[PATCH 1/4] arm/arm64: smccc/psci: add arm_smccc_get_conduit()

[Mark Rutland]

SMCCC callers are currently amassing a collection of enums for the SMCCC
conduit, and are having to dig into the PSCI driver's internals in order
to figure out what to do.

Let's clean this up, with common SMCCC_CONDUIT_* definitions, and an
arm_smccc_get_conduit() helper that abstracts the PSCI driver's internal
state.

We can kill off the PSCI_CONDUIT_* definitions once we've migrated users
over to the nerw interface.

Signed-off-by: Mark Rutland <mark.rutland at arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
Cc: Will Deacon <will.deacon at arm.com>
Cc: Catalin Marinas <catalin.marinas at arm.com>
---
 drivers/firmware/psci.c   | 15 +++++++++++++++
 include/linux/arm-smccc.h | 16 ++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index c80ec1d03274..310882185ca4 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -64,6 +64,21 @@ struct psci_operations psci_ops = {
 	.smccc_version = SMCCC_VERSION_1_0,
 };
 
+enum arm_smccc_conduit arm_smccc_get_conduit(void)
+{
+	if (psci_ops.smccc_version < SMCCC_VERSION_1_1)
+		return SMCCC_CONDUIT_NONE;
+
+	switch (psci_ops.conduit) {
+	case PSCI_CONDUIT_SMC:
+		return SMCCC_CONDUIT_SMC;
+	case PSCI_CONDUIT_HVC:
+		return SMCCC_CONDUIT_HVC;
+	default:
+		return SMCCC_CONDUIT_NONE;
+	}
+}
+
 typedef unsigned long (psci_fn)(unsigned long, unsigned long,
 				unsigned long, unsigned long);
 static psci_fn *invoke_psci_fn;
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index a031897fca76..193e9d8a1ac2 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -84,6 +84,22 @@
 
 #include <linux/linkage.h>
 #include <linux/types.h>
+
+enum arm_smccc_conduit {
+	SMCCC_CONDUIT_NONE,
+	SMCCC_CONDUIT_SMC,
+	SMCCC_CONDUIT_HVC,
+};
+
+/**
+ * arm_smccc_get_conduit()
+ *
+ * Returns the conduit to be used for SMCCCv1.1 or later.
+ *
+ * When SMCCCv1.1 is not present, returns SMCCC_CONDUIT_NONE.
+ */
+enum arm_smccc_conduit arm_smccc_get_conduit(void);
+
 /**
  * struct arm_smccc_res - Result from SMC/HVC call
  * @a0-a3 result values from registers 0 to 3
-- 
2.11.0