diff --git a/drivers/st/scmi-msg/base.c b/drivers/st/scmi-msg/base.c
new file mode 100644
index 0000000..e44bc52
--- /dev/null
+++ b/drivers/st/scmi-msg/base.c
@@ -0,0 +1,198 @@
+// SPDX-License-Identifier: BSD-3-Clause
+/*
+ * Copyright (c) 2015-2019, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2019-2020, Linaro Limited
+ */
+#include <assert.h>
+#include <string.h>
+
+#include <drivers/st/scmi-msg.h>
+#include <drivers/st/scmi.h>
+#include <lib/utils.h>
+#include <lib/utils_def.h>
+
+#include "common.h"
+
+static bool message_id_is_supported(unsigned int message_id);
+
+static void report_version(struct scmi_msg *msg)
+{
+	struct scmi_protocol_version_p2a return_values = {
+		.status = SCMI_SUCCESS,
+		.version = SCMI_PROTOCOL_VERSION_BASE,
+	};
+
+	if (msg->in_size != 0U) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	scmi_write_response(msg, &return_values, sizeof(return_values));
+}
+
+static void report_attributes(struct scmi_msg *msg)
+{
+	size_t protocol_count = plat_scmi_protocol_count();
+	struct scmi_protocol_attributes_p2a return_values = {
+		.status = SCMI_SUCCESS,
+		/* Null agent count since agent discovery is not supported */
+		.attributes = SCMI_BASE_PROTOCOL_ATTRIBUTES(protocol_count, 0U),
+	};
+
+	if (msg->in_size != 0U) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	scmi_write_response(msg, &return_values, sizeof(return_values));
+}
+
+static void report_message_attributes(struct scmi_msg *msg)
+{
+	struct scmi_protocol_message_attributes_a2p *in_args = (void *)msg->in;
+	struct scmi_protocol_message_attributes_p2a return_values = {
+		.status = SCMI_SUCCESS,
+		/* For this protocol, attributes shall be zero */
+		.attributes = 0U,
+	};
+
+	if (msg->in_size != sizeof(*in_args)) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	if (!message_id_is_supported(in_args->message_id)) {
+		scmi_status_response(msg, SCMI_NOT_FOUND);
+		return;
+	}
+
+	scmi_write_response(msg, &return_values, sizeof(return_values));
+}
+
+static void discover_vendor(struct scmi_msg *msg)
+{
+	const char *name = plat_scmi_vendor_name();
+	struct scmi_base_discover_vendor_p2a return_values = {
+		.status = SCMI_SUCCESS,
+	};
+
+	if (msg->in_size != 0U) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	COPY_NAME_IDENTIFIER(return_values.vendor_identifier, name);
+
+	scmi_write_response(msg, &return_values, sizeof(return_values));
+}
+
+static void discover_sub_vendor(struct scmi_msg *msg)
+{
+	const char *name = plat_scmi_sub_vendor_name();
+	struct scmi_base_discover_sub_vendor_p2a return_values = {
+		.status = SCMI_SUCCESS,
+	};
+
+	if (msg->in_size != 0U) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	COPY_NAME_IDENTIFIER(return_values.sub_vendor_identifier, name);
+
+	scmi_write_response(msg, &return_values, sizeof(return_values));
+}
+
+static void discover_implementation_version(struct scmi_msg *msg)
+{
+	struct scmi_protocol_version_p2a return_values = {
+		.status = SCMI_SUCCESS,
+		.version = SCMI_IMPL_VERSION,
+	};
+
+	if (msg->in_size != 0U) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	scmi_write_response(msg, &return_values, sizeof(return_values));
+}
+
+static unsigned int count_protocols_in_list(const uint8_t *protocol_list)
+{
+	unsigned int count = 0U;
+
+	if (protocol_list != NULL) {
+		while (protocol_list[count] != 0U) {
+			count++;
+		}
+	}
