1 files changed, 69 insertions, 0 deletions

diff --git a/arch/x86/kernel/pmtimer_64.c b/arch/x86/kernel/pmtimer_64.c
new file mode 100644
index 000000000000..ae8f91214f15
--- /dev/null
+++ b/arch/x86/kernel/pmtimer_64.c
@@ -0,0 +1,69 @@
+/* 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>
+
+#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);
+}
+
+static unsigned pmtimer_wait_tick(void)
+{
+        u32 a, b;
+        for (a = b = inl(pmtmr_ioport) & ACPI_PM_MASK;
+             a == b;
+             b = inl(pmtmr_ioport) & ACPI_PM_MASK)
+                cpu_relax();
+        return b;
+}
+
+/* note: wait time is rounded up to one tick */
+void pmtimer_wait(unsigned us)
+{
+        u32 a, b;
+        a = pmtimer_wait_tick();
+        do {
+                b = inl(pmtmr_ioport);
+                cpu_relax();
+        } while (cyc2us(b - a) < us);
+}
+
+static int __init nopmtimer_setup(char *s)
+{
+        pmtmr_ioport = 0;
+        return 1;
+}
+
+__setup("nopmtimer", nopmtimer_setup);