kernel_samsung_msm8974/Documentation/devicetree/bindings/arm/msm/ext-buck-control.txt

* MSM EXT BUCK REGULATOR CONTROL

External buck regulator is used to power up the APC rail.
This buck can be turn-on & turn-off by toggling a gpio
line which is connected to buck enable pin. This driver
control the external regulator behaviour with the help
of RPM by sending the sleep and active sets when APPS
decide to enter into low power state with RPM assisted.

The required properties for EXT BUCK CONTROL are:

- compatible: "qcom,ext-buck-control"

The optional properties are:
- qcom,gpio-num: Indicates the GPIO number which will turn-on and turn-off
		 the external buck.
- qcom,settling-time-us: Indicates the settling time for the external buck to
			 get turn-on or turn-off. Settling time is calculated
			 in terms of QTIMER(19.2MHz) and the value is in us.

Example:
	qcom,ext-buck-control {
		compatible = "qcom,ext-buck-control";
		qcom,gpio-num = <50>;
		qcom,settling-time-us = <2580>;
};