dt-bindings: phy: Add the Amlogic Meson8 HDMI TX PHY bindings

Amlogic Meson8, Meson8b and Meson8m2 all include an identical (or at
least very similar) HDMI TX PHY. The PHY registers are part of the HHI
register area.
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20211020195107.1564533-2-martin.blumenstingl@googlemail.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/amlogic,meson8-hdmi-tx-phy.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/phy/amlogic,meson8-hdmi-tx-phy.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: Amlogic Meson8, Meson8b and Meson8m2 HDMI TX PHY
+
+maintainers:
+  - Martin Blumenstingl <martin.blumenstingl@googlemail.com>
+
+description: |+
+  The HDMI TX PHY node should be the child of a syscon node with the
+  required property:
+
+  compatible = "amlogic,meson-hhi-sysctrl", "simple-mfd", "syscon"
+
+  Refer to the bindings described in
+  Documentation/devicetree/bindings/mfd/syscon.yaml
+
+properties:
+  $nodename:
+    pattern: "^hdmi-phy@[0-9a-f]+$"
+
+  compatible:
+    oneOf:
+      - items:
+          - enum:
+              - amlogic,meson8b-hdmi-tx-phy
+              - amlogic,meson8m2-hdmi-tx-phy
+          - const: amlogic,meson8-hdmi-tx-phy
+      - const: amlogic,meson8-hdmi-tx-phy
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    minItems: 1
+    description:
+      HDMI TMDS clock
+
+  "#phy-cells":
+    const: 0
+
+required:
+  - compatible
+  - "#phy-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    hdmi-phy@3a0 {
+      compatible = "amlogic,meson8-hdmi-tx-phy";
+      reg = <0x3a0 0xc>;
+      clocks = <&tmds_clock>;
+      #phy-cells = <0>;
+    };
+  - |
+    hdmi-phy@3a0 {
+      compatible = "amlogic,meson8b-hdmi-tx-phy", "amlogic,meson8-hdmi-tx-phy";
+      reg = <0x3a0 0xc>;
+      clocks = <&tmds_clock>;
+      #phy-cells = <0>;
+    };