dt-bindings: usb: add documentation for aspeed usb-vhub

# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)

# Copyright (c) 2020 Facebook Inc.

%YAML 1.2

---

$id: http://devicetree.org/schemas/usb/aspeed,usb-vhub.yaml#

$schema: http://devicetree.org/meta-schemas/core.yaml#

title: ASPEED USB 2.0 Virtual Hub Controller

maintainers:

  - Benjamin Herrenschmidt <benh@kernel.crashing.org>

description: |+

  The ASPEED USB 2.0 Virtual Hub Controller implements 1 set of USB Hub

  register and several sets of Device and Endpoint registers to support

  the Virtual Hub's downstream USB devices.

  Supported number of devices and endpoints vary depending on hardware

  revisions. AST2400 and AST2500 Virtual Hub supports 5 downstream devices

  and 15 generic endpoints, while AST2600 Virtual Hub supports 7 downstream

  devices and 21 generic endpoints.

properties:

  compatible:

    enum:

      - aspeed,ast2400-usb-vhub

      - aspeed,ast2500-usb-vhub

      - aspeed,ast2600-usb-vhub

  reg:

    maxItems: 1

  clocks:

    maxItems: 1

  interrupts:

    maxItems: 1

  aspeed,vhub-downstream-ports:

    description: Number of downstream ports supported by the Virtual Hub

    allOf:

      - $ref: /schemas/types.yaml#/definitions/uint32

      - default: 5

        minimum: 1

        maximum: 7

  aspeed,vhub-generic-endpoints:

    description: Number of generic endpoints supported by the Virtual Hub

    allOf:

      - $ref: /schemas/types.yaml#/definitions/uint32

      - default: 15

        minimum: 1

        maximum: 21

required:

  - compatible

  - reg

  - clocks

  - interrupts

  - aspeed,vhub-downstream-ports

  - aspeed,vhub-generic-endpoints

additionalProperties: false

examples:

  - |

    #include <dt-bindings/clock/aspeed-clock.h>

    vhub: usb-vhub@1e6a0000 {

            compatible = "aspeed,ast2500-usb-vhub";

            reg = <0x1e6a0000 0x300>;

            interrupts = <5>;

            clocks = <&syscon ASPEED_CLK_GATE_USBPORT1CLK>;

            aspeed,vhub-downstream-ports = <5>;

            aspeed,vhub-generic-endpoints = <15>;

            pinctrl-names = "default";

            pinctrl-0 = <&pinctrl_usb2ad_default>;

    };