i2c_client *, enum i2c_alert_protocol protocol,
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;
bool disable_i2c_core_irq_mapping;
};看一下RTC设备的驱动
Browse the source code of linux/drivers/rtc/rtc-ds1307.c
static struct i2c_driver ds1307_driver = {
.driver = {
.name = "rtc-ds1307",
.of_match_table = of_match_ptr(ds1307_of_match),
.acpi_match_table = ACPI_PTR(ds1307_acpi_ids),
},
.probe = ds1307_probe,
.id_table = ds1307_id,
};