psci.yaml

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    1 # SPDX-License-Identifier: GPL-2.0
    2 %YAML 1.2
    3 ---
    4 $id: http://devicetree.org/schemas/arm/psci.yaml#
    5 $schema: http://devicetree.org/meta-schemas/core.yaml#
    6 
    7 title: Power State Coordination Interface (PSCI)
    8 
    9 maintainers:
   10   - Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
   11 
   12 description: |+
   13   Firmware implementing the PSCI functions described in ARM document number
   14   ARM DEN 0022A ("Power State Coordination Interface System Software on ARM
   15   processors") can be used by Linux to initiate various CPU-centric power
   16   operations.
   17 
   18   Issue A of the specification describes functions for CPU suspend, hotplug
   19   and migration of secure software.
   20 
   21   Functions are invoked by trapping to the privilege level of the PSCI
   22   firmware (specified as part of the binding below) and passing arguments
   23   in a manner similar to that specified by AAPCS:
   24 
   25      r0       => 32-bit Function ID / return value
   26     {r1 - r3}   => Parameters
   27 
   28   Note that the immediate field of the trapping instruction must be set
   29   to #0.
   30 
   31   [2] Power State Coordination Interface (PSCI) specification
   32     http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf
   33 
   34 properties:
   35   $nodename:
   36     const: psci
   37 
   38   compatible:
   39     oneOf:
   40       - description:
   41           For implementations complying to PSCI versions prior to 0.2.
   42         const: arm,psci
   43 
   44       - description:
   45           For implementations complying to PSCI 0.2.
   46         const: arm,psci-0.2
   47 
   48       - description:
   49           For implementations complying to PSCI 0.2.
   50           Function IDs are not required and should be ignored by an OS with
   51           PSCI 0.2 support, but are permitted to be present for compatibility
   52           with existing software when "arm,psci" is later in the compatible
   53           list.
   54         items:
   55           - const: arm,psci-0.2
   56           - const: arm,psci
   57 
   58       - description:
   59           For implementations complying to PSCI 1.0.
   60         const: arm,psci-1.0
   61 
   62       - description:
   63           For implementations complying to PSCI 1.0.
   64           PSCI 1.0 is backward compatible with PSCI 0.2 with minor
   65           specification updates, as defined in the PSCI specification[2].
   66         items:
   67           - const: arm,psci-1.0
   68           - const: arm,psci-0.2
   69 
   70   method:
   71     description: The method of calling the PSCI firmware.
   72     $ref: /schemas/types.yaml#/definitions/string-array
   73     enum:
   74       - smc
   75       # HVC #0, with the register assignments specified in this binding.
   76       - hvc
   77 
   78   cpu_suspend:
   79     $ref: /schemas/types.yaml#/definitions/uint32
   80     description: Function ID for CPU_SUSPEND operation
   81 
   82   cpu_off:
   83     $ref: /schemas/types.yaml#/definitions/uint32
   84     description: Function ID for CPU_OFF operation
   85 
   86   cpu_on:
   87     $ref: /schemas/types.yaml#/definitions/uint32
   88     description: Function ID for CPU_ON operation
   89 
   90   migrate:
   91     $ref: /schemas/types.yaml#/definitions/uint32
   92     description: Function ID for MIGRATE operation
   93 
   94   arm,psci-suspend-param:
   95     $ref: /schemas/types.yaml#/definitions/uint32
   96     description: |
   97       power_state parameter to pass to the PSCI suspend call.
   98 
   99       Device tree nodes that require usage of PSCI CPU_SUSPEND function (ie
  100       idle state nodes with entry-method property is set to "psci", as per
  101       bindings in [1]) must specify this property.
  102 
  103       [1] Kernel documentation - ARM idle states bindings
  104         Documentation/devicetree/bindings/cpu/idle-states.yaml
  105 
  106 patternProperties:
  107   "^power-domain-":
  108     $ref: "../power/power-domain.yaml#"
  109 
  110     type: object
  111     description: |
  112       ARM systems can have multiple cores, sometimes in an hierarchical
  113       arrangement. This often, but not always, maps directly to the processor
  114       power topology of the system. Individual nodes in a topology have their
  115       own specific power states and can be better represented hierarchically.
  116 
  117       For these cases, the definitions of the idle states for the CPUs and the
  118       CPU topology, must conform to the binding in [3]. The idle states
