[PATCH net-next 02/11] timecounter: provide a helper function to shift the time.

[Richard Cochran <richardcochran@gmail.com>]

Some PTP Hardware Clock drivers use a struct timecounter to represent
their clock. To adjust the time by a given offset, these drivers all
perform a two step read/write of their timecounter. However, it is
better and simpler just to adjust the offset in one step. This patch
introduces a little routine to help drivers implement the adjtime
method.

Suggested-by: Janusz Użycki <j.uzycki@elproma.com.pl>
Signed-off-by: Richard Cochran <richardcochran@gmail.com>
---
 include/linux/timecounter.h |    9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/include/linux/timecounter.h b/include/linux/timecounter.h
index 146f07a..af3dfa4 100644
--- a/include/linux/timecounter.h
+++ b/include/linux/timecounter.h
@@ -79,6 +79,15 @@ static inline u64 cyclecounter_cyc2ns(const struct cyclecounter *cc,
 }
 
 /**
+ * timecounter_adjtime - Shifts the time of the clock.
+ * @delta:	Desired change in nanoseconds.
+ */
+static inline void timecounter_adjtime(struct timecounter *tc, s64 delta)
+{
+	tc->nsec += delta;
+}
+
+/**
  * timecounter_init - initialize a time counter
  * @tc:			Pointer to time counter which is to be initialized/reset
  * @cc:			A cycle counter, ready to be used.
-- 
1.7.10.4