[PATCH 13/14] firmware/psci: Expose SMCCC version through psci_ops

[Marc Zyngier <marc.zyngier@arm.com>]

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 <marc.zyngier@arm.com>
---
 drivers/firmware/psci.c | 22 ++++++++++++++++++++++
 include/linux/psci.h    |  6 ++++++
 2 files changed, 28 insertions(+)

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index 570187e5d084..b260bbf637a2 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -509,6 +509,27 @@ 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 ||
+	    (PSCI_VERSION_MAJOR(ver) == 1 && PSCI_VERSION_MINOR(ver) >= 0))
+		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");
@@ -555,6 +576,7 @@ static int __init psci_probe(void)
 	psci_0_2_set_functions();
 
 	psci_init_migrate();
+	psci_init_smccc(ver);
 
 	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;
 };
 
 extern struct psci_operations psci_ops;
-- 
2.14.2