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 <[e-mail]>
Acked-by: John Stultz <[e-mail]>
Cc: Rodolfo Giometti <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/pps_kernel.h

···
 };
 
 struct pps_event_time {
+#ifdef CONFIG_NTP_PPS
+	struct timespec ts_raw;
+#endif /* CONFIG_NTP_PPS */
 	struct timespec ts_real;
 };
 
···
 	kt->nsec = ts.tv_nsec;
 }
 
+#ifdef CONFIG_NTP_PPS
+
+static inline void pps_get_ts(struct pps_event_time *ts)
+{
+	getnstime_raw_and_real(&ts->ts_raw, &ts->ts_real);
+}
+
+#else /* CONFIG_NTP_PPS */
+
 static inline void pps_get_ts(struct pps_event_time *ts)
 {
 	getnstimeofday(&ts->ts_real);
 }
+
+#endif /* CONFIG_NTP_PPS */
 
 #endif /* LINUX_PPS_KERNEL_H */
 

include/linux/time.h

···
 extern int do_getitimer(int which, struct itimerval *value);
 extern void getnstimeofday(struct timespec *tv);
 extern void getrawmonotonic(struct timespec *ts);
+extern void getnstime_raw_and_real(struct timespec *ts_raw,
+		struct timespec *ts_real);
 extern void getboottime(struct timespec *ts);
 extern void monotonic_to_bootbased(struct timespec *ts);
 

kernel/time/timekeeping.c

···
 }
 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