ASoC: meson: gx: add sound card dt-binding documentation

Add the dt-binding documentation of sound card supporting the amlogic
GX SoC family
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20200213155159.3235792-9-jbrunet@baylibre.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/amlogic,gx-sound-card.yaml

+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/sound/amlogic,gx-sound-card.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Amlogic GX sound card
+
+maintainers:
+  - Jerome Brunet <jbrunet@baylibre.com>
+
+properties:
+  compatible:
+    items:
+      - const: amlogic,gx-sound-card
+
+  audio-aux-devs:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    description: list of auxiliary devices
+
+  audio-routing:
+    $ref: /schemas/types.yaml#/definitions/non-unique-string-array
+    minItems: 2
+    description: |-
+      A list of the connections between audio components. Each entry is a
+      pair of strings, the first being the connection's sink, the second
+      being the connection's source.
+
+  audio-widgets:
+    $ref: /schemas/types.yaml#/definitions/non-unique-string-array
+    minItems: 2
+    description: |-
+      A list off component DAPM widget. Each entry is a pair of strings,
+      the first being the widget type, the second being the widget name
+
+  model:
+    $ref: /schemas/types.yaml#/definitions/string
+    description: User specified audio sound card name
+
+patternProperties:
+  "^dai-link-[0-9]+$":
+    type: object
+    description: |-
+      dai-link child nodes:
+        Container for dai-link level properties and the CODEC sub-nodes.
+        There should be at least one (and probably more) subnode of this type
+
+    properties:
+      dai-format:
+        $ref: /schemas/types.yaml#/definitions/string
+        enum: [ i2s, left-j, dsp_a ]
+
+      mclk-fs:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        description: |-
+          Multiplication factor between the frame rate and master clock
+          rate
+
+      sound-dai:
+        $ref: /schemas/types.yaml#/definitions/phandle
+        description: phandle of the CPU DAI
+
+    patternProperties:
+      "^codec-[0-9]+$":
+        type: object
+        description: |-
+          Codecs:
+          dai-link representing backend links should have at least one subnode.
+          One subnode for each codec of the dai-link. dai-link representing
+          frontend links have no codec, therefore have no subnodes
+
+        properties:
+          sound-dai:
+            $ref: /schemas/types.yaml#/definitions/phandle
+            description: phandle of the codec DAI
+
+        required:
+          - sound-dai
+
+    required:
+      - sound-dai
+
+required:
+  - model
+  - dai-link-0
+
+examples:
+  - |
+    sound {
+        compatible = "amlogic,gx-sound-card";
+        model = "GXL-ACME-S905X-FOO";
+        audio-aux-devs = <&amp>;
+        audio-routing = "I2S ENCODER I2S IN", "I2S FIFO Playback";
+
+        dai-link-0 {
+               sound-dai = <&i2s_fifo>;
+        };
+
+        dai-link-1 {
+                sound-dai = <&i2s_encoder>;
+                dai-format = "i2s";
+                mclk-fs = <256>;
+
+                codec-0 {
+                        sound-dai = <&codec0>;
+                };
+
+                codec-1 {
+                        sound-dai = <&codec1>;
+                };
+        };
+    };
+