1 files changed, 16 insertions, 0 deletions

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index ce89ffb474d0..10a1347597fd 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -153,6 +153,7 @@ void tick_nohz_stop_sched_tick(void)
         unsigned long seq, last_jiffies, next_jiffies, delta_jiffies, flags;
         struct tick_sched *ts;
         ktime_t last_update, expires, now, delta;
+        struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
         int cpu;
 
         local_irq_save(flags);
@@ -302,11 +303,26 @@ void tick_nohz_stop_sched_tick(void)
 out:
         ts->next_jiffies = next_jiffies;
         ts->last_jiffies = last_jiffies;
+        ts->sleep_length = ktime_sub(dev->next_event, now);
 end:
         local_irq_restore(flags);
 }
 
 /**
+ * tick_nohz_get_sleep_length - return the length of the current sleep
+ *
+ * Called from power state control code with interrupts disabled
+ */
+ktime_t tick_nohz_get_sleep_length(void)
+{
+        struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
+
+        return ts->sleep_length;
+}
+
+EXPORT_SYMBOL_GPL(tick_nohz_get_sleep_length);
+
+/**
  * nohz_restart_sched_tick - restart the idle tick from the idle task
  *
  * Restart the idle tick when the CPU is woken up from idle