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

[Weizhao Ouyang]

Hi Abdellatif,

On Fri, Jan 26, 2024 at 7:20 PM Abdellatif El Khlifi
<abdellatif.elkhlifi at arm.com> wrote:
>
> Hi Weizhao,
>
> On Thu, Jan 25, 2024 at 02:05:00PM +0000, 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>
> > ---
> >  drivers/firmware/psci.c   | 2 +-
> >  include/linux/arm-smccc.h | 1 +
> >  2 files changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
> > index c6b9efab41..894be8128d 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;
>
> I suggest we add checks on the SMCCC version like this:
>
>     if SMCCC_VERSION >= 1.1
>        assume SMCCC_ARCH_FEATURES is supported
>        discover arch features and bind drivers/devices
>     else
>        error

Okay, I will add it.

BR,
Weizhao

>
> For more details [1][2].
>
>
> [1]: SMC Calling Convention 1.5 (https://developer.arm.com/documentation/den0028/latest/)
>
> SMCCC_ARCH_FEATURES MANDATORY from SMCCC v1.1
>
> The implementation of this function can be detected by checking the SMCCC version. This function is mandatory
> if SMCCC_VERSION indicates that version 1.1 or later is implemented.
>
> [2]: Linux checks SMCCC v1.1: https://elixir.bootlin.com/linux/latest/source/drivers/firmware/psci/psci.c#L597
>
> Cheers,
> Abdellatif