diff --git a/package-21.02/kernel/tops/src/inc/mbox.h b/package-21.02/kernel/tops/src/inc/mbox.h
new file mode 100644
index 0000000..002f2c6
--- /dev/null
+++ b/package-21.02/kernel/tops/src/inc/mbox.h
@@ -0,0 +1,157 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) 2023 MediaTek Inc. All Rights Reserved.
+ *
+ * Author: Ren-Ting Wang <ren-ting.wang@mediatek.com>
+ */
+
+#ifndef _TOPS_MBOX_H_
+#define _TOPS_MBOX_H_
+
+#include <linux/list.h>
+
+#include "mbox_id.h"
+#include "tops.h"
+
+/* mbox device macros */
+#define MBOX_DEV(core_id, cmd)				\
+	.core = core_id,					\
+	.cmd_id = cmd,
+
+#define MBOX_SEND_DEV(core_id, cmd)			\
+	{						\
+		MBOX_DEV(core_id, cmd)			\
+	}
+
+#define MBOX_SEND_MGMT_DEV(cmd)				\
+	MBOX_SEND_DEV(CORE_MGMT, MBOX_AP2CM_CMD_ ## cmd)
+
+#define MBOX_SEND_OFFLOAD_DEV(core_id, cmd)		\
+	MBOX_SEND_DEV(CORE_OFFLOAD_ ## core_id, MBOX_AP2CX_CMD_ ## cmd)
+
+#define MBOX_RECV_DEV(core_id, cmd, handler)		\
+	{						\
+		MBOX_DEV(core_id, cmd)			\
+		.mbox_handler = handler,		\
+	}
+
+#define MBOX_RECV_MGMT_DEV(cmd, handler)		\
+	MBOX_RECV_DEV(CORE_MGMT, MBOX_CM2AP_CMD_ ## cmd, handler)
+
+#define MBOX_RECV_OFFLOAD_DEV(core_id, cmd, handler)	\
+	MBOX_RECV_DEV(CORE_OFFLOAD_ ## core_id, MBOX_CX2AP_CMD_ ## cmd, handler)
+
+/* Base Address */
+#define MBOX_TOP_BASE				(0x010000)
+#define MBOX_CLUST0_BASE			(0x510000)
+
+/* TOP Mailbox */
+#define TOPS_TOP_CM_SLOT			(MBOX_TOP_BASE + 0x000)
+#define TOPS_TOP_AP_SLOT			(MBOX_TOP_BASE + 0x004)
+
+#define TOPS_TOP_AP_TO_CM_CMD_SET		(MBOX_TOP_BASE + 0x200)
+#define TOPS_TOP_AP_TO_CM_CMD_CLR		(MBOX_TOP_BASE + 0x204)
+#define TOPS_TOP_CM_TO_AP_CMD_SET		(MBOX_TOP_BASE + 0x21C)
+#define TOPS_TOP_CM_TO_AP_CMD_CLR		(MBOX_TOP_BASE + 0x220)
+
+#define TOPS_TOP_AP_TO_CM_MSG_N(n)		(MBOX_TOP_BASE + 0x208 + 0x4 * (n))
+#define TOPS_TOP_CM_TO_AP_MSG_N(n)		(MBOX_TOP_BASE + 0x224 + 0x4 * (n))
+
+/* CLUST Mailbox */
+#define TOPS_CLUST0_CX_SLOT(x)			(MBOX_CLUST0_BASE + (0x4 * (x)))
+#define TOPS_CLUST0_CM_SLOT			(MBOX_CLUST0_BASE + 0x10)
+#define TOPS_CLUST0_AP_SLOT			(MBOX_CLUST0_BASE + 0x14)
+
+#define TOPS_CLUST0_CX_TO_CY_CMD_SET(x, y)	\
+		(MBOX_CLUST0_BASE + 0x100 + ((x) * 0x200) + ((y) * 0x40))
+#define TOPS_CLUST0_CX_TO_CY_CMD_CLR(x, y)	\
+		(MBOX_CLUST0_BASE + 0x104 + ((x) * 0x200) + ((y) * 0x40))
+#define TOPS_CLUST0_CX_TO_CM_CMD_SET(x)		\
+		(MBOX_CLUST0_BASE + 0x200 + ((x) * 0x200))
+#define TOPS_CLUST0_CX_TO_CM_CMD_CLR(x)		\
+		(MBOX_CLUST0_BASE + 0x204 + ((x) * 0x200))
+#define TOPS_CLUST0_CX_TO_AP_CMD_SET(x)		\
+		(MBOX_CLUST0_BASE + 0x240 + ((x) * 0x200))
+#define TOPS_CLUST0_CX_TO_AP_CMD_CLR(x)		\
