input: Add support for the WM831x ON pin

The WM831x series of PMICs support control of initial power on
through the ON pin on the device with soft control of the pin
at other times. Represent this to userspace as KEY_POWER.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index cbe21bc..852941d 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -279,4 +279,14 @@
 	  To compile this driver as a module, choose M here: the
 	  module will be called bfin-rotary.
 
+config INPUT_WM831X_ON
+	tristate "WM831X ON pin"
+	depends on MFD_WM831X
+	help
+	  Support the ON pin of WM831X PMICs as an input device
+	  reporting power button status.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called wm831x_on.
+
 endif