diff --git a/drivers/video/bt431.h b/drivers/video/bt431.h
new file mode 100644
index 0000000..c826f27
--- /dev/null
+++ b/drivers/video/bt431.h
@@ -0,0 +1,236 @@
+/*
+ *	linux/drivers/video/bt431.h
+ *
+ *	Copyright 2003  Thiemo Seufer <seufer@csv.ica.uni-stuttgart.de>
+ *
+ *	This file is subject to the terms and conditions of the GNU General
+ *	Public License. See the file COPYING in the main directory of this
+ *	archive for more details.
+ */
+#include <linux/types.h>
+#include <asm/system.h>
+
+/*
+ * Bt431 cursor generator registers, 32-bit aligned.
+ * Two twin Bt431 are used on the DECstation's PMAG-AA.
+ */
+struct bt431_regs {
+	volatile u16 addr_lo;
+	u16 pad0;
+	volatile u16 addr_hi;
+	u16 pad1;
+	volatile u16 addr_cmap;
+	u16 pad2;
+	volatile u16 addr_reg;
+	u16 pad3;
+};
+
+static inline u16 bt431_set_value(u8 val)
+{
+	return ((val << 8) | (val & 0xff)) & 0xffff;
+}
+
+static inline u8 bt431_get_value(u16 val)
+{
+	return val & 0xff;
+}
+
+/*
+ * Additional registers addressed indirectly.
+ */
+#define BT431_REG_CMD		0x0000
+#define BT431_REG_CXLO		0x0001
+#define BT431_REG_CXHI		0x0002
+#define BT431_REG_CYLO		0x0003
+#define BT431_REG_CYHI		0x0004
+#define BT431_REG_WXLO		0x0005
+#define BT431_REG_WXHI		0x0006
+#define BT431_REG_WYLO		0x0007
+#define BT431_REG_WYHI		0x0008
+#define BT431_REG_WWLO		0x0009
+#define BT431_REG_WWHI		0x000a
+#define BT431_REG_WHLO		0x000b
+#define BT431_REG_WHHI		0x000c
+
+#define BT431_REG_CRAM_BASE	0x0000
+#define BT431_REG_CRAM_END	0x01ff
+
+/*
+ * Command register.
+ */
+#define BT431_CMD_CURS_ENABLE	0x40
+#define BT431_CMD_XHAIR_ENABLE	0x20
+#define BT431_CMD_OR_CURSORS	0x10
+#define BT431_CMD_AND_CURSORS	0x00
+#define BT431_CMD_1_1_MUX	0x00
+#define BT431_CMD_4_1_MUX	0x04
+#define BT431_CMD_5_1_MUX	0x08
+#define BT431_CMD_xxx_MUX	0x0c
+#define BT431_CMD_THICK_1	0x00
+#define BT431_CMD_THICK_3	0x01
+#define BT431_CMD_THICK_5	0x02
+#define BT431_CMD_THICK_7	0x03
+
+static inline void bt431_select_reg(struct bt431_regs *regs, int ir)
+{
+	/*
+	 * The compiler splits the write in two bytes without these
+	 * helper variables.
+	 */
+	volatile u16 *lo = &(regs->addr_lo);
+	volatile u16 *hi = &(regs->addr_hi);
+
+	mb();
+	*lo = bt431_set_value(ir & 0xff);
+	wmb();
+	*hi = bt431_set_value((ir >> 8) & 0xff);
+}
+
+/* Autoincrement read/write. */
+static inline u8 bt431_read_reg_inc(struct bt431_regs *regs)
+{
+	/*
+	 * The compiler splits the write in two bytes without the
+	 * helper variable.
+	 */
+	volatile u16 *r = &(regs->addr_reg);
+
+	mb();
+	return bt431_get_value(*r);
+}
+
+static inline void bt431_write_reg_inc(struct bt431_regs *regs, u8 value)
+{
+	/*
+	 * The compiler splits the write in two bytes without the
+	 * helper variable.