+
+	return count;
+}
+
+#define MAX_PROTOCOL_IN_LIST		8U
+
+static void discover_list_protocols(struct scmi_msg *msg)
+{
+	const struct scmi_base_discover_list_protocols_a2p *a2p = NULL;
+	struct scmi_base_discover_list_protocols_p2a p2a = {
+		.status = SCMI_SUCCESS,
+	};
+	uint8_t outargs[sizeof(p2a) + MAX_PROTOCOL_IN_LIST] = { 0U };
+	const uint8_t *list = NULL;
+	unsigned int count = 0U;
+
+	if (msg->in_size != sizeof(*a2p)) {
+		scmi_status_response(msg, SCMI_PROTOCOL_ERROR);
+		return;
+	}
+
+	assert(msg->out_size > sizeof(outargs));
+
+	a2p = (void *)msg->in;
+
+	list = plat_scmi_protocol_list(msg->agent_id);
+	count = count_protocols_in_list(list);
+	if (count > a2p->skip) {
+		count = MIN(count - a2p->skip, MAX_PROTOCOL_IN_LIST);
+	} else {
+		count = 0U;
+	}
+
+	p2a.num_protocols = count;
+
+	memcpy(outargs, &p2a, sizeof(p2a));
+	memcpy(outargs + sizeof(p2a), list + a2p->skip, count);
+
+	scmi_write_response(msg, outargs, sizeof(outargs));
+}
+
+static const scmi_msg_handler_t scmi_base_handler_table[] = {
+	[SCMI_PROTOCOL_VERSION] = report_version,
+	[SCMI_PROTOCOL_ATTRIBUTES] = report_attributes,
+	[SCMI_PROTOCOL_MESSAGE_ATTRIBUTES] = report_message_attributes,
+	[SCMI_BASE_DISCOVER_VENDOR] = discover_vendor,
+	[SCMI_BASE_DISCOVER_SUB_VENDOR] = discover_sub_vendor,
+	[SCMI_BASE_DISCOVER_IMPLEMENTATION_VERSION] =
+					discover_implementation_version,
+	[SCMI_BASE_DISCOVER_LIST_PROTOCOLS] = discover_list_protocols,
+};
+
+static bool message_id_is_supported(unsigned int message_id)
+{
+	return (message_id < ARRAY_SIZE(scmi_base_handler_table)) &&
+	       (scmi_base_handler_table[message_id] != NULL);
+}
+
+scmi_msg_handler_t scmi_msg_get_base_handler(struct scmi_msg *msg)
+{
+	unsigned int message_id = SPECULATION_SAFE_VALUE(msg->message_id);
+
+	if (message_id >= ARRAY_SIZE(scmi_base_handler_table)) {
+		VERBOSE("Base handle not found %u\n", msg->message_id);
+		return NULL;
+	}
+
+	return scmi_base_handler_table[message_id];
+}
diff --git a/drivers/st/scmi-msg/base.h b/drivers/st/scmi-msg/base.h
new file mode 100644
index 0000000..c4a9c64
--- /dev/null
+++ b/drivers/st/scmi-msg/base.h
@@ -0,0 +1,75 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Copyright (c) 2015-2019, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2019-2020, Linaro Limited
+ */
+
+#ifndef SCMI_MSG_BASE_H
+#define SCMI_MSG_BASE_H
+
+#include <stdint.h>
+
+#define SCMI_PROTOCOL_VERSION_BASE	0x20000U
+
+#define SCMI_DEFAULT_STRING_LENGTH	16U
+
+enum scmi_base_message_id {
+	SCMI_BASE_DISCOVER_VENDOR			= 0x003,
+	SCMI_BASE_DISCOVER_SUB_VENDOR			= 0x004,
+	SCMI_BASE_DISCOVER_IMPLEMENTATION_VERSION	= 0x005,
+	SCMI_BASE_DISCOVER_LIST_PROTOCOLS		= 0x006,
+	SCMI_BASE_DISCOVER_AGENT			= 0x007,
+	SCMI_BASE_NOTIFY_ERRORS				= 0x008,
+};
+
+/*
+ * PROTOCOL_ATTRIBUTES
+ */
+
+#define SCMI_BASE_PROTOCOL_ATTRS_NUM_PROTOCOLS_POS	0
+#define SCMI_BASE_PROTOCOL_ATTRS_NUM_AGENTS_POS		8
+
+#define SCMI_BASE_PROTOCOL_ATTRS_NUM_PROTOCOLS_MASK	0xFFU
+#define SCMI_BASE_PROTOCOL_ATTRS_NUM_AGENTS_MASK	0xFF00U
+
+#define SCMI_BASE_PROTOCOL_ATTRIBUTES(NUM_PROTOCOLS, NUM_AGENTS) \
+	((((NUM_PROTOCOLS) << SCMI_BASE_PROTOCOL_ATTRS_NUM_PROTOCOLS_POS) & \
+	  SCMI_BASE_PROTOCOL_ATTRS_NUM_PROTOCOLS_MASK) | \
+	(((NUM_AGENTS) << SCMI_BASE_PROTOCOL_ATTRS_NUM_AGENTS_POS) & \
+	 SCMI_BASE_PROTOCOL_ATTRS_NUM_AGENTS_MASK))
+
+/*
+ * BASE_DISCOVER_VENDOR
