[PATCH] Input: goodix - Fix touch coords on WinBook TW100

[Bastien Nocera <hadess@hadess.net>]

The touchscreen on the WinBook TW100 doesn't match the default display,
with 0,0 touches being reported when touching at the bottom right of
the screen.

  1280,800             0,800
         +-------------+
         |             |
         |             |
         |             |
         +-------------+
    1280,0             0,0

It's unfortunately impossible to detect this problem with data from the
DSDT, or other auxiliary metadata, so fallback to quirking this specific
model of tablet instead.

Signed-off-by: Bastien Nocera <hadess@hadess.net>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
---
 drivers/input/touchscreen/goodix.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/input/touchscreen/goodix.c b/drivers/input/touchscreen/goodix.c
index b4d12e2..6f56ef9 100644
--- a/drivers/input/touchscreen/goodix.c
+++ b/drivers/input/touchscreen/goodix.c
@@ -15,6 +15,7 @@
  */
 
 #include <linux/kernel.h>
+#include <linux/dmi.h>
 #include <linux/i2c.h>
 #include <linux/input.h>
 #include <linux/input/mt.h>
@@ -34,6 +35,7 @@ struct goodix_ts_data {
 	int abs_y_max;
 	unsigned int max_touch_num;
 	unsigned int int_trigger_type;
+	bool rotated_screen;
 };
 
 #define GOODIX_MAX_HEIGHT		4096
@@ -60,6 +62,19 @@ static const unsigned long goodix_irq_flags[] = {
 	IRQ_TYPE_LEVEL_HIGH,
 };
 
+/* Those tablets have their coords origin at the bottom right
+ * of the tablet, as if rotated 180 degrees */
+static const struct dmi_system_id rotated_screen[] = {
+	{
+		.ident = "Winbook TW100",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "WinBook"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "TW100")
+		},
+	},
+	{}
+};
+
 /**
  * goodix_i2c_read - read data from a register of the i2c slave device.
  *
@@ -129,6 +144,11 @@ static void goodix_ts_report_touch(struct goodix_ts_data *ts, u8 *coor_data)
 	int input_y = get_unaligned_le16(&coor_data[3]);
 	int input_w = get_unaligned_le16(&coor_data[5]);
 
+	if (ts->rotated_screen) {
+		input_x = ts->abs_x_max - input_x;
+		input_y = ts->abs_y_max - 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);
@@ -223,6 +243,12 @@ static void goodix_read_config(struct goodix_ts_data *ts)
 		ts->abs_y_max = GOODIX_MAX_HEIGHT;
 		ts->max_touch_num = GOODIX_MAX_CONTACTS;
 	}
+
+	ts->rotated_screen = dmi_check_system(rotated_screen);
+	if (ts->rotated_screen) {
+		dev_dbg(&ts->client->dev,
+			 "Applying '180 degrees rotated screen' quirk\n");
+	}
 }
 
 /**
-- 
2.4.3