Using Regmap register access functions

Remap register access methods handle data parsing, formatting, and transmission. In most cases, device accesses are performed with regmap_read(), regmap_write(), and regmap_update_bits(), which are the three important APIs when it comes to writing/reading data into/from the device. Their respective prototypes are the following:

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,
               ...