Input: MT - handle semi-mt devices in core

Most semi-mt drivers use the slots in a manual way, but really only
need to treat the finger count manually. With this patch, a semi-mt
driver may use the input-mt core for everything else.
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/input-mt.c

@@ -79,6 +79,8 @@ int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots,
 	}
 	if (flags & INPUT_MT_DIRECT)
 		__set_bit(INPUT_PROP_DIRECT, dev->propbit);
+	if (flags & INPUT_MT_SEMI_MT)
+		__set_bit(INPUT_PROP_SEMI_MT, dev->propbit);
 	if (flags & INPUT_MT_TRACK) {
 		unsigned int n2 = num_slots * num_slots;
 		mt->red = kcalloc(n2, sizeof(*mt->red), GFP_KERNEL);
@@ -246,6 +248,7 @@ void input_mt_sync_frame(struct input_dev *dev)
 {
 	struct input_mt *mt = dev->mt;
 	struct input_mt_slot *s;
+	bool use_count = false;
 
 	if (!mt)
 		return;
@@ -259,7 +262,10 @@ void input_mt_sync_frame(struct input_dev *dev)
 		}
 	}
 
-	input_mt_report_pointer_emulation(dev, (mt->flags & INPUT_MT_POINTER));
+	if ((mt->flags & INPUT_MT_POINTER) && !(mt->flags & INPUT_MT_SEMI_MT))
+		use_count = true;
+
+	input_mt_report_pointer_emulation(dev, use_count);
 
 	mt->frame++;
 }

include/linux/input/mt.h

@@ -19,6 +19,7 @@
 #define INPUT_MT_DIRECT		0x0002	/* direct device, e.g. touchscreen */
 #define INPUT_MT_DROP_UNUSED	0x0004	/* drop contacts not seen in frame */
 #define INPUT_MT_TRACK		0x0008	/* use in-kernel tracking */
+#define INPUT_MT_SEMI_MT	0x0010	/* semi-mt device, finger count handled manually */
 
 /**
  * struct input_mt_slot - represents the state of an input MT slot