On 29/01/18 18:39, Lorenzo Pieralisi wrote:

On Mon, Jan 29, 2018 at 05:45:56PM +0000, Marc Zyngier wrote:

quoted

Since PSCI 1.0 allows the SMCCC version to be (indirectly) probed,
let's do that at boot time, and expose the version of the calling
convention as part of the psci_ops structure.

Signed-off-by: Marc Zyngier <redacted>
---
 drivers/firmware/psci.c | 21 +++++++++++++++++++++
 include/linux/psci.h    |  6 ++++++
 2 files changed, 27 insertions(+)

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index e9493da2b111..dd035aaa1c33 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c

@@ -511,6 +511,26 @@ static void __init psci_init_migrate(void)
 	pr_info("Trusted OS resident on physical CPU 0x%lx\n", cpuid);
 }
 
+static void __init psci_init_smccc(u32 ver)
+{
+	int feature = PSCI_RET_NOT_SUPPORTED;
+
+	if (PSCI_VERSION_MAJOR(ver) >= 1)
+		feature = psci_features(ARM_SMCCC_VERSION_FUNC_ID);
+
+	if (feature == PSCI_RET_NOT_SUPPORTED) {
+		psci_ops.variant = SMCCC_VARIANT_1_0;
+	} else {
+		ver = invoke_psci_fn(ARM_SMCCC_VERSION_FUNC_ID, 0, 0, 0);
+		if (ver != ARM_SMCCC_VERSION_1_1)
+			psci_ops.variant = SMCCC_VARIANT_1_0;
+		else
+			psci_ops.variant = SMCCC_VARIANT_1_1;
+	}
+
+	pr_info("SMC Calling Convention v1.%d\n", psci_ops.variant);
+}
+
 static void __init psci_0_2_set_functions(void)
 {
 	pr_info("Using standard PSCI v0.2 function IDs\n");

@@ -557,6 +577,7 @@ static int __init psci_probe(void)
 	psci_0_2_set_functions();
 
 	psci_init_migrate();
+	psci_init_smccc(ver);

Given that SMCCC_VARIANT_1_0 is already the default value (unless you do
the same we did with the conduit) we can move psci_init_smccc() call
inside the if below (that is there to detect a callable psci_features())
and remove the check in psci_init_smccc(), up to you.

Yes, this makes sense.

quoted

 
 	if (PSCI_VERSION_MAJOR(ver) >= 1) {
 		psci_init_cpu_suspend();

diff --git a/include/linux/psci.h b/include/linux/psci.h
index f2679e5faa4f..83fd16a37be3 100644
--- a/include/linux/psci.h
+++ b/include/linux/psci.h

@@ -31,6 +31,11 @@ enum psci_conduit {
 	PSCI_CONDUIT_HVC,
 };
 
+enum smccc_variant {
+	SMCCC_VARIANT_1_0,
+	SMCCC_VARIANT_1_1,
+};
+
 struct psci_operations {
 	u32 (*get_version)(void);
 	int (*cpu_suspend)(u32 state, unsigned long entry_point);

@@ -41,6 +46,7 @@ struct psci_operations {
 			unsigned long lowest_affinity_level);
 	int (*migrate_info_type)(void);
 	enum psci_conduit conduit;
+	enum smccc_variant variant;

Nit: I would add an smccc_ prefix to the variant field (or rename it
to smccc_version).

I've renamed both the field and the enum to smccc_version (as well as
the members of the enum). This is definitely more consistent with the
symbols exposed by arm-smccc.h.

You can add my:

Acked-by: Lorenzo Pieralisi <redacted>

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...