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ARM: psci: add devicetree binding for describing PSCI firmware
This patch adds a new devicetree binding for describing PSCI firmware
to Linux.
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
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Documentation/devicetree/bindings/arm/psci.txt
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Documentation/devicetree/bindings/arm/psci.txt
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* Power State Coordination Interface (PSCI)
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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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Main node required properties:
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- compatible : Must be "arm,psci"
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- method : The method of calling the PSCI firmware. Permitted
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values are:
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"smc" : SMC #0, with the register assignments specified
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in this binding.
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"hvc" : HVC #0, with the register assignments specified
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in this binding.
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Main node optional properties:
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- cpu_suspend : Function ID for CPU_SUSPEND operation
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- cpu_off : Function ID for CPU_OFF operation
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- cpu_on : Function ID for CPU_ON operation
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- migrate : Function ID for MIGRATE operation
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Example:
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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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};