dt-bindings: regulator: add document bindings for mp5416

Add device tree binding information for mp5416 regulator driver.
Signed-off-by: Saravanan Sekar <sravanhome@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200204110419.25933-2-sravanhome@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/mps,mp5416.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/regulator/mps,mp5416.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Monolithic Power System MP5416 PMIC
+
+maintainers:
+  - Saravanan Sekar <sravanhome@gmail.com>
+
+properties:
+  $nodename:
+    pattern: "^pmic@[0-9a-f]{1,2}$"
+  compatible:
+    enum:
+      - mps,mp5416
+
+  reg:
+    maxItems: 1
+
+  regulators:
+    type: object
+    description: |
+      list of regulators provided by this controller, must be named
+      after their hardware counterparts BUCK[1-4] and LDO[1-4]
+
+    patternProperties:
+      "^buck[1-4]$":
+        allOf:
+          - $ref: "regulator.yaml#"
+        type: object
+
+      "^ldo[1-4]$":
+        allOf:
+          - $ref: "regulator.yaml#"
+        type: object
+
+    additionalProperties: false
+  additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - regulators
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        pmic@69 {
+          compatible = "mps,mp5416";
+          reg = <0x69>;
+
+          regulators {
+
+            buck1 {
+             regulator-name = "buck1";
+             regulator-min-microvolt = <600000>;
+             regulator-max-microvolt = <2187500>;
+             regulator-min-microamp  = <3800000>;
+             regulator-max-microamp  = <6800000>;
+             regulator-boot-on;
+            };
+
+            ldo2 {
+             regulator-name = "ldo2";
+             regulator-min-microvolt = <800000>;
+             regulator-max-microvolt = <3975000>;
+            };
+         };
+       };
+     };
+...