  119       themselves must conform to the binding in [4] and must specify the
  120       arm,psci-suspend-param property.
  121 
  122       It should also be noted that, in PSCI firmware v1.0 the OS-Initiated
  123       (OSI) CPU suspend mode is introduced. Using a hierarchical representation
  124       helps to implement support for OSI mode and OS implementations may choose
  125       to mandate it.
  126 
  127       [3] Documentation/devicetree/bindings/power/power-domain.yaml
  128       [4] Documentation/devicetree/bindings/power/domain-idle-state.yaml
  129 
  130 required:
  131   - compatible
  132   - method
  133 
  134 allOf:
  135   - if:
  136       properties:
  137         compatible:
  138           contains:
  139             const: arm,psci
  140     then:
  141       required:
  142         - cpu_off
  143         - cpu_on
  144 
  145 additionalProperties: false
  146 
  147 examples:
  148   - |+
  149 
  150     // Case 1: PSCI v0.1 only.
  151 
  152     psci {
  153       compatible      = "arm,psci";
  154       method          = "smc";
  155       cpu_suspend     = <0x95c10000>;
  156       cpu_off         = <0x95c10001>;
  157       cpu_on          = <0x95c10002>;
  158       migrate         = <0x95c10003>;
  159     };
  160 
  161   - |+
  162 
  163     // Case 2: PSCI v0.2 only
  164 
  165     psci {
  166       compatible      = "arm,psci-0.2";
  167       method          = "smc";
  168     };
  169 
  170 
  171   - |+
  172 
  173     // Case 3: PSCI v0.2 and PSCI v0.1.
  174 
  175     /*
  176      * A DTB may provide IDs for use by kernels without PSCI 0.2 support,
  177      * enabling firmware and hypervisors to support existing and new kernels.
  178      * These IDs will be ignored by kernels with PSCI 0.2 support, which will
  179      * use the standard PSCI 0.2 IDs exclusively.
  180      */
  181 
  182     psci {
  183       compatible = "arm,psci-0.2", "arm,psci";
  184       method = "hvc";
  185 
  186       cpu_on = <0x95c10002>;
  187       cpu_off = <0x95c10001>;
  188     };
  189 
  190   - |+
  191 
  192     // Case 4: CPUs and CPU idle states described using the hierarchical model.
  193 
  194     cpus {
  195       #size-cells = <0>;
  196       #address-cells = <1>;
  197 
  198       CPU0: cpu@0 {
  199         device_type = "cpu";
  200         compatible = "arm,cortex-a53";
  201         reg = <0x0>;
  202         enable-method = "psci";
  203         power-domains = <&CPU_PD0>;
  204         power-domain-names = "psci";
  205       };
  206 
  207       CPU1: cpu@1 {
  208         device_type = "cpu";
  209         compatible = "arm,cortex-a53";
  210         reg = <0x100>;
  211         enable-method = "psci";
  212         power-domains = <&CPU_PD1>;
  213         power-domain-names = "psci";
  214       };
  215 
  216       idle-states {
  217 
  218         CPU_PWRDN: cpu-power-down {
  219           compatible = "arm,idle-state";
  220           arm,psci-suspend-param = <0x0000001>;
  221           entry-latency-us = <10>;
  222           exit-latency-us = <10>;
  223           min-residency-us = <100>;
  224         };
  225       };
  226 
  227       domain-idle-states {
  228 
  229         CLUSTER_RET: cluster-retention {
  230           compatible = "domain-idle-state";
  231           arm,psci-suspend-param = <0x1000011>;
  232           entry-latency-us = <500>;
  233           exit-latency-us = <500>;
  234           min-residency-us = <2000>;
  235         };
  236 
  237         CLUSTER_PWRDN: cluster-power-down {
  238           compatible = "domain-idle-state";
  239           arm,psci-suspend-param = <0x1000031>;
  240           entry-latency-us = <2000>;
  241           exit-latency-us = <2000>;
  242           min-residency-us = <6000>;
  243         };
  244       };
  245     };
  246 
  247     psci {
  248       compatible = "arm,psci-1.0";
  249       method = "smc";
  250 
  251       CPU_PD0: power-domain-cpu0 {
  252         #power-domain-cells = <0>;
  253         domain-idle-states = <&CPU_PWRDN>;
  254         power-domains = <&CLUSTER_PD>;
  255       };
  256 
  257       CPU_PD1: power-domain-cpu1 {
  258         #power-domain-cells = <0>;
  259         domain-idle-states =  <&CPU_PWRDN>;
  260         power-domains = <&CLUSTER_PD>;
  261       };
  262 
  263       CLUSTER_PD: power-domain-cluster {
  264         #power-domain-cells = <0>;
  265         domain-idle-states = <&CLUSTER_RET>, <&CLUSTER_PWRDN>;
  266       };
  267     };
  268 ...

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FreeBSD/Linux Kernel Cross Reference sys/contrib/device-tree/Bindings/arm/psci.yaml

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sys/contrib/device-tree/Bindings/arm/psci.yaml