diff --git a/configs/stm32mp15_defconfig b/configs/stm32mp15_defconfig
index 4c6a52f..7b844a3 100644
--- a/configs/stm32mp15_defconfig
+++ b/configs/stm32mp15_defconfig
@@ -77,6 +77,7 @@
 CONFIG_FASTBOOT_CMD_OEM_FORMAT=y
 CONFIG_FASTBOOT_CMD_OEM_PARTCONF=y
 CONFIG_FASTBOOT_CMD_OEM_BOOTBUS=y
+# CONFIG_SCMI_AGENT_MAILBOX is not set
 CONFIG_GPIO_HOG=y
 CONFIG_DM_HWSPINLOCK=y
 CONFIG_HWSPINLOCK_STM32=y
diff --git a/configs/stm32mp15_trusted_defconfig b/configs/stm32mp15_trusted_defconfig
index feca26e..270cbaa 100644
--- a/configs/stm32mp15_trusted_defconfig
+++ b/configs/stm32mp15_trusted_defconfig
@@ -78,6 +78,7 @@
 CONFIG_FASTBOOT_CMD_OEM_FORMAT=y
 CONFIG_FASTBOOT_CMD_OEM_PARTCONF=y
 CONFIG_FASTBOOT_CMD_OEM_BOOTBUS=y
+# CONFIG_SCMI_AGENT_MAILBOX is not set
 CONFIG_GPIO_HOG=y
 CONFIG_DM_HWSPINLOCK=y
 CONFIG_HWSPINLOCK_STM32=y
diff --git a/doc/device-tree-bindings/arm/arm,scmi.txt b/doc/device-tree-bindings/arm/arm,scmi.txt
index a76124f..92572ea 100644
--- a/doc/device-tree-bindings/arm/arm,scmi.txt
+++ b/doc/device-tree-bindings/arm/arm,scmi.txt
@@ -14,7 +14,8 @@
 
 The scmi node with the following properties shall be under the /firmware/ node.
 
-- compatible : shall be "arm,scmi" or "arm,scmi-smc" for smc/hvc transports
+- compatible : shall be "arm,scmi" or "arm,scmi-smc" for smc/hvc transports,
+	  or "linaro,scmi-optee" for OP-TEE transport.
 - mboxes: List of phandle and mailbox channel specifiers. It should contain
 	  exactly one or two mailboxes, one for transmitting messages("tx")
 	  and another optional for receiving the notifications("rx") if
@@ -26,6 +27,8 @@
 - #size-cells : should be '0' as 'reg' property doesn't have any size
 	  associated with it.
 - arm,smc-id : SMC id required when using smc or hvc transports
+- linaro,optee-channel-id : Channel specifier required when using OP-TEE
+	  transport.
 
 Optional properties:
 
@@ -33,16 +36,16 @@
 
 See Documentation/devicetree/bindings/mailbox/mailbox.txt for more details
 about the generic mailbox controller and client driver bindings.
-
-The mailbox is the only permitted method of calling the SCMI firmware.
 Mailbox doorbell is used as a mechanism to alert the presence of a
 messages and/or notification.
 
 Each protocol supported shall have a sub-node with corresponding compatible
 as described in the following sections. If the platform supports dedicated
-communication channel for a particular protocol, the 3 properties namely:
-mboxes, mbox-names and shmem shall be present in the sub-node corresponding
-to that protocol.
+communication channel for a particular protocol, properties shall be present
+in the sub-node corresponding to that protocol. These properties are:
+- mboxes, mbox-names and shmem for mailbox transport
+- arm,smc-id and shmem for smc/hvc transport
+- linaro,optee-channel-id and possibly shmem for OP-TEE transport
 
