Input: add driver for Allwinner sunxi SoC's rtp controller

Note the sun4i-ts controller is capable of detecting a second touch, but
when a second touch is present then the accuracy becomes so bad the
reported touch location is not useable.

The original android driver contains some complicated heuristics using the
aprox. distance between the 2 touches to see if the user is making a pinch
open / close movement, and then reports emulated multi-touch events around
the last touch coordinate (as the dual-touch coordinates are worthless).

These kinds of heuristics are just asking for trouble (and don't belong in
the kernel). So this driver offers straight forward, reliable single touch
functionality only.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/input/touchscreen/sun4i.txt b/Documentation/devicetree/bindings/input/touchscreen/sun4i.txt
new file mode 100644
index 000000000000..881aea713fc3
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/sun4i.txt
@@ -0,0 +1,15 @@
+sun4i resistive touchscreen controller
+--------------------------------------
+
+Required properties:
+ - compatible: "allwinner,sun4i-a10-ts"
+ - reg: mmio address range of the chip
+ - interrupts: interrupt to which the chip is connected
+
+Example:
+
+        rtp: rtp@01c25000 {
+                compatible = "allwinner,sun4i-a10-ts";
+                reg = <0x01c25000 0x100>;
+                interrupts = <29>;
+        };