+ */
+struct scmi_base_discover_vendor_p2a {
+	int32_t status;
+	char vendor_identifier[SCMI_DEFAULT_STRING_LENGTH];
+};
+
+/*
+ * BASE_DISCOVER_SUB_VENDOR
+ */
+struct scmi_base_discover_sub_vendor_p2a {
+	int32_t status;
+	char sub_vendor_identifier[SCMI_DEFAULT_STRING_LENGTH];
+};
+
+/*
+ * BASE_DISCOVER_IMPLEMENTATION_VERSION
+ * No special structure right now, see protocol_version.
+ */
+
+/*
+ * BASE_DISCOVER_LIST_PROTOCOLS
+ */
+struct scmi_base_discover_list_protocols_a2p {
+	uint32_t skip;
+};
+
+struct scmi_base_discover_list_protocols_p2a {
+	int32_t status;
+	uint32_t num_protocols;
+	uint32_t protocols[];
+};
+
+#endif /* SCMI_MSG_BASE_H */
diff --git a/drivers/st/scmi-msg/common.h b/drivers/st/scmi-msg/common.h
new file mode 100644
index 0000000..4777dbe
--- /dev/null
+++ b/drivers/st/scmi-msg/common.h
@@ -0,0 +1,120 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Copyright (c) 2015-2019, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2019-2020, Linaro Limited
+ */
+#ifndef SCMI_MSG_COMMON_H
+#define SCMI_MSG_COMMON_H
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "base.h"
+
+#define SCMI_VERSION			0x20000U
+#define SCMI_IMPL_VERSION		0U
+
+#define SCMI_PLAYLOAD_MAX		92U
+
+/*
+ * Copy name identifier in target buffer following the SCMI specification
+ * that state name identifier shall be a null terminated string.
+ */
+#define COPY_NAME_IDENTIFIER(_dst_array, _name)				\
+	do {								\
+		assert(strlen(_name) < sizeof(_dst_array));		\
+		strlcpy((_dst_array), (_name), sizeof(_dst_array));	\
+	} while (0)
+
+/* Common command identifiers shared by all procotols */
+enum scmi_common_message_id {
+	SCMI_PROTOCOL_VERSION = 0x000,
+	SCMI_PROTOCOL_ATTRIBUTES = 0x001,
+	SCMI_PROTOCOL_MESSAGE_ATTRIBUTES = 0x002
+};
+
+/* Common platform-to-agent (p2a) PROTOCOL_VERSION structure */
+struct scmi_protocol_version_p2a {
+	int32_t status;
+	uint32_t version;
+};
+
+/* Generic platform-to-agent (p2a) PROTOCOL_ATTRIBUTES structure */
+struct scmi_protocol_attributes_p2a {
+	int32_t status;
+	uint32_t attributes;
+};
+
+/* Generic agent-to-platform (a2p) PROTOCOL_MESSAGE_ATTRIBUTES structure */
+struct scmi_protocol_message_attributes_a2p {
+	uint32_t message_id;
+};
+
+/* Generic platform-to-agent (p2a) PROTOCOL_MESSAGE_ATTRIBUTES structure */
+struct scmi_protocol_message_attributes_p2a {
+	int32_t status;
+	uint32_t attributes;
+};
+
+/*
+ * struct scmi_msg - SCMI message context
+ *
+ * @agent_id: SCMI agent ID, safely set from secure world
+ * @protocol_id: SCMI protocol ID for the related message, set by caller agent
+ * @message_id: SCMI message ID for the related message, set by caller agent
+ * @in: Address of the incoming message payload copied in secure memory
+ * @in_size: Byte length of the incoming message payload, set by caller agent
+ * @out: Address of of the output message payload message in non-secure memory
+ * @out_size: Byte length of the provisionned output buffer
+ * @out_size_out: Byte length of the output message payload
+ */
+struct scmi_msg {
+	unsigned int agent_id;
+	unsigned int protocol_id;
+	unsigned int message_id;
+	char *in;
+	size_t in_size;
+	char *out;
+	size_t out_size;
+	size_t out_size_out;
+};
+
+/*
+ * Type scmi_msg_handler_t is used by procotol drivers to safely find
+ * the handler function for the incoming message ID.
