tee: optee: report OP-TEE revision information

When the driver initializes, report the following information
about the OP-TEE OS:
- major and minor version,
- build identifier (if available).
Signed-off-by: Jerome Forissier <jerome.forissier@linaro.org>
Reviewed-by: Matthias Brugger <mbruger@suse.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

drivers/tee/optee/core.c

@@ -356,6 +356,27 @@ static bool optee_msg_api_uid_is_optee_api(optee_invoke_fn *invoke_fn)
 	return false;
 }
 
+static void optee_msg_get_os_revision(optee_invoke_fn *invoke_fn)
+{
+	union {
+		struct arm_smccc_res smccc;
+		struct optee_smc_call_get_os_revision_result result;
+	} res = {
+		.result = {
+			.build_id = 0
+		}
+	};
+
+	invoke_fn(OPTEE_SMC_CALL_GET_OS_REVISION, 0, 0, 0, 0, 0, 0, 0,
+		  &res.smccc);
+
+	if (res.result.build_id)
+		pr_info("revision %lu.%lu (%08lx)", res.result.major,
+			res.result.minor, res.result.build_id);
+	else
+		pr_info("revision %lu.%lu", res.result.major, res.result.minor);
+}
+
 static bool optee_msg_api_revision_is_compatible(optee_invoke_fn *invoke_fn)
 {
 	union {
@@ -547,6 +568,8 @@ static struct optee *optee_probe(struct device_node *np)
 		return ERR_PTR(-EINVAL);
 	}
 
+	optee_msg_get_os_revision(invoke_fn);
+
 	if (!optee_msg_api_revision_is_compatible(invoke_fn)) {
 		pr_warn("api revision mismatch\n");
 		return ERR_PTR(-EINVAL);