linux/Documentation/devicetree/bindings/timer/arm,arch_timer_mmio.yaml

# SPDX-License-Identifier: GPL-2.0
%YAML 1.2
---
$id: http://devicetree.org/schemas/timer/arm,arch_timer_mmio.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: ARM memory mapped architected timer

maintainers:
  - Marc Zyngier <marc.zyngier@arm.com>
  - Mark Rutland <mark.rutland@arm.com>

description: |+
  ARM cores may have a memory mapped architected timer, which provides up to 8
  frames with a physical and optional virtual timer per frame.

  The memory mapped timer is attached to a GIC to deliver its interrupts via SPIs.

properties:
  compatible:
    items:
      - enum:
          - arm,armv7-timer-mem

  reg:
    maxItems: 1
    description: The control frame base address

  '#address-cells':
    enum: [1, 2]

  '#size-cells':
    const: 1

  ranges: true

  clock-frequency:
    description: The frequency of the main counter, in Hz. Should be present
      only where necessary to work around broken firmware which does not configure
      CNTFRQ on all CPUs to a uniform correct value. Use of this property is
      strongly discouraged; fix your firmware unless absolutely impossible.

  always-on:
    type: boolean
    description: If present, the timer is powered through an always-on power
      domain, therefore it never loses context.

  arm,cpu-registers-not-fw-configured:
    type: boolean
    description: Firmware does not initialize any of the generic timer CPU
      registers, which contain their architecturally-defined reset values. Only
      supported for 32-bit systems which follow the ARMv7 architected reset
      values.

  arm,no-tick-in-suspend:
    type: boolean
    description: The main counter does not tick when the system is in
      low-power system suspend on some SoCs. This behavior does not match the
      Architecture Reference Manual's specification that the system counter "must
      be implemented in an always-on power domain."

patternProperties:
  '^frame@[0-9a-f]+$':
    type: object
    additionalProperties: false
    description: A timer node has up to 8 frame sub-nodes, each with the following properties.
    properties:
      frame-number:
        $ref: /schemas/types.yaml#/definitions/uint32
        minimum: 0
        maximum: 7

      interrupts:
        minItems: 1
        items:
          - description: physical timer irq
          - description: virtual timer irq

      reg:
        minItems: 1
        items:
          - description: 1st view base address
          - description: 2nd optional view base address

    required:
      - frame-number
      - interrupts
      - reg

required:
  - compatible
  - reg
  - '#address-cells'
  - '#size-cells'

additionalProperties: false

examples:
  - |
    timer@f0000000 {
      compatible = "arm,armv7-timer-mem";
      #address-cells = <1>;
      #size-cells = <1>;
      ranges = <0 0xf0001000 0x1000>;
      reg = <0xf0000000 0x1000>;
      clock-frequency = <50000000>;

      frame@0 {
        frame-number = <0>;
        interrupts = <0 13 0x8>,
               <0 14 0x8>;
        reg = <0x0000 0x1000>,
              <0x1000 0x1000>;
      };

      frame@2000 {
        frame-number = <1>;
        interrupts = <0 15 0x8>;
        reg = <0x2000 0x1000>;
      };
    };

...