 Clock/Performance bindings for the clocks/OPPs based on SCMI Message Protocol
 ------------------------------------------------------------
diff --git a/drivers/clk/clk_scmi.c b/drivers/clk/clk_scmi.c
index 93a4819..9a0a6f6 100644
--- a/drivers/clk/clk_scmi.c
+++ b/drivers/clk/clk_scmi.c
@@ -2,6 +2,9 @@
 /*
  * Copyright (C) 2019-2020 Linaro Limited
  */
+
+#define LOG_CATEGORY UCLASS_CLK
+
 #include <common.h>
 #include <clk-uclass.h>
 #include <dm.h>
diff --git a/drivers/firmware/scmi/Kconfig b/drivers/firmware/scmi/Kconfig
index c3a109b..8cf85f0 100644
--- a/drivers/firmware/scmi/Kconfig
+++ b/drivers/firmware/scmi/Kconfig
@@ -2,7 +2,7 @@
 	bool "Enable SCMI support"
 	select FIRMWARE
 	select OF_TRANSLATE
-	depends on SANDBOX || DM_MAILBOX || ARM_SMCCC
+	depends on SANDBOX || DM_MAILBOX || ARM_SMCCC || OPTEE
 	help
 	  System Control and Management Interface (SCMI) is a communication
 	  protocol that defines standard interfaces for power, performance
@@ -14,6 +14,30 @@
 	  or a companion host in the CPU system.
 
 	  Communications between agent (client) and the SCMI server are
-	  based on message exchange. Messages can be exchange over tranport
+	  based on message exchange. Messages can be exchanged over transport
 	  channels as a mailbox device or an Arm SMCCC service with some
 	  piece of identified shared memory.
+
+config SCMI_AGENT_MAILBOX
+	bool "Enable SCMI agent mailbox"
+	depends on SCMI_FIRMWARE && DM_MAILBOX
+	default y
+	help
+	  Enable the SCMI communication channel based on mailbox
+	  for compatible "arm,scmi".
+
+config SCMI_AGENT_SMCCC
+	bool "Enable SCMI agent SMCCC"
+	depends on SCMI_FIRMWARE && ARM_SMCCC
+	default y
+	help
+	  Enable the SCMI communication channel based on Arm SMCCC service for
+	  compatible "arm,scmi-smc".
+
+config SCMI_AGENT_OPTEE
+	bool "Enable SCMI agent OP-TEE"
+	depends on SCMI_FIRMWARE && OPTEE
+	default y
+	help
+	  Enable the SCMI communication channel based on OP-TEE transport
+	  for compatible "linaro,scmi-optee".
diff --git a/drivers/firmware/scmi/Makefile b/drivers/firmware/scmi/Makefile
index 966475e..b2ff483 100644
--- a/drivers/firmware/scmi/Makefile
+++ b/drivers/firmware/scmi/Makefile
@@ -1,5 +1,6 @@
 obj-y	+= scmi_agent-uclass.o
 obj-y	+= smt.o
-obj-$(CONFIG_ARM_SMCCC)		+= smccc_agent.o
-obj-$(CONFIG_DM_MAILBOX)	+= mailbox_agent.o
+obj-$(CONFIG_SCMI_AGENT_SMCCC)		+= smccc_agent.o
+obj-$(CONFIG_SCMI_AGENT_MAILBOX)	+= mailbox_agent.o
+obj-$(CONFIG_SCMI_AGENT_OPTEE)	+= optee_agent.o
 obj-$(CONFIG_SANDBOX)		+= sandbox-scmi_agent.o sandbox-scmi_devices.o
diff --git a/drivers/firmware/scmi/mailbox_agent.c b/drivers/firmware/scmi/mailbox_agent.c
index ea35e7e..8e4af0c 100644
--- a/drivers/firmware/scmi/mailbox_agent.c
+++ b/drivers/firmware/scmi/mailbox_agent.c
@@ -33,7 +33,7 @@
 
 static int scmi_mbox_process_msg(struct udevice *dev, struct scmi_msg *msg)
 {
-	struct scmi_mbox_channel *chan = dev_get_priv(dev);
+	struct scmi_mbox_channel *chan = dev_get_plat(dev);
 	int ret;
 
 	ret = scmi_write_msg_to_smt(dev, &chan->smt, msg);
@@ -62,9 +62,9 @@
 	return ret;
 }
 
