Re: [Xen-devel] [PATCH v3 3/6] ARM: psci: add devicetree binding for describing PSCI firmware

[Nicolas Pitre <nicolas.pitre@xxxxxxxxxx>]

On Tue, 18 Dec 2012, Will Deacon wrote:

> This patch adds a new devicetree binding for describing PSCI firmware
> to Linux.
> 
> Signed-off-by: Will Deacon <will.deacon@xxxxxxx>

Acked-by: Nicolas Pitre <nico@xxxxxxxxxx>


> ---
>  Documentation/devicetree/bindings/arm/psci.txt | 55 
> ++++++++++++++++++++++++++
>  1 file changed, 55 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/psci.txt
> 
> diff --git a/Documentation/devicetree/bindings/arm/psci.txt 
> b/Documentation/devicetree/bindings/arm/psci.txt
> new file mode 100644
> index 0000000..433afe9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/psci.txt
> @@ -0,0 +1,55 @@
> +* Power State Coordination Interface (PSCI)
> +
> +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.
> +
> +
> +Main node required properties:
> +
> + - compatible    : Must be "arm,psci"
> +
> + - method        : The method of calling the PSCI firmware. Permitted
> +                   values are:
> +
> +                   "smc" : SMC #0, with the register assignments specified
> +                        in this binding.
> +
> +                   "hvc" : HVC #0, with the register assignments specified
> +                        in this binding.
> +
> +Main node optional properties:
> +
> + - cpu_suspend   : Function ID for CPU_SUSPEND operation
> +
> + - cpu_off       : Function ID for CPU_OFF operation
> +
> + - cpu_on        : Function ID for CPU_ON operation
> +
> + - migrate       : Function ID for MIGRATE operation
> +
> +
> +Example:
> +
> +     psci {
> +             compatible      = "arm,psci";
> +             method          = "smc";
> +             cpu_suspend     = <0x95c10000>;
> +             cpu_off         = <0x95c10001>;
> +             cpu_on          = <0x95c10002>;
> +             migrate         = <0x95c10003>;
> +     };
> -- 
> 1.8.0
> 

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