+ */
+typedef void (*scmi_msg_handler_t)(struct scmi_msg *msg);
+
+/*
+ * scmi_msg_get_base_handler - Return a handler for a base message
+ * @msg - message to process
+ * Return a function handler for the message or NULL
+ */
+scmi_msg_handler_t scmi_msg_get_base_handler(struct scmi_msg *msg);
+
+/*
+ * Process Read, process and write response for input SCMI message
+ *
+ * @msg: SCMI message context
+ */
+void scmi_process_message(struct scmi_msg *msg);
+
+/*
+ * Write SCMI response payload to output message shared memory
+ *
+ * @msg: SCMI message context
+ * @payload: Output message payload
+ * @size: Byte size of output message payload
+ */
+void scmi_write_response(struct scmi_msg *msg, void *payload, size_t size);
+
+/*
+ * Write status only SCMI response payload to output message shared memory
+ *
+ * @msg: SCMI message context
+ * @status: SCMI status value returned to caller
+ */
+void scmi_status_response(struct scmi_msg *msg, int32_t status);
+#endif /* SCMI_MSG_COMMON_H */
diff --git a/drivers/st/scmi-msg/entry.c b/drivers/st/scmi-msg/entry.c
new file mode 100644
index 0000000..cd62413
--- /dev/null
+++ b/drivers/st/scmi-msg/entry.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: BSD-3-Clause
+/*
+ * Copyright (c) 2015-2020, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2019-2020, Linaro Limited
+ */
+
+#include <assert.h>
+
+#include <drivers/st/scmi-msg.h>
+#include <drivers/st/scmi.h>
+
+#include "common.h"
+
+void scmi_status_response(struct scmi_msg *msg, int32_t status)
+{
+	assert(msg->out && msg->out_size >= sizeof(int32_t));
+
+	memcpy(msg->out, &status, sizeof(int32_t));
+	msg->out_size_out = sizeof(int32_t);
+}
+
+void scmi_write_response(struct scmi_msg *msg, void *payload, size_t size)
+{
+	/*
+	 * Output payload shall be at least the size of the status
+	 * Output buffer shall be at least be the size of the status
+	 * Output paylaod shall fit in output buffer
+	 */
+	assert(payload && size >= sizeof(int32_t) && size <= msg->out_size &&
+	       msg->out && msg->out_size >= sizeof(int32_t));
+
+	memcpy(msg->out, payload, size);
+	msg->out_size_out = size;
+}
+
+void scmi_process_message(struct scmi_msg *msg)
+{
+	scmi_msg_handler_t handler = NULL;
+
+	switch (msg->protocol_id) {
+	case SCMI_PROTOCOL_ID_BASE:
+		handler = scmi_msg_get_base_handler(msg);
+		break;
+	default:
+		break;
+	}
+
+	if (handler) {
+		handler(msg);
+		return;
+	}
+
+	ERROR("Agent %u Protocol 0x%x Message 0x%x: not supported",
+	      msg->agent_id, msg->protocol_id, msg->message_id);
+
+	scmi_status_response(msg, SCMI_NOT_SUPPORTED);
+}
diff --git a/include/drivers/st/scmi-msg.h b/include/drivers/st/scmi-msg.h
new file mode 100644
index 0000000..af683e2
--- /dev/null
+++ b/include/drivers/st/scmi-msg.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Copyright (c) 2015-2019, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2019, Linaro Limited