-int scmi_mbox_probe(struct udevice *dev)
+int scmi_mbox_of_to_plat(struct udevice *dev)
 {
-	struct scmi_mbox_channel *chan = dev_get_priv(dev);
+	struct scmi_mbox_channel *chan = dev_get_plat(dev);
 	int ret;
 
 	chan->timeout_us = TIMEOUT_US_10MS;
@@ -72,17 +72,13 @@
 	ret = mbox_get_by_index(dev, 0, &chan->mbox);
 	if (ret) {
 		dev_err(dev, "Failed to find mailbox: %d\n", ret);
-		goto out;
+		return ret;
 	}
 
 	ret = scmi_dt_get_smt_buffer(dev, &chan->smt);
 	if (ret)
 		dev_err(dev, "Failed to get shm resources: %d\n", ret);
 
-out:
-	if (ret)
-		devm_kfree(dev, chan);
-
 	return ret;
 }
 
@@ -99,7 +95,7 @@
 	.name		= "scmi-over-mailbox",
 	.id		= UCLASS_SCMI_AGENT,
 	.of_match	= scmi_mbox_ids,
-	.priv_auto	= sizeof(struct scmi_mbox_channel),
-	.probe		= scmi_mbox_probe,
+	.plat_auto	= sizeof(struct scmi_mbox_channel),
+	.of_to_plat	= scmi_mbox_of_to_plat,
 	.ops		= &scmi_mbox_ops,
 };
diff --git a/drivers/firmware/scmi/optee_agent.c b/drivers/firmware/scmi/optee_agent.c
new file mode 100644
index 0000000..1f26592
--- /dev/null
+++ b/drivers/firmware/scmi/optee_agent.c
@@ -0,0 +1,312 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2020-2021 Linaro Limited.
+ */
+
+#define LOG_CATEGORY UCLASS_SCMI_AGENT
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <scmi_agent.h>
+#include <scmi_agent-uclass.h>
+#include <string.h>
+#include <tee.h>
+#include <asm/types.h>
+#include <dm/device_compat.h>
+#include <dm/devres.h>
+#include <linux/arm-smccc.h>
+#include <linux/bug.h>
+#include <linux/compat.h>
+
+#include "smt.h"
+
+#define SCMI_SHM_SIZE		128
+
+/**
+ * struct scmi_optee_channel - Description of an SCMI OP-TEE transport
+ * @channel_id:		Channel identifier
+ * @smt:		Shared memory buffer with synchronisation protocol
+ * @dyn_shm:		True if using dynamically allocated shared memory
+ */
+struct scmi_optee_channel {
+	unsigned int channel_id;
+	struct scmi_smt smt;
+	bool dyn_shm;
+};
+
+/**
+ * struct channel_session - Aggreates SCMI service session context references
+ * @tee:		OP-TEE device to invoke
+ * @tee_session:	OP-TEE session identifier
+ * @tee_shm:		Dynamically allocated OP-TEE shared memory, or NULL
+ * @channel_hdl:	Channel handle provided by OP-TEE SCMI service
+ */
+struct channel_session {
+	struct udevice *tee;
+	u32 tee_session;
+	struct tee_shm *tee_shm;
+	u32 channel_hdl;
+};
+
+#define TA_SCMI_UUID { 0xa8cfe406, 0xd4f5, 0x4a2e, \
+		      { 0x9f, 0x8d, 0xa2, 0x5d, 0xc7, 0x54, 0xc0, 0x99 } }
+
+enum optee_smci_pta_cmd {
+	/*
+	 * PTA_SCMI_CMD_CAPABILITIES - Get channel capabilities
+	 *
+	 * [out]    value[0].a: Capability bit mask (enum pta_scmi_caps)
+	 * [out]    value[0].b: Extended capabilities or 0
+	 */
+	PTA_SCMI_CMD_CAPABILITIES = 0,
+
+	/*
+	 * PTA_SCMI_CMD_PROCESS_SMT_CHANNEL - Process SCMI message in SMT buffer
+	 *
+	 * [in]     value[0].a: Channel handle
+	 *
+	 * Shared memory used for SCMI message/response exhange is expected
+	 * already identified and bound to channel handle in both SCMI agent
+	 * and SCMI server (OP-TEE) parts.
+	 * The memory uses SMT header to carry SCMI meta-data (protocol ID and
+	 * protocol message ID).
+	 */
