Input: add new sun4i-lradc-keys driver

Allwinnner sunxi SoCs have a low resolution adc (called lradc) which is
specifically designed to have various (tablet) keys (ie home, back, search,
etc). attached to it using a resistor network. This adds a driver for this.

There are 2 channels, currently this driver only supports chan0 since there
are no boards known to use chan1.

This has been tested on an olimex a10s-olinuxino-micro, a13-olinuxino, and
a20-olinuxino-micro.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index f73bb41..21b834b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8806,6 +8806,13 @@
 F:	arch/m68k/include/asm/sun3*
 F:	drivers/net/ethernet/i825xx/sun3*
 
+SUN4I LOW RES ADC ATTACHED TABLET KEYS DRIVER
+M:	Hans de Goede <hdegoede@redhat.com>
+L:	linux-input@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/input/sun4i-lradc-keys.txt
+F:	drivers/input/keyboard/sun4i-lradc-keys.c
+
 SUNDANCE NETWORK DRIVER
 M:	Denis Kirjanov <kda@linux-powerpc.org>
 L:	netdev@vger.kernel.org