xref: /kernel/linux/linux-5.10/Documentation/devicetree/bindings/interrupt-controller/sifive,plic-1.0.0.yaml

# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
# Copyright (C) 2020 SiFive, Inc.
%YAML 1.2
---
$id: http://devicetree.org/schemas/interrupt-controller/sifive,plic-1.0.0.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: SiFive Platform-Level Interrupt Controller (PLIC)

description:
  SiFive SOCs include an implementation of the Platform-Level Interrupt Controller
  (PLIC) high-level specification in the RISC-V Privileged Architecture
  specification. The PLIC connects all external interrupts in the system to all
  hart contexts in the system, via the external interrupt source in each hart.

  A hart context is a privilege mode in a hardware execution thread. For example,
  in an 4 core system with 2-way SMT, you have 8 harts and probably at least two
  privilege modes per hart; machine mode and supervisor mode.

  Each interrupt can be enabled on per-context basis. Any context can claim
  a pending enabled interrupt and then release it once it has been handled.

  Each interrupt has a configurable priority. Higher priority interrupts are
  serviced first.  Each context can specify a priority threshold. Interrupts
  with priority below this threshold will not cause the PLIC to raise its
  interrupt line leading to the context.

  While the PLIC supports both edge-triggered and level-triggered interrupts,
  interrupt handlers are oblivious to this distinction and therefore it is not
  specified in the PLIC device-tree binding.

  While the RISC-V ISA doesn't specify a memory layout for the PLIC, the
  "sifive,plic-1.0.0" device is a concrete implementation of the PLIC that
  contains a specific memory layout, which is documented in chapter 8 of the
  SiFive U5 Coreplex Series Manual <https://static.dev.sifive.com/U54-MC-RVCoreIP.pdf>.

maintainers:
  - Sagar Kadam <sagar.kadam@sifive.com>
  - Paul Walmsley  <paul.walmsley@sifive.com>
  - Palmer Dabbelt <palmer@dabbelt.com>

properties:
  compatible:
    items:
      - const: sifive,fu540-c000-plic
      - const: sifive,plic-1.0.0

  reg:
    maxItems: 1

  '#address-cells':
    const: 0

  '#interrupt-cells':
    const: 1

  interrupt-controller: true

  interrupts-extended:
    minItems: 1
    description:
      Specifies which contexts are connected to the PLIC, with "-1" specifying
      that a context is not present. Each node pointed to should be a
      riscv,cpu-intc node, which has a riscv node as parent.

  riscv,ndev:
    $ref: "/schemas/types.yaml#/definitions/uint32"
    description:
      Specifies how many external interrupts are supported by this controller.

required:
  - compatible
  - '#address-cells'
  - '#interrupt-cells'
  - interrupt-controller
  - reg
  - interrupts-extended
  - riscv,ndev

additionalProperties: false

examples:
  - |
    plic: interrupt-controller@c000000 {
      #address-cells = <0>;
      #interrupt-cells = <1>;
      compatible = "sifive,fu540-c000-plic", "sifive,plic-1.0.0";
      interrupt-controller;
      interrupts-extended = <
        &cpu0_intc 11
        &cpu1_intc 11 &cpu1_intc 9
        &cpu2_intc 11 &cpu2_intc 9
        &cpu3_intc 11 &cpu3_intc 9
        &cpu4_intc 11 &cpu4_intc 9>;
      reg = <0xc000000 0x4000000>;
      riscv,ndev = <10>;
    };