+	PTA_SCMI_CMD_PROCESS_SMT_CHANNEL = 1,
+
+	/*
+	 * PTA_SCMI_CMD_PROCESS_SMT_CHANNEL_MESSAGE - Process SMT/SCMI message
+	 *
+	 * [in]     value[0].a: Channel handle
+	 * [in/out] memref[1]: Message/response buffer (SMT and SCMI payload)
+	 *
+	 * Shared memory used for SCMI message/response is a SMT buffer
+	 * referenced by param[1]. It shall be 128 bytes large to fit response
+	 * payload whatever message playload size.
+	 * The memory uses SMT header to carry SCMI meta-data (protocol ID and
+	 * protocol message ID).
+	 */
+	PTA_SCMI_CMD_PROCESS_SMT_CHANNEL_MESSAGE = 2,
+
+	/*
+	 * PTA_SCMI_CMD_GET_CHANNEL - Get channel handle
+	 *
+	 * SCMI shm information are 0 if agent expects to use OP-TEE regular SHM
+	 *
+	 * [in]     value[0].a: Channel identifier
+	 * [out]    value[0].a: Returned channel handle
+	 * [in]     value[0].b: Requested capabilities mask (enum pta_scmi_caps)
+	 */
+	PTA_SCMI_CMD_GET_CHANNEL = 3,
+};
+
+/*
+ * OP-TEE SCMI service capabilities bit flags (32bit)
+ *
+ * PTA_SCMI_CAPS_SMT_HEADER
+ * When set, OP-TEE supports command using SMT header protocol (SCMI shmem) in
+ * shared memory buffers to carry SCMI protocol synchronisation information.
+ */
+#define PTA_SCMI_CAPS_NONE		0
+#define PTA_SCMI_CAPS_SMT_HEADER	BIT(0)
+
+static int open_channel(struct udevice *dev, struct channel_session *sess)
+{
+	const struct tee_optee_ta_uuid uuid = TA_SCMI_UUID;
+	struct scmi_optee_channel *chan = dev_get_plat(dev);
+	struct tee_open_session_arg sess_arg = { };
+	struct tee_invoke_arg cmd_arg = { };
+	struct tee_param param[1] = { };
+	int ret;
+
+	memset(sess, 0, sizeof(sess));
+
+	sess->tee = tee_find_device(NULL, NULL, NULL, NULL);
+	if (!sess->tee)
+		return -ENODEV;
+
+	sess_arg.clnt_login = TEE_LOGIN_REE_KERNEL;
+	tee_optee_ta_uuid_to_octets(sess_arg.uuid, &uuid);
+
+	ret = tee_open_session(sess->tee, &sess_arg, 0, NULL);
+	if (ret) {
+		dev_err(dev, "can't open session: %d\n", ret);
+		return ret;
+	}
+
+	cmd_arg.func = PTA_SCMI_CMD_GET_CHANNEL;
+	cmd_arg.session = sess_arg.session;
+
+	param[0].attr = TEE_PARAM_ATTR_TYPE_VALUE_INOUT;
+	param[0].u.value.a = chan->channel_id;
+	param[0].u.value.b = PTA_SCMI_CAPS_SMT_HEADER;
+
+	ret = tee_invoke_func(sess->tee, &cmd_arg, ARRAY_SIZE(param), param);
+	if (ret || cmd_arg.ret) {
+		dev_err(dev, "Invoke failed: %d, 0x%x\n", ret, cmd_arg.ret);
+		if (!ret)
+			ret = -EPROTO;
+
+		tee_close_session(sess->tee, sess_arg.session);
+		return ret;
+	}
+
+	sess->tee_session = sess_arg.session;
+	sess->channel_hdl = param[0].u.value.a;
+
+	return 0;
+}
+
+static void close_channel(struct channel_session *sess)
+{
+	tee_close_session(sess->tee, sess->tee_session);
+}
+
+static int invoke_cmd(struct udevice *dev, struct channel_session *sess,
+		      struct scmi_msg *msg)
+{
+	struct scmi_optee_channel *chan = dev_get_plat(dev);
+	struct tee_invoke_arg arg = { };
+	struct tee_param param[2] = { };
+	int ret;
+
+	scmi_write_msg_to_smt(dev, &chan->smt, msg);
+
+	arg.session = sess->tee_session;
+	param[0].attr = TEE_PARAM_ATTR_TYPE_VALUE_INPUT;
+	param[0].u.value.a = sess->channel_hdl;
+
+	if (chan->dyn_shm) {
+		arg.func = PTA_SCMI_CMD_PROCESS_SMT_CHANNEL_MESSAGE;