+		(MBOX_CLUST0_BASE + 0x244 + ((x) * 0x200))
+#define TOPS_CLUST0_CM_TO_CX_CMD_SET(x)		\
+		(MBOX_CLUST0_BASE + 0x900 + ((x) * 0x40))
+#define TOPS_CLUST0_CM_TO_CX_CMD_CLR(x)		\
+		(MBOX_CLUST0_BASE + 0x904 + ((x) * 0x40))
+#define TOPS_CLUST0_AP_TO_CX_CMD_SET(x)		\
+		(MBOX_CLUST0_BASE + 0xB00 + ((x) * 0x40))
+#define TOPS_CLUST0_AP_TO_CX_CMD_CLR(x)		\
+		(MBOX_CLUST0_BASE + 0xB04 + ((x) * 0x40))
+
+#define TOPS_CLUST0_CX_TO_CY_MSG_N(x, y, n)	\
+		(MBOX_CLUST0_BASE + 0x108 + ((n) * 0x4) + ((x) * 0x200) + ((y) * 0x40))
+#define TOPS_CLUST0_CX_TO_CM_MSG_N(x, n)	\
+		(MBOX_CLUST0_BASE + 0x208 + ((n) * 0x4) + ((x) * 0x200))
+#define TOPS_CLUST0_CX_TO_AP_MSG_N(x, n)	\
+		(MBOX_CLUST0_BASE + 0x248 + ((n) * 0x4) + ((x) * 0x200))
+#define TOPS_CLUST0_CM_TO_CX_MSG_N(x, n)	\
+		(MBOX_CLUST0_BASE + 0x908 + ((n) * 0x4) + ((x) * 0x40))
+#define TOPS_CLUST0_AP_TO_CX_MSG_N(x, n)	\
+		(MBOX_CLUST0_BASE + 0xB08 + ((n) * 0x4) + ((x) * 0x40))
+
+#define MBOX_TOP_MBOX_FROM_C0			(0x1)
+#define MBOX_TOP_MBOX_FROM_C1			(0x2)
+#define MBOX_TOP_MBOX_FROM_C2			(0x4)
+#define MBOX_TOP_MBOX_FROM_C3			(0x8)
+#define MBOX_TOP_MBOX_FROM_AP			(0x10)
+#define MBOX_TOP_MBOX_FROM_CM			(0x20) /* TODO: need DE update */
+
+#define MBOX_CLUST0_MBOX_FROM_C0		(0x1)
+#define MBOX_CLUST0_MBOX_FROM_C1		(0x2)
+#define MBOX_CLUST0_MBOX_FROM_C2		(0x4)
+#define MBOX_CLUST0_MBOX_FROM_C3		(0x8)
+#define MBOX_CLUST0_MBOX_FROM_CM		(0x10)
+#define MBOX_CLUST0_MBOX_FROM_AP		(0x20)
+
+struct mailbox_msg;
+struct mailbox_dev;
+enum mbox_msg_cnt;
+
+typedef void (*mbox_ret_func_t)(void *priv, struct mailbox_msg *msg);
+typedef enum mbox_msg_cnt (*mbox_handler_func_t)(struct mailbox_dev *mdev,
+						 struct mailbox_msg *msg);
+
+enum mbox_act {
+	MBOX_SEND,
+	MBOX_RECV,
+	MBOX_ACT_MAX,
+};
+
+enum mbox_msg_cnt {
+	MBOX_NO_RET_MSG,
+	MBOX_RET_MSG1,
+	MBOX_RET_MSG2,
+	MBOX_RET_MSG3,
+	MBOX_RET_MSG4,
+};
+
+struct mailbox_msg {
+	u32 msg1;
+	u32 msg2;
+	u32 msg3;
+	u32 msg4;
+};
+
+struct mailbox_dev {
+	struct list_head list;
+	enum core_id core;
+	mbox_handler_func_t mbox_handler;
+	void *priv;
+	u8 cmd_id;
+};
+
+int mbox_send_msg_no_wait_irq(struct mailbox_dev *mdev, struct mailbox_msg *msg);
+int mbox_send_msg_no_wait(struct mailbox_dev *mdev, struct mailbox_msg *msg);
+int mbox_send_msg(struct mailbox_dev *mdev, struct mailbox_msg *msg, void *priv,
+		  mbox_ret_func_t ret_handler);
+int register_mbox_dev(enum mbox_act act, struct mailbox_dev *mdev);
+int unregister_mbox_dev(enum mbox_act act, struct mailbox_dev *mdev);
+void mtk_tops_mbox_clear_all_cmd(void);
+int mtk_tops_mbox_init(void);
+void mtk_tops_mbox_exit(void);
+#endif /* _TOPS_MBOX_H_ */