[PATCH 2/2] input: mousedev: Emulate right and middle buttons for single-button touchpads

[Henrik Rydberg <rydberg@euromail.se>]

On most linux-based systems, the right and middle buttons are used
extensively. On computers lacking either of those buttons, such as
the Apple Macbooks, emulation is needed. This patch adds emulation
of the missing buttons via two-fingers-and-click and three-fingers-
and-click operations, which has recently become standard, both in
MacOS and in the Xorg synaptics driver.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
---
 drivers/input/mousedev.c |   31 +++++++++++++++++++++++++++++++
 1 files changed, 31 insertions(+), 0 deletions(-)

diff --git a/drivers/input/mousedev.c b/drivers/input/mousedev.c
index 27e1d73..a1e929f 100644
--- a/drivers/input/mousedev.c
+++ b/drivers/input/mousedev.c
@@ -53,6 +53,14 @@ static unsigned tap_move = 20;
 module_param(tap_move, uint, 0644);
 MODULE_PARM_DESC(tap_move, "Tap distance for touchpads in absolute mode (res)");

+static unsigned two_finger_code = BTN_RIGHT;
+module_param(two_finger_code, uint, 0644);
+MODULE_PARM_DESC(two_finger_code, "Button code of two-finger click");
+
+static unsigned three_finger_code = BTN_MIDDLE;
+module_param(three_finger_code, uint, 0644);
+MODULE_PARM_DESC(three_finger_code, "Button code of three-finger click");
+
 struct mousedev_hw_data {
 	int dx, dy, dz;
 	int x, y;
@@ -81,6 +89,7 @@ struct mousedev {
 	int frac_dx, frac_dy;
 	unsigned long touch;
 	int touch_dx, touch_dy;
+	int double_tap, triple_tap;
 };

 enum mousedev_emul {
@@ -225,11 +234,31 @@ static void mousedev_rel_event(struct mousedev *mousedev,
 	}
 }

+/* multi-finger emulation of non-existing buttons */
+static unsigned int get_button_code(const struct mousedev *mousedev)
+{
+	unsigned int code = BTN_LEFT;
+	if (mousedev->double_tap)
+		code = two_finger_code;
+	if (mousedev->triple_tap)
+		code = three_finger_code;
+	if (test_bit(code, mousedev->handle.dev->keybit))
+		code = BTN_LEFT;
+	return code;
+}
+
 static void mousedev_key_event(struct mousedev *mousedev,
 				unsigned int code, int value)
 {
 	int index;

+	if (code == BTN_TOOL_DOUBLETAP)
+		mousedev->double_tap = value;
+	if (code == BTN_TOOL_TRIPLETAP)
+		mousedev->triple_tap = value;
+	if (code == BTN_LEFT)
+		code = get_button_code(mousedev);
+
 	switch (code) {

 	case BTN_TOUCH:
@@ -327,6 +356,8 @@ static void mousedev_touchpad_touch(struct mousedev *mousedev, int value)
 {
 	if (!value) {
 		if (mousedev->touch &&
+		    !mousedev->double_tap &&
+		    !mousedev->triple_tap &&
 		    abs(mousedev->touch_dx) < tap_move &&
 		    abs(mousedev->touch_dy) < tap_move &&
 		    time_before(jiffies,
-- 
1.5.4.3