Documentation/devicetree/bindings/mailbox/fsl,mu.yaml

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

title: NXP i.MX Messaging Unit (MU)

maintainers:
  - Dong Aisheng <aisheng.dong@nxp.com>

description: |
  The Messaging Unit module enables two processors within the SoC to
  communicate and coordinate by passing messages (e.g. data, status
  and control) through the MU interface. The MU also provides the ability
  for one processor to signal the other processor using interrupts.

  Because the MU manages the messaging between processors, the MU uses
  different clocks (from each side of the different peripheral buses).
  Therefore, the MU must synchronize the accesses from one side to the
  other. The MU accomplishes synchronization using two sets of matching
  registers (Processor A-facing, Processor B-facing).

properties:
  compatible:
    oneOf:
      - const: fsl,imx6sx-mu
      - const: fsl,imx7ulp-mu
      - const: fsl,imx8ulp-mu
      - const: fsl,imx8-mu-scu
      - const: fsl,imx8-mu-seco
      - const: fsl,imx93-mu-s4
      - const: fsl,imx8ulp-mu-s4
      - items:
          - const: fsl,imx93-mu
          - const: fsl,imx8ulp-mu
      - items:
          - enum:
              - fsl,imx7s-mu
              - fsl,imx8mq-mu
              - fsl,imx8mm-mu
              - fsl,imx8mn-mu
              - fsl,imx8mp-mu
              - fsl,imx8qm-mu
              - fsl,imx8qxp-mu
          - const: fsl,imx6sx-mu
      - description: To communicate with i.MX8 SCU with fast IPC
        items:
          - const: fsl,imx8-mu-scu
          - enum:
              - fsl,imx8qm-mu
              - fsl,imx8qxp-mu
          - const: fsl,imx6sx-mu

  reg:
    maxItems: 1

  interrupts:
    minItems: 1
    maxItems: 2

  interrupt-names:
    minItems: 1
    items:
      - const: tx
      - const: rx

  "#mbox-cells":
    description: |
      <&phandle type channel>
      phandle   : Label name of controller
      type      : Channel type
      channel   : Channel number

      This MU support 5 type of unidirectional channels, each type
      has 4 channels except RST channel which only has 1 channel.
      A total of 17 channels.  Following types are
      supported:
      0 - TX channel with 32bit transmit register and IRQ transmit
          acknowledgment support.
      1 - RX channel with 32bit receive register and IRQ support
      2 - TX doorbell channel. Without own register and no ACK support.
      3 - RX doorbell channel.
      4 - RST channel
    const: 2

  clocks:
    maxItems: 1

  fsl,mu-side-b:
    description: boolean, if present, means it is for side B MU.
    type: boolean

  power-domains:
    maxItems: 1

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

allOf:
  - if:
      properties:
        compatible:
          enum:
            - fsl,imx93-mu-s4
    then:
      properties:
        interrupt-names:
          minItems: 2
        interrupts:
          minItems: 2

    else:
      properties:
        interrupts:
          maxItems: 1
      not:
        required:
          - interrupt-names

additionalProperties: false

examples:
  - |
    #include <dt-bindings/interrupt-controller/arm-gic.h>

    mailbox@5d1b0000 {
        compatible = "fsl,imx8qxp-mu", "fsl,imx6sx-mu";
        reg = <0x5d1b0000 0x10000>;
        interrupts = <GIC_SPI 176 IRQ_TYPE_LEVEL_HIGH>;
        #mbox-cells = <2>;
    };