linux_dsm_epyc7002/Documentation/devicetree/bindings/power/power-domain.yaml

# SPDX-License-Identifier: GPL-2.0
%YAML 1.2
---
$id: http://devicetree.org/schemas/power/power-domain.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#

title: Generic PM domains

maintainers:
  - Rafael J. Wysocki <rjw@rjwysocki.net>
  - Kevin Hilman <khilman@kernel.org>
  - Ulf Hansson <ulf.hansson@linaro.org>

description: |+
  System on chip designs are often divided into multiple PM domains that can be
  used for power gating of selected IP blocks for power saving by reduced leakage
  current.

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

properties:
  $nodename:
    pattern: "^(power-controller|power-domain)(@.*)?$"

  domain-idle-states:
    $ref: /schemas/types.yaml#/definitions/phandle-array
    description:
      A phandle of an idle-state that shall be soaked into a generic domain
      power state. The idle state definitions are compatible with
      domain-idle-state specified in
      Documentation/devicetree/bindings/power/domain-idle-state.txt
      phandles that are not compatible with domain-idle-state will be ignored.
      The domain-idle-state property reflects the idle state of this PM domain
      and not the idle states of the devices or sub-domains in the PM domain.
      Devices and sub-domains have their own idle-states independent
      of the parent domain's idle states. In the absence of this property,
      the domain would be considered as capable of being powered-on
      or powered-off.

  operating-points-v2:
    $ref: /schemas/types.yaml#/definitions/phandle-array
    description:
      Phandles to the OPP tables of power domains provided by a power domain
      provider. If the provider provides a single power domain only or all
      the power domains provided by the provider have identical OPP tables,
      then this shall contain a single phandle. Refer to ../opp/opp.txt
      for more information.

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

  power-domains:
    description:
       A phandle and PM domain specifier as defined by bindings of the power
       controller specified by phandle. Some power domains might be powered
       from another power domain (or have other hardware specific
       dependencies). For representing such dependency a standard PM domain
       consumer binding is used. When provided, all domains created
       by the given provider should be subdomains of the domain specified
       by this binding.

required:
  - "#power-domain-cells"

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

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

  - |
    parent2: power-controller@12340000 {
        compatible = "foo,power-controller";
        reg = <0x12340000 0x1000>;
        #power-domain-cells = <1>;
    };

    child2: power-controller@12341000 {
        compatible = "foo,power-controller";
        reg = <0x12341000 0x1000>;
        power-domains = <&parent2 0>;
        #power-domain-cells = <1>;
    };

    // The nodes above define two power controllers: 'parent' and 'child'.
    // Domains created by the 'child' power controller are subdomains of '0' power
    // domain provided by the 'parent' power controller.    

  - |
    parent3: power-controller@12340000 {
        compatible = "foo,power-controller";
        reg = <0x12340000 0x1000>;
        #power-domain-cells = <0>;
        domain-idle-states = <&DOMAIN_RET>, <&DOMAIN_PWR_DN>;
    };

    child3: power-controller@12341000 {
        compatible = "foo,power-controller";
        reg = <0x12341000 0x1000>;
        power-domains = <&parent3>;
        #power-domain-cells = <0>;
        domain-idle-states = <&DOMAIN_PWR_DN>;
    };

    DOMAIN_RET: state@0 {
        compatible = "domain-idle-state";
        reg = <0x0 0x0>;
        entry-latency-us = <1000>;
        exit-latency-us = <2000>;
        min-residency-us = <10000>;
    };

    DOMAIN_PWR_DN: state@1 {
        compatible = "domain-idle-state";
        reg = <0x1 0x0>;
        entry-latency-us = <5000>;
        exit-latency-us = <8000>;
        min-residency-us = <7000>;
    };