Input: generic driver for rotary encoders on GPIOs

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>
diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 67e5553..806d2e6 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -227,4 +227,15 @@
 	 Say Y to include support for delivering  PMU events via  input
 	 layer on NXP PCF50633.
 
+config INPUT_GPIO_ROTARY_ENCODER
+	tristate "Rotary encoders connected to GPIO pins"
+	depends on GPIOLIB && GENERIC_GPIO
+	help
+	  Say Y here to add support for rotary encoders connected to GPIO lines.
+	  Check file:Documentation/incput/rotary_encoder.txt for more
+	  information.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called rotary_encoder.
+
 endif