linux-kernel - Re: [PATCH v3 6/7] firmware: smccc: Add function to fetch SMCCC version

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Date:   Fri, 15 May 2020 13:08:11 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Sudeep Holla <sudeep.holla@....com>
Cc:     linux-arm-kernel@...ts.infradead.org,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Steven Price <steven.price@....com>,
        linux-kernel@...r.kernel.org, Arnd Bergmann <arnd@...db.de>,
        harb@...erecomputing.com
Subject: Re: [PATCH v3 6/7] firmware: smccc: Add function to fetch SMCCC
 version

On Wed, May 06, 2020 at 05:44:10PM +0100, Sudeep Holla wrote:
> For backward compatibility reasons, PSCI maintains SMCCC version as
> SMCCC didn't provide ARM_SMCCC_VERSION_FUNC_ID until v1.1
> 
> Let us provide accessors to fetch the SMCCC version in PSCI so that
> other SMCCC v1.1+ features can use it.

Stale commit message? This was factored out of PSCI in the prior commit.

> Reviewed-by: Steven Price <steven.price@....com>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>  drivers/firmware/smccc/smccc.c | 4 ++++
>  include/linux/arm-smccc.h      | 9 +++++++++
>  2 files changed, 13 insertions(+)
> 
> diff --git a/drivers/firmware/smccc/smccc.c b/drivers/firmware/smccc/smccc.c
> index 488699aae24f..672974df0dfe 100644
> --- a/drivers/firmware/smccc/smccc.c
> +++ b/drivers/firmware/smccc/smccc.c
> @@ -24,3 +24,7 @@ enum arm_smccc_conduit arm_smccc_1_1_get_conduit(void)
>  	return smccc_conduit;
>  }
>  
> +u32 arm_smccc_version_get(void)
> +{
> +	return smccc_version;
> +}

Could we please call this arm_smccc_get_version(), to align with the
existing arm_smccc_1_1_get_conduit()?

> diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> index 11fb20bfa8f7..8dd54dad1ec5 100644
> --- a/include/linux/arm-smccc.h
> +++ b/include/linux/arm-smccc.h
> @@ -109,6 +109,15 @@ void __init arm_smccc_version_init(u32 version, enum arm_smccc_conduit conduit);
>   */
>  enum arm_smccc_conduit arm_smccc_1_1_get_conduit(void);
>  
> +/**
> + * arm_smccc_version_get()
> + *
> + * Returns the version to be used for SMCCCv1.1 or later.
> + *
> + * When SMCCCv1.1 or above is not present, assumes and returns SMCCCv1.0.
> + */
> +u32 arm_smccc_version_get(void);

Can we please reword the last line to something like:

| When SMCCCv1.1 or above is not present, returns SMCCCv1.0, but this
| does not imply the presence of firmware or a valid conduit. Callers
| handling SMCCCv1.0 must determine the conduit by other means.

With all that:

Acked-by: Mark Rutland <mark.rutland@....com>

Thanks,
Mark.