Add support for encoders that have two detents per input signal period.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Acked-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>

In particular, several occurances of funny versions of 'success',
'unknown', 'therefore', 'acknowledge', 'argument', 'achieve', 'address',
'beginning', 'desirable', 'separate' and 'necessary' are fixed.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Cc: Joe Perches <joe@perches.com>
Cc: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

The rotary encoder driver only supports returning input events
for ABS_* axes, this adds support for REL_* axes.  The relative
axis input event is reported as -1 for each counter-clockwise
step and +1 for each clockwise step.

The ability to clamp the position of ABS_* axes between 0 and
a maximum of "steps" has also been added.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

This patch adds a generic driver for rotary encoders connected to GPIO
pins of a system. It relies on gpiolib and generic hardware irqs. The
documentation that also comes with this patch explains the concept and
how to use the driver.

Signed-off-by: Daniel Mack <daniel@caiaq.de>
Tested-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>