linux-kernel - Re: [PATCH v2 4/5] firmware: psci: Add function to fetch SMCCC version

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Date:   Mon, 4 May 2020 15:11:10 +0100
From:   Steven Price <steven.price@....com>
To:     Sudeep Holla <sudeep.holla@....com>,
        linux-arm-kernel@...ts.infradead.org
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        linux-kernel@...r.kernel.org, harb@...erecomputing.com
Subject: Re: [PATCH v2 4/5] firmware: psci: Add function to fetch SMCCC
 version

On 04/05/2020 10:29, 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.

Since it seems there is a good reason for this patch... ;)

Reviewed-by: Steven Price <steven.price@....com>

Steve

> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>   drivers/firmware/psci/psci.c | 5 +++++
>   include/linux/arm-smccc.h    | 9 +++++++++
>   2 files changed, 14 insertions(+)
> 
> diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
> index 6a56d7196697..04426e16fee6 100644
> --- a/drivers/firmware/psci/psci.c
> +++ b/drivers/firmware/psci/psci.c
> @@ -65,6 +65,11 @@ enum arm_smccc_conduit arm_smccc_1_1_get_conduit(void)
>   	return psci_ops.conduit;
>   }
>   
> +u32 arm_smccc_get_version(void)
> +{
> +	return psci_ops.smccc_version;
> +}
> +
>   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 9d9a2e42e919..d6b0f4acc707 100644
> --- a/include/linux/arm-smccc.h
> +++ b/include/linux/arm-smccc.h
> @@ -98,6 +98,15 @@ enum arm_smccc_conduit {
>    */
>   enum arm_smccc_conduit arm_smccc_1_1_get_conduit(void);
>   
> +/**
> + * arm_smccc_get_version()
> + *
> + * 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_get_version(void);
> +
>   /**
>    * struct arm_smccc_res - Result from SMC/HVC call
>    * @a0-a3 result values from registers 0 to 3
>