[PATCH] HID: multitouch: Add quirks for flipped axes

[Allen Ballway]

Certain touchscreen devices, such as the ELAN9034, are oriented
incorrectly and report touches on opposite points on the X and Y axes.
For example, a 100x200 screen touched at (10,20) would report (90, 180)
and vice versa.

This is fixed by adding device quirks to transform the touch points
into the correct spaces, from X -> MAX(X) - X, and Y -> MAX(Y) - Y.

Signed-off-by: Allen Ballway <ballway@xxxxxxxxxxxx>
---

 drivers/hid/hid-multitouch.c | 46 ++++++++++++++++++++++++++++++++----
 1 file changed, 42 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index 91a4d3fc30e08..5e14cc4b00f53 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -71,6 +71,8 @@ MODULE_LICENSE("GPL");
 #define MT_QUIRK_SEPARATE_APP_REPORT	BIT(19)
 #define MT_QUIRK_FORCE_MULTI_INPUT	BIT(20)
 #define MT_QUIRK_DISABLE_WAKEUP		BIT(21)
+#define MT_QUIRK_FLIP_X			BIT(22)
+#define MT_QUIRK_FLIP_Y			BIT(23)
 
 #define MT_INPUTMODE_TOUCHSCREEN	0x02
 #define MT_INPUTMODE_TOUCHPAD		0x03
@@ -212,6 +214,7 @@ static void mt_post_parse(struct mt_device *td, struct mt_application *app);
 #define MT_CLS_GOOGLE				0x0111
 #define MT_CLS_RAZER_BLADE_STEALTH		0x0112
 #define MT_CLS_SMART_TECH			0x0113
+#define MT_CLS_ELAN_FLIPPED			0x0114
 
 #define MT_DEFAULT_MAXCONTACT	10
 #define MT_MAX_MAXCONTACT	250
@@ -396,6 +399,17 @@ static const struct mt_class mt_classes[] = {
 			MT_QUIRK_CONTACT_CNT_ACCURATE |
 			MT_QUIRK_SEPARATE_APP_REPORT,
 	},
+	{ .name = MT_CLS_ELAN_FLIPPED,
+		.quirks = MT_QUIRK_ALWAYS_VALID |
+			MT_QUIRK_IGNORE_DUPLICATES |
+			MT_QUIRK_HOVERING |
+			MT_QUIRK_CONTACT_CNT_ACCURATE |
+			MT_QUIRK_STICKY_FINGERS |
+			MT_QUIRK_WIN8_PTP_BUTTONS |
+			MT_QUIRK_FLIP_X |
+			MT_QUIRK_FLIP_Y,
+		.export_all_inputs = true },
+
 	{ }
 };
 
@@ -1115,10 +1129,30 @@ static int mt_process_slot(struct mt_device *td, struct input_dev *input,
 			minor = minor >> 1;
 		}
 
-		input_event(input, EV_ABS, ABS_MT_POSITION_X, *slot->x);
-		input_event(input, EV_ABS, ABS_MT_POSITION_Y, *slot->y);
-		input_event(input, EV_ABS, ABS_MT_TOOL_X, *slot->cx);
-		input_event(input, EV_ABS, ABS_MT_TOOL_Y, *slot->cy);
+		if (quirks & MT_QUIRK_FLIP_X) {
+			/* Inputs with a flipped X axis need to report MAX - X */
+			int x = input_abs_get_max(input, ABS_MT_POSITION_X) - *slot->x;
+			int cx = input_abs_get_max(input, ABS_MT_TOOL_X) - *slot->cx;
+
+			input_event(input, EV_ABS, ABS_MT_POSITION_X, x);
+			input_event(input, EV_ABS, ABS_MT_TOOL_X, cx);
+		} else {
+			input_event(input, EV_ABS, ABS_MT_POSITION_X, *slot->x);
+			input_event(input, EV_ABS, ABS_MT_TOOL_X, *slot->cx);
+		}
+
+		if (quirks & MT_QUIRK_FLIP_Y) {
+			/* Inputs with a flipped Y axis need to report MAX - Y */
+			int y = input_abs_get_max(input, ABS_MT_POSITION_Y) - *slot->y;
+			int cy = input_abs_get_max(input, ABS_MT_TOOL_Y) - *slot->cy;
+
+			input_event(input, EV_ABS, ABS_MT_POSITION_Y, y);
+			input_event(input, EV_ABS, ABS_MT_TOOL_Y, cy);
+		} else {
+			input_event(input, EV_ABS, ABS_MT_POSITION_Y, *slot->y);
+			input_event(input, EV_ABS, ABS_MT_TOOL_Y, *slot->cy);
+		}
+
 		input_event(input, EV_ABS, ABS_MT_DISTANCE, !*slot->tip_state);
 		input_event(input, EV_ABS, ABS_MT_ORIENTATION, orientation);
 		input_event(input, EV_ABS, ABS_MT_PRESSURE, *slot->p);
@@ -1963,6 +1997,10 @@ static const struct hid_device_id mt_devices[] = {
 			USB_DEVICE_ID_DWAV_EGALAX_MULTITOUCH_C002) },
 
 	/* Elan devices */
+	{ .driver_data = MT_CLS_ELAN_FLIPPED,
+		HID_DEVICE(BUS_I2C, HID_GROUP_MULTITOUCH_WIN_8,
+			USB_VENDOR_ID_ELAN, 0x2dcd) },
+
 	{ .driver_data = MT_CLS_WIN_8_FORCE_MULTI_INPUT,
 		HID_DEVICE(BUS_I2C, HID_GROUP_MULTITOUCH_WIN_8,
 			USB_VENDOR_ID_ELAN, 0x313a) },
-- 
2.39.0.rc0.267.gcb52ba06e7-goog