diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
index 6920979..164dea0 100644
--- a/drivers/thunderbolt/tb.c
+++ b/drivers/thunderbolt/tb.c
@@ -9,6 +9,7 @@
 #include <linux/delay.h>
 
 #include "tb.h"
+#include "tb_regs.h"
 
 /* hotplug handling */
 
@@ -100,6 +101,10 @@ struct tb *thunderbolt_alloc_and_start(struct tb_nhi *nhi)
 {
 	struct tb *tb;
 
+	BUILD_BUG_ON(sizeof(struct tb_regs_switch_header) != 5 * 4);
+	BUILD_BUG_ON(sizeof(struct tb_regs_port_header) != 8 * 4);
+	BUILD_BUG_ON(sizeof(struct tb_regs_hop) != 2 * 4);
+
 	tb = kzalloc(sizeof(*tb), GFP_KERNEL);
 	if (!tb)
 		return NULL;
diff --git a/drivers/thunderbolt/tb_regs.h b/drivers/thunderbolt/tb_regs.h
new file mode 100644
index 0000000..6577af7
--- /dev/null
+++ b/drivers/thunderbolt/tb_regs.h
@@ -0,0 +1,213 @@
+/*
+ * Thunderbolt Cactus Ridge driver - Port/Switch config area registers
+ *
+ * Every thunderbolt device consists (logically) of a switch with multiple
+ * ports. Every port contains up to four config regions (HOPS, PORT, SWITCH,
+ * COUNTERS) which are used to configure the device.
+ *
+ * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
+ */
+
+#ifndef _TB_REGS
+#define _TB_REGS
+
+#include <linux/types.h>
+
+
+#define TB_ROUTE_SHIFT 8  /* number of bits in a port entry of a route */
+
+
+/*
+ * TODO: should be 63? But we do not know how to receive frames larger than 256
+ * bytes at the frame level. (header + checksum = 16, 60*4 = 240)
+ */
+#define TB_MAX_CONFIG_RW_LENGTH 60
+
+enum tb_cap {
+	TB_CAP_PHY		= 0x0001,
+	TB_CAP_TIME1		= 0x0003,
+	TB_CAP_PCIE		= 0x0004,
+	TB_CAP_I2C		= 0x0005,
+	TB_CAP_PLUG_EVENTS	= 0x0105, /* also EEPROM */
+	TB_CAP_TIME2		= 0x0305,
+	TB_CAL_IECS		= 0x0405,
+	TB_CAP_LINK_CONTROLLER	= 0x0605, /* also IECS */
+};
+
+enum tb_port_state {
+	TB_PORT_DISABLED	= 0, /* tb_cap_phy.disable == 1 */
+	TB_PORT_CONNECTING	= 1, /* retry */
+	TB_PORT_UP		= 2,
+	TB_PORT_UNPLUGGED	= 7,
+};
+
+/* capability headers */
+
+struct tb_cap_basic {
+	u8 next;
+	/* enum tb_cap cap:8; prevent "narrower than values of its type" */
+	u8 cap; /* if cap == 0x05 then we have a extended capability */
+} __packed;
+
+struct tb_cap_extended_short {
+	u8 next; /* if next and length are zero then we have a long cap */
+	enum tb_cap cap:16;
+	u8 length;
+} __packed;
+
+struct tb_cap_extended_long {
+	u8 zero1;
+	enum tb_cap cap:16;
+	u8 zero2;
+	u16 next;
+	u16 length;
+} __packed;
+
+/* capabilities */
+
+struct tb_cap_link_controller {
+	struct tb_cap_extended_long cap_header;
+	u32 count:4; /* number of link controllers */
+	u32 unknown1:4;
+	u32 base_offset:8; /*
+			    * offset (into this capability) of the configuration
+			    * area of the first link controller
+			    */
+	u32 length:12; /* link controller configuration area length */
+	u32 unknown2:4; /* TODO check that length is correct */
+} __packed;
+
+struct tb_cap_phy {
+	struct tb_cap_basic cap_header;
+	u32 unknown1:16;
+	u32 unknown2:14;
+	bool disable:1;
+	u32 unknown3:11;
+	enum tb_port_state state:4;
+	u32 unknown4:2;
+} __packed;
+
+struct tb_eeprom_ctl {
