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Diffstat (limited to 'Documentation/devicetree/bindings/arm/psci.yaml')
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diff --git a/Documentation/devicetree/bindings/arm/psci.yaml b/Documentation/devicetree/bindings/arm/psci.yaml new file mode 100644 index 000000000000..7abdf58b335e --- /dev/null +++ b/Documentation/devicetree/bindings/arm/psci.yaml @@ -0,0 +1,163 @@ +# SPDX-License-Identifier: GPL-2.0 +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/arm/psci.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Power State Coordination Interface (PSCI) + +maintainers: + - Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> + +description: |+ + Firmware implementing the PSCI functions described in ARM document number + ARM DEN 0022A ("Power State Coordination Interface System Software on ARM + processors") can be used by Linux to initiate various CPU-centric power + operations. + + Issue A of the specification describes functions for CPU suspend, hotplug + and migration of secure software. + + Functions are invoked by trapping to the privilege level of the PSCI + firmware (specified as part of the binding below) and passing arguments + in a manner similar to that specified by AAPCS: + + r0 => 32-bit Function ID / return value + {r1 - r3} => Parameters + + Note that the immediate field of the trapping instruction must be set + to #0. + + [2] Power State Coordination Interface (PSCI) specification + http://infocenter.arm.com/help/topic/com.arm.doc.den0022c/DEN0022C_Power_State_Coordination_Interface.pdf + +properties: + compatible: + oneOf: + - description: + For implementations complying to PSCI versions prior to 0.2. + const: arm,psci + + - description: + For implementations complying to PSCI 0.2. + const: arm,psci-0.2 + + - description: + For implementations complying to PSCI 0.2. + Function IDs are not required and should be ignored by an OS with + PSCI 0.2 support, but are permitted to be present for compatibility + with existing software when "arm,psci" is later in the compatible + list. + items: + - const: arm,psci-0.2 + - const: arm,psci + + - description: + For implementations complying to PSCI 1.0. + const: arm,psci-1.0 + + - description: + For implementations complying to PSCI 1.0. + PSCI 1.0 is backward compatible with PSCI 0.2 with minor + specification updates, as defined in the PSCI specification[2]. + items: + - const: arm,psci-1.0 + - const: arm,psci-0.2 + + method: + description: The method of calling the PSCI firmware. + allOf: + - $ref: /schemas/types.yaml#/definitions/string-array + - enum: + # SMC #0, with the register assignments specified in this binding. + - smc + # HVC #0, with the register assignments specified in this binding. + - hvc + + cpu_suspend: + $ref: /schemas/types.yaml#/definitions/uint32 + description: Function ID for CPU_SUSPEND operation + + cpu_off: + $ref: /schemas/types.yaml#/definitions/uint32 + description: Function ID for CPU_OFF operation + + cpu_on: + $ref: /schemas/types.yaml#/definitions/uint32 + description: Function ID for CPU_ON operation + + migrate: + $ref: /schemas/types.yaml#/definitions/uint32 + description: Function ID for MIGRATE operation + + arm,psci-suspend-param: + $ref: /schemas/types.yaml#/definitions/uint32 + description: | + power_state parameter to pass to the PSCI suspend call. + + Device tree nodes that require usage of PSCI CPU_SUSPEND function (ie + idle state nodes with entry-method property is set to "psci", as per + bindings in [1]) must specify this property. + + [1] Kernel documentation - ARM idle states bindings + Documentation/devicetree/bindings/arm/idle-states.txt + + +required: + - compatible + - method + +allOf: + - if: + properties: + compatible: + contains: + const: arm,psci + then: + required: + - cpu_off + - cpu_on + +examples: + - |+ + + // Case 1: PSCI v0.1 only. + + psci { + compatible = "arm,psci"; + method = "smc"; + cpu_suspend = <0x95c10000>; + cpu_off = <0x95c10001>; + cpu_on = <0x95c10002>; + migrate = <0x95c10003>; + }; + + - |+ + + // Case 2: PSCI v0.2 only + + psci { + compatible = "arm,psci-0.2"; + method = "smc"; + }; + + + - |+ + + // Case 3: PSCI v0.2 and PSCI v0.1. + + /* + * A DTB may provide IDs for use by kernels without PSCI 0.2 support, + * enabling firmware and hypervisors to support existing and new kernels. + * These IDs will be ignored by kernels with PSCI 0.2 support, which will + * use the standard PSCI 0.2 IDs exclusively. + */ + + psci { + compatible = "arm,psci-0.2", "arm,psci"; + method = "hvc"; + + cpu_on = <0x95c10002>; + cpu_off = <0x95c10001>; + }; +... |