regulator: dt-bindings: add MCP16502 regulator bindings

This patch describes the compatible and the device tree
bindings necessary for the MCP16502 PMIC.
Signed-off-by: NAndrei Stefanescu <andrei.stefanescu@microchip.com>
Reviewed-by: NRob Herring <robh@kernel.org>
Signed-off-by: NMark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/mcp16502-regulator.txt

+MCP16502 PMIC
+
+Required properties:
+- compatible: "microchip,mcp16502"
+- reg: I2C slave address
+- lpm-gpios: GPIO for LPM pin. Note that this GPIO *must* remain high during
+	     suspend-to-ram, keeping the PMIC into HIBERNATE mode.
+- regulators: A node that houses a sub-node for each regulator within
+              the device. Each sub-node is identified using the node's
+              name. The content of each sub-node is defined by the
+              standard binding for regulators; see regulator.txt.
+
+Regualtors of MCP16502 PMIC:
+1) VDD_IO	- Buck (1.2 - 3.7 V)
+2) VDD_DDR	- Buck (0.6 - 1.85 V)
+3) VDD_CORE	- Buck (0.6 - 1.85 V)
+4) VDD_OTHER	- BUCK (0.6 - 1.85 V)
+5) LDO1		- LDO  (1.2 - 3.7 V)
+6) LDO2		- LDO  (1.2 - 3.7 V)
+
+Regulator modes:
+2 - FPWM: higher precision, higher consumption
+4 - AutoPFM: lower precision, lower consumption
+
+Each regulator is defined using the standard binding for regulators.
+
+Example:
+
+mcp16502@5b {
+	compatible = "microchip,mcp16502";
+	reg = <0x5b>;
+	status = "okay";
+	lpm-gpios = <&pioBU 7 GPIO_ACTIVE_HIGH>;
+
+	regulators {
+		VDD_IO {
+			regulator-name = "VDD_IO";
+			regulator-min-microvolt = <1200000>;
+			regulator-max-microvolt = <3700000>;
+			regulator-initial-mode = <2>;
+			regulator-allowed-modes = <2>, <4>;
+			regulator-always-on;
+
+			regulator-state-standby {
+				regulator-on-in-suspend;
+				regulator-mode = <4>;
+			};
+
+			regulator-state-mem {
+				regulator-off-in-suspend;
+				regulator-mode = <4>;
+			};
+		};
+
+		VDD_DDR {
+			regulator-name = "VDD_DDR";
+			regulator-min-microvolt = <600000>;
+			regulator-max-microvolt = <1850000>;
+			regulator-initial-mode = <2>;
+			regulator-allowed-modes = <2>, <4>;
+			regulator-always-on;
+
+			regulator-state-standby {
+				regulator-on-in-suspend;
+				regulator-mode = <4>;
+			};
+
+			regulator-state-mem {
+				regulator-on-in-suspend;
+				regulator-mode = <4>;
+			};
+		};
+
+		VDD_CORE {
+			regulator-name = "VDD_CORE";
+			regulator-min-microvolt = <600000>;
+			regulator-max-microvolt = <1850000>;
+			regulator-initial-mode = <2>;
+			regulator-allowed-modes = <2>, <4>;
+			regulator-always-on;
+
+			regulator-state-standby {
+				regulator-on-in-suspend;
+				regulator-mode = <4>;
+			};
+
+			regulator-state-mem {
+				regulator-off-in-suspend;
+				regulator-mode = <4>;
+			};
+		};
+
+		VDD_OTHER {
+			regulator-name = "VDD_OTHER";
+			regulator-min-microvolt = <600000>;
+			regulator-max-microvolt = <1850000>;
+			regulator-initial-mode = <2>;
+			regulator-allowed-modes = <2>, <4>;
+			regulator-always-on;
+
+			regulator-state-standby {
+				regulator-on-in-suspend;
+				regulator-mode = <4>;
+			};
+
+			regulator-state-mem {
+				regulator-off-in-suspend;
+				regulator-mode = <4>;
+			};
+		};
+
+		LDO1 {
+			regulator-name = "LDO1";
+			regulator-min-microvolt = <1200000>;
+			regulator-max-microvolt = <3700000>;
+			regulator-always-on;
+
+			regulator-state-standby {
+				regulator-on-in-suspend;
+			};
+
+			regulator-state-mem {
+				regulator-off-in-suspend;
+			};
+		};
+
+		LDO2 {
+			regulator-name = "LDO2";
+			regulator-min-microvolt = <1200000>;
+			regulator-max-microvolt = <3700000>;
+			regulator-always-on;
+
+			regulator-state-standby {
+				regulator-on-in-suspend;
+			};
+
+			regulator-state-mem {
+				regulator-off-in-suspend;
+			};
+		};
+
+	};
+};