diff --git a/mbox.h b/mbox.h
new file mode 100644
index 0000000..f772558
--- /dev/null
+++ b/mbox.h
@@ -0,0 +1,53 @@
+/* Copyright 2016 IBM
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *	Unless required by applicable law or agreed to in writing, software
+ *	distributed under the License is distributed on an "AS IS" BASIS,
+ *	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *	See the License for the specific language governing permissions and
+ *	limitations under the License.
+ *
+ */
+
+#define MBOX_C_RESET_STATE 0x01
+#define MBOX_C_GET_MBOX_INFO 0x02
+#define MBOX_C_GET_FLASH_INFO 0x03
+#define MBOX_C_READ_WINDOW 0x04
+#define MBOX_C_CLOSE_WINDOW 0x05
+#define MBOX_C_WRITE_WINDOW 0x06
+#define MBOX_C_WRITE_DIRTY 0x07
+#define MBOX_C_WRITE_FENCE 0x08
+#define MBOX_C_ACK 0x09
+#define MBOX_C_COMPLETED_COMMANDS 0x0a
+
+#define MBOX_R_SUCCESS 0x01
+#define MBOX_R_PARAM_ERROR 0x02
+#define MBOX_R_WRITE_ERROR 0x03
+#define MBOX_R_SYSTEM_ERROR 0x4
+#define MBOX_R_TIMEOUT 0x05
+
+#define MBOX_HOST_PATH "/dev/aspeed-mbox"
+#define MBOX_HOST_TIMEOUT_SEC 1
+#define MBOX_DATA_BYTES 11
+#define MBOX_REG_BYTES 16
+#define MBOX_HOST_BYTE 14
+#define MBOX_BMC_BYTE 15
+
+struct mbox_msg {
+	uint8_t command;
+	uint8_t seq;
+	uint8_t data[MBOX_DATA_BYTES];
+	uint8_t response;
+};
+
+union mbox_regs {
+	char raw[MBOX_REG_BYTES];
+	struct mbox_msg msg;
+};
+
+