diff --git a/arch/mips/dec/ioasic-irq.c b/arch/mips/dec/ioasic-irq.c
new file mode 100644
index 0000000..d5bca5d
--- /dev/null
+++ b/arch/mips/dec/ioasic-irq.c
@@ -0,0 +1,157 @@
+/*
+ *	linux/arch/mips/dec/ioasic-irq.c
+ *
+ *	DEC I/O ASIC interrupts.
+ *
+ *	Copyright (c) 2002, 2003  Maciej W. Rozycki
+ *
+ *	This program is free software; you can redistribute it and/or
+ *	modify it under the terms of the GNU General Public License
+ *	as published by the Free Software Foundation; either version
+ *	2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+#include <asm/dec/ioasic.h>
+#include <asm/dec/ioasic_addrs.h>
+#include <asm/dec/ioasic_ints.h>
+
+
+static DEFINE_SPINLOCK(ioasic_lock);
+
+static int ioasic_irq_base;
+
+
+static inline void unmask_ioasic_irq(unsigned int irq)
+{
+	u32 simr;
+
+	simr = ioasic_read(IO_REG_SIMR);
+	simr |= (1 << (irq - ioasic_irq_base));
+	ioasic_write(IO_REG_SIMR, simr);
+}
+
+static inline void mask_ioasic_irq(unsigned int irq)
+{
+	u32 simr;
+
+	simr = ioasic_read(IO_REG_SIMR);
+	simr &= ~(1 << (irq - ioasic_irq_base));
+	ioasic_write(IO_REG_SIMR, simr);
+}
+
+static inline void clear_ioasic_irq(unsigned int irq)
+{
+	u32 sir;
+
+	sir = ~(1 << (irq - ioasic_irq_base));
+	ioasic_write(IO_REG_SIR, sir);
+}
+
+static inline void enable_ioasic_irq(unsigned int irq)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ioasic_lock, flags);
+	unmask_ioasic_irq(irq);
+	spin_unlock_irqrestore(&ioasic_lock, flags);
+}
+
+static inline void disable_ioasic_irq(unsigned int irq)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ioasic_lock, flags);
+	mask_ioasic_irq(irq);
+	spin_unlock_irqrestore(&ioasic_lock, flags);
+}
+
+
+static inline unsigned int startup_ioasic_irq(unsigned int irq)
+{
+	enable_ioasic_irq(irq);
+	return 0;
+}
+
+#define shutdown_ioasic_irq disable_ioasic_irq
+
+static inline void ack_ioasic_irq(unsigned int irq)
+{
+	spin_lock(&ioasic_lock);
+	mask_ioasic_irq(irq);
+	spin_unlock(&ioasic_lock);
+	fast_iob();
+}
+
+static inline void end_ioasic_irq(unsigned int irq)
+{
+	if (!(irq_desc[irq].status & (IRQ_DISABLED | IRQ_INPROGRESS)))
+		enable_ioasic_irq(irq);
+}
+
+static struct hw_interrupt_type ioasic_irq_type = {
+	.typename = "IO-ASIC",
+	.startup = startup_ioasic_irq,
+	.shutdown = shutdown_ioasic_irq,
+	.enable = enable_ioasic_irq,
+	.disable = disable_ioasic_irq,
+	.ack = ack_ioasic_irq,
+	.end = end_ioasic_irq,
+};
+
+
+#define startup_ioasic_dma_irq startup_ioasic_irq
+
+#define shutdown_ioasic_dma_irq shutdown_ioasic_irq
+
+#define enable_ioasic_dma_irq enable_ioasic_irq
+
+#define disable_ioasic_dma_irq disable_ioasic_irq
+
+#define ack_ioasic_dma_irq ack_ioasic_irq
+
+static inline void end_ioasic_dma_irq(unsigned int irq)
+{
+	clear_ioasic_irq(irq);
+	fast_iob();
+	end_ioasic_irq(irq);
+}
+
+static struct hw_interrupt_type ioasic_dma_irq_type = {
+	.typename = "IO-ASIC-DMA",
+	.startup = startup_ioasic_dma_irq,
+	.shutdown = shutdown_ioasic_dma_irq,
+	.enable = enable_ioasic_dma_irq,
+	.disable = disable_ioasic_dma_irq,
+	.ack = ack_ioasic_dma_irq,
+	.end = end_ioasic_dma_irq,
+};
+
+
+void __init init_ioasic_irqs(int base)
+{
+	int i;
+
+	/* Mask interrupts. */
+	ioasic_write(IO_REG_SIMR, 0);
+	fast_iob();
+
+	for (i = base; i < base + IO_INR_DMA; i++) {
+		irq_desc[i].status = IRQ_DISABLED;
+		irq_desc[i].action = 0;
+		irq_desc[i].depth = 1;
+		irq_desc[i].handler = &ioasic_irq_type;
+	}
+	for (; i < base + IO_IRQ_LINES; i++) {
+		irq_desc[i].status = IRQ_DISABLED;
+		irq_desc[i].action = 0;
+		irq_desc[i].depth = 1;
+		irq_desc[i].handler = &ioasic_dma_irq_type;
+	}
+
+	ioasic_irq_base = base;
+}