Hello Weizhao, On Wed, Jan 31, 2024 at 3:15 PM Weizhao Ouyang <[email protected]> wrote: > > According to PSCI specification DEN0022F, PSCI_FEATURES is used to check > whether the SMCCC is implemented by discovering SMCCC_VERSION. > Could you please add more details to your commit message or as a comment explaining what exact steps should be done for a full discovery sequence of Arm Architecture Service functions, so people don't need to search for that information explicitly?
For instance: Step 1: Determine if SMCCC_VERSION is implemented - Use firmware data, device tree PSCI node, or ACPI FADT PSCI flag, to determine whether a PSCI implementation is present. - Use PSCI_VERSION to learn whether PSCI_FEATURES is provided. PSCI_FEATURES is mandatory from version 1.0 of PSCI Step 2. etc. I would just pull that info from the latest SMC Calling Convention version 1.5, from 9 Appendix B: Discovery of Arm Architecture Service functions. Thank you! > Signed-off-by: Weizhao Ouyang <[email protected]> > --- > v3: remove fallback smc call > v2: check SMCCC_ARCH_FEATURES > --- > drivers/firmware/psci.c | 5 ++++- > include/linux/arm-smccc.h | 6 ++++++ > 2 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c > index c6b9efab41..03544d76ed 100644 > --- a/drivers/firmware/psci.c > +++ b/drivers/firmware/psci.c > @@ -135,10 +135,13 @@ 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; > > + if (invoke_psci_fn(ARM_SMCCC_VERSION, 0, 0, 0) < > ARM_SMCCC_VERSION_1_1) > + return 0; > + IMO, to fully comply with SMC Calling Convention version 1.5 we should also check for SMCCC_ARCH_WORKAROUND_1: >From 9 Appendix B: Discovery of Arm Architecture Service functions, Step 2: Determine if Arm Architecture Service function is implemented - Use SMCCC_VERSION to learn whether the calling convention complies to version 1.1 or above. - Use SMCCC_ARCH_FEATURES to query whether the Arm Architecture Service function is implemented on this system <--- we lack of this step > if (psci_method == PSCI_METHOD_HVC) > pdata->invoke_fn = smccc_invoke_hvc; > else > 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__ > -- > 2.39.2 > -- Best regards - Freundliche Grüsse - Meilleures salutations Igor Opaniuk Senior Software Engineer, Embedded & Security E: [email protected] W: www.foundries.io
