dt-bindings:iio:dac:microchip,mcp4725 yaml conversion

I'm not sure vdd-supply absolutely has to be provided if vref-supply
is, but as the previous binding docs stated it was required it seems
reasonable to leave it as such.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Tomas Novotny <tomas@novotny.cz>
Link: https://lore.kernel.org/r/20201031134110.724233-21-jic23@kernel.org

Documentation/devicetree/bindings/iio/dac/mcp4725.txt

-Microchip mcp4725 and mcp4726 DAC device driver
-
-Required properties:
-	- compatible: Must be "microchip,mcp4725" or "microchip,mcp4726"
-	- reg: Should contain the DAC I2C address
-	- vdd-supply: Phandle to the Vdd power supply. This supply is used as a
-	  voltage reference on mcp4725. It is used as a voltage reference on
-	  mcp4726 if there is no vref-supply specified.
-
-Optional properties (valid only for mcp4726):
-	- vref-supply: Optional phandle to the Vref power supply. Vref pin is
-	  used as a voltage reference when this supply is specified.
-	- microchip,vref-buffered: Boolean to enable buffering of the external
-	  Vref pin. This boolean is not valid without the vref-supply. Quoting
-	  the datasheet: This is offered in cases where the reference voltage
-	  does not have the current capability not to drop its voltage when
-	  connected to the internal resistor ladder circuit.
-
-Examples:
-
-	/* simple mcp4725 */
-	mcp4725@60 {
-		compatible = "microchip,mcp4725";
-		reg = <0x60>;
-		vdd-supply = <&vdac_vdd>;
-	};
-
-	/* mcp4726 with the buffered external reference voltage */
-	mcp4726@60 {
-		compatible = "microchip,mcp4726";
-		reg = <0x60>;
-		vdd-supply = <&vdac_vdd>;
-		vref-supply = <&vdac_vref>;
-		microchip,vref-buffered;
-	};

Documentation/devicetree/bindings/iio/dac/microchip,mcp4725.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/dac/microchip,mcp4725.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip mcp4725 and mcp4726 DAC
+
+maintainers:
+  - Tomas Novotny <tomas@novotny.cz>
+
+properties:
+  compatible:
+    enum:
+      - microchip,mcp4725
+      - microchip,mcp4726
+
+  reg:
+    maxItems: 1
+
+  vdd-supply:
+    description: |
+      Provides both power and acts as the reference supply on the mcp4725.
+      For the mcp4726 it will be used as the reference voltage if vref-supply
+      is not provided.
+
+  vref-supply:
+    description:
+      Vref pin is used as a voltage reference when this supply is specified.
+
+  microchip,vref-buffered:
+    type: boolean
+    description: |
+      Enable buffering of the external Vref pin. This boolean is not valid
+      without the vref-supply. Quoting the datasheet: This is offered in
+      cases where the reference voltage does not have the current
+      capability not to drop its voltage when connected to the internal
+      resistor ladder circuit.
+
+allOf:
+  - if:
+      not:
+        properties:
+          compatible:
+            contains:
+              const: microchip,mcp4726
+    then:
+      properties:
+        vref-supply: false
+        microchip,vref-buffered: false
+
+required:
+  - compatible
+  - reg
+  - vdd-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        mcp4725@60 {
+            compatible = "microchip,mcp4725";
+            reg = <0x60>;
+            vdd-supply = <&vdac_vdd>;
+        };
+    };
+...