dt-bindings: phy: add Amlogic AXG MIPI D-PHY bindings

The Amlogic AXg SoCs embeds a MIPI D-PHY to communicate with DSI
panels, this adds the bindings.

This D-PHY depends on a separate analog PHY.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201116101315.71720-2-narmstrong@baylibre.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/amlogic,axg-mipi-dphy.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+# Copyright 2020 BayLibre, SAS
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/phy/amlogic,axg-mipi-dphy.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: Amlogic AXG MIPI D-PHY
+
+maintainers:
+  - Neil Armstrong <narmstrong@baylibre.com>
+
+properties:
+  compatible:
+    enum:
+      - amlogic,axg-mipi-dphy
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    items:
+      - const: pclk
+
+  resets:
+    maxItems: 1
+
+  reset-names:
+    items:
+      - const: phy
+
+  "#phy-cells":
+    const: 0
+
+  phys:
+    maxItems: 1
+
+  phy-names:
+    items:
+      - const: analog
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+  - resets
+  - reset-names
+  - phys
+  - phy-names
+  - "#phy-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    phy@ff640000 {
+            compatible = "amlogic,axg-mipi-dphy";
+            reg = <0xff640000 0x100>;
+            clocks = <&clk_mipi_dsi_phy>;
+            clock-names = "pclk";
+            resets = <&reset_phy>;
+            reset-names = "phy";
+            phys = <&mipi_pcie_analog_dphy>;
+            phy-names = "analog";
+            #phy-cells = <0>;
+    };