1 files changed, 101 insertions, 0 deletions
diff --git a/arch/x86_64/kernel/pmtimer.c b/arch/x86_64/kernel/pmtimer.c
new file mode 100644
index 0000000000000..feb5f108dd26e
--- /dev/null
+++ b/arch/x86_64/kernel/pmtimer.c
@@ -0,0 +1,101 @@
+/* Ported over from i386 by AK, original copyright was:
+ *
+ * (C) Dominik Brodowski <linux@brodo.de> 2003
+ *
+ * Driver to use the Power Management Timer (PMTMR) available in some
+ * southbridges as primary timing source for the Linux kernel.
+ *
+ * Based on parts of linux/drivers/acpi/hardware/hwtimer.c, timer_pit.c,
+ * timer_hpet.c, and on Arjan van de Ven's implementation for 2.4.
+ *
+ * This file is licensed under the GPL v2.
+ *
+ * Dropped all the hardware bug workarounds for now. Hopefully they
+ * are not needed on 64bit chipsets.
+ */
+
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/cpumask.h>
+#include <asm/io.h>
+#include <asm/proto.h>
+#include <asm/msr.h>
+#include <asm/vsyscall.h>
+
+/* The I/O port the PMTMR resides at.
+ * The location is detected during setup_arch(),
+ * in arch/i386/kernel/acpi/boot.c */
+u32 pmtmr_ioport;
+
+/* value of the Power timer at last timer interrupt */
+static u32 offset_delay;
+static u32 last_pmtmr_tick;
+
+#define ACPI_PM_MASK 0xFFFFFF /* limit it to 24 bits */
+
+static inline u32 cyc2us(u32 cycles)
+{
+	/* The Power Management Timer ticks at 3.579545 ticks per microsecond.
+	 * 1 / PM_TIMER_FREQUENCY == 0.27936511 =~ 286/1024 [error: 0.024%]
+	 *
+	 * Even with HZ = 100, delta is at maximum 35796 ticks, so it can
+	 * easily be multiplied with 286 (=0x11E) without having to fear
+	 * u32 overflows.
+	 */
+	cycles *= 286;
+	return (cycles >> 10);
+}
+
+int pmtimer_mark_offset(void)
+{
+	static int first_run = 1;
+	unsigned long tsc;
+	u32 lost;
+
+	u32 tick = inl(pmtmr_ioport);
+	u32 delta;
+
+	delta = cyc2us((tick - last_pmtmr_tick) & ACPI_PM_MASK);
+
+	last_pmtmr_tick = tick;
+	monotonic_base += delta * NSEC_PER_USEC;
+
+	delta += offset_delay;
+
+	lost = delta / (USEC_PER_SEC / HZ);
+	offset_delay = delta % (USEC_PER_SEC / HZ);
+
+	rdtscll(tsc);
+	vxtime.last_tsc = tsc - offset_delay * cpu_khz;
+
+	/* don't calculate delay for first run,
+	   or if we've got less then a tick */
+	if (first_run || (lost < 1)) {
+		first_run = 0;
+		offset_delay = 0;
+	}
+
+	return lost - 1;
+}
+
+unsigned int do_gettimeoffset_pm(void)
+{
+	u32 now, offset, delta = 0;
+
+	offset = last_pmtmr_tick;
+	now = inl(pmtmr_ioport);
+	delta = (now - offset) & ACPI_PM_MASK;
+
+	return offset_delay + cyc2us(delta);
+}
+
+
+static int __init nopmtimer_setup(char *s)
+{
+	pmtmr_ioport = 0;
+	return 0;
+}
+
+__setup("nopmtimer", nopmtimer_setup);