First cut on an implementation of an ACPI power management counter

backend for timecounters.
Due to known bugs in some chipsets, always read until we get 3 successive
samples which are monotonic, as FreeBSD does in its "safe" variant.
This can be refined later, either by chipset quirks or by a test (as
FreeBSD does).

sys/dev/acpi/acpi.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: acpi.c,v 1.89 2006/06/20 12:31:19 cube Exp $	*/
+/*	$NetBSD: acpi.c,v 1.90 2006/06/21 17:47:23 drochner Exp $	*/
 
 /*-
  * Copyright (c) 2003 The NetBSD Foundation, Inc.
@@ -77,7 +77,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: acpi.c,v 1.89 2006/06/20 12:31:19 cube Exp $");
+__KERNEL_RCSID(0, "$NetBSD: acpi.c,v 1.90 2006/06/21 17:47:23 drochner Exp $");
 
 #include "opt_acpi.h"
 #include "opt_pcifixup.h"
@@ -94,6 +94,7 @@ __KERNEL_RCSID(0, "$NetBSD: acpi.c,v 1.89 2006/06/20 12:31:19 cube Exp $");
 #include <dev/acpi/acpireg.h>
 #include <dev/acpi/acpivar.h>
 #include <dev/acpi/acpi_osd.h>
+#include <dev/acpi/acpi_timer.h>
 #ifdef ACPIVERBOSE
 #include <dev/acpi/acpidevs_data.h>
 #endif
@@ -351,6 +352,7 @@ acpi_attach(struct device *parent, struct device *self, void *aux)
 	 * Check for fixed-hardware features.
 	 */
 	acpi_enable_fixed_events(sc);
+	acpitimer_init();
 
 	/*
 	 * Fix up PCI devices.

sys/dev/acpi/acpi_timer.c

@@ -0,0 +1,73 @@
+/* $NetBSD: acpi_timer.c,v 1.1 2006/06/21 17:47:23 drochner Exp $ */
+
+#include <sys/types.h>
+
+#ifdef __HAVE_TIMECOUNTER
+
+#include <sys/systm.h>
+#include <sys/time.h>
+#include <sys/timetc.h>
+#include <dev/acpi/acpica.h>
+#include <dev/acpi/acpi_timer.h>
+
+static u_int acpitimer_read(struct timecounter *);
+
+static struct timecounter acpi_timecounter = {
+	acpitimer_read,
+	0,
+	0x00ffffff,
+	PM_TIMER_FREQUENCY,
+	"ACPI_PM_TMR",
+	900
+};
+
+int
+acpitimer_init()
+{
+	uint32_t bits;
+	ACPI_STATUS res;
+
+	res = AcpiGetTimerResolution(&bits);
+	if (res != AE_OK)
+		return (-1);
+
+	if (bits == 32)
+		acpi_timecounter.tc_counter_mask = 0xffffffff;
+	tc_init(&acpi_timecounter);
+
+	printf("acpitimer: %d bits\n", bits);
+
+	return (0);
+}
+
+/*
+ * Some chipsets (PIIX4 variants) do not latch correctly; there
+ * is a chance that a transition is hit.
+ * For now, just be conservative. We might detect the situation later
+ * (by testing, or chipset quirks).
+ */
+static u_int
+acpitimer_read(struct timecounter *tc)
+{
+	uint32_t t1, t2, t3;
+
+	AcpiGetTimer(&t2);
+	AcpiGetTimer(&t3);
+	do {
+		t1 = t2;
+		t2 = t3;
+		AcpiGetTimer(&t3);
+	} while ((t1 > t2) || (t2 > t3));
+	return (t2);
+}
+
+#else
+
+int
+acpitimer_init()
+{
+
+	return (0);
+}
+
+#endif

sys/dev/acpi/acpi_timer.h

@@ -0,0 +1,3 @@
+/* $NetBSD: acpi_timer.h,v 1.1 2006/06/21 17:47:23 drochner Exp $ */
+
+int acpitimer_init(void);

sys/dev/acpi/files.acpi

@@ -1,4 +1,4 @@
-#	$NetBSD: files.acpi,v 1.35 2006/01/31 09:30:06 kochi Exp $
+#	$NetBSD: files.acpi,v 1.36 2006/06/21 17:47:23 drochner Exp $
 
 include "dev/acpi/acpica/files.acpica"
 
@@ -12,6 +12,7 @@ file	dev/acpi/acpi_resource.c	acpi
 file	dev/acpi/acpi_powerres.c	acpi
 file	dev/acpi/acpi_madt.c		acpi & mpacpi
 file	dev/acpi/acpi_quirks.c		acpi
+file	dev/acpi/acpi_timer.c		acpi
 
 # ACPI Embedded Controller
 device	acpiec