dt-bindings: phy: Add bindings doc for Sunplus USB2 PHY driver

Add bindings doc for Sunplus USB2 PHY driver
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Vincent Shih <vincent.sunplus@gmail.com>
Link: https://lore.kernel.org/r/1658717052-26142-3-git-send-email-vincent.sunplus@gmail.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/sunplus,sp7021-usb2-phy.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+# Copyright (C) Sunplus Co., Ltd. 2021
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/phy/sunplus,sp7021-usb2-phy.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: Sunplus SP7021 USB 2.0 PHY Controller
+
+maintainers:
+  - Vincent Shih <vincent.sunplus@gmail.com>
+
+properties:
+  compatible:
+    const: sunplus,sp7021-usb2-phy
+
+  reg:
+    items:
+      - description: UPHY register region
+      - description: MOON4 register region
+
+  reg-names:
+    items:
+      - const: phy
+      - const: moon4
+
+  clocks:
+    maxItems: 1
+
+  resets:
+    maxItems: 1
+
+  "#phy-cells":
+    const: 0
+
+  nvmem-cell-names:
+    description: names corresponding to the nvmem cells of disconnect voltage
+    const: disc_vol
+
+  nvmem-cells:
+    description: nvmem cell address of disconnect voltage
+    maxItems: 1
+
+  sunplus,disc-vol-addr-off:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: the otp address offset of disconnect voltage
+
+required:
+  - compatible
+  - reg
+  - reg-names
+  - clocks
+  - resets
+  - "#phy-cells"
+  - nvmem-cell-names
+  - nvmem-cells
+  - sunplus,disc-vol-addr-off
+
+additionalProperties: false
+
+examples:
+  - |
+    sp_uphy0: usb-phy@9c004a80 {
+      compatible = "sunplus,sp7021-usb2-phy";
+      reg = <0x9c004a80 0x80>, <0x9c000248 0x10>;
+      reg-names = "phy", "moon4";
+      clocks = <&clkc 0x3d>;
+      resets = <&rstc 0x2d>;
+      #phy-cells = <0>;
+      nvmem-cell-names = "disc_vol";
+      nvmem-cells = <&disc_vol>;
+      sunplus,disc-vol-addr-off = <0>;
+    };

MAINTAINERS

@@ -19494,6 +19494,7 @@ SUNPLUS USB2 PHY DRIVER
 M:	Vincent Shih <vincent.sunplus@gmail.com>
 L:	linux-usb@vger.kernel.org
 S:	Maintained
+F:	Documentation/devicetree/bindings/phy/sunplus,sp7021-usb2-phy.yaml
 F:	drivers/phy/sunplus/Kconfig
 F:	drivers/phy/sunplus/Makefile
 F:	drivers/phy/sunplus/phy-sunplus-usb2.c