Subject: [PATCH for-stable-v4.4 14/53] firmware/psci: Expose SMCCC version through psci_ops

From: Ard Biesheuvel <[email-masked]>
Date: Tue, 5 Nov 2019 21:58:07 +0100

From: Mark Rutland <[email-masked]>

From: Marc Zyngier <[email-masked]>

commit e78eef554a912ef6c1e0bbf97619dafbeae3339f upstream.

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.

Acked-by: Lorenzo Pieralisi <[email-masked]>
Reviewed-by: Robin Murphy <[email-masked]>
Tested-by: Ard Biesheuvel <[email-masked]>
Signed-off-by: Marc Zyngier <[email-masked]>
Signed-off-by: Catalin Marinas <[email-masked]>
Signed-off-by: Mark Rutland <[email-masked]> [v4.9 backport]
Tested-by: Greg Hackmann <[email-masked]>
Signed-off-by: Greg Kroah-Hartman <[email-masked]>
Signed-off-by: Ard Biesheuvel <[email-masked]>
---
 drivers/firmware/psci.c | 27 ++++++++++++++++++++
 include/linux/psci.h    |  6 +++++
 2 files changed, 33 insertions(+)

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index eb5f9161ff10..bc3efe6c9279 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -57,6 +57,7 @@ bool psci_tos_resident_on(int cpu)
 
 struct psci_operations psci_ops = {
 	.conduit = PSCI_CONDUIT_NONE,
+	.smccc_version = SMCCC_VERSION_1_0,
 };
 
 typedef unsigned long (psci_fn)(unsigned long, unsigned long,
@@ -339,6 +340,31 @@ 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(void)
+{
+	u32 ver = ARM_SMCCC_VERSION_1_0;
+	int feature;
+
+	feature = psci_features(ARM_SMCCC_VERSION_FUNC_ID);
+
+	if (feature != PSCI_RET_NOT_SUPPORTED) {
+		u32 ret;
+		ret = invoke_psci_fn(ARM_SMCCC_VERSION_FUNC_ID, 0, 0, 0);
+		if (ret == ARM_SMCCC_VERSION_1_1) {
+			psci_ops.smccc_version = SMCCC_VERSION_1_1;
+			ver = ret;
+		}
+	}
+
+	/*
+	 * Conveniently, the SMCCC and PSCI versions are encoded the
+	 * same way. No, this isn't accidental.
+	 */
+	pr_info("SMC Calling Convention v%d.%d\n",
+		PSCI_VERSION_MAJOR(ver), PSCI_VERSION_MINOR(ver));
+
+}
+
 static void __init psci_0_2_set_functions(void)
 {
 	pr_info("Using standard PSCI v0.2 function IDs\n");
@@ -385,6 +411,7 @@ static int __init psci_probe(void)
 	psci_init_migrate();
 
 	if (PSCI_VERSION_MAJOR(ver) >= 1) {
+		psci_init_smccc();
 		psci_init_cpu_suspend();
 		psci_init_system_suspend();
 	}
diff --git a/include/linux/psci.h b/include/linux/psci.h
index 864cdede8d15..f78438214a59 100644
--- a/include/linux/psci.h
+++ b/include/linux/psci.h
@@ -30,6 +30,11 @@ enum psci_conduit {
 	PSCI_CONDUIT_HVC,
 };
 
+enum smccc_version {
+	SMCCC_VERSION_1_0,
+	SMCCC_VERSION_1_1,
+};
+
 struct psci_operations {
 	int (*cpu_suspend)(u32 state, unsigned long entry_point);
 	int (*cpu_off)(u32 state);
@@ -39,6 +44,7 @@ struct psci_operations {
 			unsigned long lowest_affinity_level);
 	int (*migrate_info_type)(void);
 	enum psci_conduit conduit;
+	enum smccc_version smccc_version;
 };
 
 extern struct psci_operations psci_ops;
-- 
2.17.1

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