+		param[1].attr = TEE_PARAM_ATTR_TYPE_MEMREF_INOUT;
+		param[1].u.memref.shm = sess->tee_shm;
+		param[1].u.memref.size = SCMI_SHM_SIZE;
+	} else {
+		arg.func = PTA_SCMI_CMD_PROCESS_SMT_CHANNEL;
+	}
+
+	ret = tee_invoke_func(sess->tee, &arg, ARRAY_SIZE(param), param);
+	if (ret || arg.ret) {
+		if (!ret)
+			ret = -EPROTO;
+	} else {
+		ret = scmi_read_resp_from_smt(dev, &chan->smt, msg);
+	}
+
+	scmi_clear_smt_channel(&chan->smt);
+
+	return ret;
+}
+
+static int prepare_shm(struct udevice *dev, struct channel_session *sess)
+{
+	struct scmi_optee_channel *chan = dev_get_plat(dev);
+	int ret;
+
+	/* Static shm is already prepared by the firmware: nothing to do */
+	if (!chan->dyn_shm)
+		return 0;
+
+	chan->smt.size = SCMI_SHM_SIZE;
+
+	ret = tee_shm_alloc(sess->tee, chan->smt.size, 0, &sess->tee_shm);
+	if (ret) {
+		dev_err(dev, "Failed to allocated shmem: %d\n", ret);
+		return ret;
+	}
+
+	chan->smt.buf = sess->tee_shm->addr;
+
+	/* Initialize shm buffer for message exchanges */
+	scmi_clear_smt_channel(&chan->smt);
+
+	return 0;
+}
+
+static void release_shm(struct udevice *dev, struct channel_session *sess)
+{
+	struct scmi_optee_channel *chan = dev_get_plat(dev);
+
+	if (chan->dyn_shm)
+		tee_shm_free(sess->tee_shm);
+}
+
+static int scmi_optee_process_msg(struct udevice *dev, struct scmi_msg *msg)
+{
+	struct channel_session sess;
+	int ret;
+
+	ret = open_channel(dev, &sess);
+	if (ret)
+		return ret;
+
+	ret = prepare_shm(dev, &sess);
+	if (ret)
+		goto out;
+
+	ret = invoke_cmd(dev, &sess, msg);
+
+	release_shm(dev, &sess);
+
+out:
+	close_channel(&sess);
+
+	return ret;
+}
+
+static int scmi_optee_of_to_plat(struct udevice *dev)
+{
+	struct scmi_optee_channel *chan = dev_get_plat(dev);
+	int ret;
+
+	if (dev_read_u32(dev, "linaro,optee-channel-id", &chan->channel_id)) {
+		dev_err(dev, "Missing property linaro,optee-channel-id\n");
+		return -EINVAL;
+	}
+
+	if (dev_read_prop(dev, "shmem", NULL)) {
+		ret = scmi_dt_get_smt_buffer(dev, &chan->smt);
+		if (ret) {
+			dev_err(dev, "Failed to get smt resources: %d\n", ret);
+			return ret;
+		}
+		chan->dyn_shm = false;
+	} else {
+		chan->dyn_shm = true;
+	}
+
+	return 0;
+}
+
+static int scmi_optee_probe(struct udevice *dev)
+{
+	struct channel_session sess;
+	int ret;
+
+	/* Check OP-TEE service acknowledges the SCMI channel */
+	ret = open_channel(dev, &sess);
+	if (!ret)
+		close_channel(&sess);
+
+	return ret;
+}
+
+static const struct udevice_id scmi_optee_ids[] = {
+	{ .compatible = "linaro,scmi-optee" },
+	{ }
+};
+
+static const struct scmi_agent_ops scmi_optee_ops = {
+	.process_msg = scmi_optee_process_msg,
+};
+
+U_BOOT_DRIVER(scmi_optee) = {
+	.name		= "scmi-over-optee",
+	.id		= UCLASS_SCMI_AGENT,
+	.of_match	= scmi_optee_ids,
+	.plat_auto	= sizeof(struct scmi_optee_channel),
+	.of_to_plat	= scmi_optee_of_to_plat,
+	.probe		= scmi_optee_probe,
+	.flags		= DM_FLAG_OS_PREPARE,
+	.ops		= &scmi_optee_ops,
+};
diff --git a/drivers/firmware/scmi/smccc_agent.c b/drivers/firmware/scmi/smccc_agent.c
index f185891..5e166ca 100644
--- a/drivers/firmware/scmi/smccc_agent.c
+++ b/drivers/firmware/scmi/smccc_agent.c
@@ -32,7 +32,7 @@
 
