Index: sys/x86/isa/atrtc.c
===================================================================
--- sys/x86/isa/atrtc.c	(revision 268728)
+++ sys/x86/isa/atrtc.c	(working copy)
@@ -31,6 +31,7 @@
 __FBSDID("$FreeBSD$");
 
 #include "opt_isa.h"
+#include "opt_acpi.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -53,12 +54,19 @@
 #include <machine/intr_machdep.h>
 #include "clock_if.h"
 
+#include <contrib/dev/acpica/include/acpi.h>
+#include <contrib/dev/acpica/include/accommon.h>
+#include <dev/acpica/acpivar.h>
+
 #define	RTC_LOCK	do { if (!kdb_active) mtx_lock_spin(&clock_lock); } while (0)
 #define	RTC_UNLOCK	do { if (!kdb_active) mtx_unlock_spin(&clock_lock); } while (0)
 
+#define IO_DELAY()	(void)inb(0x84)
+#define IO_RTC_ADDR	(IO_RTC + 0)
+#define IO_RTC_DATA	(IO_RTC + 1)
+
 int	atrtcclock_disable = 0;
 
-static	int	rtc_reg = -1;
 static	u_char	rtc_statusa = RTCSA_DIVIDER | RTCSA_NOPROF;
 static	u_char	rtc_statusb = RTCSB_24HR;
 
@@ -66,39 +74,52 @@
  * RTC support routines
  */
 
-int
-rtcin(int reg)
+static void
+acpi_cmos_read(ACPI_PHYSICAL_ADDRESS address, UINT8 *buf, UINT32 buflen)
 {
-	u_char val;
+	UINT32 offset;
 
 	RTC_LOCK;
-	if (rtc_reg != reg) {
-		inb(0x84);
-		outb(IO_RTC, reg);
-		rtc_reg = reg;
-		inb(0x84);
+	for (offset = 0; offset < buflen; ++offset) {
+		IO_DELAY();
+		outb(IO_RTC_ADDR, ((address + offset) | 0x80) & 0xFF);
+		IO_DELAY();
+		buf[offset] = inb(IO_RTC_DATA);
 	}
-	val = inb(IO_RTC + 1);
 	RTC_UNLOCK;
-	return (val);
 }
 
-void
-writertc(int reg, u_char val)
+static void
+acpi_cmos_write(ACPI_PHYSICAL_ADDRESS address, const UINT8 *buf, UINT32 buflen)
 {
+	UINT32 offset;
 
 	RTC_LOCK;
-	if (rtc_reg != reg) {
-		inb(0x84);
-		outb(IO_RTC, reg);
-		rtc_reg = reg;
-		inb(0x84);
+	for (offset = 0; offset < buflen; ++offset) {
+		IO_DELAY();
+		outb(IO_RTC_ADDR, ((address + offset) | 0x80) & 0xFF);
+		IO_DELAY();
+		outb(IO_RTC_DATA, buf[offset]);
 	}
-	outb(IO_RTC + 1, val);
-	inb(0x84);
+	IO_DELAY();
 	RTC_UNLOCK;
 }
 
+int
+rtcin(int reg)
+{
+	u_char val;
+
+	acpi_cmos_read(reg & 0xFF, &val, 1);
+	return (val);
+}
+
+void
+writertc(int reg, u_char val)
+{
+	acpi_cmos_write(reg & 0xFF, &val, 1);
+}
+
 static __inline int
 readrtc(int port)
 {
@@ -144,7 +165,6 @@
 {
 
