Documentation/devicetree/bindings/timer/arm,arch_timer.yaml

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

title: ARM architected timer

maintainers:
  - Marc Zyngier <marc.zyngier@arm.com>
  - Mark Rutland <mark.rutland@arm.com>
description: |+
  ARM cores may have a per-core architected timer, which provides per-cpu timers,
  or a memory mapped architected timer, which provides up to 8 frames with a
  physical and optional virtual timer per frame.

  The per-core architected timer is attached to a GIC to deliver its
  per-processor interrupts via PPIs. The memory mapped timer is attached to a GIC
  to deliver its interrupts via SPIs.

properties:
  compatible:
    oneOf:
      - items:
          - enum:
              - arm,cortex-a15-timer
          - enum:
              - arm,armv7-timer
      - items:
          - enum:
            - arm,armv7-timer
      - items:
          - enum:
            - arm,armv8-timer

  interrupts:
    items:
      - description: secure timer irq
      - description: non-secure timer irq
      - description: virtual timer irq
      - description: hypervisor timer irq

  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.

  fsl,erratum-a008585:
    type: boolean
    description: Indicates the presence of QorIQ erratum A-008585, which says
      that reading the counter is unreliable unless the same value is returned
      by back-to-back reads. This also affects writes to the tval register, due
      to the implicit counter read.

  hisilicon,erratum-161010101:
    type: boolean
    description: Indicates the presence of Hisilicon erratum 161010101, which
      says that reading the counters is unreliable in some cases, and reads may
      return a value 32 beyond the correct value. This also affects writes to
      the tval registers, due to the implicit counter read.

  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."

required:
  - compatible

oneOf:
  - required:
      - interrupts
  - required:
      - interrupts-extended

examples:
  - |
    timer {
      compatible = "arm,cortex-a15-timer",
             "arm,armv7-timer";
      interrupts = <1 13 0xf08>,
             <1 14 0xf08>,
             <1 11 0xf08>,
             <1 10 0xf08>;
      clock-frequency = <100000000>;
    };

...