+	bool clock:1; /* send pulse to transfer one bit */
+	bool access_low:1; /* set to 0 before access */
+	bool data_out:1; /* to eeprom */
+	bool data_in:1; /* from eeprom */
+	bool access_high:1; /* set to 1 before access */
+	bool not_present:1; /* should be 0 */
+	bool unknown1:1;
+	bool present:1; /* should be 1 */
+	u32 unknown2:24;
+} __packed;
+
+struct tb_cap_plug_events {
+	struct tb_cap_extended_short cap_header;
+	u32 __unknown1:2;
+	u32 plug_events:5;
+	u32 __unknown2:25;
+	u32 __unknown3;
+	u32 __unknown4;
+	struct tb_eeprom_ctl eeprom_ctl;
+	u32 __unknown5[7];
+	u32 drom_offset; /* 32 bit register, but eeprom addresses are 16 bit */
+} __packed;
+
+/* device headers */
+
+/* Present on port 0 in TB_CFG_SWITCH at address zero. */
+struct tb_regs_switch_header {
+	/* DWORD 0 */
+	u16 vendor_id;
+	u16 device_id;
+	/* DWORD 1 */
+	u32 first_cap_offset:8;
+	u32 upstream_port_number:6;
+	u32 max_port_number:6;
+	u32 depth:3;
+	u32 __unknown1:1;
+	u32 revision:8;
+	/* DWORD 2 */
+	u32 route_lo;
+	/* DWORD 3 */
+	u32 route_hi:31;
+	bool enabled:1;
+	/* DWORD 4 */
+	u32 plug_events_delay:8; /*
+				  * RW, pause between plug events in
+				  * milliseconds. Writing 0x00 is interpreted
+				  * as 255ms.
+				  */
+	u32 __unknown4:16;
+	u32 thunderbolt_version:8;
+} __packed;
+
+enum tb_port_type {
+	TB_TYPE_INACTIVE	= 0x000000,
+	TB_TYPE_PORT		= 0x000001,
+	TB_TYPE_NHI		= 0x000002,
+	/* TB_TYPE_ETHERNET	= 0x020000, lower order bits are not known */
+	/* TB_TYPE_SATA		= 0x080000, lower order bits are not known */
+	TB_TYPE_DP_HDMI_IN	= 0x0e0101,
+	TB_TYPE_DP_HDMI_OUT	= 0x0e0102,
+	TB_TYPE_PCIE_DOWN	= 0x100101,
+	TB_TYPE_PCIE_UP		= 0x100102,
+	/* TB_TYPE_USB		= 0x200000, lower order bits are not known */
+};
+
+/* Present on every port in TB_CF_PORT at address zero. */
+struct tb_regs_port_header {
+	/* DWORD 0 */
+	u16 vendor_id;
+	u16 device_id;
+	/* DWORD 1 */
+	u32 first_cap_offset:8;
+	u32 max_counters:11;
+	u32 __unknown1:5;
+	u32 revision:8;
+	/* DWORD 2 */
+	enum tb_port_type type:24;
+	u32 thunderbolt_version:8;
+	/* DWORD 3 */
+	u32 __unknown2:20;
+	u32 port_number:6;
+	u32 __unknown3:6;
+	/* DWORD 4 */
+	u32 nfc_credits;
+	/* DWORD 5 */
+	u32 max_in_hop_id:11;
+	u32 max_out_hop_id:11;
+	u32 __unkown4:10;
+	/* DWORD 6 */
+	u32 __unknown5;
+	/* DWORD 7 */
+	u32 __unknown6;
+
+} __packed;
+
+/* Hop register from TB_CFG_HOPS. 8 byte per entry. */
+struct tb_regs_hop {
+	/* DWORD 0 */
+	u32 next_hop:11; /*
+			  * hop to take after sending the packet through
+			  * out_port (on the incoming port of the next switch)
+			  */
+	u32 out_port:6; /* next port of the path (on the same switch) */
+	u32 initial_credits:8;
+	u32 unknown1:6; /* set to zero */
+	bool enable:1;
+
+	/* DWORD 1 */
+	u32 weight:4;
+	u32 unknown2:4; /* set to zero */
+	u32 priority:3;
+	bool drop_packages:1;
+	u32 counter:11; /* index into TB_CFG_COUNTERS on this port */
+	bool counter_enable:1;
+	bool ingress_fc:1;
+	bool egress_fc:1;
+	bool ingress_shared_buffer:1;
+	bool egress_shared_buffer:1;
+	u32 unknown3:4; /* set to zero */
+} __packed;
+
+
+#endif
