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>

4 files changed, 120 insertions, 43 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);
diff --git a/drivers/input/tablet/wacom_wac.c b/drivers/input/tablet/wacom_wac.c
index f26e2238f6ca..0b0525486711 100644
--- a/drivers/input/tablet/wacom_wac.c
+++ b/drivers/input/tablet/wacom_wac.c
@@ -863,19 +863,21 @@ static int wacom_bpt_touch(struct wacom_wac *wacom)
         struct wacom_features *features = &wacom->features;
         struct input_dev *input = wacom->input;
         unsigned char *data = wacom->data;
-        int sp = 0, sx = 0, sy = 0, count = 0;
         int i;
 
         for (i = 0; i < 2; i++) {
                 int p = data[9 * i + 2];
+                bool touch = p && !wacom->shared->stylus_in_proximity;
+
                 input_mt_slot(input, i);
+                input_mt_report_slot_state(input, MT_TOOL_FINGER, touch);
                 /*
                  * Touch events need to be disabled while stylus is
                  * in proximity because user's hand is resting on touchpad
                  * and sending unwanted events.  User expects tablet buttons
                  * to continue working though.
                  */
-                if (p && !wacom->shared->stylus_in_proximity) {
+                if (touch) {
                         int x = get_unaligned_be16(&data[9 * i + 3]) & 0x7ff;
                         int y = get_unaligned_be16(&data[9 * i + 5]) & 0x7ff;
                         if (features->quirks & WACOM_QUIRK_BBTOUCH_LOWRES) {
@@ -885,23 +887,10 @@ static int wacom_bpt_touch(struct wacom_wac *wacom)
                         input_report_abs(input, ABS_MT_PRESSURE, p);
                         input_report_abs(input, ABS_MT_POSITION_X, x);
                         input_report_abs(input, ABS_MT_POSITION_Y, y);
-                        if (wacom->id[i] < 0)
-                                wacom->id[i] = wacom->trk_id++ & MAX_TRACKING_ID;
-                        if (!count++)
-                                sp = p, sx = x, sy = y;
-                } else {
-                        wacom->id[i] = -1;
                 }
-                input_report_abs(input, ABS_MT_TRACKING_ID, wacom->id[i]);
         }
 
-        input_report_key(input, BTN_TOUCH, count > 0);
-        input_report_key(input, BTN_TOOL_FINGER, count == 1);
-        input_report_key(input, BTN_TOOL_DOUBLETAP, count == 2);
-
-        input_report_abs(input, ABS_PRESSURE, sp);
-        input_report_abs(input, ABS_X, sx);
-        input_report_abs(input, ABS_Y, sy);
+        input_mt_report_pointer_emulation(input, true);
 
         input_report_key(input, BTN_LEFT, (data[1] & 0x08) != 0);
         input_report_key(input, BTN_FORWARD, (data[1] & 0x04) != 0);
@@ -1283,8 +1272,6 @@ void wacom_setup_input_capabilities(struct input_dev *input_dev,
                         input_set_abs_params(input_dev, ABS_MT_PRESSURE,
                                              0, features->pressure_max,
                                              features->pressure_fuzz, 0);
-                        input_set_abs_params(input_dev, ABS_MT_TRACKING_ID, 0,
-                                             MAX_TRACKING_ID, 0, 0);
                 } else if (features->device_type == BTN_TOOL_PEN) {
                         __set_bit(BTN_TOOL_RUBBER, input_dev->keybit);
                         __set_bit(BTN_TOOL_PEN, input_dev->keybit);
diff --git a/drivers/input/tablet/wacom_wac.h b/drivers/input/tablet/wacom_wac.h
index 00ca01541d89..b1310ec9720c 100644
--- a/drivers/input/tablet/wacom_wac.h
+++ b/drivers/input/tablet/wacom_wac.h
@@ -42,9 +42,6 @@
 #define WACOM_QUIRK_MULTI_INPUT         0x0001
 #define WACOM_QUIRK_BBTOUCH_LOWRES      0x0002
 
