dt-bindings: usb: dwc3: add support for SpacemiT K1

Add support for the USB 3.0 Dual-Role Device (DRD) controller embedded
in the SpacemiT K1 SoC. The controller is based on the Synopsys
DesignWare Core USB 3 (DWC3) IP, supporting USB3.0 host mode and USB 2.0
DRD mode.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Ze Huang <huang.ze@linux.dev>
Link: https://lore.kernel.org/r/20250913-dwc3_generic-v8-1-b50f81f05f95@linux.dev
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250913-dwc3_generic-v8-1-b50f81f05f95@linux.dev

Documentation/devicetree/bindings/usb/spacemit,k1-dwc3.yaml

@@ -0,0 +1,121 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/usb/spacemit,k1-dwc3.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: SpacemiT K1 SuperSpeed DWC3 USB SoC Controller
+
+maintainers:
+  - Ze Huang <huang.ze@linux.dev>
+
+description: |
+  The SpacemiT K1 embeds a DWC3 USB IP Core which supports Host functions
+  for USB 3.0 and DRD for USB 2.0.
+
+  Key features:
+  - USB3.0 SuperSpeed and USB2.0 High/Full/Low-Speed support
+  - Supports low-power modes (USB2.0 suspend, USB3.0 U1/U2/U3)
+  - Internal DMA controller and flexible endpoint FIFO sizing
+
+  Communication Interface:
+  - Use of PIPE3 (125MHz) interface for USB3.0 PHY
+  - Use of UTMI+ (30/60MHz) interface for USB2.0 PHY
+
+allOf:
+  - $ref: snps,dwc3-common.yaml#
+
+properties:
+  compatible:
+    const: spacemit,k1-dwc3
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    const: usbdrd30
+
+  interrupts:
+    maxItems: 1
+
+  phys:
+    items:
+      - description: phandle to USB2/HS PHY
+      - description: phandle to USB3/SS PHY
+
+  phy-names:
+    items:
+      - const: usb2-phy
+      - const: usb3-phy
+
+  resets:
+    items:
+      - description: USB3.0 AHB reset
+      - description: USB3.0 VCC reset
+      - description: USB3.0 PHY reset
+
+  reset-names:
+    items:
+      - const: ahb
+      - const: vcc
+      - const: phy
+
+  reset-delay:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    default: 2
+    description: delay after reset sequence [us]
+
+  vbus-supply:
+    description: A phandle to the regulator supplying the VBUS voltage.
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+  - interrupts
+  - phys
+  - phy-names
+  - resets
+  - reset-names
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    usb@c0a00000 {
+        compatible = "spacemit,k1-dwc3";
+        reg = <0xc0a00000 0x10000>;
+        clocks = <&syscon_apmu 16>;
+        clock-names = "usbdrd30";
+        interrupts = <125>;
+        phys = <&usb2phy>, <&usb3phy>;
+        phy-names = "usb2-phy", "usb3-phy";
+        resets = <&syscon_apmu 8>,
+                 <&syscon_apmu 9>,
+                 <&syscon_apmu 10>;
+        reset-names = "ahb", "vcc", "phy";
+        reset-delay = <2>;
+        vbus-supply = <&usb3_vbus>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        hub_2_0: hub@1 {
+            compatible = "usb2109,2817";
+            reg = <1>;
+            vdd-supply = <&usb3_vhub>;
+            peer-hub = <&hub_3_0>;
+            reset-gpios = <&gpio 3 28 1>;
+        };
+
+        hub_3_0: hub@2 {
+            compatible = "usb2109,817";
+            reg = <2>;
+            vdd-supply = <&usb3_vhub>;
+            peer-hub = <&hub_2_0>;
+            reset-gpios = <&gpio 3 28 1>;
+        };
+    };