[PATCH 2/3] tee: optee: add an RPMI ABI placeholder

[marouene . boubakri]

From: Marouene Boubakri <marouene.boubakri@xxxxxxxxxxx>

On RISC-V there is no SMC Calling Convention: OP-TEE runs in a domain
isolated by the M-mode firmware and is reached through the RISC-V
Platform Management Interface (RPMI), carried on an SBI Message Proxy
(MPXY) channel.

Add the skeleton of an RPMI ABI next to the SMC and FF-A ABIs so that
the build plumbing is in place: an OPTEE_RPMI_ABI option, built when the
MPXY mailbox driver is enabled, rpmi_abi.c and its registration from the
driver core. The transport itself is not implemented yet, so
optee_rpmi_abi_register() fails with -EOPNOTSUPP and the driver keeps
probing through its other ABIs only.

Signed-off-by: Marouene Boubakri <marouene.boubakri@xxxxxxxxxxx>
---
 drivers/tee/optee/Kconfig         |  8 ++++++++
 drivers/tee/optee/Makefile        |  1 +
 drivers/tee/optee/core.c          |  8 ++++++--
 drivers/tee/optee/optee_private.h | 13 +++++++++++++
 drivers/tee/optee/rpmi_abi.c      | 23 +++++++++++++++++++++++
 5 files changed, 51 insertions(+), 2 deletions(-)
 create mode 100644 drivers/tee/optee/rpmi_abi.c

diff --git a/drivers/tee/optee/Kconfig b/drivers/tee/optee/Kconfig
index 50d2051f7f20..0eaedb34673d 100644
--- a/drivers/tee/optee/Kconfig
+++ b/drivers/tee/optee/Kconfig
@@ -9,6 +9,14 @@ config OPTEE
 	  This implements the OP-TEE Trusted Execution Environment (TEE)
 	  driver.
 
+config OPTEE_RPMI_ABI
+	bool
+	depends on OPTEE && RISCV_SBI_MPXY_MBOX
+	default y
+	help
+	  Reach OP-TEE through the RISC-V Platform Management Interface
+	  (RPMI) carried on an SBI Message Proxy (MPXY) channel.
+
 config OPTEE_INSECURE_LOAD_IMAGE
 	bool "Load OP-TEE image as firmware"
 	default n
diff --git a/drivers/tee/optee/Makefile b/drivers/tee/optee/Makefile
index 183cdde1ac04..a588f6f4cb2f 100644
--- a/drivers/tee/optee/Makefile
+++ b/drivers/tee/optee/Makefile
@@ -9,6 +9,7 @@ optee-objs += supp.o
 optee-objs += device.o
 optee-$(CONFIG_HAVE_ARM_SMCCC) += smc_abi.o
 optee-$(CONFIG_ARM_FFA_TRANSPORT) += ffa_abi.o
+optee-$(CONFIG_OPTEE_RPMI_ABI) += rpmi_abi.o
 
 # for tracing framework to find optee_trace.h
 CFLAGS_smc_abi.o := -I$(src)
diff --git a/drivers/tee/optee/core.c b/drivers/tee/optee/core.c
index a52c1f498b99..42a8bcab0cb8 100644
--- a/drivers/tee/optee/core.c
+++ b/drivers/tee/optee/core.c
@@ -220,6 +220,7 @@ void optee_remove_common(struct optee *optee)
 
 static int smc_abi_rc;
 static int ffa_abi_rc;
+static int rpmi_abi_rc;
 static bool intf_is_regged;
 
 static int __init optee_core_init(void)
@@ -245,9 +246,10 @@ static int __init optee_core_init(void)
 
 	smc_abi_rc = optee_smc_abi_register();
 	ffa_abi_rc = optee_ffa_abi_register();
+	rpmi_abi_rc = optee_rpmi_abi_register();
 
-	/* If both failed there's no point with this module */
-	if (smc_abi_rc && ffa_abi_rc) {
+	/* If all failed there's no point with this module */
+	if (smc_abi_rc && ffa_abi_rc && rpmi_abi_rc) {
 		if (IS_REACHABLE(CONFIG_RPMB)) {
 			rpmb_interface_unregister(&rpmb_class_intf);
 			intf_is_regged = false;
@@ -268,6 +270,8 @@ static void __exit optee_core_exit(void)
 
 	if (!smc_abi_rc)
 		optee_smc_abi_unregister();
+	if (!rpmi_abi_rc)
+		optee_rpmi_abi_unregister();
 	if (!ffa_abi_rc)
 		optee_ffa_abi_unregister();
 }
diff --git a/drivers/tee/optee/optee_private.h b/drivers/tee/optee/optee_private.h
index 94a4f251f5cf..5b57d69f1f34 100644
--- a/drivers/tee/optee/optee_private.h
+++ b/drivers/tee/optee/optee_private.h
@@ -463,5 +463,18 @@ static inline void optee_ffa_abi_unregister(void)
 {
 }
 #endif
+#if IS_ENABLED(CONFIG_OPTEE_RPMI_ABI)
+int optee_rpmi_abi_register(void);
+void optee_rpmi_abi_unregister(void);
+#else
+static inline int optee_rpmi_abi_register(void)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void optee_rpmi_abi_unregister(void)
+{
+}
+#endif
 
 #endif /*OPTEE_PRIVATE_H*/
diff --git a/drivers/tee/optee/rpmi_abi.c b/drivers/tee/optee/rpmi_abi.c
new file mode 100644
index 000000000000..01d08892eb55
--- /dev/null
+++ b/drivers/tee/optee/rpmi_abi.c
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2026 NXP
+ *
+ * OP-TEE ABI over the RISC-V Platform Management Interface (RPMI),
+ * carried on an SBI Message Proxy (MPXY) channel.
+ *
+ * This is a placeholder: the transport is not implemented yet, so the
+ * ABI never registers and the driver only probes through its other ABIs.
+ */
+
+#include <linux/errno.h>
+
+#include "optee_private.h"
+
+int optee_rpmi_abi_register(void)
+{
+	return -EOPNOTSUPP;
+}
+
+void optee_rpmi_abi_unregister(void)
+{
+}
-- 
2.43.0