 static int scmi_smccc_process_msg(struct udevice *dev, struct scmi_msg *msg)
 {
-	struct scmi_smccc_channel *chan = dev_get_priv(dev);
+	struct scmi_smccc_channel *chan = dev_get_plat(dev);
 	struct arm_smccc_res res;
 	int ret;
 
@@ -51,9 +51,9 @@
 	return ret;
 }
 
-static int scmi_smccc_probe(struct udevice *dev)
+static int scmi_smccc_of_to_plat(struct udevice *dev)
 {
-	struct scmi_smccc_channel *chan = dev_get_priv(dev);
+	struct scmi_smccc_channel *chan = dev_get_plat(dev);
 	u32 func_id;
 	int ret;
 
@@ -65,12 +65,10 @@
 	chan->func_id = func_id;
 
 	ret = scmi_dt_get_smt_buffer(dev, &chan->smt);
-	if (ret) {
+	if (ret)
 		dev_err(dev, "Failed to get smt resources: %d\n", ret);
-		return ret;
-	}
 
-	return 0;
+	return ret;
 }
 
 static const struct udevice_id scmi_smccc_ids[] = {
@@ -86,7 +84,7 @@
 	.name		= "scmi-over-smccc",
 	.id		= UCLASS_SCMI_AGENT,
 	.of_match	= scmi_smccc_ids,
-	.priv_auto	= sizeof(struct scmi_smccc_channel),
-	.probe		= scmi_smccc_probe,
+	.plat_auto	= sizeof(struct scmi_smccc_channel),
+	.of_to_plat	= scmi_smccc_of_to_plat,
 	.ops		= &scmi_smccc_ops,
 };
diff --git a/drivers/power/regulator/scmi_regulator.c b/drivers/power/regulator/scmi_regulator.c
index b3142bf..3ddeaf4 100644
--- a/drivers/power/regulator/scmi_regulator.c
+++ b/drivers/power/regulator/scmi_regulator.c
@@ -2,6 +2,9 @@
 /*
  * Copyright (C) 2020-2021 Linaro Limited
  */
+
+#define LOG_CATEGORY UCLASS_REGULATOR
+
 #include <common.h>
 #include <dm.h>
 #include <errno.h>
diff --git a/drivers/reset/reset-scmi.c b/drivers/reset/reset-scmi.c
index 1bff807..ca0135a 100644
--- a/drivers/reset/reset-scmi.c
+++ b/drivers/reset/reset-scmi.c
@@ -2,6 +2,9 @@
 /*
  * Copyright (C) 2019-2020 Linaro Limited
  */
+
+#define LOG_CATEGORY UCLASS_RESET
+
 #include <common.h>
 #include <dm.h>
 #include <errno.h>
diff --git a/drivers/tee/optee/optee_msg.h b/drivers/tee/optee/optee_msg.h
index 8d40ce6..a8ef926 100644
--- a/drivers/tee/optee/optee_msg.h
+++ b/drivers/tee/optee/optee_msg.h
@@ -87,16 +87,6 @@
 #define OPTEE_MSG_ATTR_CACHE_PREDEFINED		0
 
