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.
> Main node optional properties:
>
> - - cpu_suspend : Function ID for CPU_SUSPEND operation
> + - cpu_suspend[-<32|64] : Function ID for CPU_SUSPEND operation
> +
> + - cpu_off : Function ID for CPU_OFF operation
> +
> + - cpu_on[-<32|64] : Function ID for CPU_ON operation
> +
> + - affinity_info[-<32|64] : Function ID for AFFINITY_INFO operation
>
> - - cpu_off : Function ID for CPU_OFF operation
> + - migrate[-<32|64] : Function ID for MIGRATE operation
>
> - - cpu_on : Function ID for CPU_ON operation
> + - migrate_info_type : Function ID for MIGRATE_INFO_TYPE operation
>
> - - migrate : Function ID for MIGRATE operation
> + - migrate_info_up_cpu[-<32|64] : Function ID for MIGRATE_INFO_UP_CPU operation
>
> + - system_reset : Function ID for SYSTEM_RESET operation
> +
> + - system_off : Function ID for SYSTEM_OFF operation
> +
> +Some function IDs support 32-bit and 64-bit calling conventions. If no size is
> +specified, then the 32-bit calling convention is used. Therefore, all function
> +IDs for 64-bit calling convention are required to have "-64" suffix. Use of the
> +"-32" suffix is recommended, but not required for backwards compatibility.
I don't think we can say that non suffixed IDs mean use the 32-bit
calling convention -- the arm64 PSCI code uses 64-bit parameters at the
moment for non-suffixed IDs.
I think if we say that callers should use their native register width
calling convention for non-suffixed IDs, it's compatible with all PSCI
implementations using DT in the wild currently. Implementations on v7
don't have AArch64 state, so can't ever use the 64-bit convention, and
existing 64-bit implementations like KVM has are implemented at EL2, so
the guest is stuck at a particular register width.
Given that, how about the below?
Some functions have have separate IDs for 32-bit and 64-bit calling
conventions. These separate function IDs are described with function
names with "-64" and "-32" suffixes (e.g. cpu_on-64). Where a function
name does not have a suffix, the ID may be used with either calling
convention depending on the CPU state -- AArch32 callers should use the
32-bit calling convention, and AArch64 callers should use the 64-bit
calling convention.
Thanks,
Mark.
>
> Example:
>
> psci {
> - compatible = "arm,psci";
> + compatible = "arm,psci-0.2";
> method = "smc";
> - cpu_suspend = <0x95c10000>;
> - cpu_off = <0x95c10001>;
> - cpu_on = <0x95c10002>;
> - migrate = <0x95c10003>;
> + psci_version = <0x84000000>;
> + cpu_suspend-32 = <0x84000001>;
> + cpu_suspend-64 = <0xc4000001>;
> + cpu_off = <0x84000002>;
> + cpu_on-32 = <0x84000003>;
> + cpu_on-64 = <0xc4000003>;
> + affinity_info-32 = <0x84000004>;
> + affinity_info-64 = <0xc4000004>;
> + migrate-32 = <0x84000005>;
> + migrate-64 = <0xc4000005>;
> + migrate_info_type = <0x84000006>;
> + migrate_info_up_cpu-32 = <0x84000007>;
> + migrate_info_up_cpu-64 = <0xc4000007>;
> + system_off = <0x84000008>;
> + system_reset = <0x84000009>;
> };
> +
> --
> 1.8.1.2
>
>
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