regulator: bindings: add document bindings for mpq7920

Add device tree binding information for mpq7920 regulator driver.
Example bindings for mpq7920 are added.
Signed-off-by: Saravanan Sekar <sravanhome@gmail.com>
Link: https://lore.kernel.org/r/20200108131234.24128-3-sravanhome@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/mps,mpq7920.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/regulator/mps,mpq7920.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Monolithic Power System MPQ7920 PMIC
+
+maintainers:
+  - Saravanan Sekar <sravanhome@gmail.com>
+
+properties:
+  $nodename:
+    pattern: "pmic@[0-9a-f]{1,2}"
+  compatible:
+    enum:
+      - mps,mpq7920
+
+  reg:
+    maxItems: 1
+
+  regulators:
+    type: object
+    description: |
+      list of regulators provided by this controller, must be named
+      after their hardware counterparts BUCK[1-4], one LDORTC, and LDO[2-5]
+
+      mps,switch-freq:
+        description: |
+          switching frequency must be one of following corresponding value
+          1.1MHz, 1.65MHz, 2.2MHz, 2.75MHz
+        $ref: "/schemas/types.yaml#/definitions/uint8"
+        enum: [ 0, 1, 2, 3 ]
+        default: 2
+
+      buck1:
+        type: object
+        $ref: "regulator.yaml#"
+        description: |
+          4.5A DC-DC step down converter
+
+        mps,buck-softstart:
+           $ref: "/schemas/types.yaml#/definitions/uint8"
+           enum: [ 0, 1, 2, 3 ]
+           default: 1
+           description: |
+             defines the soft start time of this buck, must be one of the following
+             corresponding values 150us, 300us, 610us, 920us
+
+         mps,buck-phase-delay:
+           $ref: "/schemas/types.yaml#/definitions/uint8"
+           enum: [ 0, 1, 2, 3 ]
+           default: 0
+           description: |
+             defines the phase delay of this buck, must be one of the following
+             corresponding values 0deg, 90deg, 180deg, 270deg
+
+         mps,buck-ovp-disable:
+           type: boolean
+           description: |
+             disables over voltage protection of this buck
+
+      buck2:
+        type: object
+        $ref: "regulator.yaml#"
+        description: |
+          2.5A DC-DC step down converter
+
+        mps,buck-softstart:
+          description: |
+            defines the soft start time of this buck, must be one of the following
+            corresponding values 150us, 300us, 610us, 920us
+          $ref: "/schemas/types.yaml#/definitions/uint8"
+          enum: [ 0, 1, 2, 3 ]
+          default: 1
+
+        mps,buck-phase-delay:
+          description: |
+            defines the phase delay of this buck, must be one of the following
+            corresponding values 0deg, 90deg, 180deg, 270deg
+          $ref: "/schemas/types.yaml#/definitions/uint8"
+          enum: [ 0, 1, 2, 3 ]
+          default: 0
+
+        mps,buck-ovp-disable:
+          description: |
+            disables over voltage protection of this buck
+          type: boolean
+
+      buck3:
+        type: object
+        $ref: "regulator.yaml#"
+        description: |
+          4.5A DC-DC step down converter
+
+        mps,buck-softstart:
+           description: |
+             defines the soft start time of this buck, must be one of the following
+             corresponding values 150us, 300us, 610us, 920us
+           $ref: "/schemas/types.yaml#/definitions/uint8"
+           enum: [ 0, 1, 2, 3 ]
+           default: 1
+
+         mps,buck-phase-delay:
+           description: |
+             defines the phase delay of this buck, must be one of the following
+             corresponding values 0deg, 90deg, 180deg, 270deg
+           $ref: "/schemas/types.yaml#/definitions/uint8"
+           enum: [ 0, 1, 2, 3 ]
+           default: 1
+
+         mps,buck-ovp-disable:
+           description: |
+             disables over voltage protection of this buck
+           type: boolean
+
+      buck4:
+        type: object
+        $ref: "regulator.yaml#"
+        description: |
+          2.5A DC-DC step down converter
+
+        mps,buck-softstart:
+          description: |
+            defines the soft start time of this buck, must be one of the following
+            corresponding values 150us, 300us, 610us, 920us
+          $ref: "/schemas/types.yaml#/definitions/uint8"
+          enum: [ 0, 1, 2, 3 ]
+          default: 1
+
+        mps,buck-phase-delay:
+          description: |
+            defines the phase delay of this buck, must be one of the following
+            corresponding values 0deg, 90deg, 180deg, 270deg
+          $ref: "/schemas/types.yaml#/definitions/uint8"
+          enum: [ 0, 1, 2, 3 ]
+          default: 1
+
+        mps,buck-ovp-disable:
+          description: |
+            disables over voltage protection of this buck
+          type: boolean
+
+      ldortc:
+        $ref: "regulator.yaml#"
+        description: |
+          regulator with 0.65V-3.5875V for RTC, always enabled
+
+      ldo2:
+        $ref: "regulator.yaml#"
+        description: |
+          regulator with 0.65V-3.5875V
+
+      ldo3:
+        $ref: "regulator.yaml#"
+        description: |
+          regulator with 0.65V-3.5875V
+
+      ldo4:
+        $ref: "regulator.yaml#"
+        description: |
+          regulator with 0.65V-3.5875V
+
+      ldo5:
+        $ref: "regulator.yaml#"
+        description: |
+          regulator with 0.65V-3.5875V
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        pmic@69 {
+          compatible = "mps,mpq7920";
+          reg = <0x69>;
+
+          regulators {
+            mps,switch-freq = <1>;
+
+            buck1 {
+             regulator-name = "buck1";
+             regulator-min-microvolt = <400000>;
+             regulator-max-microvolt = <3587500>;
+             regulator-min-microamp  = <460000>;
+             regulator-max-microamp  = <7600000>;
+             regulator-boot-on;
+             mps,buck-ovp-disable;
+             mps,buck-phase-delay = <2>;
+             mps,buck-softstart = <1>;
+            };
+
+            ldo2 {
+             regulator-name = "ldo2";
+             regulator-min-microvolt = <650000>;
+             regulator-max-microvolt = <3587500>;
+            };
+         };
+       };
+     };
+...