Linux Device Drivers Development

Case study – Intersil ISL6271A voltage regulator

This PMIC provides three regulator's devices, among which only one can have its output value changed. The two others provide fixed voltages:

struct isl_pmic { 
   struct i2c_client *client; 
   struct regulator_dev    *rdev[3]; 
   struct mutex            mtx; 
}; 

First, we define ops callbacks, to set up a struct regulator_desc:

1. A callback to handle a get_voltage_sel operation:

static int isl6271a_get_voltage_sel(struct regulator_dev *rdev) 
{ 
   struct isl_pmic *pmic = rdev_get_drvdata(dev); 
   int idx = rdev_get_id(rdev); 
   idx = i2c_smbus_read_byte(pmic->client); 
   if (idx < 0) 
         [...] /* handle this error */ 
 
   return idx; 
} 

The following is the callback to handle a set_voltage_sel operation:

static int isl6271a_set_voltage_sel( ...