-/* largest reported tracking id */
-#define MAX_TRACKING_ID                 0xfff
-
 enum {
         PENPARTNER = 0,
         GRAPHIRE,
@@ -100,7 +97,6 @@ struct wacom_wac {
         int id[3];
         __u32 serial[2];
         int last_finger;
-        int trk_id;
         struct wacom_features features;
         struct wacom_shared *shared;
         struct input_dev *input;
diff --git a/drivers/input/touchscreen/wacom_w8001.c b/drivers/input/touchscreen/wacom_w8001.c
index 4a2e8cf4c8ef..2a0bec12d12a 100644
--- a/drivers/input/touchscreen/wacom_w8001.c
+++ b/drivers/input/touchscreen/wacom_w8001.c
@@ -48,8 +48,6 @@ MODULE_LICENSE("GPL");
 #define W8001_PKTLEN_TPCCTL     11      /* control packet */
 #define W8001_PKTLEN_TOUCH2FG   13
 
-#define MAX_TRACKING_ID         0xFF    /* arbitrarily chosen */
-
 struct w8001_coord {
         u8 rdy;
         u8 tsw;
@@ -87,7 +85,6 @@ struct w8001 {
         char phys[32];
         int type;
         unsigned int pktlen;
-        int trkid[2];
 };
 
 static void parse_data(u8 *data, struct w8001_coord *coord)
@@ -116,28 +113,23 @@ static void parse_data(u8 *data, struct w8001_coord *coord)
 
 static void parse_touch(struct w8001 *w8001)
 {
-        static int trkid;
         struct input_dev *dev = w8001->dev;
         unsigned char *data = w8001->data;
         int i;
 
         for (i = 0; i < 2; i++) {
-                input_mt_slot(dev, i);
+                bool touch = data[0] & (1 << i);
 
-                if (data[0] & (1 << i)) {
+                input_mt_slot(dev, i);
+                input_mt_report_slot_state(dev, MT_TOOL_FINGER, touch);
+                if (touch) {
                         int x = (data[6 * i + 1] << 7) | (data[6 * i + 2]);
                         int y = (data[6 * i + 3] << 7) | (data[6 * i + 4]);
                         /* data[5,6] and [11,12] is finger capacity */
 
                         input_report_abs(dev, ABS_MT_POSITION_X, x);
                         input_report_abs(dev, ABS_MT_POSITION_Y, y);
-                        input_report_abs(dev, ABS_MT_TOOL_TYPE, MT_TOOL_FINGER);
-                        if (w8001->trkid[i] < 0)
-                                w8001->trkid[i] = trkid++ & MAX_TRACKING_ID;
-                } else {
-                        w8001->trkid[i] = -1;
                 }
-                input_report_abs(dev, ABS_MT_TRACKING_ID, w8001->trkid[i]);
         }
 
         input_sync(dev);
@@ -319,14 +311,12 @@ static int w8001_setup(struct w8001 *w8001)
                         w8001->pktlen = W8001_PKTLEN_TOUCH2FG;
 
                         input_mt_init_slots(dev, 2);
-                        input_set_abs_params(dev, ABS_MT_TRACKING_ID,
-                                                0, MAX_TRACKING_ID, 0, 0);
                         input_set_abs_params(dev, ABS_MT_POSITION_X,
                                                 0, touch.x, 0, 0);
                         input_set_abs_params(dev, ABS_MT_POSITION_Y,
                                                 0, touch.y, 0, 0);
                         input_set_abs_params(dev, ABS_MT_TOOL_TYPE,
-                                                0, 0, 0, 0);
+                                                0, MT_TOOL_MAX, 0, 0);
                         break;
                 }
         }
@@ -372,7 +362,6 @@ static int w8001_connect(struct serio *serio, struct serio_driver *drv)
         w8001->serio = serio;
         w8001->id = serio->id.id;
         w8001->dev = input_dev;
-        w8001->trkid[0] = w8001->trkid[1] = -1;
         init_completion(&w8001->cmd_done);
         snprintf(w8001->phys, sizeof(w8001->phys), "%s/input0", serio->phys);