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 */