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pps: capture MONOTONIC_RAW timestamps as well

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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>
This commit is contained in:
Alexander Gordeev
2011-01-12 17:00:57 -08:00
committed by Linus Torvalds
parent 025b40abe7
commit e2c18e49a0
3 changed files with 59 additions and 0 deletions
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43
kernel/time/timekeeping.c
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@ -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