UM0851 datasheet(81/245 Pages) STMICROELECTRONICS

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UM0851

Communication device drivers

Doc ID 16604 Rev 2

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adapter gets a number, counting from 0. You can examine /sys/class/i2c-dev/ to see what

number corresponds to which adapter. I2C device files are character device files with major

device number 89 and a minor device number corresponding to the number assigned as

explained above. They should be called "i2c-%d" (i2c-0, i2c-1, ...,i2c-10, ...). All 256 minor

device numbers are reserved for i2c.

4.5.4

Adding a new I2C client driver

To add a new client driver, you should be familiar with struct i2c_driver.The struct i2c_driver

describes an I2C chip driver. This structure is defined in the include/linux/i2c.h file. Only the

following fields are necessary to create a working chip driver.

/* set to a descriptive name of the I2C chip driver. This value shows up in the sysfs

file name created for every I2C chip device */

char name[I2C_NAME_SIZE];

/* called whenever a new I2C bus driver is loaded in the system. This function is

described in more detail below. */

int (*attach_adapter)(struct i2c_adapter *);

/* called when the i2c_client device is to be removed from the system. */

int (*detach_client)(struct i2c_client *);

static struct i2c_driver eeprom_driver = {

.driver = {

.name

= "eeprom",

.id

= I2C_DRIVERID_eeprom,

.attach_adapter = eeprom_attach_adapter,

.detach_client

= eeprom_detach_client,

};

Registering a chip driver

To register this I2C chip driver, the function i2c_add_driver() should be called with a pointer

to the struct i2c_driver.

static int __init eeprom_init(void)

{

return i2c_add_driver(&eeprom_driver);

}

Unregistering a chip driver

To unregister the I2C chip driver, the i2c_del_driver() function should be called with the

same pointer to the struct i2c_driver. I2c_del_driver() is defined in include/linux/i2c.h which

will internally call i2c_unregister_driver() defined in drivers/i2c/i2c-core.c

static void __exit eeprom_exit(void)

{

i2c_del_driver(&eeprom_driver);

}

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