dt-bindings: usb: Add Apple dwc3 bindings

Apple Silicon SoCs such as the M1 have multiple USB controllers based on
the Synopsys DesignWare USB3 controller.
References to the ATC PHY required for SuperSpeed are left out for now
until support has been upstreamed as well.

Signed-off-by: Sven Peter <sven@svenpeter.dev>

Author: svenpeter42

Documentation/devicetree/bindings/usb/apple,dwc3.yaml

@@ -0,0 +1,64 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/usb/apple,dwc3.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Apple Silicon DWC3 USB controller
+
+maintainers:
+  - Sven Peter <sven@svenpeter.dev>
+
+description:
+  On Apple Silicon SoCs such as the M1 each Type-C port has a corresponding
+  USB controller based on the Synopsys DesignWare USB3 controller.
+
+  The common content of this binding is defined in snps,dwc3.yaml.
+
+allOf:
+  - $ref: snps,dwc3.yaml#
+
+select:
+  properties:
+    compatible:
+      contains:
+        const: apple,dwc3
+  required:
+    - compatible
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - apple,t8103-dwc3
+          - apple,t6000-dwc3
+      - const: apple,dwc3
+      - const: snps,dwc3
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+unevaluatedProperties: false
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/apple-aic.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    usb@82280000 {
+      compatible = "apple,t8103-dwc3", "apple,dwc3", "snps,dwc3";
+      reg = <0x82280000 0x10000>;
+      interrupts = <AIC_IRQ 777 IRQ_TYPE_LEVEL_HIGH>;
+
+      dr_mode = "otg";
+      usb-role-switch;
+      role-switch-default-mode = "host";
+    };