regulator: core: Add regulator_set_voltage_time_sel to calculate ramp delay.

This patch adds regulator_set_voltage_time_sel(), to move into core, the
commonly used code by drivers to provide the .set_voltage_time_sel callback.
It will also allow us to configure different ramp delay for different
regulators easily.

Signed-off-by: Yadwinder Singh Brar <yadi.brar@samsung.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index 8022638..ae5c253 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -170,6 +170,7 @@
  *
  * @min_uV: Voltage given by the lowest selector (if linear mapping)
  * @uV_step: Voltage increase with each selector (if linear mapping)
+ * @ramp_delay: Time to settle down after voltage change (unit: mV/us)
  * @volt_table: Voltage mapping table (if table based mapping)
  *
  * @vsel_reg: Register for selector when using regulator_regmap_X_voltage_
@@ -189,6 +190,7 @@
 
 	unsigned int min_uV;
 	unsigned int uV_step;
+	unsigned int ramp_delay;
 
 	const unsigned int *volt_table;
 
@@ -285,6 +287,9 @@
 int regulator_is_enabled_regmap(struct regulator_dev *rdev);
 int regulator_enable_regmap(struct regulator_dev *rdev);
 int regulator_disable_regmap(struct regulator_dev *rdev);
+int regulator_set_voltage_time_sel(struct regulator_dev *rdev,
+				   unsigned int old_selector,
+				   unsigned int new_selector);
 
 void *regulator_get_init_drvdata(struct regulator_init_data *reg_init_data);