 	/* Restore all of the RTC's "status" (actually, control) registers. */
-	rtcin(RTC_STATUSA);	/* dummy to get rtc_reg set */
 	writertc(RTC_STATUSB, RTCSB_24HR);
 	writertc(RTC_STATUSA, rtc_statusa);
 	writertc(RTC_STATUSB, rtc_statusb);
@@ -161,9 +181,58 @@
 	struct resource *intr_res;
 	void *intr_handler;
 	struct eventtimer et;
+	ACPI_HANDLE acpi_handle;	/* Handle of the PNP0B00 node */
 };
 
 static int
+acpi_check_rtc_byteaccess(int is_read, u_long addr)
+{
+	int retval = 1;	/* Success */
+
+	if (is_read) {
+		/* Reading 0x0C will muck with interrupts */
+		if (addr == 0x0C)
+			retval = 0;
+	} else {
+		/* No writing RTC control regs */
+		if (addr >= 0x0A && addr <= 0x0D)
+			retval = 0;
+	}
+	return retval;
+}
+
+static ACPI_STATUS
+acpi_rtc_cmos_handler(UINT32 function, ACPI_PHYSICAL_ADDRESS address,
+    UINT32 width, UINT64 *value, void *context, void *region_context)
+{
+	struct atrtc_softc *sc;
+
+	sc = (struct atrtc_softc *)context;
+	if (!value || !sc)
+		return AE_BAD_PARAMETER;
+	if (width > 32 || (width & 0x07) || address >= 64)
+		return AE_BAD_PARAMETER;
+	if (!acpi_check_rtc_byteaccess(function == ACPI_READ, address))
+		return AE_BAD_PARAMETER;
+
+	switch (function) {
+		case ACPI_READ:
+			acpi_cmos_read(address, (UINT8 *)value, width >> 3);
+			break;
+		case ACPI_WRITE:
+			acpi_cmos_write(address, (const UINT8 *)value,
+			    width >> 3);
+			break;
+		default:
+			return AE_BAD_PARAMETER;
+	}
+	printf("%s: %-5s%02u address=%04lx value=%08x\n",
+	    __FUNCTION__, function == ACPI_READ ? "READ" : "WRITE", width >> 3,
+	    address, *((UINT32 *)value));
+	return AE_OK;
+}
+
+static int
 rtc_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
 {
 
@@ -245,10 +314,17 @@
 	int i;
 
 	sc = device_get_softc(dev);
+	sc->acpi_handle = acpi_get_handle(dev);
 	sc->port_res = bus_alloc_resource(dev, SYS_RES_IOPORT, &sc->port_rid,
 	    IO_RTC, IO_RTC + 1, 2, RF_ACTIVE);
 	if (sc->port_res == NULL)
 		device_printf(dev, "Warning: Couldn't map I/O.\n");
+	if (ACPI_FAILURE(AcpiInstallAddressSpaceHandler(sc->acpi_handle,
+						ACPI_ADR_SPACE_CMOS, acpi_rtc_cmos_handler, NULL, sc)))
+	{
+		device_printf(dev, "Error registering ACPI CMOS address space handler.\n");
+		return 0;
+	}
 	atrtc_start();
 	clock_register(dev, 1000000);
 	bzero(&sc->et, sizeof(struct eventtimer));
@@ -286,6 +362,15 @@
 	return(0);
 }
 
+static int atrtc_detach(device_t dev)
+{
+	struct atrtc_softc *sc;
+
+	sc = device_get_softc(dev);
+	AcpiRemoveAddressSpaceHandler(sc->acpi_handle, ACPI_ADR_SPACE_CMOS, acpi_rtc_cmos_handler);
+	return bus_generic_detach(dev);
+}
+
 static int
 atrtc_resume(device_t dev)
 {
@@ -366,7 +451,7 @@
 	/* Device interface */
 	DEVMETHOD(device_probe,		atrtc_probe),
 	DEVMETHOD(device_attach,	atrtc_attach),
-	DEVMETHOD(device_detach,	bus_generic_detach),
+	DEVMETHOD(device_detach,	atrtc_detach),
 	DEVMETHOD(device_shutdown,	bus_generic_shutdown),
 	DEVMETHOD(device_suspend,	bus_generic_suspend),
 		/* XXX stop statclock? */