diff --git a/plat/rpi3/rpi3_hw.h b/plat/rpi3/rpi3_hw.h
index f411acb..a83a0ad 100644
--- a/plat/rpi3/rpi3_hw.h
+++ b/plat/rpi3/rpi3_hw.h
@@ -17,6 +17,27 @@
 #define RPI3_IO_SIZE			ULL(0x01000000)
 
 /*
+ * ARM <-> VideoCore mailboxes
+ */
+#define RPI3_MBOX_OFFSET		ULL(0x0000B880)
+#define RPI3_MBOX_BASE			(RPI3_IO_BASE + RPI3_MBOX_OFFSET)
+/* VideoCore -> ARM */
+#define RPI3_MBOX0_READ_OFFSET		ULL(0x00000000)
+#define RPI3_MBOX0_PEEK_OFFSET		ULL(0x00000010)
+#define RPI3_MBOX0_SENDER_OFFSET	ULL(0x00000014)
+#define RPI3_MBOX0_STATUS_OFFSET	ULL(0x00000018)
+#define RPI3_MBOX0_CONFIG_OFFSET	ULL(0x0000001C)
+/* ARM -> VideoCore */
+#define RPI3_MBOX1_WRITE_OFFSET		ULL(0x00000020)
+#define RPI3_MBOX1_PEEK_OFFSET		ULL(0x00000030)
+#define RPI3_MBOX1_SENDER_OFFSET	ULL(0x00000034)
+#define RPI3_MBOX1_STATUS_OFFSET	ULL(0x00000038)
+#define RPI3_MBOX1_CONFIG_OFFSET	ULL(0x0000003C)
+/* Mailbox status constants */
+#define RPI3_MBOX_STATUS_FULL_MASK	U(0x80000000) /* Set if full */
+#define RPI3_MBOX_STATUS_EMPTY_MASK	U(0x40000000) /* Set if empty */
+
+/*
  * Power management, reset controller, watchdog.
  */
 #define RPI3_IO_PM_OFFSET		ULL(0x00100000)