14 Jan, 2011
5 commits
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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
Acked-by: John Stultz
Cc: Rodolfo Giometti
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Using device index as a pointer needs some unnecessary work to be done
every time the pointer is needed (in irq handler for example). Using a
direct pointer is much more easy (and safe as well).Signed-off-by: Alexander Gordeev
Acked-by: Rodolfo Giometti
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add a helper function to gather timestamps. This way clients don't have
to duplicate it.Signed-off-by: Alexander Gordeev
Acked-by: Rodolfo Giometti
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
There was a race in PPS_FETCH ioctl handler when several processes want to
obtain PPS data simultaneously using sleeping PPS_FETCH. They all sleep
most of the time in the system call.With the old approach when the first process waiting on the pps queue is
waken up it makes new system call right away and zeroes pps->go. So other
processes continue to sleep. This is a clear race condition because of
the global 'go' variable.With the new approach pps->last_ev holds some value increasing at each PPS
event. PPS_FETCH ioctl handler saves current value to the local variable
at the very beginning so it can safely check that there is a new event by
just comparing both variables.Signed-off-by: Alexander Gordeev
Acked-by: Rodolfo Giometti
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Here are some very trivial fixes combined:
- add macro definitions to protect header file from including several times
- remove declaration for an unexistent array
- fix typos
Signed-off-by: Alexander Gordeev
Acked-by: Rodolfo Giometti
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
19 Jun, 2009
1 commit
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This patch adds the kernel side of the PPS support currently named
"LinuxPPS".PPS means "pulse per second" and a PPS source is just a device which
provides a high precision signal each second so that an application can
use it to adjust system clock time.Common use is the combination of the NTPD as userland program with a GPS
receiver as PPS source to obtain a wallclock-time with sub-millisecond
synchronisation to UTC.To obtain this goal the userland programs shoud use the PPS API
specification (RFC 2783 - Pulse-Per-Second API for UNIX-like Operating
Systems, Version 1.0) which in part is implemented by this patch. It
provides a set of chars devices, one per PPS source, which can be used to
get the time signal. The RFC's functions can be implemented by accessing
to these char devices.Signed-off-by: Rodolfo Giometti
Cc: David Woodhouse
Cc: Greg KH
Cc: Randy Dunlap
Cc: Kay Sievers
Acked-by: Alan Cox
Cc: Michael Kerrisk
Cc: Christoph Hellwig
Cc: Roman Zippel
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
