Input: usbtouchscreen - allow reporting calibrated data

This patch adds a module parameter to report either the raw
coordinate data or the hardware-calibrated coordinate data for
MicroTouch/3M touchscreens.  The default is set to the raw
coordinates for backwards compatibilty.
Signed-off-by: NDan Streetman <ddstreet@ieee.org>
Signed-off-by: NDmitry Torokhov <dtor@mail.ru>

drivers/input/touchscreen/usbtouchscreen.c

@@ -60,6 +60,10 @@ static int swap_xy;
 module_param(swap_xy, bool, 0644);
 MODULE_PARM_DESC(swap_xy, "If set X and Y axes are swapped.");
 
+static int hwcalib_xy;
+module_param(hwcalib_xy, bool, 0644);
+MODULE_PARM_DESC(hwcalib_xy, "If set hw-calibrated X/Y are used if available");
+
 /* device specifc data/functions */
 struct usbtouch_usb;
 struct usbtouch_device_info {
@@ -260,8 +264,13 @@ static int panjit_read_data(struct usbtouch_usb *dev, unsigned char *pkt)
 
 static int mtouch_read_data(struct usbtouch_usb *dev, unsigned char *pkt)
 {
-	dev->x = (pkt[8] << 8) | pkt[7];
-	dev->y = (pkt[10] << 8) | pkt[9];
+	if (hwcalib_xy) {
+		dev->x = (pkt[4] << 8) | pkt[3];
+		dev->y = 0xffff - ((pkt[6] << 8) | pkt[5]);
+	} else {
+		dev->x = (pkt[8] << 8) | pkt[7];
+		dev->y = (pkt[10] << 8) | pkt[9];
+	}
 	dev->touch = (pkt[2] & 0x40) ? 1 : 0;
 
 	return 1;
@@ -294,6 +303,12 @@ static int mtouch_init(struct usbtouch_usb *usbtouch)
 			return ret;
 	}
 
+	/* Default min/max xy are the raw values, override if using hw-calib */
+	if (hwcalib_xy) {
+		input_set_abs_params(usbtouch->input, ABS_X, 0, 0xffff, 0, 0);
+		input_set_abs_params(usbtouch->input, ABS_Y, 0, 0xffff, 0, 0);
+	}
+
 	return 0;
 }
 #endif