Input: wacom_w8001 - support pen or touch only devices

Not all penabled devices support touch. The same holds true for touch
devices, so we should be setting up devices according to the results
returned when we query the hardware.
Signed-off-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/touchscreen/wacom_w8001.c

@@ -19,6 +19,7 @@
 #include <linux/serio.h>
 #include <linux/init.h>
 #include <linux/ctype.h>
+#include <linux/delay.h>
 
 #define DRIVER_DESC	"Wacom W8001 serial touchscreen driver"
 
@@ -37,6 +38,7 @@ MODULE_LICENSE("GPL");
 
 #define W8001_QUERY_PACKET	0x20
 
+#define W8001_CMD_STOP		'0'
 #define W8001_CMD_START		'1'
 #define W8001_CMD_QUERY		'*'
 #define W8001_CMD_TOUCHQUERY	'%'
@@ -279,24 +281,46 @@ static int w8001_setup(struct w8001 *w8001)
 	struct w8001_coord coord;
 	int error;
 
-	error = w8001_command(w8001, W8001_CMD_QUERY, true);
+	error = w8001_command(w8001, W8001_CMD_STOP, false);
 	if (error)
 		return error;
 
-	parse_data(w8001->response, &coord);
+	msleep(250);	/* wait 250ms before querying the device */
 
-	input_set_abs_params(dev, ABS_X, 0, coord.x, 0, 0);
-	input_set_abs_params(dev, ABS_Y, 0, coord.y, 0, 0);
-	input_set_abs_params(dev, ABS_PRESSURE, 0, coord.pen_pressure, 0, 0);
-	input_set_abs_params(dev, ABS_TILT_X, 0, coord.tilt_x, 0, 0);
-	input_set_abs_params(dev, ABS_TILT_Y, 0, coord.tilt_y, 0, 0);
+	/* penabled? */
+	error = w8001_command(w8001, W8001_CMD_QUERY, true);
+	if (!error) {
+		__set_bit(BTN_TOOL_PEN, dev->keybit);
+		__set_bit(BTN_TOOL_RUBBER, dev->keybit);
+		__set_bit(BTN_STYLUS, dev->keybit);
+		__set_bit(BTN_STYLUS2, dev->keybit);
+		parse_data(w8001->response, &coord);
+
+		input_set_abs_params(dev, ABS_X, 0, coord.x, 0, 0);
+		input_set_abs_params(dev, ABS_Y, 0, coord.y, 0, 0);
+		input_set_abs_params(dev, ABS_PRESSURE, 0, coord.pen_pressure, 0, 0);
+		if (coord.tilt_x && coord.tilt_y) {
+			input_set_abs_params(dev, ABS_TILT_X, 0, coord.tilt_x, 0, 0);
+			input_set_abs_params(dev, ABS_TILT_Y, 0, coord.tilt_y, 0, 0);
+		}
+	}
 
+	/* Touch enabled? */
 	error = w8001_command(w8001, W8001_CMD_TOUCHQUERY, true);
-	if (!error) {
+
+	/*
+	 * Some non-touch devices may reply to the touch query. But their
+	 * second byte is empty, which indicates touch is not supported.
+	 */
+	if (!error && w8001->response[1]) {
 		struct w8001_touch_query touch;
 
 		parse_touchquery(w8001->response, &touch);
 
+		input_set_abs_params(dev, ABS_X, 0, touch.x, 0, 0);
+		input_set_abs_params(dev, ABS_Y, 0, touch.y, 0, 0);
+		__set_bit(BTN_TOOL_FINGER, dev->keybit);
+
 		switch (touch.sensor_id) {
 		case 0:
 		case 2:
@@ -375,10 +399,6 @@ static int w8001_connect(struct serio *serio, struct serio_driver *drv)
 
 	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
 	__set_bit(BTN_TOUCH, input_dev->keybit);
-	__set_bit(BTN_TOOL_PEN, input_dev->keybit);
-	__set_bit(BTN_TOOL_RUBBER, input_dev->keybit);
-	__set_bit(BTN_STYLUS, input_dev->keybit);
-	__set_bit(BTN_STYLUS2, input_dev->keybit);
 
 	serio_set_drvdata(serio, w8001);
 	err = serio_open(serio, drv);