+ */
+
+#ifndef SCMI_MSG_H
+#define SCMI_MSG_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+/* Minimum size expected for SMT based shared memory message buffers */
+#define SMT_BUF_SLOT_SIZE	128U
+
+/* A channel abstract a communication path between agent and server */
+struct scmi_msg_channel;
+
+/*
+ * struct scmi_msg_channel - Shared memory buffer for a agent-to-server channel
+ *
+ * @shm_addr: Address of the shared memory for the SCMI channel
+ * @shm_size: Byte size of the shared memory for the SCMI channel
+ * @busy: True when channel is busy, flase when channel is free
+ * @agent_name: Agent name, SCMI protocol exposes 16 bytes max, or NULL
+ */
+struct scmi_msg_channel {
+	uintptr_t shm_addr;
+	size_t shm_size;
+	bool busy;
+	const char *agent_name;
+};
+
+/* Platform callback functions */
+
+/*
+ * Return the SCMI channel related to an agent
+ * @agent_id: SCMI agent ID
+ * Return a pointer to channel on success, NULL otherwise
+ */
+struct scmi_msg_channel *plat_scmi_get_channel(unsigned int agent_id);
+
+/*
+ * Return how many SCMI protocols supported by the platform
+ * According to the SCMI specification, this function does not target
+ * a specific agent ID and shall return all platform known capabilities.
+ */
+size_t plat_scmi_protocol_count(void);
+
+/*
+ * Get the count and list of SCMI protocols (but base) supported for an agent
+ *
+ * @agent_id: SCMI agent ID
+ * Return a pointer to a null terminated array supported protocol IDs.
+ */
+const uint8_t *plat_scmi_protocol_list(unsigned int agent_id);
+
+/* Get the name of the SCMI vendor for the platform */
+const char *plat_scmi_vendor_name(void);
+
+/* Get the name of the SCMI sub-vendor for the platform */
+const char *plat_scmi_sub_vendor_name(void);
+
+#endif /* SCMI_MSG_H */
diff --git a/include/drivers/st/scmi.h b/include/drivers/st/scmi.h
new file mode 100644
index 0000000..ac5dc38
--- /dev/null
+++ b/include/drivers/st/scmi.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Copyright (c) 2015-2019, Arm Limited and Contributors. All rights reserved.
+ */
+#ifndef SCMI_MSG_SCMI_H
+#define SCMI_MSG_SCMI_H
+
+#define SCMI_PROTOCOL_ID_BASE			0x10U
+#define SCMI_PROTOCOL_ID_POWER_DOMAIN		0x11U
+#define SCMI_PROTOCOL_ID_SYS_POWER		0x12U
+#define SCMI_PROTOCOL_ID_PERF			0x13U
+#define SCMI_PROTOCOL_ID_CLOCK			0x14U
+#define SCMI_PROTOCOL_ID_SENSOR			0x15U
+#define SCMI_PROTOCOL_ID_RESET_DOMAIN		0x16U
+
+/* SCMI error codes reported to agent through server-to-agent messages */
+#define SCMI_SUCCESS			0
+#define SCMI_NOT_SUPPORTED		(-1)
+#define SCMI_INVALID_PARAMETERS		(-2)
+#define SCMI_DENIED			(-3)
+#define SCMI_NOT_FOUND			(-4)
+#define SCMI_OUT_OF_RANGE		(-5)
+#define SCMI_BUSY			(-6)
+#define SCMI_COMMS_ERROR		(-7)
+#define SCMI_GENERIC_ERROR		(-8)
+#define SCMI_HARDWARE_ERROR		(-9)
+#define SCMI_PROTOCOL_ERROR		(-10)
+
+#endif /* SCMI_MSG_SCMI_H */