linux/linux-5.4.31/Documentation/devicetree/bindings/riscv/cpus.yaml

# SPDX-License-Identifier: (GPL-2.0 OR MIT)
%YAML 1.2
---
$id: http://devicetree.org/schemas/riscv/cpus.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: RISC-V bindings for 'cpus' DT nodes

maintainers:
  - Paul Walmsley <paul.walmsley@sifive.com>
  - Palmer Dabbelt <palmer@sifive.com>

description: |
  This document uses some terminology common to the RISC-V community
  that is not widely used, the definitions of which are listed here:

  hart: A hardware execution context, which contains all the state
  mandated by the RISC-V ISA: a PC and some registers.  This
  terminology is designed to disambiguate software's view of execution
  contexts from any particular microarchitectural implementation
  strategy.  For example, an Intel laptop containing one socket with
  two cores, each of which has two hyperthreads, could be described as
  having four harts.  

properties:
  compatible:
    oneOf:
      - items:
          - enum:
              - sifive,rocket0
              - sifive,e5
              - sifive,e51
              - sifive,u54-mc
              - sifive,u54
              - sifive,u5
          - const: riscv
      - const: riscv    # Simulator only
    description:
      Identifies that the hart uses the RISC-V instruction set
      and identifies the type of the hart.

  mmu-type:
    allOf:
      - $ref: "/schemas/types.yaml#/definitions/string"
      - enum:
          - riscv,sv32
          - riscv,sv39
          - riscv,sv48
    description:
      Identifies the MMU address translation mode used on this
      hart.  These values originate from the RISC-V Privileged
      Specification document, available from
      https://riscv.org/specifications/

  riscv,isa:
    allOf:
      - $ref: "/schemas/types.yaml#/definitions/string"
      - enum:
          - rv64imac
          - rv64imafdc
    description:
      Identifies the specific RISC-V instruction set architecture
      supported by the hart.  These are documented in the RISC-V
      User-Level ISA document, available from
      https://riscv.org/specifications/

      While the isa strings in ISA specification are case
      insensitive, letters in the riscv,isa string must be all
      lowercase to simplify parsing.

  # RISC-V requires 'timebase-frequency' in /cpus, so disallow it here
  timebase-frequency: false

  interrupt-controller:
    type: object
    description: Describes the CPU's local interrupt controller

    properties:
      '#interrupt-cells':
        const: 1

      compatible:
        const: riscv,cpu-intc

      interrupt-controller: true

    required:
      - '#interrupt-cells'
      - compatible
      - interrupt-controller

required:
  - riscv,isa
  - interrupt-controller

examples:
  - |
    // Example 1: SiFive Freedom U540G Development Kit
    cpus {
        #address-cells = <1>;
        #size-cells = <0>;
        timebase-frequency = <1000000>;
        cpu@0 {
                clock-frequency = <0>;
                compatible = "sifive,rocket0", "riscv";
                device_type = "cpu";
                i-cache-block-size = <64>;
                i-cache-sets = <128>;
                i-cache-size = <16384>;
                reg = <0>;
                riscv,isa = "rv64imac";
                cpu_intc0: interrupt-controller {
                        #interrupt-cells = <1>;
                        compatible = "riscv,cpu-intc";
                        interrupt-controller;
                };
        };
        cpu@1 {
                clock-frequency = <0>;
                compatible = "sifive,rocket0", "riscv";
                d-cache-block-size = <64>;
                d-cache-sets = <64>;
                d-cache-size = <32768>;
                d-tlb-sets = <1>;
                d-tlb-size = <32>;
                device_type = "cpu";
                i-cache-block-size = <64>;
                i-cache-sets = <64>;
                i-cache-size = <32768>;
                i-tlb-sets = <1>;
                i-tlb-size = <32>;
                mmu-type = "riscv,sv39";
                reg = <1>;
                riscv,isa = "rv64imafdc";
                tlb-split;
                cpu_intc1: interrupt-controller {
                        #interrupt-cells = <1>;
                        compatible = "riscv,cpu-intc";
                        interrupt-controller;
                };
        };
    };    

  - |
    // Example 2: Spike ISA Simulator with 1 Hart
    cpus {
        #address-cells = <1>;
        #size-cells = <0>;
        cpu@0 {
                device_type = "cpu";
                reg = <0>;
                compatible = "riscv";
                riscv,isa = "rv64imafdc";
                mmu-type = "riscv,sv48";
                interrupt-controller {
                        #interrupt-cells = <1>;
                        interrupt-controller;
                        compatible = "riscv,cpu-intc";
                };
        };
    };    
...