Documentation/devicetree/bindings/dvfs/performance-domain.yaml

# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/dvfs/performance-domain.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: Generic performance domains

maintainers:
  - Sudeep Holla <sudeep.holla@arm.com>

description: |+
  This binding is intended for performance management of groups of devices or
  CPUs that run in the same performance domain. Performance domains must not
  be confused with power domains. A performance domain is defined by a set
  of devices that always have to run at the same performance level. For a given
  performance domain, there is a single point of control that affects all the
  devices in the domain, making it impossible to set the performance level of
  an individual device in the domain independently from other devices in
  that domain. For example, a set of CPUs that share a voltage domain, and
  have a common frequency control, is said to be in the same performance
  domain.

  This device tree binding can be used to bind performance domain consumer
  devices with their performance domains provided by performance domain
  providers. A performance domain provider can be represented by any node in
  the device tree and can provide one or more performance domains. A consumer
  node can refer to the provider by a phandle and a set of phandle arguments
  (so called performance domain specifiers) of length specified by the
  \#performance-domain-cells property in the performance domain provider node.

select: true

properties:
  "#performance-domain-cells":
    description:
      Number of cells in a performance domain specifier. Typically 0 for nodes
      representing a single performance domain and 1 for nodes providing
      multiple performance domains (e.g. performance controllers), but can be
      any value as specified by device tree binding documentation of particular
      provider.
    enum: [ 0, 1 ]

  performance-domains:
    $ref: '/schemas/types.yaml#/definitions/phandle-array'
    maxItems: 1
    description:
      A phandle and performance domain specifier as defined by bindings of the
      performance controller/provider specified by phandle.

additionalProperties: true

examples:
  - |
    performance: performance-controller@12340000 {
        compatible = "qcom,cpufreq-hw";
        reg = <0x12340000 0x1000>;
        #performance-domain-cells = <1>;
    };

    // The node above defines a performance controller that is a performance
    // domain provider and expects one cell as its phandle argument.

    cpus {
        #address-cells = <2>;
        #size-cells = <0>;

        cpu@0 {
            device_type = "cpu";
            compatible = "arm,cortex-a57";
            reg = <0x0 0x0>;
            performance-domains = <&performance 1>;
        };
    };