diff --git a/include/lib/sprt/sprt_common.h b/include/lib/sprt/sprt_common.h
new file mode 100644
index 0000000..27d5027
--- /dev/null
+++ b/include/lib/sprt/sprt_common.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2018, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef SPRT_COMMON_H
+#define SPRT_COMMON_H
+
+#define SPRT_MAX_MSG_ARGS	6
+
+/*
+ * Message types supported.
+ */
+#define SPRT_MSG_TYPE_SERVICE_HANDLE_OPEN		1
+#define SPRT_MSG_TYPE_SERVICE_HANDLE_CLOSE		2
+/* TODO: Add other types of SPRT messages. */
+#define SPRT_MSG_TYPE_SERVICE_TUN_REQUEST		10
+
+/*
+ * Struct that defines the layout of the fields corresponding to a request in
+ * shared memory.
+ */
+struct __attribute__((__packed__)) sprt_queue_entry_message {
+	uint32_t type;		/* Type of message (result of an SPCI call). */
+	uint16_t client_id;	/* SPCI client ID */
+	uint16_t service_handle;/* SPCI service handle */
+	uint32_t session_id;	/* Optional SPCI session ID */
+	uint32_t token;		/* SPCI request token */
+	uint64_t args[SPRT_MAX_MSG_ARGS];
+};
+
+#define SPRT_QUEUE_ENTRY_MSG_SIZE	(sizeof(struct sprt_queue_entry_message))
+
+#define SPRT_QUEUE_NUM_BLOCKING		0
+#define SPRT_QUEUE_NUM_NON_BLOCKING	1
+
+#endif /* SPRT_COMMON_H */