Input: goodix - add axis swapping and axis inversion support

Implement support for the following device-tree and ACPI 5.1 DSD
properties in the goodix touchscreen driver:

 - touchscreen-inverted-x:  X axis is inverted (boolean)
 - touchscreen-inverted-y:  Y axis is inverted (boolean)
 - touchscreen-swapped-x-y: X and Y axis are swapped (boolean)

These are necessary on tablets which have a display in portrait
format while the touchscreen is in landscape format, such as e.g.
the MSI Primo 81.
Signed-off-by: Karsten Merker <merker@debian.org>
Tested-by: Bastien Nocera <hadess@hadess.net>
Tested-by: Irina Tirdea <irina.tirdea@intel.com> (with ACPI DSD properties)
Tested-by: Aleksei Mamlin <mamlinav@gmail.com> (with device-tree properties)
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/touchscreen/goodix.txt

@@ -19,6 +19,11 @@ Optional properties:
 			  interrupt gpio pin as output to reset the device.
  - reset-gpios		: GPIO pin used for reset
 
+ - touchscreen-inverted-x  : X axis is inverted (boolean)
+ - touchscreen-inverted-y  : Y axis is inverted (boolean)
+ - touchscreen-swapped-x-y : X and Y axis are swapped (boolean)
+                             (swapping is done after inverting the axis)
+
 Example:
 
 	i2c@00000000 {

drivers/input/touchscreen/goodix.c

@@ -2,6 +2,7 @@
  *  Driver for Goodix Touchscreens
  *
  *  Copyright (c) 2014 Red Hat Inc.
+ *  Copyright (c) 2015 K. Merker <merker@debian.org>
  *
  *  This code is based on gt9xx.c authored by andrew@goodix.com:
  *
@@ -35,6 +36,9 @@ struct goodix_ts_data {
 	struct input_dev *input_dev;
 	int abs_x_max;
 	int abs_y_max;
+	bool swapped_x_y;
+	bool inverted_x;
+	bool inverted_y;
 	unsigned int max_touch_num;
 	unsigned int int_trigger_type;
 	bool rotated_screen;
@@ -235,6 +239,14 @@ static void goodix_ts_report_touch(struct goodix_ts_data *ts, u8 *coor_data)
 		input_y = ts->abs_y_max - input_y;
 	}
 
+	/* Inversions have to happen before axis swapping */
+	if (ts->inverted_x)
+		input_x = ts->abs_x_max - input_x;
+	if (ts->inverted_y)
+		input_y = ts->abs_y_max - input_y;
+	if (ts->swapped_x_y)
+		swap(input_x, input_y);
+
 	input_mt_slot(ts->input_dev, id);
 	input_mt_report_slot_state(ts->input_dev, MT_TOOL_FINGER, true);
 	input_report_abs(ts->input_dev, ABS_MT_POSITION_X, input_x);
@@ -486,6 +498,8 @@ static void goodix_read_config(struct goodix_ts_data *ts)
 			 error);
 		ts->abs_x_max = GOODIX_MAX_WIDTH;
 		ts->abs_y_max = GOODIX_MAX_HEIGHT;
+		if (ts->swapped_x_y)
+			swap(ts->abs_x_max, ts->abs_y_max);
 		ts->int_trigger_type = GOODIX_INT_TRIGGER;
 		ts->max_touch_num = GOODIX_MAX_CONTACTS;
 		return;
@@ -493,6 +507,8 @@ static void goodix_read_config(struct goodix_ts_data *ts)
 
 	ts->abs_x_max = get_unaligned_le16(&config[RESOLUTION_LOC]);
 	ts->abs_y_max = get_unaligned_le16(&config[RESOLUTION_LOC + 2]);
+	if (ts->swapped_x_y)
+		swap(ts->abs_x_max, ts->abs_y_max);
 	ts->int_trigger_type = config[TRIGGER_LOC] & 0x03;
 	ts->max_touch_num = config[MAX_CONTACTS_LOC] & 0x0f;
 	if (!ts->abs_x_max || !ts->abs_y_max || !ts->max_touch_num) {
@@ -500,6 +516,8 @@ static void goodix_read_config(struct goodix_ts_data *ts)
 			"Invalid config, using defaults\n");
 		ts->abs_x_max = GOODIX_MAX_WIDTH;
 		ts->abs_y_max = GOODIX_MAX_HEIGHT;
+		if (ts->swapped_x_y)
+			swap(ts->abs_x_max, ts->abs_y_max);
 		ts->max_touch_num = GOODIX_MAX_CONTACTS;
 	}
 
@@ -622,6 +640,13 @@ static int goodix_configure_dev(struct goodix_ts_data *ts)
 {
 	int error;
 
+	ts->swapped_x_y = device_property_read_bool(&ts->client->dev,
+						    "touchscreen-swapped-x-y");
+	ts->inverted_x = device_property_read_bool(&ts->client->dev,
+						   "touchscreen-inverted-x");
+	ts->inverted_y = device_property_read_bool(&ts->client->dev,
+						   "touchscreen-inverted-y");
+
 	goodix_read_config(ts);
 
 	error = goodix_request_input_dev(ts);