dt-bindings: usb: Add Microchip LAN969x support

Microchip LAN969x has DWC3 compatible controller, though limited to 2.0(HS)
speed, so document it.

Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://patch.msgid.link/20251229184004.571837-2-robert.marko@sartura.hr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/usb/microchip,lan9691-dwc3.yaml

@@ -0,0 +1,66 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/usb/microchip,lan9691-dwc3.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip LAN969x SuperSpeed DWC3 USB SoC controller
+
+maintainers:
+  - Robert Marko <robert.marko@sartura.hr>
+
+select:
+  properties:
+    compatible:
+      contains:
+        enum:
+          - microchip,lan9691-dwc3
+  required:
+    - compatible
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - microchip,lan9691-dwc3
+      - const: snps,dwc3
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: Gated USB DRD clock
+      - description: Controller reference clock
+
+  clock-names:
+    items:
+      - const: bus_early
+      - const: ref
+
+unevaluatedProperties: false
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - clock-names
+
+allOf:
+  - $ref: snps,dwc3.yaml#
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    usb@300000 {
+        compatible = "microchip,lan9691-dwc3", "snps,dwc3";
+        reg = <0x300000 0x80000>;
+        interrupts = <GIC_SPI 80 IRQ_TYPE_LEVEL_HIGH>;
+        clocks = <&clks 12>, <&clks 11>;
+        clock-names = "bus_early", "ref";
+    };