regulator: expose regulator_find_closest_bigger

Expose and document the table lookup logic used by
regulator_set_ramp_delay_regmap, so that it can be
reused for devices that cannot be configured via
regulator_set_ramp_delay_regmap.

Tested-by: Diederik de Haas <didi.debian@cknow.org> # Rock64, Quartz64 Model A + B
Tested-by: Vincent Legoll <vincent.legoll@gmail.com> # Pine64 QuartzPro64
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20230504173618.142075-11-sebastian.reichel@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: sre

drivers/regulator/helpers.c

@@ -902,8 +902,21 @@ bool regulator_is_equal(struct regulator *reg1, struct regulator *reg2)
 }
 EXPORT_SYMBOL_GPL(regulator_is_equal);
 
-static int find_closest_bigger(unsigned int target, const unsigned int *table,
-			       unsigned int num_sel, unsigned int *sel)
+/**
+ * regulator_find_closest_bigger - helper to find offset in ramp delay table
+ *
+ * @target: targeted ramp_delay
+ * @table: table with supported ramp delays
+ * @num_sel: number of entries in the table
+ * @sel: Pointer to store table offset
+ *
+ * This is the internal helper used by regulator_set_ramp_delay_regmap to
+ * map ramp delay to register value. It should only be used directly if
+ * regulator_set_ramp_delay_regmap cannot handle a specific device setup
+ * (e.g. because the value is split over multiple registers).
+ */
+int regulator_find_closest_bigger(unsigned int target, const unsigned int *table,
+				  unsigned int num_sel, unsigned int *sel)
 {
 	unsigned int s, tmp, max, maxsel = 0;
 	bool found = false;
@@ -933,6 +946,7 @@ static int find_closest_bigger(unsigned int target, const unsigned int *table,
 
 	return 0;
 }
+EXPORT_SYMBOL_GPL(regulator_find_closest_bigger);
 
 /**
  * regulator_set_ramp_delay_regmap - set_ramp_delay() helper
@@ -951,8 +965,8 @@ int regulator_set_ramp_delay_regmap(struct regulator_dev *rdev, int ramp_delay)
 	if (WARN_ON(!rdev->desc->n_ramp_values || !rdev->desc->ramp_delay_table))
 		return -EINVAL;
 
-	ret = find_closest_bigger(ramp_delay, rdev->desc->ramp_delay_table,
-				  rdev->desc->n_ramp_values, &sel);
+	ret = regulator_find_closest_bigger(ramp_delay, rdev->desc->ramp_delay_table,
+					    rdev->desc->n_ramp_values, &sel);
 
 	if (ret) {
 		dev_warn(rdev_get_dev(rdev),

include/linux/regulator/driver.h

@@ -758,6 +758,8 @@ int regulator_set_current_limit_regmap(struct regulator_dev *rdev,
 				       int min_uA, int max_uA);
 int regulator_get_current_limit_regmap(struct regulator_dev *rdev);
 void *regulator_get_init_drvdata(struct regulator_init_data *reg_init_data);
+int regulator_find_closest_bigger(unsigned int target, const unsigned int *table,
+				  unsigned int num_sel, unsigned int *sel);
 int regulator_set_ramp_delay_regmap(struct regulator_dev *rdev, int ramp_delay);
 int regulator_sync_voltage_rdev(struct regulator_dev *rdev);