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-rw-r--r--arch/ia64/kernel/time.c29
1 files changed, 29 insertions, 0 deletions
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index 5b7e736f3b4..028a2b95936 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -249,3 +249,32 @@ time_init (void)
*/
set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec);
}
+
+#define SMALLUSECS 100
+
+void
+udelay (unsigned long usecs)
+{
+ unsigned long start;
+ unsigned long cycles;
+ unsigned long smallusecs;
+
+ /*
+ * Execute the non-preemptible delay loop (because the ITC might
+ * not be synchronized between CPUS) in relatively short time
+ * chunks, allowing preemption between the chunks.
+ */
+ while (usecs > 0) {
+ smallusecs = (usecs > SMALLUSECS) ? SMALLUSECS : usecs;
+ preempt_disable();
+ cycles = smallusecs*local_cpu_data->cyc_per_usec;
+ start = ia64_get_itc();
+
+ while (ia64_get_itc() - start < cycles)
+ cpu_relax();
+
+ preempt_enable();
+ usecs -= smallusecs;
+ }
+}
+EXPORT_SYMBOL(udelay);