On Tue, Sep 3, 2013 at 4:52 AM, Mark Rutland <mark.rutland@xxxxxxx> wrote:
> On Tue, Aug 27, 2013 at 01:50:33AM +0100, Rob Herring wrote:
>> From: Rob Herring <rob.herring@xxxxxxxxxxx>
>
> Hi Rob,
>
> Sorry for the delay on reviewing this.
>
>>
>> The PSCI spec from ARM has been updated to 0.2 version. Update the
>> binding document to reflect the spec changes. For the binding, the
>> major changes are the addition of psci_version, affinity_info,
>> migrate_info_type, migrate_info_up_cpu, system_reset and system_off
>> functions. The recommended function ID numbering has also changed.
>>
>> This update also defines 32 and 64 bit calling conventions. The calling
>> convention is defined on a per function ID basis.
>>
>> Signed-off-by: Rob Herring <rob.herring@xxxxxxxxxxx>
>> Cc: Dave Martin <Dave.Martin@xxxxxxx>
>> Cc: Mark Rutland <mark.rutland@xxxxxxx>
>> Cc: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
>> Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>> Cc: Marc Zyngier <Marc.Zyngier@xxxxxxx>
>> Cc: Christoffer Dall <christoffer.dall@xxxxxxxxxx>,
>> Cc: Charles Garcia-Tobin <Charles.Garcia-Tobin@xxxxxxx>
>> Cc: Matt Sealey <neko@xxxxxxxxxxxxx>
>> Cc: devicetree@xxxxxxxxxxxxxxx
>> ---
>> v3: This version implements Mark's suggested binding with -32 and -64 suffixes.
>>
>> Documentation/devicetree/bindings/arm/psci.txt | 62 +++++++++++++++++++-------
>> 1 file changed, 46 insertions(+), 16 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/arm/psci.txt b/Documentation/devicetree/bindings/arm/psci.txt
>> index 433afe9..209bb04 100644
>> --- a/Documentation/devicetree/bindings/arm/psci.txt
>> +++ b/Documentation/devicetree/bindings/arm/psci.txt
>> @@ -1,16 +1,17 @@
>> * 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
>> +ARM DEN 0022B ("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.
>> +Issue B of the specification describes functions for CPU suspend, hotplug,
>> +migration of secure software, and system level reset and powerdown.
>>
>> 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:
>> +as defined in ARM document "SMC Calling Convention" (ARM DEN 0028) in a manner
>> +similar to that specified by AAPCS:
>>
>> r0 => 32-bit Function ID / return value
>> {r1 - r3} => Parameters
>> @@ -21,10 +22,10 @@ to #0.
>>
>> Main node required properties:
>>
>> - - compatible : Must be "arm,psci"
>> + - compatible : Must contain "arm,psci-0.2" or "arm,psci"
>>
>> - - method : The method of calling the PSCI firmware. Permitted
>> - values are:
>> + - method : The method defines the calling convention for the PSCI
>> + firmware. Permitted values are:
>>
>> "smc" : SMC #0, with the register assignments specified
>> in this binding.
>> @@ -32,24 +33,53 @@ Main node required properties:
>> "hvc" : HVC #0, with the register assignments specified
>> in this binding.
>>
>> + - psci_version : Function ID for PSCI_VERSION operation. Required for
>> + "arm,psci-0.2" compatible version or later.
>> +
>
> While this seems sensible, I'm not sure that this needs to be mandatory.
It is quite pointless to have at all if we don't make it mandatory. I
would accept that it is pointless and the compatible string should
always reflect the version anyway, but ARM added the call and states
it is mandatory in the PSCI doc. I guess we could have mandatory for
the firmware to implement, but optional in the DT binding? That seems
silly though.
Rob
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