Sometimes one needs to be able not only to catch PPS signals but to
produce them also. For example, running a distributed simulation,
which requires computers' clock to be synchronized very tightly.
This patch adds PPS generators class in order to have a well-defined
interface for these devices.
Signed-off-by: Rodolfo Giometti <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Add SPDX license identifiers to all Make/Kconfig files which:
- Have no license information of any form
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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.
[[email protected]: fix build]
Signed-off-by: Alexander Gordeev <[email protected]>
Acked-by: Rodolfo Giometti <[email protected]>
Cc: john stultz <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Each PPS source can be registered/deregistered into the system by using
special modules called "clients". They simply define the PPS sources'
attributes and implement the time signal registration mechanism.
This patch adds a special directory for such clients and adds a dummy
client that can be useful to test system integrity on real systems.
[[email protected]: coding-style fixes]
Signed-off-by: Rodolfo Giometti <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Greg KH <[email protected]>
Cc: Alan Cox <[email protected]>
Cc: Alexander Gordeev <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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 <[email protected]>
Cc: David Woodhouse <[email protected]>
Cc: Greg KH <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Kay Sievers <[email protected]>
Acked-by: Alan Cox <[email protected]>
Cc: Michael Kerrisk <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Roman Zippel <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Rodolfo Giometti