[PATCH v2 1/3] firmware: psci: Fix bind_smccc_features psci check

[Heinrich Schuchardt]

On 31.01.24 12:12, Weizhao Ouyang wrote:
> According to PSCI specification DEN0022F, PSCI_FEATURES is used to check
> whether the SMCCC is implemented by discovering SMCCC_VERSION.
>
> Signed-off-by: Weizhao Ouyang <o451686892 at gmail.com>
> ---
> v2: check SMCCC_ARCH_FEATURES
> ---
>   drivers/firmware/psci.c   | 9 ++++++++-
>   include/linux/arm-smccc.h | 6 ++++++
>   2 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
> index c6b9efab41..ed701cd1e4 100644
> --- a/drivers/firmware/psci.c
> +++ b/drivers/firmware/psci.c
> @@ -135,7 +135,7 @@ static int bind_smccc_features(struct udevice *dev, int psci_method)
>   	    PSCI_VERSION_MAJOR(psci_0_2_get_version()) == 0)
>   		return 0;
>
> -	if (request_psci_features(ARM_SMCCC_ARCH_FEATURES) ==
> +	if (request_psci_features(ARM_SMCCC_VERSION) ==
>   	    PSCI_RET_NOT_SUPPORTED)
>   		return 0;
>
> @@ -144,6 +144,13 @@ static int bind_smccc_features(struct udevice *dev, int psci_method)
>   	else
>   		pdata->invoke_fn = smccc_invoke_smc;
>
> +	/*
> +	 * SMCCC_ARCH_FEATURES is MANDATORY from SMCCC v1.1, but we still remain
> +	 * the invoke_fn() even the SMCCC version is v1.0.

This sentence is a bit hard to understand. Did you mean,

"but we keep calling invoke_fn() even if the SMCC version is v1.0" ?

> +	 */
> +	if (invoke_psci_fn(ARM_SMCCC_VERSION, 0, 0, 0) < ARM_SMCCC_VERSION_1_1)
> +		return 0;


Why do we leave the function for
invoke_psci_fn(ARM_SMCCC_VERSION, 0, 0, 0) == ARM_SMCCC_VERSION_1_0
despite the comment above?

Best regards

Heinrich

> +
>   	feature_cnt = ll_entry_count(struct arm_smccc_feature, arm_smccc_feature);
>   	feature = ll_entry_start(struct arm_smccc_feature, arm_smccc_feature);
>
> diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> index f44e9e8f93..da3d29aabe 100644
> --- a/include/linux/arm-smccc.h
> +++ b/include/linux/arm-smccc.h
> @@ -55,8 +55,14 @@
>   #define ARM_SMCCC_QUIRK_NONE		0
>   #define ARM_SMCCC_QUIRK_QCOM_A6		1 /* Save/restore register a6 */
>
> +#define ARM_SMCCC_VERSION		0x80000000
>   #define ARM_SMCCC_ARCH_FEATURES		0x80000001
>
> +#define ARM_SMCCC_VERSION_1_0		0x10000
> +#define ARM_SMCCC_VERSION_1_1		0x10001
> +#define ARM_SMCCC_VERSION_1_2		0x10002
> +#define ARM_SMCCC_VERSION_1_3		0x10003
> +
>   #define ARM_SMCCC_RET_NOT_SUPPORTED	((unsigned long)-1)
>
>   #ifndef __ASSEMBLY__