path: root/Documentation/pps
AgeCommit message (Collapse)Author
2011-01-13pps: add parallel port PPS signal generatorAlexander Gordeev
Add PPS signal generator which utilizes STROBE pin of a parallel port to send PPS signals. It uses parport abstraction layer and hrtimers to precisely control the signal. [ fix build] Signed-off-by: Alexander Gordeev <> Acked-by: Rodolfo Giometti <> Cc: john stultz <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
2009-06-18LinuxPPS: core supportRodolfo Giometti
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 <>