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268 lines
7.5 KiB
268 lines
7.5 KiB
# SPDX-License-Identifier: GPL-2.0 |
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%YAML 1.2 |
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--- |
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$id: http://devicetree.org/schemas/arm/psci.yaml# |
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$schema: http://devicetree.org/meta-schemas/core.yaml# |
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title: Power State Coordination Interface (PSCI) |
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maintainers: |
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- Lorenzo Pieralisi <[email protected]> |
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description: |+ |
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Firmware implementing the PSCI functions described in ARM document number |
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ARM DEN 0022A ("Power State Coordination Interface System Software on ARM |
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processors") can be used by Linux to initiate various CPU-centric power |
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operations. |
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Issue A of the specification describes functions for CPU suspend, hotplug |
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and migration of secure software. |
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Functions are invoked by trapping to the privilege level of the PSCI |
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firmware (specified as part of the binding below) and passing arguments |
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in a manner similar to that specified by AAPCS: |
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r0 => 32-bit Function ID / return value |
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{r1 - r3} => Parameters |
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Note that the immediate field of the trapping instruction must be set |
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to #0. |
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[2] Power State Coordination Interface (PSCI) specification |
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http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf |
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properties: |
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$nodename: |
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const: psci |
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compatible: |
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oneOf: |
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- description: |
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For implementations complying to PSCI versions prior to 0.2. |
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const: arm,psci |
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- description: |
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For implementations complying to PSCI 0.2. |
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const: arm,psci-0.2 |
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- description: |
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For implementations complying to PSCI 0.2. |
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Function IDs are not required and should be ignored by an OS with |
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PSCI 0.2 support, but are permitted to be present for compatibility |
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with existing software when "arm,psci" is later in the compatible |
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list. |
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items: |
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- const: arm,psci-0.2 |
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- const: arm,psci |
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- description: |
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For implementations complying to PSCI 1.0. |
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const: arm,psci-1.0 |
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- description: |
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For implementations complying to PSCI 1.0. |
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PSCI 1.0 is backward compatible with PSCI 0.2 with minor |
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specification updates, as defined in the PSCI specification[2]. |
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items: |
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- const: arm,psci-1.0 |
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- const: arm,psci-0.2 |
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method: |
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description: The method of calling the PSCI firmware. |
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$ref: /schemas/types.yaml#/definitions/string-array |
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enum: |
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- smc |
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# HVC #0, with the register assignments specified in this binding. |
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- hvc |
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cpu_suspend: |
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$ref: /schemas/types.yaml#/definitions/uint32 |
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description: Function ID for CPU_SUSPEND operation |
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cpu_off: |
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$ref: /schemas/types.yaml#/definitions/uint32 |
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description: Function ID for CPU_OFF operation |
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cpu_on: |
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$ref: /schemas/types.yaml#/definitions/uint32 |
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description: Function ID for CPU_ON operation |
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migrate: |
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$ref: /schemas/types.yaml#/definitions/uint32 |
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description: Function ID for MIGRATE operation |
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arm,psci-suspend-param: |
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$ref: /schemas/types.yaml#/definitions/uint32 |
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description: | |
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power_state parameter to pass to the PSCI suspend call. |
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Device tree nodes that require usage of PSCI CPU_SUSPEND function (ie |
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idle state nodes with entry-method property is set to "psci", as per |
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bindings in [1]) must specify this property. |
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[1] Kernel documentation - ARM idle states bindings |
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Documentation/devicetree/bindings/arm/idle-states.yaml |
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patternProperties: |
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"^power-domain-": |
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$ref: "../power/power-domain.yaml#" |
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type: object |
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description: | |
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ARM systems can have multiple cores, sometimes in an hierarchical |
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arrangement. This often, but not always, maps directly to the processor |
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power topology of the system. Individual nodes in a topology have their |
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own specific power states and can be better represented hierarchically. |
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For these cases, the definitions of the idle states for the CPUs and the |
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CPU topology, must conform to the binding in [3]. The idle states |
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themselves must conform to the binding in [4] and must specify the |
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arm,psci-suspend-param property. |
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It should also be noted that, in PSCI firmware v1.0 the OS-Initiated |
