drivers/input/input-mt.c

   1 /*
   2  * Input Multitouch Library
   3  *
   4  * Copyright (c) 2008-2010 Henrik Rydberg
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 as published by
   8  * the Free Software Foundation.
   9  */
  10
  11 #include <linux/input/mt.h>
  12 #include <linux/slab.h>
  13
  14 #define TRKID_SGN       ((TRKID_MAX + 1) >> 1)
  15
  16 /**
  17  * input_mt_init_slots() - initialize MT input slots
  18  * @dev: input device supporting MT events and finger tracking
  19  * @num_slots: number of slots used by the device
  20  *
  21  * This function allocates all necessary memory for MT slot handling
  22  * in the input device, prepares the ABS_MT_SLOT and
  23  * ABS_MT_TRACKING_ID events for use and sets up appropriate buffers.
  24  * May be called repeatedly. Returns -EINVAL if attempting to
  25  * reinitialize with a different number of slots.
  26  */
  27 int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots)
  28 {
  29         int i;
  30
  31         if (!num_slots)
  32                 return 0;
  33         if (dev->mt)
  34                 return dev->mtsize != num_slots ? -EINVAL : 0;
  35
  36         dev->mt = kcalloc(num_slots, sizeof(struct input_mt_slot), GFP_KERNEL);
  37         if (!dev->mt)
  38                 return -ENOMEM;
  39
  40         dev->mtsize = num_slots;
  41         input_set_abs_params(dev, ABS_MT_SLOT, 0, num_slots - 1, 0, 0);
  42         input_set_abs_params(dev, ABS_MT_TRACKING_ID, 0, TRKID_MAX, 0, 0);
  43         input_set_events_per_packet(dev, 6 * num_slots);
  44
  45         /* Mark slots as 'unused' */
  46         for (i = 0; i < num_slots; i++)
  47                 input_mt_set_value(&dev->mt[i], ABS_MT_TRACKING_ID, -1);
  48
  49         return 0;
  50 }
  51 EXPORT_SYMBOL(input_mt_init_slots);
  52
  53 /**
  54  * input_mt_destroy_slots() - frees the MT slots of the input device
  55  * @dev: input device with allocated MT slots
  56  *
  57  * This function is only needed in error path as the input core will
  58  * automatically free the MT slots when the device is destroyed.
  59  */
  60 void input_mt_destroy_slots(struct input_dev *dev)
  61 {
  62         kfree(dev->mt);
  63         dev->mt = NULL;
  64         dev->mtsize = 0;
  65         dev->slot = 0;
  66         dev->trkid = 0;
  67 }
  68 EXPORT_SYMBOL(input_mt_destroy_slots);
  69
  70 /**
  71  * input_mt_report_slot_state() - report contact state
  72  * @dev: input device with allocated MT slots
  73  * @tool_type: the tool type to use in this slot
  74  * @active: true if contact is active, false otherwise
  75  *
  76  * Reports a contact via ABS_MT_TRACKING_ID, and optionally
  77  * ABS_MT_TOOL_TYPE. If active is true and the slot is currently
  78  * inactive, or if the tool type is changed, a new tracking id is
  79  * assigned to the slot. The tool type is only reported if the
  80  * corresponding absbit field is set.
  81  */
  82 void input_mt_report_slot_state(struct input_dev *dev,
  83                                 unsigned int tool_type, bool active)
  84 {
  85         struct input_mt_slot *mt;
  86         int id;
  87
  88         if (!dev->mt || !active) {
  89                 input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
  90                 return;
  91         }
  92
  93         mt = &dev->mt[dev->slot];
  94         id = input_mt_get_value(mt, ABS_MT_TRACKING_ID);
  95         if (id < 0 || input_mt_get_value(mt, ABS_MT_TOOL_TYPE) != tool_type)
  96                 id = input_mt_new_trkid(dev);
  97
  98         input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, id);
  99         input_event(dev, EV_ABS, ABS_MT_TOOL_TYPE, tool_type);
 100 }
 101 EXPORT_SYMBOL(input_mt_report_slot_state);
 102
 103 /**
 104  * input_mt_report_finger_count() - report contact count
 105  * @dev: input device with allocated MT slots
 106  * @count: the number of contacts
 107  *
 108  * Reports the contact count via BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP,
 109  * BTN_TOOL_TRIPLETAP and BTN_TOOL_QUADTAP.
 110  *
 111  * The input core ensures only the KEY events already setup for
 112  * this device will produce output.
 113  */
 114 void input_mt_report_finger_count(struct input_dev *dev, int count)
 115 {
 116         input_event(dev, EV_KEY, BTN_TOOL_FINGER, count == 1);
 117         input_event(dev, EV_KEY, BTN_TOOL_DOUBLETAP, count == 2);
 118         input_event(dev, EV_KEY, BTN_TOOL_TRIPLETAP, count == 3);
 119         input_event(dev, EV_KEY, BTN_TOOL_QUADTAP, count == 4);
 120 }
 121 EXPORT_SYMBOL(input_mt_report_finger_count);
 122
 123 /**
 124  * input_mt_report_pointer_emulation() - common pointer emulation
 125  * @dev: input device with allocated MT slots
 126  * @use_count: report number of active contacts as finger count
 127  *
 128  * Performs legacy pointer emulation via BTN_TOUCH, ABS_X, ABS_Y and
 129  * ABS_PRESSURE. Touchpad finger count is emulated if use_count is true.
 130  *
 131  * The input core ensures only the KEY and ABS axes already setup for
 132  * this device will produce output.
 133  */
 134 void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
 135 {
 136         struct input_mt_slot *oldest = 0;
 137         int oldid = dev->trkid;
 138         int count = 0;
 139         int i;
 140
 141         for (i = 0; i < dev->mtsize; ++i) {
 142                 struct input_mt_slot *ps = &dev->mt[i];
 143                 int id = input_mt_get_value(ps, ABS_MT_TRACKING_ID);
 144
 145                 if (id < 0)
 146                         continue;
 147                 if ((id - oldid) & TRKID_SGN) {
 148                         oldest = ps;
 149                         oldid = id;
 150                 }
 151                 count++;
 152         }
 153
 154         input_event(dev, EV_KEY, BTN_TOUCH, count > 0);
 155         if (use_count)
 156                 input_mt_report_finger_count(dev, count);
 157
 158         if (oldest) {
 159                 int x = input_mt_get_value(oldest, ABS_MT_POSITION_X);
 160                 int y = input_mt_get_value(oldest, ABS_MT_POSITION_Y);
 161                 int p = input_mt_get_value(oldest, ABS_MT_PRESSURE);
 162
 163                 input_event(dev, EV_ABS, ABS_X, x);
 164                 input_event(dev, EV_ABS, ABS_Y, y);
 165                 input_event(dev, EV_ABS, ABS_PRESSURE, p);
 166         } else {
 167                 input_event(dev, EV_ABS, ABS_PRESSURE, 0);
 168         }
 169 }
 170 EXPORT_SYMBOL(input_mt_report_pointer_emulation);