Input: elants - override touchscreen info with DT properties

Allow overriding of information from hardware and support additional
common DT properties like axis inversion. This is required for eg.
Nexus 7 and TF300T where the programmed values in firmware differ
from reality.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
[moved "prop" before DMA buffer]
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Link: https://lore.kernel.org/r/49ea996878264f7c8bde25204e4ddf4b1e85ae71.1587923061.git.mirq-linux@rere.qmqm.pl
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Author: osctobe

drivers/input/touchscreen/elants_i2c.c

@@ -33,6 +33,7 @@
 #include <linux/slab.h>
 #include <linux/firmware.h>
 #include <linux/input/mt.h>
+#include <linux/input/touchscreen.h>
 #include <linux/acpi.h>
 #include <linux/of.h>
 #include <linux/gpio/consumer.h>
@@ -137,6 +138,7 @@ struct elants_data {
 	unsigned int y_res;
 	unsigned int x_max;
 	unsigned int y_max;
+	struct touchscreen_properties prop;
 
 	enum elants_state state;
 	enum elants_iap_mode iap_mode;
@@ -876,8 +878,7 @@ static void elants_i2c_mt_event(struct elants_data *ts, u8 *buf)
 
 			input_mt_slot(input, i);
 			input_mt_report_slot_state(input, tool_type, true);
-			input_event(input, EV_ABS, ABS_MT_POSITION_X, x);
-			input_event(input, EV_ABS, ABS_MT_POSITION_Y, y);
+			touchscreen_report_pos(input, &ts->prop, x, y, true);
 			input_event(input, EV_ABS, ABS_MT_PRESSURE, p);
 			input_event(input, EV_ABS, ABS_MT_TOUCH_MAJOR, w);
 
@@ -1328,6 +1329,8 @@ static int elants_i2c_probe(struct i2c_client *client,
 	input_abs_set_res(ts->input, ABS_MT_POSITION_Y, ts->y_res);
 	input_abs_set_res(ts->input, ABS_MT_TOUCH_MAJOR, 1);
 
+	touchscreen_parse_properties(ts->input, true, &ts->prop);
+
 	error = input_mt_init_slots(ts->input, MAX_CONTACT_NUM,
 				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
 	if (error) {