iTOP4412设备驱动学习十五-I2C主机驱动

本文主要是介绍iTOP4412设备驱动学习十五-I2C主机驱动，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！

资料观看的讯为电子Linux视频教程学习。

1. I2C驱动注册和卸载：i2c_add_driver, i2c_del_driver, i2c_driver

下面直接写驱动注册程序：头文件可以参考./drivers/input/touchscreen/ft5x06_ts.c

module_init和late_initcall: 优先加载驱动和后加载驱动，驱动加载的前后关系。

关于i2c_driver的结构体定义如下：

 1 ./include/linux/i2c.h
 2 
 3 /**
 4  * struct i2c_driver - represent an I2C device driver
 5  * @class: What kind of i2c device we instantiate (for detect)
 6  * @attach_adapter: Callback for bus addition (deprecated)
 7  * @detach_adapter: Callback for bus removal (deprecated)
 8  * @probe: Callback for device binding
 9  * @remove: Callback for device unbinding
10  * @shutdown: Callback for device shutdown
11  * @suspend: Callback for device suspend
12  * @resume: Callback for device resume
13  * @alert: Alert callback, for example for the SMBus alert protocol
14  * @command: Callback for bus-wide signaling (optional)
15  * @driver: Device driver model driver
16  * @id_table: List of I2C devices supported by this driver
17  * @detect: Callback for device detection
18  * @address_list: The I2C addresses to probe (for detect)
19  * @clients: List of detected clients we created (for i2c-core use only)
20  *
21  * The driver.owner field should be set to the module owner of this driver.
22  * The driver.name field should be set to the name of this driver.
23  *
24  * For automatic device detection, both @detect and @address_data must
25  * be defined. @class should also be set, otherwise only devices forced
26  * with module parameters will be created. The detect function must
27  * fill at least the name field of the i2c_board_info structure it is
28  * handed upon successful detection, and possibly also the flags field.
29  *
30  * If @detect is missing, the driver will still work fine for enumerated
31  * devices. Detected devices simply won't be supported. This is expected
32  * for the many I2C/SMBus devices which can't be detected reliably, and
33  * the ones which can always be enumerated in practice.
34  *
35  * If @detect is missing, the driver will still work fine for enumerated
36  * devices. Detected devices simply won't be supported. This is expected
37  * for the many I2C/SMBus devices which can't be detected reliably, and
38  * the ones which can always be enumerated in practice.
39  *
40  * The i2c_client structure which is handed to the @detect callback is
41  * not a real i2c_client. It is initialized just enough so that you can
42  * call i2c_smbus_read_byte_data and friends on it. Don't do anything
43  * else with it. In particular, calling dev_dbg and friends on it is
44  * not allowed.
45  */
46 struct i2c_driver {
47         unsigned int class;
48 
49         /* Notifies the driver that a new bus has appeared or is about to be
50          * removed. You should avoid using this, it will be removed in a
51          * near future.
52          */
53         int (*attach_adapter)(struct i2c_adapter *) __deprecated;
54         int (*detach_adapter)(struct i2c_adapter *) __deprecated;
55 
56         /* Standard driver model interfaces */
57         int (*probe)(struct i2c_client *, const struct i2c_device_id *);
58         int (*remove)(struct i2c_client *);
59 
60         /* driver model interfaces that don't relate to enumeration  */
61         void (*shutdown)(struct i2c_client *);
62         int (*suspend)(struct i2c_client *, pm_message_t mesg);
63         int (*resume)(struct i2c_client *);
64 
65         /* Alert callback, for example for the SMBus alert protocol.
66          * The format and meaning of the data value depends on the protocol.
67          * For the SMBus alert protocol, there is a single bit of data passed
68          * as the alert response's low bit ("event flag").
69          */
70         void (*alert)(struct i2c_client *, unsigned int data);
71 
72         /* a ioctl like command that can be used to perform specific functions
73          * with the device.
74          */
75         int (*command)(struct i2c_client *client, unsigned int cmd, void *arg);
76 
77         struct device_driver driver;
78         const struct i2c_device_id *id_table;
79 
80         /* Device detection callback for automatic device creation */
81         int (*detect)(struct i2c_client *, struct i2c_board_info *);
82         const unsigned short *address_list;
83         struct list_head clients;
84 };

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