1 files changed, 45 insertions, 17 deletions

diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index 0e3b60e1ac5b..735b6767c8ed 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -26,6 +26,8 @@
 #include <linux/sysdev.h>
 #include <linux/bcd.h>
 #include <linux/kallsyms.h>
+#include <linux/acpi.h>
+#include <acpi/achware.h>       /* for PM timer frequency */
 #include <asm/8253pit.h>
 #include <asm/pgtable.h>
 #include <asm/vsyscall.h>
@@ -396,6 +398,10 @@ static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
                         (offset - vxtime.last)*(NSEC_PER_SEC/HZ) / hpet_tick;
 
                 vxtime.last = offset;
+#ifdef CONFIG_X86_PM_TIMER
+        } else if (vxtime.mode == VXTIME_PMTMR) {
+                lost = pmtimer_mark_offset();
+#endif
         } else {
                 offset = (((tsc - vxtime.last_tsc) *
                            vxtime.tsc_quot) >> 32) - (USEC_PER_SEC / HZ);
@@ -898,6 +904,13 @@ void __init time_init(void)
                         hpet_period;
                 cpu_khz = hpet_calibrate_tsc();
                 timename = "HPET";
+#ifdef CONFIG_X86_PM_TIMER
+        } else if (pmtmr_ioport) {
+                vxtime_hz = PM_TIMER_FREQUENCY;
+                timename = "PM";
+                pit_init();
+                cpu_khz = pit_calibrate_tsc();
+#endif
         } else {
                 pit_init();
                 cpu_khz = pit_calibrate_tsc();
@@ -923,35 +936,50 @@ void __init time_init(void)
 }
 
 /*
+ * Make an educated guess if the TSC is trustworthy and synchronized
+ * over all CPUs.
+ */
+static __init int unsynchronized_tsc(void)
+{
+#ifdef CONFIG_SMP
+        if (oem_force_hpet_timer())
+                return 1;
+        /* Intel systems are normally all synchronized. Exceptions
+           are handled in the OEM check above. */
+        if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
+                return 0;
+        /* All in a single socket - should be synchronized */
+        if (cpus_weight(cpu_core_map[0]) == num_online_cpus())
+                return 0;
+#endif
+        /* Assume multi socket systems are not synchronized */
+        return num_online_cpus() > 1;
+}
+
+/*
  * Decide after all CPUs are booted what mode gettimeofday should use.
  */
 void __init time_init_gtod(void)
 {
         char *timetype;
 
-        /*
-         * AMD systems with more than one CPU don't have fully synchronized
-         * TSCs. Always use HPET gettimeofday for these, although it is slower.
-         * Intel SMP systems usually have synchronized TSCs, so use always
-         * the TSC.
-         *
-         * Exceptions:
-         * IBM Summit2 checked by oem_force_hpet_timer().
-         * AMD dual core may also not need HPET. Check me.
-         *
-         * Can be turned off with "notsc".
-         */
-        if (num_online_cpus() > 1 &&
-            boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
-                notsc = 1;
-        /* Some systems will want to disable TSC and use HPET. */
-        if (oem_force_hpet_timer())
+        if (unsynchronized_tsc())
                 notsc = 1;
         if (vxtime.hpet_address && notsc) {
                 timetype = "HPET";
                 vxtime.last = hpet_readl(HPET_T0_CMP) - hpet_tick;
                 vxtime.mode = VXTIME_HPET;
                 do_gettimeoffset = do_gettimeoffset_hpet;
+#ifdef CONFIG_X86_PM_TIMER
+        /* Using PM for gettimeofday is quite slow, but we have no other
+           choice because the TSC is too unreliable on some systems. */
+        } else if (pmtmr_ioport && !vxtime.hpet_address && notsc) {
+                timetype = "PM";
+                do_gettimeoffset = do_gettimeoffset_pm;
+                vxtime.mode = VXTIME_PMTMR;
+                sysctl_vsyscall = 0;
+                printk(KERN_INFO "Disabling vsyscall due to use of PM timer\n");
+#endif
         } else {
                 timetype = vxtime.hpet_address ? "HPET/TSC" : "PIT/TSC";
                 vxtime.mode = VXTIME_TSC;