Linux Device Drivers Development

Device access functions

The API handles data parsing, formatting, and transmission. In most cases, device access is performed with regmap_read, regmap_write, and regmap_update_bits. These are the three most important functions you should always remember when it comes to storing/fetching data into/from the device. Their respective prototypes are:

int regmap_read(struct regmap *map, unsigned int reg, 
                 unsigned int *val); 
int regmap_write(struct regmap *map, unsigned int reg, 
                 unsigned int val); 
int regmap_update_bits(struct regmap *map, unsigned int reg, 
                 unsigned int mask, unsigned int val); 

• regmap_write: This writes data to the device. If max_register is set in regmap_config, then it will be used to check if the register address is valid. ...