Input: MT - Add in-kernel tracking

With the INPUT_MT_TRACK flag set, the function input_mt_assign_slots()
can be used to match a new set of contacts against the currently used
slots. The algorithm used is based on Lagrange relaxation, and performs
very well in practice; slower than mtdev for a few corner cases, but
faster in most commonly occuring cases.

Tested-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

1 files changed, 21 insertions, 0 deletions

diff --git a/include/linux/input/mt.h b/include/linux/input/mt.h
index 94989189878d..6b6f7c8e95bf 100644
--- a/include/linux/input/mt.h
+++ b/include/linux/input/mt.h
@@ -18,6 +18,8 @@
 #define INPUT_MT_POINTER        0x0001  /* pointer device, e.g. trackpad */
 #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 */
+
 /**
  * struct input_mt_slot - represents the state of an input MT slot
  * @abs: holds current values of ABS_MT axes for this slot
@@ -35,6 +37,7 @@ struct input_mt_slot {
  * @slot: MT slot currently being transmitted
  * @flags: input_mt operation flags
  * @frame: increases every time input_mt_sync_frame() is called
+ * @red: reduced cost matrix for in-kernel tracking
  * @slots: array of slots holding current values of tracked contacts
  */
 struct input_mt {
@@ -43,6 +46,7 @@ struct input_mt {
         int slot;
         unsigned int flags;
         unsigned int frame;
+        int *red;
         struct input_mt_slot slots[];
 };
 
@@ -58,6 +62,11 @@ static inline int input_mt_get_value(const struct input_mt_slot *slot,
         return slot->abs[code - ABS_MT_FIRST];
 }
 
+static inline bool input_mt_is_active(const struct input_mt_slot *slot)
+{
+        return input_mt_get_value(slot, ABS_MT_TRACKING_ID) >= 0;
+}
+
 int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots,
                         unsigned int flags);
 void input_mt_destroy_slots(struct input_dev *dev);
@@ -90,4 +99,16 @@ void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count);
 
 void input_mt_sync_frame(struct input_dev *dev);
 
+/**
+ * struct input_mt_pos - contact position
+ * @x: horizontal coordinate
+ * @y: vertical coordinate
+ */
+struct input_mt_pos {
+        s16 x, y;
+};
+
+int input_mt_assign_slots(struct input_dev *dev, int *slots,
+                          const struct input_mt_pos *pos, int num_pos);
+
 #endif