Documentation/devicetree/bindings/firmware/arm,scmi.yaml

# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
# Copyright 2021 ARM Ltd.
%YAML 1.2
---
$id: http://devicetree.org/schemas/firmware/arm,scmi.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: System Control and Management Interface (SCMI) Message Protocol bindings

maintainers:
  - Sudeep Holla <sudeep.holla@arm.com>

description: |
  The SCMI is intended to allow agents such as OSPM to manage various functions
  that are provided by the hardware platform it is running on, including power
  and performance functions.

  This binding is intended to define the interface the firmware implementing
  the SCMI as described in ARM document number ARM DEN 0056 ("ARM System Control
  and Management Interface Platform Design Document")[0] provide for OSPM in
  the device tree.

  [0] https://developer.arm.com/documentation/den0056/latest

properties:
  $nodename:
    const: scmi

  compatible:
    oneOf:
      - description: SCMI compliant firmware with mailbox transport
        items:
          - const: arm,scmi
      - description: SCMI compliant firmware with ARM SMC/HVC transport
        items:
          - const: arm,scmi-smc
      - description: SCMI compliant firmware with SCMI Virtio transport.
                     The virtio transport only supports a single device.
        items:
          - const: arm,scmi-virtio

  interrupts:
    description:
      The interrupt that indicates message completion by the platform
      rather than by the return of the smc call. This should not be used
      except when the platform requires such behavior.
    maxItems: 1

  interrupt-names:
    const: a2p

  mbox-names:
    description:
      Specifies the mailboxes used to communicate with SCMI compliant
      firmware.
    items:
      - const: tx
      - const: rx

  mboxes:
    description:
      List of phandle and mailbox channel specifiers. It should contain
      exactly one or two mailboxes, one for transmitting messages("tx")
      and another optional for receiving the notifications("rx") if supported.
    minItems: 1
    maxItems: 2

  shmem:
    description:
      List of phandle pointing to the shared memory(SHM) area, for each
      transport channel specified.
    minItems: 1
    maxItems: 2

  '#address-cells':
    const: 1

  '#size-cells':
    const: 0

  arm,smc-id:
    $ref: /schemas/types.yaml#/definitions/uint32
    description:
      SMC id required when using smc or hvc transports

  protocol@11:
    type: object
    properties:
      reg:
        const: 0x11

      '#power-domain-cells':
        const: 1

    required:
      - '#power-domain-cells'

  protocol@13:
    type: object
    properties:
      reg:
        const: 0x13

      '#clock-cells':
        const: 1

    required:
      - '#clock-cells'

  protocol@14:
    type: object
    properties:
      reg:
        const: 0x14

      '#clock-cells':
        const: 1

    required:
      - '#clock-cells'

  protocol@15:
    type: object
    properties:
      reg:
        const: 0x15

      '#thermal-sensor-cells':
        const: 1

    required:
      - '#thermal-sensor-cells'

  protocol@16:
    type: object
    properties:
      reg:
        const: 0x16

      '#reset-cells':
        const: 1

    required:
      - '#reset-cells'

  protocol@17:
    type: object
    properties:
      reg:
        const: 0x17

      regulators:
        type: object
        description:
          The list of all regulators provided by this SCMI controller.

        patternProperties:
          '^regulators@[0-9a-f]+$':
            type: object
            $ref: "../regulator/regulator.yaml#"

            properties:
              reg:
                maxItems: 1
                description: Identifier for the voltage regulator.

            required:
              - reg

additionalProperties: false

patternProperties:
  '^protocol@[0-9a-f]+$':
    type: object
    description:
      Each sub-node represents a protocol supported. If the platform
      supports a dedicated communication channel for a particular protocol,
      then the corresponding transport properties must be present.
      The virtio transport does not support a dedicated communication channel.

    properties:
      reg:
        maxItems: 1

      mbox-names:
        items:
          - const: tx
          - const: rx

      mboxes:
        minItems: 1
        maxItems: 2

      shmem:
        minItems: 1
        maxItems: 2

    required:
      - reg

required:
  - compatible

if:
  properties:
    compatible:
      contains:
        const: arm,scmi
then:
  properties:
    interrupts: false
    interrupt-names: false

  required:
    - mboxes
    - shmem

else:
  if:
    properties:
      compatible:
        contains:
          const: arm,scmi-smc
  then:
    required:
      - arm,smc-id
      - shmem

examples:
  - |
    firmware {
        scmi {
            compatible = "arm,scmi";
            mboxes = <&mhuB 0 0>,
                     <&mhuB 0 1>;
            mbox-names = "tx", "rx";
            shmem = <&cpu_scp_lpri0>,
                    <&cpu_scp_lpri1>;

            #address-cells = <1>;
            #size-cells = <0>;

            scmi_devpd: protocol@11 {
                reg = <0x11>;
                #power-domain-cells = <1>;
            };

            scmi_dvfs: protocol@13 {
                reg = <0x13>;
                #clock-cells = <1>;

                mboxes = <&mhuB 1 0>,
                         <&mhuB 1 1>;
                mbox-names = "tx", "rx";
                shmem = <&cpu_scp_hpri0>,
                        <&cpu_scp_hpri1>;
            };

            scmi_clk: protocol@14 {
                reg = <0x14>;
                #clock-cells = <1>;
            };

            scmi_sensors: protocol@15 {
                reg = <0x15>;
                #thermal-sensor-cells = <1>;
            };

            scmi_reset: protocol@16 {
                reg = <0x16>;
                #reset-cells = <1>;
            };

            scmi_voltage: protocol@17 {
                reg = <0x17>;
                regulators {
                    #address-cells = <1>;
                    #size-cells = <0>;

                    regulator_devX: regulator@0 {
                        reg = <0x0>;
                        regulator-max-microvolt = <3300000>;
                    };

                    regulator_devY: regulator@9 {
                        reg = <0x9>;
                        regulator-min-microvolt = <500000>;
                        regulator-max-microvolt = <4200000>;
                    };
                };
            };
        };
    };

    soc {
        #address-cells = <2>;
        #size-cells = <2>;

        sram@50000000 {
            compatible = "mmio-sram";
            reg = <0x0 0x50000000 0x0 0x10000>;

            #address-cells = <1>;
            #size-cells = <1>;
            ranges = <0 0x0 0x50000000 0x10000>;

            cpu_scp_lpri0: scp-sram-section@0 {
                compatible = "arm,scmi-shmem";
                reg = <0x0 0x80>;
            };

            cpu_scp_lpri1: scp-sram-section@80 {
                compatible = "arm,scmi-shmem";
                reg = <0x80 0x80>;
            };

            cpu_scp_hpri0: scp-sram-section@100 {
                compatible = "arm,scmi-shmem";
                reg = <0x100 0x80>;
            };

            cpu_scp_hpri2: scp-sram-section@180 {
                compatible = "arm,scmi-shmem";
                reg = <0x180 0x80>;
            };
        };
    };

  - |
    firmware {
        scmi {
            compatible = "arm,scmi-smc";
            shmem = <&cpu_scp_lpri0 &cpu_scp_lpri1>;
            arm,smc-id = <0xc3000001>;

            #address-cells = <1>;
            #size-cells = <0>;

            scmi_devpd1: protocol@11 {
                reg = <0x11>;
                #power-domain-cells = <1>;
            };

        };
    };

...