dt-bindings: iio: frequency: add adrf6780 doc

Add device tree bindings for the ADRF6780 Upconverter.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Link: https://lore.kernel.org/r/20211021113244.56936-2-antoniu.miclaus@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/frequency/adi,adrf6780.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/frequency/adi,adrf6780.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ADRF6780 Microwave Upconverter
+
+maintainers:
+  - Antoniu Miclaus <antoniu.miclaus@analog.com>
+
+description: |
+   Wideband, microwave upconverter optimized for point to point microwave
+   radio designs operating in the 5.9 GHz to 23.6 GHz frequency range.
+
+   https://www.analog.com/en/products/adrf6780.html
+
+properties:
+  compatible:
+    enum:
+      - adi,adrf6780
+
+  reg:
+    maxItems: 1
+
+  spi-max-frequency:
+    maximum: 1000000
+
+  clocks:
+    description:
+      Definition of the external clock.
+    minItems: 1
+
+  clock-names:
+    items:
+      - const: lo_in
+
+  clock-output-names:
+    maxItems: 1
+
+  adi,vga-buff-en:
+    description:
+      RF Variable Gain Amplifier Buffer Enable. Gain is controlled by
+      the voltage on the VATT pin.
+    type: boolean
+
+  adi,lo-buff-en:
+    description:
+      Local Oscillator Amplifier Enable. Disable to put the part in
+      a power down state.
+    type: boolean
+
+  adi,if-mode-en:
+    description:
+      Intermediate Frequency Mode Enable. Either IF Mode or I/Q Mode
+      can be enabled at a time.
+    type: boolean
+
+  adi,iq-mode-en:
+    description:
+      I/Q Mode Enable. Either IF Mode or I/Q Mode can be enabled at a
+      time.
+    type: boolean
+
+  adi,lo-x2-en:
+    description:
+      Double the Local Oscillator output frequency from the Local
+      Oscillator Input Frequency. Either LOx1 or LOx2 can be enabled
+      at a time.
+    type: boolean
+
+  adi,lo-ppf-en:
+    description:
+      Local Oscillator input frequency equal to the Local Oscillator
+      output frequency (LO x1). Either LOx1 or LOx2 can be enabled
+      at a time.
+    type: boolean
+
+  adi,lo-en:
+    description:
+      Enable additional cirtuitry in the LO chain. Disable to put the
+      part in a power down state.
+    type: boolean
+
+  adi,uc-bias-en:
+    description:
+      Enable all bias circuitry thourghout the entire part.
+      Disable to put the part in a power down state.
+    type: boolean
+
+  adi,lo-sideband:
+    description:
+      Switch to the Lower LO Sideband. By default the Upper LO
+      sideband is enabled.
+    type: boolean
+
+  adi,vdet-out-en:
+    description:
+      VDET Output Select Enable. Expose the RF detector output to the
+      VDET external pin.
+    type: boolean
+
+  '#clock-cells':
+    const: 0
+
+dependencies:
+  adi,lo-x2-en: [ "adi,lo-en" ]
+  adi,lo-ppf-en: [ "adi,lo-en" ]
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+
+additionalProperties: false
+
+examples:
+  - |
+    spi {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      adrf6780@0 {
+        compatible = "adi,adrf6780";
+        reg = <0>;
+        spi-max-frequency = <1000000>;
+        clocks = <&adrf6780_lo>;
+        clock-names = "lo_in";
+      };
+    };
+...