dt-bindings: regulator: add stub regulator bindings

Add stub-regulator device bindings.  These devices can be used to
simulate any particular voltage regulator.

Change-Id: Icb701dcc358b63490b88698d2710e4b19d9448bd

bindings/regulator/stub-regulator.txt

@@ -0,0 +1,48 @@
+Stub Voltage Regulators
+
+stub-regulators are place-holder regulator devices which do not impact any
+hardware state.  They provide a means for consumer devices to utilize all
+regulator features for testing purposes.
+
+Required properties:
+- compatible:      Must be "qcom,stub-regulator".
+- regulator-name:  A string used as a descriptive name for regulator outputs.
+
+Optional properties:
+- parent-supply:     phandle to the parent supply/regulator node if one exists.
+- qcom,hpm-min-load: Load current in uA which corresponds to the minimum load
+			which requires the regulator to be in high power mode.
+- qcom,system-load:  Load in uA present on regulator that is not captured by any
+			consumer request.
+
+All properties specified within the core regulator framework can also be used.
+These bindings can be found in regulator.txt.
+
+Example:
+
+/ {
+	pm8026_s3: regulator-s3 {
+		compatible = "qcom,stub-regulator";
+		regulator-name = "8026_s3";
+		qcom,hpm-min-load = <100000>;
+		regulator-min-microvolt = <1300000>;
+		regulator-max-microvolt = <1300000>;
+	};
+
+	pm8026_l1: regulator-l1 {
+		compatible = "qcom,stub-regulator";
+		regulator-name = "8026_l1";
+		parent-supply = <&pm8026_s3>;
+		qcom,hpm-min-load = <10000>;
+		regulator-min-microvolt = <1225000>;
+		regulator-max-microvolt = <1225000>;
+	};
+
+	pm8026_l20: regulator-l20 {
+		compatible = "qcom,stub-regulator";
+		regulator-name = "8026_l20";
+		qcom,hpm-min-load = <5000>;
+		regulator-min-microvolt = <3075000>;
+		regulator-max-microvolt = <3075000>;
+	};
+};