regulator: core: Allow drivers to set voltage mapping table in regulator_desc

Some regulator hardware use table based mapping can set volt_table in
regulator_desc and use regulator_list_voltage_table() for their list_voltage
callback.
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

drivers/regulator/core.c

@@ -1882,6 +1882,31 @@ int regulator_list_voltage_linear(struct regulator_dev *rdev,
 }
 EXPORT_SYMBOL_GPL(regulator_list_voltage_linear);
 
+/**
+ * regulator_list_voltage_table - List voltages with table based mapping
+ *
+ * @rdev: Regulator device
+ * @selector: Selector to convert into a voltage
+ *
+ * Regulators with table based mapping between voltages and
+ * selectors can set volt_table in the regulator descriptor
+ * and then use this function as their list_voltage() operation.
+ */
+int regulator_list_voltage_table(struct regulator_dev *rdev,
+				 unsigned int selector)
+{
+	if (!rdev->desc->volt_table) {
+		BUG_ON(!rdev->desc->volt_table);
+		return -EINVAL;
+	}
+
+	if (selector >= rdev->desc->n_voltages)
+		return -EINVAL;
+
+	return rdev->desc->volt_table[selector];
+}
+EXPORT_SYMBOL_GPL(regulator_list_voltage_table);
+
 /**
  * regulator_list_voltage - enumerate supported voltages
  * @regulator: regulator source

include/linux/regulator/driver.h

@@ -170,6 +170,7 @@ enum regulator_type {
  *
  * @min_uV: Voltage given by the lowest selector (if linear mapping)
  * @uV_step: Voltage increase with each selector (if linear mapping)
+ * @volt_table: Voltage mapping table (if table based mapping)
  *
  * @vsel_reg: Register for selector when using regulator_regmap_X_voltage_
  * @vsel_mask: Mask for register bitfield used for selector
@@ -189,6 +190,8 @@ struct regulator_desc {
 	unsigned int min_uV;
 	unsigned int uV_step;
 
+	const unsigned int *volt_table;
+
 	unsigned int vsel_reg;
 	unsigned int vsel_mask;
 	unsigned int enable_reg;
@@ -271,6 +274,8 @@ int regulator_mode_to_status(unsigned int);
 
 int regulator_list_voltage_linear(struct regulator_dev *rdev,
 				  unsigned int selector);
+int regulator_list_voltage_table(struct regulator_dev *rdev,
+				  unsigned int selector);
 int regulator_map_voltage_linear(struct regulator_dev *rdev,
 				  int min_uV, int max_uV);
 int regulator_map_voltage_iterate(struct regulator_dev *rdev,