diff --git a/sys/arch/dreamcast/dreamcast/clock_machdep.c b/sys/arch/dreamcast/dreamcast/clock_machdep.c
index 71f5008b9758..388ead58a377 100644
--- a/sys/arch/dreamcast/dreamcast/clock_machdep.c
+++ b/sys/arch/dreamcast/dreamcast/clock_machdep.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: clock_machdep.c,v 1.2 2003/07/15 01:31:41 lukem Exp $	*/
+/*	$NetBSD: clock_machdep.c,v 1.3 2003/08/07 23:14:13 marcus Exp $	*/
 
 /*-
  * Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: clock_machdep.c,v 1.2 2003/07/15 01:31:41 lukem Exp $");
+__KERNEL_RCSID(0, "$NetBSD: clock_machdep.c,v 1.3 2003/08/07 23:14:13 marcus Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -42,19 +42,22 @@ __KERNEL_RCSID(0, "$NetBSD: clock_machdep.c,v 1.2 2003/07/15 01:31:41 lukem Exp
 #include <dev/clock_subr.h>
 #include <sh3/clock.h>
 
+#include <dreamcast/dev/g2/g2busvar.h>
+
 #ifdef DEBUG
 #define STATIC
 #else
 #define STATIC static
 #endif
 
-#define DREAMCAST_RTC		0xa0710000
+#define DREAMCAST_RTC		0x00710000
 
 STATIC void dreamcast_rtc_init(void *);
 STATIC void dreamcast_rtc_get(void *, time_t, struct clock_ymdhms *);
 STATIC void dreamcast_rtc_set(void *, struct clock_ymdhms *);
 
 STATIC u_int32_t dreamcast_read_rtc(void);
+STATIC void dreamcast_write_rtc(u_int32_t);
 
 STATIC struct rtc_ops dreamcast_rtc_ops = {
 	.init	= dreamcast_rtc_init,
@@ -62,6 +65,9 @@ STATIC struct rtc_ops dreamcast_rtc_ops = {
 	.set	= dreamcast_rtc_set
 };
 
+static bus_space_tag_t rtc_tag;
+static bus_space_handle_t rtc_handle;
+
 void
 machine_clock_init()
 {
@@ -72,7 +78,20 @@ machine_clock_init()
 void
 dreamcast_rtc_init(void *cookie)
 {
-	/* Nothing to do */
+	struct device *dv;
+
+	/* Find g2bus device */
+	for (dv = TAILQ_FIRST(&alldevs); dv != NULL;
+	     dv = TAILQ_NEXT(dv, dv_list))
+		if (!strcmp(dv->dv_xname, "g2bus0"))
+			break;
+
+	if (!dv)
+		panic("No g2bus!");
+
+	rtc_tag = &((struct g2bus_softc *)dv)->sc_memt;
+
+	bus_space_map(rtc_tag, DREAMCAST_RTC, 12, 0, &rtc_handle);
 }
 
 void
@@ -86,19 +105,21 @@ void
 dreamcast_rtc_set(void *cookie, struct clock_ymdhms *dt)
 {
 	
-	/* Not suppoted */
+	dreamcast_write_rtc(clock_ymdhms_to_secs(dt));
 }
 
 u_int32_t
 dreamcast_read_rtc()
 {
-	__volatile__ u_int32_t *rtc = (__volatile__ u_int32_t *)DREAMCAST_RTC;
 	u_int32_t new, old;
 	int i;
 	
 	for (old = 0;;) {
 		for (i = 0; i < 3; i++) {
-			new = ((rtc[0] & 0xffff) << 16) | (rtc[1] & 0xffff);
+			new = ((bus_space_read_4(rtc_tag, rtc_handle, 0)
+				& 0xffff) << 16) 
+			  | (bus_space_read_4(rtc_tag, rtc_handle, 4) 
+			     & 0xffff);
 			if (new != old)
 				break;
 		}
@@ -111,3 +132,33 @@ dreamcast_read_rtc()
 	/* offset 20 years */
 	return (new - 631152000);
 }
+
+void
+dreamcast_write_rtc(u_int32_t secs)
+{
+	u_int32_t new;
+	int i, retry;
+
+	/* offset 20 years */
+	secs += 631152000;
+
+	for (retry = 0; retry < 5; retry++) {
+
+		/* Don't change an order */
+		bus_space_write_4(rtc_tag, rtc_handle, 8, 1);
+		bus_space_write_4(rtc_tag, rtc_handle, 4, secs & 0xffff);
+		bus_space_write_4(rtc_tag, rtc_handle, 0, secs >> 16);
+
+		/* verify */
+		for (i = 0; i < 3; i++) {
+			new = ((bus_space_read_4(rtc_tag, rtc_handle, 0)
+				& 0xffff) << 16)
+			  | (bus_space_read_4(rtc_tag, rtc_handle, 4)
+			     & 0xffff);
+			if (new == secs)
+				return;
+		}
+	}
+	/* set failure. but nothing to do */
+}
+