Input: synaptics - add support for ForcePads

ForcePads are found on HP EliteBook 1040 laptops. They lack any kind of
physical buttons, instead they generate primary button click when user
presses somewhat hard on the surface of the touchpad. Unfortunately they
also report primary button click whenever there are 2 or more contacts
on the pad, messing up all multi-finger gestures (2-finger scrolling,
multi-finger tapping, etc). To cope with this behavior we introduce a
delay (currently 50 msecs) in reporting primary press in case more
contacts appear.

Cc: stable@vger.kernel.org
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 52 insertions, 16 deletions

diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
index e8573c68f77e..fd23181c1fb7 100644
--- a/drivers/input/mouse/synaptics.c
+++ b/drivers/input/mouse/synaptics.c
@@ -629,10 +629,61 @@ static int synaptics_parse_hw_state(const unsigned char buf[],
 			 ((buf[0] & 0x04) >> 1) |
 			 ((buf[3] & 0x04) >> 2));
 
+		if ((SYN_CAP_ADV_GESTURE(priv->ext_cap_0c) ||
+			SYN_CAP_IMAGE_SENSOR(priv->ext_cap_0c)) &&
+		    hw->w == 2) {
+			synaptics_parse_agm(buf, priv, hw);
+			return 1;
+		}
+
+		hw->x = (((buf[3] & 0x10) << 8) |
+			 ((buf[1] & 0x0f) << 8) |
+			 buf[4]);
+		hw->y = (((buf[3] & 0x20) << 7) |
+			 ((buf[1] & 0xf0) << 4) |
+			 buf[5]);
+		hw->z = buf[2];
+
 		hw->left  = (buf[0] & 0x01) ? 1 : 0;
 		hw->right = (buf[0] & 0x02) ? 1 : 0;
 
-		if (SYN_CAP_CLICKPAD(priv->ext_cap_0c)) {
+		if (SYN_CAP_FORCEPAD(priv->ext_cap_0c)) {
+			/*
+			 * ForcePads, like Clickpads, use middle button
+			 * bits to report primary button clicks.
+			 * Unfortunately they report primary button not
+			 * only when user presses on the pad above certain
+			 * threshold, but also when there are more than one
+			 * finger on the touchpad, which interferes with
+			 * out multi-finger gestures.
+			 */
+			if (hw->z == 0) {
+				/* No contacts */
+				priv->press = priv->report_press = false;
+			} else if (hw->w >= 4 && ((buf[0] ^ buf[3]) & 0x01)) {
+				/*
+				 * Single-finger touch with pressure above
+				 * the threshold. If pressure stays long
+				 * enough, we'll start reporting primary
+				 * button. We rely on the device continuing
+				 * sending data even if finger does not
+				 * move.
+				 */
+				if  (!priv->press) {
+					priv->press_start = jiffies;
+					priv->press = true;
+				} else if (time_after(jiffies,
+						priv->press_start +
+							msecs_to_jiffies(50))) {
+					priv->report_press = true;
+				}
+			} else {
+				priv->press = false;
+			}
+
+			hw->left = priv->report_press;
+
+		} else if (SYN_CAP_CLICKPAD(priv->ext_cap_0c)) {
 			/*
 			 * Clickpad's button is transmitted as middle button,
 			 * however, since it is primary button, we will report
@@ -651,21 +702,6 @@ static int synaptics_parse_hw_state(const unsigned char buf[],
 			hw->down = ((buf[0] ^ buf[3]) & 0x02) ? 1 : 0;
 		}
 
-		if ((SYN_CAP_ADV_GESTURE(priv->ext_cap_0c) ||
-			SYN_CAP_IMAGE_SENSOR(priv->ext_cap_0c)) &&
-		    hw->w == 2) {
-			synaptics_parse_agm(buf, priv, hw);
-			return 1;
-		}
-
-		hw->x = (((buf[3] & 0x10) << 8) |
-			 ((buf[1] & 0x0f) << 8) |
-			 buf[4]);
-		hw->y = (((buf[3] & 0x20) << 7) |
-			 ((buf[1] & 0xf0) << 4) |
-			 buf[5]);
-		hw->z = buf[2];
-
 		if (SYN_CAP_MULTI_BUTTON_NO(priv->ext_cap) &&
 		    ((buf[0] ^ buf[3]) & 0x02)) {
 			switch (SYN_CAP_MULTI_BUTTON_NO(priv->ext_cap) & ~0x01) {