dt-bindings: iio: dac: AD5766 yaml documentation

This adds device tree bindings for the AD5766 DAC.
Signed-off-by: Cristian Pop <cristian.pop@analog.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210115112105.58652-1-cristian.pop@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/dac/adi,ad5766.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+# Copyright 2020 Analog Devices Inc.
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/dac/adi,ad5766.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices AD5766 DAC device driver
+
+maintainers:
+  - Cristian Pop <cristian.pop@analog.com>
+
+description: |
+  Bindings for the Analog Devices AD5766 current DAC device. Datasheet can be
+  found here:
+    https://www.analog.com/media/en/technical-documentation/data-sheets/ad5766-5767.pdf
+
+properties:
+  compatible:
+    enum:
+      - adi,ad5766
+      - adi,ad5767
+
+  output-range-microvolts:
+    description: Select converter output range.
+
+  reg:
+    maxItems: 1
+
+  spi-max-frequency:
+    maximum: 1000000
+
+  spi-cpol: true
+
+  reset-gpios:
+    description: GPIO spec for the RESET pin. As the line is active low, it
+      should be marked GPIO_ACTIVE_LOW.
+    maxItems: 1
+
+required:
+  - compatible
+  - output-range-microvolts
+  - reg
+  - spi-max-frequency
+  - spi-cpol
+
+additionalProperties: false
+
+examples:
+  - |
+    spi {
+          #address-cells = <1>;
+          #size-cells = <0>;
+
+          ad5766@0 {
+              compatible = "adi,ad5766";
+              output-range-microvolts = <(-5000) 5000>;
+              reg = <0>;
+              spi-cpol;
+              spi-max-frequency = <1000000>;
+              reset-gpios = <&gpio 22 0>;
+            };
+      };