diff --git a/mbox.h b/mbox.h
index f772558..d9a8d03 100644
--- a/mbox.h
+++ b/mbox.h
@@ -1,53 +1,168 @@
-/* Copyright 2016 IBM
+/*
+ * 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
+ * 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.
+ * 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
+#ifndef MBOX_H
+#define MBOX_H
 
-#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
+#include <mtd/mtd-abi.h>
+#include <systemd/sd-bus.h>
 
-#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;
+enum api_version {
+	API_VERSION_INVAL	= 0,
+	API_VERSION_1		= 1,
+	API_VERSION_2		= 2
 };
 
-union mbox_regs {
-	char raw[MBOX_REG_BYTES];
-	struct mbox_msg msg;
+#define API_MIN_VERSION			API_VERSION_1
+#define API_MAX_VERSION			API_VERSION_2
+
+#define THIS_NAME			"Mailbox Daemon"
+#define SUB_VERSION			0
+
+/* Command Values */
+#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_FLUSH		0x08
+#define MBOX_C_ACK			0x09
+#define MBOX_C_WRITE_ERASE		0x0a
+#define NUM_MBOX_CMDS			MBOX_C_WRITE_ERASE
+
+/* Response Values */
+#define MBOX_R_SUCCESS			0x01
+#define MBOX_R_PARAM_ERROR		0x02
+#define MBOX_R_WRITE_ERROR		0x03
+#define MBOX_R_SYSTEM_ERROR		0x04
+#define MBOX_R_TIMEOUT			0x05
+#define MBOX_R_BUSY			0x06
+#define MBOX_R_WINDOW_ERROR		0x07
+
+/* Argument Flags */
+#define FLAGS_NONE			0x00
+#define FLAGS_SHORT_LIFETIME		0x01
+
+/* BMC Event Notification */
+#define BMC_EVENT_REBOOT		0x01
+#define BMC_EVENT_WINDOW_RESET		0x02
+#define BMC_EVENT_ACK_MASK		(BMC_EVENT_REBOOT | \
+					BMC_EVENT_WINDOW_RESET)
+#define BMC_EVENT_FLASH_CTRL_LOST	0x40
+#define BMC_EVENT_DAEMON_READY		0x80
+#define BMC_EVENT_V1_MASK		BMC_EVENT_REBOOT
+#define BMC_EVENT_V2_MASK		(BMC_EVENT_REBOOT | \
+					BMC_EVENT_WINDOW_RESET | \
+					BMC_EVENT_FLASH_CTRL_LOST | \
+					BMC_EVENT_DAEMON_READY)
+
+/* MBOX Registers */
+#define MBOX_HOST_PATH			"/dev/aspeed-mbox"
+#define MBOX_HOST_TIMEOUT_SEC		1
+#define MBOX_ARGS_BYTES			11
+#define MBOX_REG_BYTES			16
+#define MBOX_HOST_EVENT			14
+#define MBOX_BMC_EVENT			15
+
+#define BLOCK_SIZE_SHIFT_V1		12 /* 4K */
+
+/* Window Dirty/Erase bytemap masks */
+#define WINDOW_CLEAN			0x00
+#define WINDOW_DIRTY			0x01
+#define WINDOW_ERASED			0x02
+
+/* Put polled file descriptors first */
+#define DBUS_FD			0
+#define MBOX_FD			1
+#define SIG_FD			2
+#define POLL_FDS		3 /* Number of FDs we poll on */
+#define LPC_CTRL_FD		3
+#define MTD_FD			4
+#define TOTAL_FDS		5
+
+#define MAPS_FLASH		(1 << 0)
+#define MAPS_MEM		(1 << 1)
+#define STATE_SUSPENDED		(1 << 7)
+enum mbox_state {
+	/* Still Initing */
+	UNINITIALISED = 0,
+	/* Active and LPC Maps Flash */
+	ACTIVE_MAPS_FLASH = MAPS_FLASH,
+	/* Suspended and LPC Maps Flash */
+	SUSPEND_MAPS_FLASH = STATE_SUSPENDED | MAPS_FLASH,
+	/* Active and LPC Maps Memory */
+	ACTIVE_MAPS_MEM = MAPS_MEM,
+	/* Suspended and LPC Maps Memory */
+	SUSPEND_MAPS_MEM = STATE_SUSPENDED | MAPS_MEM
 };
 
+#define FLASH_OFFSET_UNINIT	0xFFFFFFFF
 
+struct window_context {
+	void *mem;			/* Portion of Reserved Memory Region */
+	uint32_t flash_offset;		/* Flash area the window maps (bytes) */
+	uint32_t size;			/* Window Size (bytes) power-of-2 */
+	uint8_t *dirty_bmap;		/* Bytemap of the dirty/erased state */
+	uint32_t age;			/* Used for LRU eviction scheme */
+};
+
+struct window_list {
+	uint32_t num;
+	uint32_t max_age;
+	uint32_t default_size;
+	struct window_context *window;
+};
+
+struct mbox_context {
+/* System State */
+	enum mbox_state state;
+	enum api_version version;
+	struct pollfd fds[TOTAL_FDS];
+	sd_bus *bus;
+	bool terminate;
+	uint8_t bmc_events;
+
+/* Window State */
+	/* The window list struct containing all current "windows" */
+	struct window_list windows;
+	/* The window the host is currently pointed at */
+	struct window_context *current;
+	/* Is the current window a write one */
+	bool current_is_write;
+
+/* Memory & Flash State */
+	/* Reserved Memory Region */
+	void *mem;
+	/* Reserved Mem Size (bytes) */
+	uint32_t mem_size;
+	/* LPC Bus Base Address (bytes) */
+	uint32_t lpc_base;
+	/* Flash size from command line (bytes) */
+	uint32_t flash_size;
+	/* Bytemap of the erased state of the entire flash */
+	uint8_t *flash_bmap;
+	/* Erase size (as a shift) */
+	uint32_t erase_size_shift;
+	/* Block size (as a shift) */
+	uint32_t block_size_shift;
+	/* Actual Flash Info */
+	struct mtd_info_user mtd_info;
+};
+
+#endif /* MBOX_H */