dt-bindings: phy: spacemit: add K1 USB2 PHY

Add support for USB2 PHY found on SpacemiT K1 SoC.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Ze Huang <huang.ze@linux.dev>
Tested-by: Aurelien Jarno <aurelien@aurel32.net>
Tested-by: Junzhong Pan <panjunzhong@linux.spacemit.com>
Link: https://patch.msgid.link/20251017-k1-usb2phy-v6-1-7cf9ea2477a1@linux.dev
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/phy/spacemit,usb2-phy.yaml

@@ -0,0 +1,40 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/phy/spacemit,usb2-phy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: SpacemiT K1 SoC USB 2.0 PHY
+
+maintainers:
+  - Ze Huang <huang.ze@linux.dev>
+
+properties:
+  compatible:
+    const: spacemit,k1-usb2-phy
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  "#phy-cells":
+    const: 0
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - "#phy-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    usb-phy@c09c0000 {
+        compatible = "spacemit,k1-usb2-phy";
+        reg = <0xc09c0000 0x200>;
+        clocks = <&syscon_apmu 15>;
+        #phy-cells = <0>;
+    };