pps: capture MONOTONIC_RAW timestamps as well

MONOTONIC_RAW clock timestamps are ideally suited for frequency
calculation and also fit well into the original NTP hardpps design.  Now
phase and frequency can be adjusted separately: the former based on
REALTIME clock and the latter based on MONOTONIC_RAW clock.

A new function getnstime_raw_and_real is added to timekeeping subsystem to
capture both timestamps at the same time and atomically.

Signed-off-by: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Rodolfo Giometti <giometti@enneenne.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 43 insertions, 0 deletions

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 5bb86da82003..5536aaf3ba36 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -288,6 +288,49 @@ void ktime_get_ts(struct timespec *ts)
 }
 EXPORT_SYMBOL_GPL(ktime_get_ts);
 
+#ifdef CONFIG_NTP_PPS
+
+/**
+ * getnstime_raw_and_real - get day and raw monotonic time in timespec format
+ * @ts_raw:     pointer to the timespec to be set to raw monotonic time
+ * @ts_real:    pointer to the timespec to be set to the time of day
+ *
+ * This function reads both the time of day and raw monotonic time at the
+ * same time atomically and stores the resulting timestamps in timespec
+ * format.
+ */
+void getnstime_raw_and_real(struct timespec *ts_raw, struct timespec *ts_real)
+{
+        unsigned long seq;
+        s64 nsecs_raw, nsecs_real;
+
+        WARN_ON_ONCE(timekeeping_suspended);
+
+        do {
+                u32 arch_offset;
+
+                seq = read_seqbegin(&xtime_lock);
+
+                *ts_raw = raw_time;
+                *ts_real = xtime;
+
+                nsecs_raw = timekeeping_get_ns_raw();
+                nsecs_real = timekeeping_get_ns();
+
+                /* If arch requires, add in gettimeoffset() */
+                arch_offset = arch_gettimeoffset();
+                nsecs_raw += arch_offset;
+                nsecs_real += arch_offset;
+
+        } while (read_seqretry(&xtime_lock, seq));
+
+        timespec_add_ns(ts_raw, nsecs_raw);
+        timespec_add_ns(ts_real, nsecs_real);
+}
+EXPORT_SYMBOL(getnstime_raw_and_real);
+
+#endif /* CONFIG_NTP_PPS */
+
 /**
  * do_gettimeofday - Returns the time of day in a timeval
  * @tv:         pointer to the timeval to be set