regulator: bindings: ROHM bd70528 regulator bindings

ROHM bd70528 is a ultra low power PMIC which includes
3 bucks, 3 LDOs and 2 LED drivers. Document the bindings
for them.

Signed-off-by: Matti Vaittinen <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

Documentation/devicetree/bindings/regulator/rohm,bd70528-regulator.txt

···
+ROHM BD70528 Power Management Integrated Circuit regulator bindings
+
+Required properties:
+ - regulator-name: should be "buck1", "buck2", "buck3", "ldo1", "ldo2", "ldo3",
+		   "led_ldo1", "led_ldo2"
+
+List of regulators provided by this controller. BD70528 regulators node
+should be sub node of the BD70528 MFD node. See BD70528 MFD bindings at
+Documentation/devicetree/bindings/mfd/rohm,bd70528-pmic.txt
+
+The valid names for BD70528 regulator nodes are:
+BUCK1, BUCK2, BUCK3, LDO1, LDO2, LDO3, LED_LDO1, LED_LDO2
+
+Optional properties:
+- Any optional property defined in bindings/regulator/regulator.txt
+
+Example:
+regulators {
+	buck1: BUCK1 {
+		regulator-name = "buck1";
+		regulator-min-microvolt = <1200000>;
+		regulator-max-microvolt = <3400000>;
+		regulator-boot-on;
+		regulator-ramp-delay = <125>;
+	};
+	buck2: BUCK2 {
+		regulator-name = "buck2";
+		regulator-min-microvolt = <1200000>;
+		regulator-max-microvolt = <3300000>;
+		regulator-boot-on;
+		regulator-ramp-delay = <125>;
+	};
+	buck3: BUCK3 {
+		regulator-name = "buck3";
+		regulator-min-microvolt = <800000>;
+		regulator-max-microvolt = <1800000>;
+		regulator-boot-on;
+		regulator-ramp-delay = <250>;
+	};
+	ldo1: LDO1 {
+		regulator-name = "ldo1";
+		regulator-min-microvolt = <1650000>;
+		regulator-max-microvolt = <3300000>;
+		regulator-boot-on;
+	};
+	ldo2: LDO2 {
+		regulator-name = "ldo2";
+		regulator-min-microvolt = <1650000>;
+		regulator-max-microvolt = <3300000>;
+		regulator-boot-on;
+	};
+
+	ldo3: LDO3 {
+		regulator-name = "ldo3";
+		regulator-min-microvolt = <1650000>;
+		regulator-max-microvolt = <3300000>;
+	};
+	led_ldo1: LED_LDO1 {
+		regulator-name = "led_ldo1";
+		regulator-min-microvolt = <200000>;
+		regulator-max-microvolt = <300000>;
+	};
+	led_ldo2: LED_LDO2 {
+		regulator-name = "led_ldo2";
+		regulator-min-microvolt = <200000>;
+		regulator-max-microvolt = <300000>;
+	};
+};