Hello Weizhao,
On Wed, Jan 31, 2024 at 3:15 PM Weizhao Ouyang o451686892@gmail.com 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 o451686892@gmail.com
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; elsediff --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