commit b98abe52fa8e ("Input: add common DT binding for touchscreens")
introduced common DT bindings for touchscreens [1] and a helper function to
parse the DT.
This has been integrated and interpretation of the inversion (flipping)
properties for the x and y axis has been added to accommodate any
orientation of the touch in relation to the LCD.
By scaling the min/max ADC values to the screen size it is now possible to
pre-calibrate the touch so that is (almost) exactly matches the LCD it is
glued onto. This allows to well enough operate the touch before a user
space calibration can improve the precision.
[1]: Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt
Signed-off-by: H. Nikolaus Schaller
---
.../devicetree/bindings/input/ads7846.txt | 8 ++-
drivers/input/touchscreen/ads7846.c| 72 --
2 files changed, 74 insertions(+), 6 deletions(-)
diff --git a/Documentation/devicetree/bindings/input/ads7846.txt
b/Documentation/devicetree/bindings/input/ads7846.txt
index df8b127..ae56355 100644
--- a/Documentation/devicetree/bindings/input/ads7846.txt
+++ b/Documentation/devicetree/bindings/input/ads7846.txt
@@ -26,12 +26,17 @@ Additional required properties:
Optional properties:
+You can optionally specify any of the touchscreen parameters described in
+
+ Documentation/devicetree/bindings/input/touchscreen/touchscreen.txt
+
+This allows to scale, invert or swap coordinates and define the fuzz factors.
+
ti,vref-delay-usecs vref supply delay in usecs, 0 for
external vref (u16).
ti,vref-mv The VREF voltage, in millivolts (u16).
ti,keep-vref-on set to keep vref on for differential
measurements as well
- ti,swap-xy swap x and y axis
ti,settle-delay-usecSettling time of the analog signals;
a function of Vcc and the capacitance
on the X/Y drivers. If set to non-zero,
@@ -79,6 +84,7 @@ Example for a TSC2046 chip connected to an McSPI controller
of an OMAP SoC::
pendown-gpio = <&gpio1 8 0>;
vcc-supply = <®_vcc3>;
+ touchscreen-swapped-x-y;
ti,x-min = /bits/ 16 <0>;
ti,x-max = /bits/ 16 <8000>;
ti,y-min = /bits/ 16 <0>;
diff --git a/drivers/input/touchscreen/ads7846.c
b/drivers/input/touchscreen/ads7846.c
index 04edc8f..4525f00 100644
--- a/drivers/input/touchscreen/ads7846.c
+++ b/drivers/input/touchscreen/ads7846.c
@@ -34,6 +34,7 @@
#include
#include
#include
+#include
#include
/*
@@ -109,8 +110,14 @@ struct ads7846 {
u16 vref_delay_usecs;
u16 x_plate_ohms;
u16 pressure_max;
+ u16 x_min;
+ u16 x_max;
+ u16 y_min;
+ u16 y_max;
boolswap_xy;
+ boolinvert_x;
+ boolinvert_y;
booluse_internal;
struct ads7846_packet *packet;
@@ -828,9 +835,48 @@ static void ads7846_report_state(struct ads7846 *ts)
if (Rt) {
struct input_dev *input = ts->input;
+ dev_dbg(&ts->spi->dev,
+ "Raw point(%4d,%4d), pressure (%4u)\n",
+ x, y, Rt);
+ /* clamp to expected ADC range */
+ if (x < ts->x_min)
+ x = ts->x_min;
+ if (x > ts->x_max)
+ x = ts->x_max;
+ if (y < ts->y_min)
+ y = ts->y_min;
+ if (y > ts->y_max)
+ y = ts->y_max;
+
+ dev_dbg(&ts->spi->dev,
+ "Clamped point(%4d,%4d), pressure (%4u)\n",
+ x, y, Rt);
+
+ /* flip */
+ if (ts->invert_x)
+ x = (ts->x_max - x) + ts->x_min;
+ if (ts->invert_y)
+ y = (ts->y_max - y) + ts->y_min;
+
+ dev_dbg(&ts->spi->dev,
+ "Flipped point(%4d,%4d), pressure (%4u)\n",
+ x, y, Rt);
+
+ /* scale to desired output range */
+ x = (input->absinfo[ABS_X].maximum * (x - ts->x_min))
+ / (ts->x_max - ts->x_min);
+ y = (input->absinfo[ABS_Y].maximum * (y - ts->y_min))
+ / (ts->y_max - ts->y_min);
+
+ dev_dbg(&ts->spi->dev,
+ "Scaled point(%4d,%4d), pressure (%4u)\n",
+ x, y, Rt);
+
+
