serial:serial_core: Allow use of CTS for PPS line discipline
authorSteve Sakoman <steve@sakoman.com>
Thu, 20 Sep 2018 19:20:34 +0000 (09:20 -1000)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tue, 2 Oct 2018 20:38:55 +0000 (13:38 -0700)
commitc550f01c810f2197c98e6e3103f81797f5e063be
treeb799d0991c3aa188982b1bcdacd263b406e39f77
parent669c5d8d5f2be781d411ad8d52274038c795f257
serial:serial_core: Allow use of CTS for PPS line discipline

Add a "pps_4wire" file to serial ports in sysfs in case the kernel is
configured with CONFIG_PPS_CLIENT_LDISC. Writing 1 to the file enables
the use of CTS instead of DCD for PPS signal input. This is necessary
in case a serial port is not completely wired.
Though this affects PPS processing the patch is against the serial core
as the source of the serial port PPS event dispatching has to be
modified. Furthermore it should be possible to modify the source of
serial port PPS event dispatching before changing the line discipline.

Signed-off-by: Andreas Steinmetz <ast@domdv.de>
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Tested-by: Steve Sakoman <steve@sakoman.com>
Tested-by: Eric Gallimore <egallimore@ucsd.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Documentation/ABI/testing/sysfs-tty
drivers/tty/serial/serial_core.c
include/linux/serial_core.h