+	 */
+	volatile u16 *r = &(regs->addr_reg);
+
+	mb();
+	*r = bt431_set_value(value);
+}
+
+static inline u8 bt431_read_reg(struct bt431_regs *regs, int ir)
+{
+	bt431_select_reg(regs, ir);
+	return bt431_read_reg_inc(regs);
+}
+
+static inline void bt431_write_reg(struct bt431_regs *regs, int ir, u8 value)
+{
+	bt431_select_reg(regs, ir);
+	bt431_write_reg_inc(regs, value);
+}
+
+/* Autoincremented read/write for the cursor map. */
+static inline u16 bt431_read_cmap_inc(struct bt431_regs *regs)
+{
+	/*
+	 * The compiler splits the write in two bytes without the
+	 * helper variable.
+	 */
+	volatile u16 *r = &(regs->addr_cmap);
+
+	mb();
+	return *r;
+}
+
+static inline void bt431_write_cmap_inc(struct bt431_regs *regs, u16 value)
+{
+	/*
+	 * The compiler splits the write in two bytes without the
+	 * helper variable.
+	 */
+	volatile u16 *r = &(regs->addr_cmap);
+
+	mb();
+	*r = value;
+}
+
+static inline u16 bt431_read_cmap(struct bt431_regs *regs, int cr)
+{
+	bt431_select_reg(regs, cr);
+	return bt431_read_cmap_inc(regs);
+}
+
+static inline void bt431_write_cmap(struct bt431_regs *regs, int cr, u16 value)
+{
+	bt431_select_reg(regs, cr);
+	bt431_write_cmap_inc(regs, value);
+}
+
+static inline void bt431_enable_cursor(struct bt431_regs *regs)
+{
+	bt431_write_reg(regs, BT431_REG_CMD,
+			BT431_CMD_CURS_ENABLE | BT431_CMD_OR_CURSORS
+			| BT431_CMD_4_1_MUX | BT431_CMD_THICK_1);
+}
+
+static inline void bt431_erase_cursor(struct bt431_regs *regs)
+{
+	bt431_write_reg(regs, BT431_REG_CMD, BT431_CMD_4_1_MUX);
+}
+
+static inline void bt431_position_cursor(struct bt431_regs *regs, u16 x, u16 y)
+{
+	/*
+	 * Magic from the MACH sources.
+	 *
+	 * Cx = x + D + H - P
+	 *  P = 37 if 1:1, 52 if 4:1, 57 if 5:1
+	 *  D = pixel skew between outdata and external data
+	 *  H = pixels between HSYNCH falling and active video
+	 *
+	 * Cy = y + V - 32
+	 *  V = scanlines between HSYNCH falling, two or more
+	 *      clocks after VSYNCH falling, and active video
+	 */
+	x += 412 - 52;
+	y += 68 - 32;
+
+	/* Use autoincrement. */
+	bt431_select_reg(regs, BT431_REG_CXLO);
+	bt431_write_reg_inc(regs, x & 0xff); /* BT431_REG_CXLO */
+	bt431_write_reg_inc(regs, (x >> 8) & 0x0f); /* BT431_REG_CXHI */
+	bt431_write_reg_inc(regs, y & 0xff); /* BT431_REG_CYLO */
+	bt431_write_reg_inc(regs, (y >> 8) & 0x0f); /* BT431_REG_CYHI */
+}
+
+static inline void bt431_set_font(struct bt431_regs *regs, u8 fgc,
+				  u16 width, u16 height)
+{
+	int i;
+	u16 fgp = fgc ? 0xffff : 0x0000;
+	u16 bgp = fgc ? 0x0000 : 0xffff;
+
+	bt431_select_reg(regs, BT431_REG_CRAM_BASE);
+	for (i = BT431_REG_CRAM_BASE; i <= BT431_REG_CRAM_END; i++) {
+		u16 value;
+
+		if (height << 6 <= i << 3)
+			value = bgp;
+		else if (width <= i % 8 << 3)
+			value = bgp;
+		else if (((width >> 3) & 0xffff) > i % 8)
+			value = fgp;
+		else
+			value = fgp & ~(bgp << (width % 8 << 1));
+
+		bt431_write_cmap_inc(regs, value);
+	}
+}
+
+static inline void bt431_init_cursor(struct bt431_regs *regs)
+{
+	/* no crosshair window */
+	bt431_select_reg(regs, BT431_REG_WXLO);
+	bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WXLO */
+	bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WXHI */
+	bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WYLO */
+	bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WYHI */
+	bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WWLO */
+	bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WWHI */
+	bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WHLO */
+	bt431_write_reg_inc(regs, 0x00); /* BT431_REG_WHHI */
+}