aboutsummaryrefslogtreecommitdiff
path: root/arch/ia64/sn/kernel/sn2/timer.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/ia64/sn/kernel/sn2/timer.c')
-rw-r--r--arch/ia64/sn/kernel/sn2/timer.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/arch/ia64/sn/kernel/sn2/timer.c b/arch/ia64/sn/kernel/sn2/timer.c
index deb9baf4d47..56a88b6df4b 100644
--- a/arch/ia64/sn/kernel/sn2/timer.c
+++ b/arch/ia64/sn/kernel/sn2/timer.c
@@ -14,6 +14,7 @@
#include <asm/hw_irq.h>
#include <asm/system.h>
+#include <asm/timex.h>
#include <asm/sn/leds.h>
#include <asm/sn/shub_mmr.h>
@@ -28,9 +29,27 @@ static struct time_interpolator sn2_interpolator = {
.source = TIME_SOURCE_MMIO64
};
+/*
+ * sn udelay uses the RTC instead of the ITC because the ITC is not
+ * synchronized across all CPUs, and the thread may migrate to another CPU
+ * if preemption is enabled.
+ */
+static void
+ia64_sn_udelay (unsigned long usecs)
+{
+ unsigned long start = rtc_time();
+ unsigned long end = start +
+ usecs * sn_rtc_cycles_per_second / 1000000;
+
+ while (time_before((unsigned long)rtc_time(), end))
+ cpu_relax();
+}
+
void __init sn_timer_init(void)
{
sn2_interpolator.frequency = sn_rtc_cycles_per_second;
sn2_interpolator.addr = RTC_COUNTER_ADDR;
register_time_interpolator(&sn2_interpolator);
+
+ ia64_udelay = &ia64_sn_udelay;
}