HID: magicmouse: simplify touch data bit manipulation

The new format should be easier to read to determine which bits
correspond to which data. It also brings all the manipulation logic to
the top of the function. This makes size and orientation reading more
clear.

Note that the impetus for this change is the forthcoming support for the
Magic Trackpad, which has a different touch data protocol.
Signed-off-by: Chase Douglas <chase.douglas@canonical.com>
Acked-by: Michael Poole <mdpoole@troilus.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-magicmouse.c

@@ -158,18 +158,21 @@ static void magicmouse_emit_buttons(struct magicmouse_sc *msc, int state)
 static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tdata)
 {
 	struct input_dev *input = msc->input;
-	__s32 x_y = tdata[0] << 8 | tdata[1] << 16 | tdata[2] << 24;
-	int misc = tdata[5] | tdata[6] << 8;
-	int id = (misc >> 6) & 15;
-	int x = x_y << 12 >> 20;
-	int y = -(x_y >> 20);
-	int down = (tdata[7] & TOUCH_STATE_MASK) != TOUCH_STATE_NONE;
+	int id = (tdata[6] << 2 | tdata[5] >> 6) & 0xf;
+	int x = (tdata[1] << 28 | tdata[0] << 20) >> 20;
+	int y = -((tdata[2] << 24 | tdata[1] << 16) >> 20);
+	int size = tdata[5] & 0x3f;
+	int orientation = (tdata[6] >> 2) - 32;
+	int touch_major = tdata[3];
+	int touch_minor = tdata[4];
+	int state = tdata[7] & TOUCH_STATE_MASK;
+	int down = state != TOUCH_STATE_NONE;
 
 	/* Store tracking ID and other fields. */
 	msc->tracking_ids[raw_id] = id;
 	msc->touches[id].x = x;
 	msc->touches[id].y = y;
-	msc->touches[id].size = misc & 63;
+	msc->touches[id].size = size;
 
 	/* If requested, emulate a scroll wheel by detecting small
 	 * vertical touch motions.
@@ -180,7 +183,7 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tda
 		int step_y = msc->touches[id].scroll_y - y;
 
 		/* Calculate and apply the scroll motion. */
-		switch (tdata[7] & TOUCH_STATE_MASK) {
+		switch (state) {
 		case TOUCH_STATE_START:
 			msc->touches[id].scroll_x = x;
 			msc->touches[id].scroll_y = y;
@@ -216,11 +219,9 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tda
 
 	/* Generate the input events for this touch. */
 	if (report_touches && down) {
-		int orientation = (misc >> 10) - 32;
-
 		input_report_abs(input, ABS_MT_TRACKING_ID, id);
-		input_report_abs(input, ABS_MT_TOUCH_MAJOR, tdata[3]);
-		input_report_abs(input, ABS_MT_TOUCH_MINOR, tdata[4]);
+		input_report_abs(input, ABS_MT_TOUCH_MAJOR, touch_major);
+		input_report_abs(input, ABS_MT_TOUCH_MINOR, touch_minor);
 		input_report_abs(input, ABS_MT_ORIENTATION, orientation);
 		input_report_abs(input, ABS_MT_POSITION_X, x);
 		input_report_abs(input, ABS_MT_POSITION_Y, y);