Documentation/devicetree/bindings/mailbox/apple,mailbox.yaml

# SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
%YAML 1.2
---
$id: http://devicetree.org/schemas/mailbox/apple,mailbox.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: Apple Mailbox Controller

maintainers:
  - Hector Martin <marcan@marcan.st>
  - Sven Peter <sven@svenpeter.dev>

description:
  The Apple mailbox consists of two FIFOs used to exchange 64+32 bit
  messages between the main CPU and a co-processor. Multiple instances
  of this mailbox can be found on Apple SoCs.
  One of the two FIFOs is used to send data to a co-processor while the other
  FIFO is used for the other direction.
  Various clients implement different IPC protocols based on these simple
  messages and shared memory buffers.

properties:
  compatible:
    oneOf:
      - description:
          ASC mailboxes are the most common variant found on the M1 used
          for example for the display controller, the system management
          controller and the NVMe coprocessor.
        items:
          - const: apple,t8103-asc-mailbox

      - description:
          M3 mailboxes are an older variant with a slightly different MMIO
          interface still found on the M1. It is used for the Thunderbolt
          co-processors.
        items:
          - const: apple,t8103-m3-mailbox

  reg:
    maxItems: 1

  interrupts:
    items:
      - description: send fifo is empty interrupt
      - description: send fifo is not empty interrupt
      - description: receive fifo is empty interrupt
      - description: receive fifo is not empty interrupt

  interrupt-names:
    items:
      - const: send-empty
      - const: send-not-empty
      - const: recv-empty
      - const: recv-not-empty

  "#mbox-cells":
    const: 0

required:
  - compatible
  - reg
  - interrupts
  - interrupt-names
  - "#mbox-cells"

additionalProperties: false

examples:
  - |
        mailbox@77408000 {
                compatible = "apple,t8103-asc-mailbox";
                reg = <0x77408000 0x4000>;
                interrupts = <1 583 4>, <1 584 4>, <1 585 4>, <1 586 4>;
                interrupt-names = "send-empty", "send-not-empty",
                 "recv-empty", "recv-not-empty";
                #mbox-cells = <0>;
        };