This patch implements the pps echo functionality for pps-gpio, that
sysfs claims is available already.
Configuration is done via device tree bindings.
This patch was originally written by Lukas Senger as part of a masters
thesis project and modified for inclusion into the linux kernel by Tom
Signed-off-by: Lukas Senger <lukas@xxxxxxxxxxxx>
Signed-off-by: Tom Burkart <tom@xxxxxxxxxx>