dm: regulator: add function device_get_supply_regulator()

Some devices are supplied by configurable regulator's output.
But there was no function for getting it. This commit adds
function, that allows for getting the supply device by it's phandle.

The returned regulator device can be used with regulator uclass's API.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

drivers/power/regulator/regulator-uclass.c

@@ -138,6 +138,13 @@ int regulator_get_by_devname(const char *devname, struct udevice **devp)
 	return uclass_get_device_by_name(UCLASS_REGULATOR, devname, devp);
 }
 
+int device_get_supply_regulator(struct udevice *dev, const char *supply_name,
+				struct udevice **devp)
+{
+	return uclass_get_device_by_phandle(UCLASS_REGULATOR, dev,
+					    supply_name, devp);
+}
+
 int regulator_autoset(struct udevice *dev)
 {
 	struct dm_regulator_uclass_platdata *uc_pdata;

include/power/regulator.h

@@ -419,4 +419,20 @@ int regulator_get_by_devname(const char *devname, struct udevice **devp);
  */
 int regulator_get_by_platname(const char *platname, struct udevice **devp);
 
+/**
+ * device_get_supply_regulator: returns the pointer to the supply regulator.
+ * Search by phandle, found in device's node.
+ *
+ * Note: Please pay attention to proper order of device bind sequence.
+ * The regulator device searched by the phandle, must be binded before
+ * this function call.
+ *
+ * @dev         - device with supply phandle
+ * @supply_name - phandle name of regulator
+ * @devp        - returned pointer to the supply device
+ * @return 0 on success or negative value of errno.
+ */
+int device_get_supply_regulator(struct udevice *dev, const char *supply_name,
+				struct udevice **devp);
+
 #endif /* _INCLUDE_REGULATOR_H_ */