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(OSI) CPU suspend mode is introduced. Using a hierarchical representation |
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helps to implement support for OSI mode and OS implementations may choose |
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to mandate it. |
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[3] Documentation/devicetree/bindings/power/power-domain.yaml |
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[4] Documentation/devicetree/bindings/power/domain-idle-state.yaml |
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required: |
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- compatible |
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- method |
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allOf: |
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- if: |
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properties: |
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compatible: |
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contains: |
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const: arm,psci |
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then: |
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required: |
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- cpu_off |
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- cpu_on |
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additionalProperties: false |
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examples: |
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- |+ |
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// Case 1: PSCI v0.1 only. |
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psci { |
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compatible = "arm,psci"; |
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method = "smc"; |
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cpu_suspend = <0x95c10000>; |
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cpu_off = <0x95c10001>; |
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cpu_on = <0x95c10002>; |
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migrate = <0x95c10003>; |
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}; |
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- |+ |
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// Case 2: PSCI v0.2 only |
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psci { |
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compatible = "arm,psci-0.2"; |
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method = "smc"; |
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}; |
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- |+ |
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// Case 3: PSCI v0.2 and PSCI v0.1. |
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/* |
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* A DTB may provide IDs for use by kernels without PSCI 0.2 support, |
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* enabling firmware and hypervisors to support existing and new kernels. |
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* These IDs will be ignored by kernels with PSCI 0.2 support, which will |
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* use the standard PSCI 0.2 IDs exclusively. |
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*/ |
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psci { |
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compatible = "arm,psci-0.2", "arm,psci"; |
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method = "hvc"; |
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cpu_on = <0x95c10002>; |
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cpu_off = <0x95c10001>; |
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}; |
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- |+ |
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// Case 4: CPUs and CPU idle states described using the hierarchical model. |
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cpus { |
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#size-cells = <0>; |
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#address-cells = <1>; |
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CPU0: cpu@0 { |
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device_type = "cpu"; |
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compatible = "arm,cortex-a53"; |
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reg = <0x0>; |
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enable-method = "psci"; |
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power-domains = <&CPU_PD0>; |
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power-domain-names = "psci"; |
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}; |
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CPU1: cpu@1 { |
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device_type = "cpu"; |
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compatible = "arm,cortex-a53"; |
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reg = <0x100>; |
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enable-method = "psci"; |
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power-domains = <&CPU_PD1>; |
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power-domain-names = "psci"; |
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}; |
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idle-states { |
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CPU_PWRDN: cpu-power-down { |
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compatible = "arm,idle-state"; |
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arm,psci-suspend-param = <0x0000001>; |
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entry-latency-us = <10>; |
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exit-latency-us = <10>; |
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min-residency-us = <100>; |
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}; |
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}; |
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domain-idle-states { |
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CLUSTER_RET: cluster-retention { |
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compatible = "domain-idle-state"; |
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arm,psci-suspend-param = <0x1000011>; |
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entry-latency-us = <500>; |
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exit-latency-us = <500>; |
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min-residency-us = <2000>; |
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}; |
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CLUSTER_PWRDN: cluster-power-down { |
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compatible = "domain-idle-state"; |
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arm,psci-suspend-param = <0x1000031>; |
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entry-latency-us = <2000>; |
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exit-latency-us = <2000>; |
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min-residency-us = <6000>; |
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}; |
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}; |
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}; |
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psci { |
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compatible = "arm,psci-1.0"; |
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method = "smc"; |
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CPU_PD0: power-domain-cpu0 { |
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#power-domain-cells = <0>; |
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domain-idle-states = <&CPU_PWRDN>; |
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power-domains = <&CLUSTER_PD>; |
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}; |
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CPU_PD1: power-domain-cpu1 { |
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#power-domain-cells = <0>; |
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domain-idle-states = <&CPU_PWRDN>; |
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power-domains = <&CLUSTER_PD>; |
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}; |
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CLUSTER_PD: power-domain-cluster { |
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#power-domain-cells = <0>; |
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domain-idle-states = <&CLUSTER_RET>, <&CLUSTER_PWRDN>; |
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}; |
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}; |
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...
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