[PATCHv7 13/16] pps: capture MONOTONIC_RAW timestamps as well

Alexander Gordeev
2010-12-20T11:55:43Z

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.

Acked-by: John Stultz <johnstul@us.ibm.com>
Signed-off-by: Alexander Gordeev <lasaine@lvk.cs.msu.su>
---
include/linux/pps_kernel.h | 14 ++++++++++++++
include/linux/time.h | 2 ++
kernel/time/timekeeping.c | 43 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 59 insertions(+), 0 deletions(-)

diff --git a/include/linux/pps_kernel.h b/include/linux/pps_kernel.h
index 1aedf50..9404854 100644
--- a/include/linux/pps_kernel.h
+++ b/include/linux/pps_kernel.h
@@ -47,6 +47,9 @@ struct pps_source_info {
};

struct pps_event_time {
+#ifdef CONFIG_NTP_PPS
+ struct timespec ts_raw;
+#endif /* CONFIG_NTP_PPS */
struct timespec ts_real;
};

@@ -97,10 +100,21 @@ static inline void timespec_to_pps_ktime(struct pps_ktime *kt,
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 */

diff --git a/include/linux/time.h b/include/linux/time.h
index 9f15ac7..1e6d3b5 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -158,6 +158,8 @@ extern unsigned int alarm_setitimer(unsigned int seconds);
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);

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 49010d8..5c4be30 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -284,6 +284,49 @@ 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
--
1.7.2.3