diff --git a/sys/arch/arc/arc/bus_space.c b/sys/arch/arc/arc/bus_space.c
index 00503c844bfa..828aa6eb3fc9 100644
--- a/sys/arch/arc/arc/bus_space.c
+++ b/sys/arch/arc/arc/bus_space.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: bus_space.c,v 1.3 2000/11/09 06:05:40 thorpej Exp $	*/
+/*	$NetBSD: bus_space.c,v 1.4 2001/09/04 06:57:26 thorpej Exp $	*/
 /*	NetBSD: bus_machdep.c,v 1.1 2000/01/26 18:48:00 drochner Exp 	*/
 
 /*-
@@ -68,6 +68,7 @@ arc_bus_space_init(bst, name, paddr, vaddr, start, size)
 	bst->bs_map = arc_bus_space_map;
 	bst->bs_unmap = arc_bus_space_unmap;
 	bst->bs_subregion = arc_bus_space_subregion;
+	bst->bs_mmap = arc_bus_space_mmap;
 	bst->bs_alloc = arc_bus_space_alloc;
 	bst->bs_free = arc_bus_space_free;
 	bst->bs_aux = NULL;
@@ -252,6 +253,27 @@ arc_bus_space_subregion(bst, bsh, offset, size, nbshp)
 	return (0);
 }
 
+paddr_t
+arc_bus_space_mmap(bst, addr, off, prot, flags)
+	bus_space_tag_t bst;
+	bus_addr_t addr;
+	off_t off;
+	int prot;
+	int flags;
+{
+
+	/*
+	 * XXX We do not disallow mmap'ing of EISA/PCI I/O space here,
+	 * XXX which we should be doing.
+	 */
+
+	if (addr < bst->bs_start ||
+	    (addr + off) >= (bst->bs_start + bst->bs_size))
+		return (-1);
+
+	return (mips_btop(bst->bs_pbase + (addr - bst->bs_start) + off));
+}
+
 int
 arc_bus_space_alloc(bst, start, end, size, align, boundary, flags, addrp, bshp)
 	bus_space_tag_t bst;
diff --git a/sys/arch/arc/include/bus.h b/sys/arch/arc/include/bus.h
index 76d074f0aac2..3d70d336a871 100644
--- a/sys/arch/arc/include/bus.h
+++ b/sys/arch/arc/include/bus.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: bus.h,v 1.11 2001/07/19 15:32:11 thorpej Exp $	*/
+/*	$NetBSD: bus.h,v 1.12 2001/09/04 06:57:27 thorpej Exp $	*/
 /*	NetBSD: bus.h,v 1.27 2000/03/15 16:44:50 drochner Exp 	*/
 /*	$OpenBSD: bus.h,v 1.15 1999/08/11 23:15:21 niklas Exp $	*/
 
@@ -158,6 +158,7 @@ struct arc_bus_space {
 				bus_size_t));
 	int	(*bs_subregion) __P((bus_space_tag_t, bus_space_handle_t,
 				bus_size_t, bus_size_t,	bus_space_handle_t *));
+	paddr_t	(*bs_mmap) __P((bus_space_tag_t, bus_addr_t, off_t, int, int));
 
 	/* allocation/deallocation */
 	int	(*bs_alloc) __P((bus_space_tag_t, bus_addr_t, bus_addr_t,
@@ -208,6 +209,7 @@ void	arc_bus_space_unmap __P((bus_space_tag_t, bus_space_handle_t,
 	    bus_size_t));
 int	arc_bus_space_subregion __P((bus_space_tag_t, bus_space_handle_t,
 	    bus_size_t, bus_size_t, bus_space_handle_t *));
+paddr_t	arc_bus_space_mmap __P((bus_space_tag_t, bus_addr_t, off_t, int, int));
 int	arc_bus_space_alloc __P((bus_space_tag_t, bus_addr_t, bus_addr_t,
 	    bus_size_t, bus_size_t, bus_size_t, int, bus_addr_t *,
 	    bus_space_handle_t *));
@@ -242,7 +244,7 @@ int	arc_bus_space_alloc __P((bus_space_tag_t, bus_addr_t, bus_addr_t,
  * MACHINE DEPENDENT, NOT PORTABLE INTERFACE:
  * (cannot be implemented on e.g. I/O space on i386, non-linear space on alpha)
  * Return physical address of a region.
- * A helper function for device mmap entry.
+ * A helper function for machine-dependent device mmap entry.
  */
 #define bus_space_paddr(bst, bsh, pap)					\
 	(*(bst)->bs_paddr)(bst, bsh, pap)
@@ -257,6 +259,15 @@ int	arc_bus_space_alloc __P((bus_space_tag_t, bus_addr_t, bus_addr_t,
 #define bus_space_vaddr(bst, bsh)					\
 	((void *)(bsh))
 
+/*
+ *	paddr_t bus_space_mmap __P((bus_space_tag_t, bus_addr_t, off_t,
+ *	    int, int));
+ *
+ * Mmap bus space on behalf of the user.
+ */
+#define	bus_space_mmap(bst, addr, off, prot, flags)			\
+	(*(bst)->bs_mmap)((bst), (addr), (off), (prot), (flags))
+
 /*
  *	int bus_space_map __P((bus_space_tag_t t, bus_addr_t addr,
  *	    bus_size_t size, int flags, bus_space_handle_t *bshp));