[S390] introduce get_clock_monotonic
Introduce get_clock_monotonic() function which can be used to get a
(fast) timestamp. Resolution is the same as for get_clock(). The
only difference is that the timestamps are monotonic and don't jump
backward or forward.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h
index cc21e3e..24aa1cd 100644
--- a/arch/s390/include/asm/timex.h
+++ b/arch/s390/include/asm/timex.h
@@ -90,4 +90,18 @@
extern u64 sched_clock_base_cc;
+/**
+ * get_clock_monotonic - returns current time in clock rate units
+ *
+ * The caller must ensure that preemption is disabled.
+ * The clock and sched_clock_base get changed via stop_machine.
+ * Therefore preemption must be disabled when calling this
+ * function, otherwise the returned value is not guaranteed to
+ * be monotonic.
+ */
+static inline unsigned long long get_clock_monotonic(void)
+{
+ return get_clock_xt() - sched_clock_base_cc;
+}
+
#endif