 /*
- * Same values as TEE_LOGIN_* from TEE Internal API
- */
-#define OPTEE_MSG_LOGIN_PUBLIC			0x00000000
-#define OPTEE_MSG_LOGIN_USER			0x00000001
-#define OPTEE_MSG_LOGIN_GROUP			0x00000002
-#define OPTEE_MSG_LOGIN_APPLICATION		0x00000004
-#define OPTEE_MSG_LOGIN_APPLICATION_USER	0x00000005
-#define OPTEE_MSG_LOGIN_APPLICATION_GROUP	0x00000006
-
-/*
  * Page size used in non-contiguous buffer entries
  */
 #define OPTEE_MSG_NONCONTIG_PAGE_SIZE		4096
@@ -279,7 +269,7 @@
  * parameters to pass the following information:
  * param[0].u.value.a-b uuid of Trusted Application
  * param[1].u.value.a-b uuid of Client
- * param[1].u.value.c Login class of client OPTEE_MSG_LOGIN_*
+ * param[1].u.value.c Login class of client TEE_LOGIN_*
  *
  * OPTEE_MSG_CMD_INVOKE_COMMAND invokes a command a previously opened
  * session to a Trusted Application.  struct optee_msg_arg::func is Trusted
diff --git a/include/scmi_agent.h b/include/scmi_agent.h
index f1be9ff..ed40c73 100644
--- a/include/scmi_agent.h
+++ b/include/scmi_agent.h
@@ -45,9 +45,9 @@
 	}
 
 /**
- * scmi_send_and_process_msg() - send and process a SCMI message
+ * devm_scmi_process_msg() - Send and process an SCMI message
  *
- * Send a message to a SCMI server through a target SCMI agent device.
+ * Send a message to an SCMI server through a target SCMI agent device.
  * Caller sets scmi_msg::out_msg_sz to the output message buffer size.
  * On return, scmi_msg::out_msg_sz stores the response payload size.
  *
diff --git a/include/tee.h b/include/tee.h
index 44e9cd4..5005149 100644
--- a/include/tee.h
+++ b/include/tee.h
@@ -32,6 +32,25 @@
 						 TEE_PARAM_ATTR_META)
 
 /*
+ * Global Platform login identifiers for tee_open_session_arg::clnt_login
+ */
+#define TEE_LOGIN_PUBLIC                  0x00000000
+#define TEE_LOGIN_USER                    0x00000001
+#define TEE_LOGIN_GROUP                   0x00000002
+#define TEE_LOGIN_APPLICATION             0x00000004
+#define TEE_LOGIN_APPLICATION_USER        0x00000005
+#define TEE_LOGIN_APPLICATION_GROUP       0x00000006
+/*
+ * Reserve use of GP implementation specific login method range
+ * (0x80000000 - 0xBFFFFFFF). This range is rather being used
+ * for REE kernel clients or TEE implementation.
+ */
+#define TEE_LOGIN_REE_KERNEL_MIN          0x80000000
+#define TEE_LOGIN_REE_KERNEL_MAX          0xBFFFFFFF
+/* Private login method for REE kernel/privileged clients */
+#define TEE_LOGIN_REE_KERNEL              0x80000000
+
+/*
  * Some Global Platform error codes which has a meaning if the
  * TEE_GEN_CAP_GP bit is returned by the driver in
  * struct tee_version_data::gen_caps
@@ -45,6 +64,7 @@
 #define TEE_ERROR_NOT_SUPPORTED		0xffff000a
 #define TEE_ERROR_COMMUNICATION		0xffff000e
 #define TEE_ERROR_SECURITY		0xffff000f
+#define TEE_ERROR_SHORT_BUFFER		0xffff0010
 #define TEE_ERROR_OUT_OF_MEMORY		0xffff000c
 #define TEE_ERROR_OVERFLOW              0xffff300f
 #define TEE_ERROR_TARGET_DEAD		0xffff3024
@@ -135,8 +155,8 @@
 /**
  * struct tee_open_session_arg - extra arguments for tee_open_session()
  * @uuid:	[in] UUID of the Trusted Application
- * @clnt_uuid:	[in] Normally zeroes
- * @clnt_login:	[in] Normally 0
+ * @clnt_uuid:	[in] UUID of client, zeroes for PUBLIC/REE_KERNEL
+ * @clnt_login:	[in] Class of client TEE_LOGIN_*
  * @session:	[out] Session id
  * @ret:	[out] return value
  * @ret_origin:	[out] origin of the return value