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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 000000000..3a2c908ff --- /dev/null +++ b/Documentation/devicetree/bindings/arm/psci.yaml @@ -0,0 +1,263 @@ +# 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: + $nodename: + const: psci + + compatible: + oneOf: + - description: + For implementations complying to PSCI versions prior to 0.2. + const: arm,psci + + - 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. + minItems: 1 + items: + - const: arm,psci-0.2 + - const: arm,psci + + - 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]. + minItems: 1 + items: + - const: arm,psci-1.0 + - const: arm,psci-0.2 + - const: arm,psci + + method: + description: The method of calling the PSCI firmware. + $ref: /schemas/types.yaml#/definitions/string-array + enum: + - 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/cpu/idle-states.yaml + +patternProperties: + "^power-domain-": + $ref: "../power/power-domain.yaml#" + + type: object + description: | + ARM systems can have multiple cores, sometimes in an hierarchical + arrangement. This often, but not always, maps directly to the processor + power topology of the system. Individual nodes in a topology have their + own specific power states and can be better represented hierarchically. + + For these cases, the definitions of the idle states for the CPUs and the + CPU topology, must conform to the binding in [3]. The idle states + themselves must conform to the binding in [4] and must specify the + arm,psci-suspend-param property. + + It should also be noted that, in PSCI firmware v1.0 the OS-Initiated + (OSI) CPU suspend mode is introduced. Using a hierarchical representation + helps to implement support for OSI mode and OS implementations may choose + to mandate it. + + [3] Documentation/devicetree/bindings/power/power-domain.yaml + [4] Documentation/devicetree/bindings/power/domain-idle-state.yaml + +required: + - compatible + - method + +allOf: + - if: + properties: + compatible: + contains: + const: arm,psci + then: + required: + - cpu_off + - cpu_on + +additionalProperties: false + +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>; + }; + + - |+ + + // Case 4: CPUs and CPU idle states described using the hierarchical model. + + cpus { + #size-cells = <0>; + #address-cells = <1>; + + CPU0: cpu@0 { + device_type = "cpu"; + compatible = "arm,cortex-a53"; + reg = <0x0>; + enable-method = "psci"; + power-domains = <&CPU_PD0>; + power-domain-names = "psci"; + }; + + CPU1: cpu@1 { + device_type = "cpu"; + compatible = "arm,cortex-a53"; + reg = <0x100>; + enable-method = "psci"; + power-domains = <&CPU_PD1>; + power-domain-names = "psci"; + }; + + idle-states { + + CPU_PWRDN: cpu-power-down { + compatible = "arm,idle-state"; + arm,psci-suspend-param = <0x0000001>; + entry-latency-us = <10>; + exit-latency-us = <10>; + min-residency-us = <100>; + }; + }; + + domain-idle-states { + + CLUSTER_RET: cluster-retention { + compatible = "domain-idle-state"; + arm,psci-suspend-param = <0x1000011>; + entry-latency-us = <500>; + exit-latency-us = <500>; + min-residency-us = <2000>; + }; + + CLUSTER_PWRDN: cluster-power-down { + compatible = "domain-idle-state"; + arm,psci-suspend-param = <0x1000031>; + entry-latency-us = <2000>; + exit-latency-us = <2000>; + min-residency-us = <6000>; + }; + }; + }; + + psci { + compatible = "arm,psci-1.0"; + method = "smc"; + + CPU_PD0: power-domain-cpu0 { + #power-domain-cells = <0>; + domain-idle-states = <&CPU_PWRDN>; + power-domains = <&CLUSTER_PD>; + }; + + CPU_PD1: power-domain-cpu1 { + #power-domain-cells = <0>; + domain-idle-states = <&CPU_PWRDN>; + power-domains = <&CLUSTER_PD>; + }; + + CLUSTER_PD: power-domain-cluster { + #power-domain-cells = <0>; + domain-idle-states = <&CLUSTER_RET>, <&CLUSTER_PWRDN>; + }; + }; +... |