Re: [PATCH v3 14/18] firmware/psci: Expose SMCCC version through psci_ops

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On 01/02/18 11:46, Marc Zyngier wrote:
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 <lorenzo.pieralisi@xxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
  drivers/firmware/psci.c | 19 +++++++++++++++++++
  include/linux/psci.h    |  6 ++++++
  2 files changed, 25 insertions(+)

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index e9493da2b111..8631906c414c 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -61,6 +61,7 @@ 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,
@@ -511,6 +512,23 @@ 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;
+
+	feature = psci_features(ARM_SMCCC_VERSION_FUNC_ID);
+
+	if (feature != PSCI_RET_NOT_SUPPORTED) {
+		ver = invoke_psci_fn(ARM_SMCCC_VERSION_FUNC_ID, 0, 0, 0);
+		if (ver != ARM_SMCCC_VERSION_1_1)
+			psci_ops.smccc_version = SMCCC_VERSION_1_0;

AFAICS, unless you somehow run psci_probe() twice *and* have schizophrenic firmware, this assignment now does precisely nothing.

With the condition flipped and the redundant else case removed (or an explanation of why I'm wrong...)

Reviewed-by: Robin Murphy <robin.murphy@xxxxxxx>

+		else
+			psci_ops.smccc_version = SMCCC_VERSION_1_1;
+	}
+
+	pr_info("SMC Calling Convention v1.%d\n", psci_ops.smccc_version);
+}
+
  static void __init psci_0_2_set_functions(void)
  {
  	pr_info("Using standard PSCI v0.2 function IDs\n");
@@ -559,6 +577,7 @@ static int __init psci_probe(void)
  	psci_init_migrate();
if (PSCI_VERSION_MAJOR(ver) >= 1) {
+		psci_init_smccc(ver);
  		psci_init_cpu_suspend();
  		psci_init_system_suspend();
  	}
diff --git a/include/linux/psci.h b/include/linux/psci.h
index f2679e5faa4f..8b1b3b5935ab 100644
--- a/include/linux/psci.h
+++ b/include/linux/psci.h
@@ -31,6 +31,11 @@ enum psci_conduit {
  	PSCI_CONDUIT_HVC,
  };
+enum smccc_version {
+	SMCCC_VERSION_1_0,
+	SMCCC_VERSION_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_version smccc_version;
  };
extern struct psci_operations psci_ops;

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