JustOS/linux-6.13/Documentation/devicetree/bindings/interrupt-controller/riscv,imsics.yaml

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

title: RISC-V Incoming MSI Controller (IMSIC)

maintainers:
  - Anup Patel <anup@brainfault.org>

description: |
  The RISC-V advanced interrupt architecture (AIA) defines a per-CPU incoming
  MSI controller (IMSIC) for handling MSIs in a RISC-V platform. The RISC-V
  AIA specification can be found at https://github.com/riscv/riscv-aia.

  The IMSIC is a per-CPU (or per-HART) device with separate interrupt file
  for each privilege level (machine or supervisor). The configuration of
  a IMSIC interrupt file is done using AIA CSRs and it also has a 4KB MMIO
  space to receive MSIs from devices. Each IMSIC interrupt file supports a
  fixed number of interrupt identities (to distinguish MSIs from devices)
  which is same for given privilege level across CPUs (or HARTs).

  The device tree of a RISC-V platform will have one IMSIC device tree node
  for each privilege level (machine or supervisor) which collectively describe
  IMSIC interrupt files at that privilege level across CPUs (or HARTs).

  The arrangement of IMSIC interrupt files in MMIO space of a RISC-V platform
  follows a particular scheme defined by the RISC-V AIA specification. A IMSIC
  group is a set of IMSIC interrupt files co-located in MMIO space and we can
  have multiple IMSIC groups (i.e. clusters, sockets, chiplets, etc) in a
  RISC-V platform. The MSI target address of a IMSIC interrupt file at given
  privilege level (machine or supervisor) encodes group index, HART index,
  and guest index (shown below).

  XLEN-1            > (HART Index MSB)                  12    0
  |                  |                                  |     |
  -------------------------------------------------------------
  |xxxxxx|Group Index|xxxxxxxxxxx|HART Index|Guest Index|  0  |
  -------------------------------------------------------------  

allOf:
  - $ref: /schemas/interrupt-controller.yaml#
  - $ref: /schemas/interrupt-controller/msi-controller.yaml#

properties:
  compatible:
    items:
      - enum:
          - qemu,imsics
      - const: riscv,imsics

  reg:
    minItems: 1
    maxItems: 16384
    description:
      Base address of each IMSIC group.

  interrupt-controller: true

  "#interrupt-cells":
    const: 0

  msi-controller: true

  "#msi-cells":
    const: 0

  interrupts-extended:
    minItems: 1
    maxItems: 16384
    description:
      This property represents the set of CPUs (or HARTs) for which given
      device tree node describes the IMSIC interrupt files. Each node pointed
      to should be a riscv,cpu-intc node, which has a CPU node (i.e. RISC-V
      HART) as parent.

  riscv,num-ids:
    $ref: /schemas/types.yaml#/definitions/uint32
    minimum: 63
    maximum: 2047
    description:
      Number of interrupt identities supported by IMSIC interrupt file.

  riscv,num-guest-ids:
    $ref: /schemas/types.yaml#/definitions/uint32
    minimum: 63
    maximum: 2047
    description:
      Number of interrupt identities are supported by IMSIC guest interrupt
      file. When not specified it is assumed to be same as specified by the
      riscv,num-ids property.

  riscv,guest-index-bits:
    minimum: 0
    maximum: 7
    default: 0
    description:
      Number of guest index bits in the MSI target address.

  riscv,hart-index-bits:
    minimum: 0
    maximum: 15
    description:
      Number of HART index bits in the MSI target address. When not
      specified it is calculated based on the interrupts-extended property.

  riscv,group-index-bits:
    minimum: 0
    maximum: 7
    default: 0
    description:
      Number of group index bits in the MSI target address.

  riscv,group-index-shift:
    $ref: /schemas/types.yaml#/definitions/uint32
    minimum: 0
    maximum: 55
    default: 24
    description:
      The least significant bit position of the group index bits in the
      MSI target address.

required:
  - compatible
  - reg
  - interrupt-controller
  - msi-controller
  - "#msi-cells"
  - interrupts-extended
  - riscv,num-ids

unevaluatedProperties: false

examples:
  - |
    // Example 1 (Machine-level IMSIC files with just one group):

    interrupt-controller@24000000 {
      compatible = "qemu,imsics", "riscv,imsics";
      interrupts-extended = <&cpu1_intc 11>,
                            <&cpu2_intc 11>,
                            <&cpu3_intc 11>,
                            <&cpu4_intc 11>;
      reg = <0x28000000 0x4000>;
      interrupt-controller;
      #interrupt-cells = <0>;
      msi-controller;
      #msi-cells = <0>;
      riscv,num-ids = <127>;
    };    

  - |
    // Example 2 (Supervisor-level IMSIC files with two groups):

    interrupt-controller@28000000 {
      compatible = "qemu,imsics", "riscv,imsics";
      interrupts-extended = <&cpu1_intc 9>,
                            <&cpu2_intc 9>,
                            <&cpu3_intc 9>,
                            <&cpu4_intc 9>;
      reg = <0x28000000 0x2000>, /* Group0 IMSICs */
            <0x29000000 0x2000>; /* Group1 IMSICs */
      interrupt-controller;
      #interrupt-cells = <0>;
      msi-controller;
      #msi-cells = <0>;
      riscv,num-ids = <127>;
      riscv,group-index-bits = <1>;
      riscv,group-index-shift = <24>;
    };    
...