Re: [PATCHv3 1/6] arm/arm64: smccc/psci: add arm_smccc_1_1_get_conduit()

[Dave Martin <Dave.Martin@arm.com>]

On Fri, Aug 09, 2019 at 02:22:40PM +0100, Mark Rutland wrote:
> SMCCC callers are currently amassing a collection of enums for the SMCCC
> conduit, and are having to dig into the PSCI driver's internals in order
> to figure out what to do.
> 
> Let's clean this up, with common SMCCC_CONDUIT_* definitions, and an
> arm_smccc_1_1_get_conduit() helper that abstracts the PSCI driver's
> internal state.
> 
> We can kill off the PSCI_CONDUIT_* definitions once we've migrated users
> over to the new interface.
> 
> Signed-off-by: Mark Rutland <mark.rutland@arm.com>
> Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Acked-by: Will Deacon <will.deacon@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> ---
>  drivers/firmware/psci/psci.c | 15 +++++++++++++++
>  include/linux/arm-smccc.h    | 16 ++++++++++++++++
>  2 files changed, 31 insertions(+)
> 
> diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
> index f82ccd39a913..5f31f1bea1af 100644
> --- a/drivers/firmware/psci/psci.c
> +++ b/drivers/firmware/psci/psci.c
> @@ -57,6 +57,21 @@ struct psci_operations psci_ops = {
>  	.smccc_version = SMCCC_VERSION_1_0,
>  };
>  
> +enum arm_smccc_conduit arm_smccc_1_1_get_conduit(void)

Do we expect this to be specific to SMCCC v1.1?

> +{
> +	if (psci_ops.smccc_version < SMCCC_VERSION_1_1)
> +		return SMCCC_CONDUIT_NONE;
> +
> +	switch (psci_ops.conduit) {
> +	case PSCI_CONDUIT_SMC:
> +		return SMCCC_CONDUIT_SMC;
> +	case PSCI_CONDUIT_HVC:
> +		return SMCCC_CONDUIT_HVC;
> +	default:
> +		return SMCCC_CONDUIT_NONE;
> +	}
> +}
> +
>  typedef unsigned long (psci_fn)(unsigned long, unsigned long,
>  				unsigned long, unsigned long);
>  static psci_fn *invoke_psci_fn;
> diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> index 080012a6f025..df01a8579034 100644
> --- a/include/linux/arm-smccc.h
> +++ b/include/linux/arm-smccc.h
> @@ -80,6 +80,22 @@
>  
>  #include <linux/linkage.h>
>  #include <linux/types.h>
> +
> +enum arm_smccc_conduit {
> +	SMCCC_CONDUIT_NONE,

If this is intended to have the value 0, is it worth making that
explicit?  I can never remember whether enums start at 1 or 0 by
default...

> +	SMCCC_CONDUIT_SMC,
> +	SMCCC_CONDUIT_HVC,
> +};

[...]

Cheers
---Dave

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