input: mt: Move tracking and pointer emulation to input-mt

The drivers using the type B protocol all report tracking information
the same way. The contact id is semantically equivalent to
ABS_MT_SLOT, and the handling of ABS_MT_TRACKING_ID only complicates
the driver. The situation can be improved upon by providing a common
pointer emulation code, thereby removing the need for the tracking id
in the driver.  This patch moves all tracking event handling over to
the input core, simplifying both the existing drivers and the ones
currently in preparation.

Acked-by: Ping Cheng <pingc@wacom.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

1 files changed, 110 insertions, 5 deletions

diff --git a/drivers/input/input-mt.c b/drivers/input/input-mt.c
index f400e47092c4..c48c81f0308d 100644
--- a/drivers/input/input-mt.c
+++ b/drivers/input/input-mt.c
@@ -11,17 +11,18 @@
 #include <linux/input/mt.h>
 #include <linux/slab.h>
 
+#define TRKID_SGN	((TRKID_MAX + 1) >> 1)
+
 /**
  * input_mt_init_slots() - initialize MT input slots
  * @dev: input device supporting MT events and finger tracking
  * @num_slots: number of slots used by the device
  *
  * This function allocates all necessary memory for MT slot handling
- * in the input device, adds ABS_MT_SLOT to the device capabilities
- * and sets up appropriate event buffers. All slots are initially
- * marked as unused by setting ABS_MT_TRACKING_ID to -1. May be called
- * repeatedly. Returns -EINVAL if attempting to reinitialize with a
- * different number of slots.
+ * in the input device, prepares the ABS_MT_SLOT and
+ * ABS_MT_TRACKING_ID events for use and sets up appropriate buffers.
+ * May be called repeatedly. Returns -EINVAL if attempting to
+ * reinitialize with a different number of slots.
  */
 int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots)
 {
@@ -38,6 +39,7 @@ int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots)
 
 	dev->mtsize = num_slots;
 	input_set_abs_params(dev, ABS_MT_SLOT, 0, num_slots - 1, 0, 0);
+	input_set_abs_params(dev, ABS_MT_TRACKING_ID, 0, TRKID_MAX, 0, 0);
 	input_set_events_per_packet(dev, 6 * num_slots);
 
 	/* Mark slots as 'unused' */
@@ -61,5 +63,108 @@ void input_mt_destroy_slots(struct input_dev *dev)
 	dev->mt = NULL;
 	dev->mtsize = 0;
 	dev->slot = 0;
+	dev->trkid = 0;
 }
 EXPORT_SYMBOL(input_mt_destroy_slots);
+
+/**
+ * input_mt_report_slot_state() - report contact state
+ * @dev: input device with allocated MT slots
+ * @tool_type: the tool type to use in this slot
+ * @active: true if contact is active, false otherwise
+ *
+ * Reports a contact via ABS_MT_TRACKING_ID, and optionally
+ * ABS_MT_TOOL_TYPE. If active is true and the slot is currently
+ * inactive, or if the tool type is changed, a new tracking id is
+ * assigned to the slot. The tool type is only reported if the
+ * corresponding absbit field is set.
+ */
+void input_mt_report_slot_state(struct input_dev *dev,
+				unsigned int tool_type, bool active)
+{
+	struct input_mt_slot *mt;
+	int id;
+
+	if (!dev->mt || !active) {
+		input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
+		return;
+	}
+
+	mt = &dev->mt[dev->slot];
+	id = input_mt_get_value(mt, ABS_MT_TRACKING_ID);
+	if (id < 0 || input_mt_get_value(mt, ABS_MT_TOOL_TYPE) != tool_type)
+		id = input_mt_new_trkid(dev);
+
+	input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, id);
+	input_event(dev, EV_ABS, ABS_MT_TOOL_TYPE, tool_type);
+}
+EXPORT_SYMBOL(input_mt_report_slot_state);
+
+/**
+ * input_mt_report_finger_count() - report contact count
+ * @dev: input device with allocated MT slots
+ * @count: the number of contacts
+ *
+ * Reports the contact count via BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP,
+ * BTN_TOOL_TRIPLETAP and BTN_TOOL_QUADTAP.
+ *
+ * The input core ensures only the KEY events already setup for
+ * this device will produce output.
+ */
+void input_mt_report_finger_count(struct input_dev *dev, int count)
+{
+	input_event(dev, EV_KEY, BTN_TOOL_FINGER, count == 1);
+	input_event(dev, EV_KEY, BTN_TOOL_DOUBLETAP, count == 2);
+	input_event(dev, EV_KEY, BTN_TOOL_TRIPLETAP, count == 3);
+	input_event(dev, EV_KEY, BTN_TOOL_QUADTAP, count == 4);
+}
+EXPORT_SYMBOL(input_mt_report_finger_count);
+
+/**
+ * input_mt_report_pointer_emulation() - common pointer emulation
+ * @dev: input device with allocated MT slots
+ * @use_count: report number of active contacts as finger count
+ *
+ * Performs legacy pointer emulation via BTN_TOUCH, ABS_X, ABS_Y and
+ * ABS_PRESSURE. Touchpad finger count is emulated if use_count is true.
+ *
+ * The input core ensures only the KEY and ABS axes already setup for
+ * this device will produce output.
+ */
+void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
+{
+	struct input_mt_slot *oldest = 0;
+	int oldid = dev->trkid;
+	int count = 0;
+	int i;
+
+	for (i = 0; i < dev->mtsize; ++i) {
+		struct input_mt_slot *ps = &dev->mt[i];
+		int id = input_mt_get_value(ps, ABS_MT_TRACKING_ID);
+
+		if (id < 0)
+			continue;
+		if ((id - oldid) & TRKID_SGN) {
+			oldest = ps;
+			oldid = id;
+		}
+		count++;
+	}
+
+	input_event(dev, EV_KEY, BTN_TOUCH, count > 0);
+	if (use_count)
+		input_mt_report_finger_count(dev, count);
+
+	if (oldest) {
+		int x = input_mt_get_value(oldest, ABS_MT_POSITION_X);
+		int y = input_mt_get_value(oldest, ABS_MT_POSITION_Y);
+		int p = input_mt_get_value(oldest, ABS_MT_PRESSURE);
+
+		input_event(dev, EV_ABS, ABS_X, x);
+		input_event(dev, EV_ABS, ABS_Y, y);
+		input_event(dev, EV_ABS, ABS_PRESSURE, p);
+	} else {
+		input_event(dev, EV_ABS, ABS_PRESSURE, 0);
+	}
+}
+EXPORT_SYMBOL(input_mt_report_pointer_emulation);