There are rotary-encoders where GPIO lines reflect the actual position
of the rotary encoder dial. For example, if dial points to 9, then four
GPIO lines connected to the rotary encoder will read HLLH(1001b = 9).
Add support for such rotary-encoder.
The driver relies on rotary-encoder,absolute-encoder DT property to
detect such encoders.
Since, GPIO IRQs are not necessary to work with
such encoders, optional polling mode support is added using
input_poll_dev skeleton. This is can be used by enabling
CONFIG_INPUT_GPIO_ROTARY_ENCODER_POLL_MODE_SUPPORT.

Signed-off-by: Vignesh R <vigneshr@ti.com>
---
 .../devicetree/bindings/input/rotary-encoder.txt   |   4 +
 Documentation/input/rotary-encoder.txt             |   9 ++
 drivers/input/misc/Kconfig                         |  11 ++
 drivers/input/misc/rotary_encoder.c                | 165 ++++++++++++++++-----
 4 files changed, 155 insertions(+), 34 deletions(-)

diff --git a/Documentation/devicetree/bindings/input/rotary-encoder.txt b/Documentation/devicetree/bindings/input/rotary-encoder.txt
index 6c9f0c8a846c..9c928dbd1500 100644
--- a/Documentation/devicetree/bindings/input/rotary-encoder.txt
+++ b/Documentation/devicetree/bindings/input/rotary-encoder.txt

@@ -12,6 +12,10 @@ Optional properties:
 - rotary-encoder,relative-axis: register a relative axis rather than an
   absolute one. Relative axis will only generate +1/-1 events on the input
   device, hence no steps need to be passed.
+- rotary-encoder,absolute-encoder: support encoders where GPIO lines
+  reflect the actual position of the rotary encoder dial. For example,
+  if dial points to 9, then four GPIO lines read HLLH(1001b = 9).
+  In this case, rotary-encoder,steps-per-period needed not be defined.