diff --git a/include/asm-mn10300/unit-asb2305/serial.h b/include/asm-mn10300/unit-asb2305/serial.h
new file mode 100644
index 0000000..73d31d6
--- /dev/null
+++ b/include/asm-mn10300/unit-asb2305/serial.h
@@ -0,0 +1,120 @@
+/* ASB2305-specific 8250 serial ports
+ *
+ * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+#ifndef _ASM_UNIT_SERIAL_H
+#define _ASM_UNIT_SERIAL_H
+
+#include <asm/cpu/cpu-regs.h>
+#include <asm/proc/irq.h>
+#include <linux/serial_reg.h>
+
+#define SERIAL_PORT0_BASE_ADDRESS	0xA6FB0000
+#define ASB2305_DEBUG_MCR	__SYSREG(0xA6FB0000 + UART_MCR * 2, u8)
+
+#define SERIAL_IRQ	XIRQ0	/* Dual serial (PC16552)	(Hi) */
+
+/*
+ * dispose of the /dev/ttyS0 serial port
+ */
+#ifndef CONFIG_GDBSTUB_ON_TTYSx
+
+#define SERIAL_PORT_DFNS						\
+	{								\
+	.baud_base		= BASE_BAUD,				\
+	.irq			= SERIAL_IRQ,				\
+	.flags			= STD_COM_FLAGS,			\
+	.iomem_base		= (u8 *) SERIAL_PORT0_BASE_ADDRESS,	\
+	.iomem_reg_shift	= 2,					\
+	.io_type		= SERIAL_IO_MEM,			\
+	},
+
+#ifndef __ASSEMBLY__
+
+static inline void __debug_to_serial(const char *p, int n)
+{
+}
+
+#endif /* !__ASSEMBLY__ */
+
+#else /* CONFIG_GDBSTUB_ON_TTYSx */
+
+#define SERIAL_PORT_DFNS /* stolen by gdb-stub */
+
+#if defined(CONFIG_GDBSTUB_ON_TTYS0)
+#define GDBPORT_SERIAL_RX	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_RX  * 4, u8)
+#define GDBPORT_SERIAL_TX	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_TX  * 4, u8)
+#define GDBPORT_SERIAL_DLL	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_DLL * 4, u8)
+#define GDBPORT_SERIAL_DLM	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_DLM * 4, u8)
+#define GDBPORT_SERIAL_IER	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_IER * 4, u8)
+#define GDBPORT_SERIAL_IIR	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_IIR * 4, u8)
+#define GDBPORT_SERIAL_FCR	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_FCR * 4, u8)
+#define GDBPORT_SERIAL_LCR	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_LCR * 4, u8)
+#define GDBPORT_SERIAL_MCR	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_MCR * 4, u8)
+#define GDBPORT_SERIAL_LSR	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_LSR * 4, u8)
+#define GDBPORT_SERIAL_MSR	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_MSR * 4, u8)
+#define GDBPORT_SERIAL_SCR	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_SCR * 4, u8)
+#define GDBPORT_SERIAL_IRQ	SERIAL_IRQ
+
+#elif defined(CONFIG_GDBSTUB_ON_TTYS1)
+#error The ASB2305 doesnt have a /dev/ttyS1
+#endif
+
+#ifndef __ASSEMBLY__
+
+#define TTYS0_TX	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_TX  * 4, u8)
+#define TTYS0_MCR	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_MCR * 4, u8)
+#define TTYS0_LSR	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_LSR * 4, u8)
+#define TTYS0_MSR	__SYSREG(SERIAL_PORT0_BASE_ADDRESS + UART_MSR * 4, u8)
+
+#define LSR_WAIT_FOR(STATE)				\
+do {							\
+	while (!(TTYS0_LSR & UART_LSR_##STATE)) {}	\
+} while (0)
+#define FLOWCTL_WAIT_FOR(LINE)				\
+do {							\
+	while (!(TTYS0_MSR & UART_MSR_##LINE)) {}	\
+} while (0)
+#define FLOWCTL_CLEAR(LINE)			\
+do {						\
+	TTYS0_MCR &= ~UART_MCR_##LINE;		\
+} while (0)
+#define FLOWCTL_SET(LINE)			\
+do {						\
+	TTYS0_MCR |= UART_MCR_##LINE;		\
+} while (0)
+#define FLOWCTL_QUERY(LINE)	({ TTYS0_MSR & UART_MSR_##LINE; })
+
+static inline void __debug_to_serial(const char *p, int n)
+{
+	char ch;
+
+	FLOWCTL_SET(DTR);
+
+	for (; n > 0; n--) {
+		LSR_WAIT_FOR(THRE);
+		FLOWCTL_WAIT_FOR(CTS);
+
+		ch = *p++;
+		if (ch == 0x0a) {
+			TTYS0_TX = 0x0d;
+			LSR_WAIT_FOR(THRE);
+			FLOWCTL_WAIT_FOR(CTS);
+		}
+		TTYS0_TX = ch;
+	}
+
+	FLOWCTL_CLEAR(DTR);
+}
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* CONFIG_GDBSTUB_ON_TTYSx */
+
+#endif /* _ASM_UNIT_SERIAL_H */