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/export.h>
  13 #include <linux/slab.h>
  14
  15 #define TRKID_SGN       ((TRKID_MAX + 1) >> 1)
  16
  17 /**
  18  * input_mt_init_slots() - initialize MT input slots
  19  * @dev: input device supporting MT events and finger tracking
  20  * @num_slots: number of slots used by the device
  21  *
  22  * This function allocates all necessary memory for MT slot handling
  23  * in the input device, prepares the ABS_MT_SLOT and
  24  * ABS_MT_TRACKING_ID events for use and sets up appropriate buffers.
  25  * May be called repeatedly. Returns -EINVAL if attempting to
  26  * reinitialize with a different number of slots.
  27  */
  28 int input_mt_init_slots(struct input_dev *dev, unsigned int num_slots)
  29 {
  30         int i;
  31
  32         if (!num_slots)
  33                 return 0;
  34         if (dev->mt)
  35                 return dev->mtsize != num_slots ? -EINVAL : 0;
  36
  37         dev->mt = kcalloc(num_slots, sizeof(struct input_mt_slot), GFP_KERNEL);
  38         if (!dev->mt)
  39                 return -ENOMEM;
  40
  41         dev->mtsize = num_slots;
  42         input_set_abs_params(dev, ABS_MT_SLOT, 0, num_slots - 1, 0, 0);
  43         input_set_abs_params(dev, ABS_MT_TRACKING_ID, 0, TRKID_MAX, 0, 0);
  44         input_set_events_per_packet(dev, 6 * num_slots);
  45
  46         /* Mark slots as 'unused' */
  47         for (i = 0; i < num_slots; i++)
  48                 input_mt_set_value(&dev->mt[i], ABS_MT_TRACKING_ID, -1);
  49
  50         return 0;
  51 }
  52 EXPORT_SYMBOL(input_mt_init_slots);
  53
  54 /**
  55  * input_mt_destroy_slots() - frees the MT slots of the input device
  56  * @dev: input device with allocated MT slots
  57  *
  58  * This function is only needed in error path as the input core will
  59  * automatically free the MT slots when the device is destroyed.
  60  */
  61 void input_mt_destroy_slots(struct input_dev *dev)
  62 {
  63         kfree(dev->mt);
  64         dev->mt = NULL;
  65         dev->mtsize = 0;
  66         dev->slot = 0;
  67         dev->trkid = 0;
  68 }
  69 EXPORT_SYMBOL(input_mt_destroy_slots);
  70
  71 /**
  72  * input_mt_report_slot_state() - report contact state
  73  * @dev: input device with allocated MT slots
  74  * @tool_type: the tool type to use in this slot
  75  * @active: true if contact is active, false otherwise
  76  *
  77  * Reports a contact via ABS_MT_TRACKING_ID, and optionally
  78  * ABS_MT_TOOL_TYPE. If active is true and the slot is currently
  79  * inactive, or if the tool type is changed, a new tracking id is
  80  * assigned to the slot. The tool type is only reported if the
  81  * corresponding absbit field is set.
  82  */
  83 void input_mt_report_slot_state(struct input_dev *dev,
  84                                 unsigned int tool_type, bool active)
  85 {
  86         struct input_mt_slot *mt;
  87         int id;
  88
  89         if (!dev->mt || !active) {
  90                 input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, -1);
  91                 return;
  92         }
  93
  94         mt = &dev->mt[dev->slot];
  95         id = input_mt_get_value(mt, ABS_MT_TRACKING_ID);
  96         if (id < 0 || input_mt_get_value(mt, ABS_MT_TOOL_TYPE) != tool_type)
  97                 id = input_mt_new_trkid(dev);
  98
  99         input_event(dev, EV_ABS, ABS_MT_TRACKING_ID, id);
 100         input_event(dev, EV_ABS, ABS_MT_TOOL_TYPE, tool_type);
 101 }
 102 EXPORT_SYMBOL(input_mt_report_slot_state);
 103
 104 /**
 105  * input_mt_report_finger_count() - report contact count
 106  * @dev: input device with allocated MT slots
 107  * @count: the number of contacts
 108  *
 109  * Reports the contact count via BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP,
 110  * BTN_TOOL_TRIPLETAP and BTN_TOOL_QUADTAP.
 111  *
 112  * The input core ensures only the KEY events already setup for
 113  * this device will produce output.
 114  */
 115 void input_mt_report_finger_count(struct input_dev *dev, int count)
 116 {
 117         input_event(dev, EV_KEY, BTN_TOOL_FINGER, count == 1);
 118         input_event(dev, EV_KEY, BTN_TOOL_DOUBLETAP, count == 2);
 119         input_event(dev, EV_KEY, BTN_TOOL_TRIPLETAP, count == 3);
 120         input_event(dev, EV_KEY, BTN_TOOL_QUADTAP, count == 4);
 121         input_event(dev, EV_KEY, BTN_TOOL_QUINTTAP, count == 5);
 122 }
 123 EXPORT_SYMBOL(input_mt_report_finger_count);
 124
 125 /**
 126  * input_mt_report_pointer_emulation() - common pointer emulation
 127  * @dev: input device with allocated MT slots
 128  * @use_count: report number of active contacts as finger count
 129  *
 130  * Performs legacy pointer emulation via BTN_TOUCH, ABS_X, ABS_Y and
 131  * ABS_PRESSURE. Touchpad finger count is emulated if use_count is true.
 132  *
 133  * The input core ensures only the KEY and ABS axes already setup for
 134  * this device will produce output.
 135  */
 136 void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
 137 {
 138         struct input_mt_slot *oldest = 0;
 139         int oldid = dev->trkid;
 140         int count = 0;
 141         int i;
 142
 143         for (i = 0; i < dev->mtsize; ++i) {
 144                 struct input_mt_slot *ps = &dev->mt[i];
 145                 int id = input_mt_get_value(ps, ABS_MT_TRACKING_ID);
 146
 147                 if (id < 0)
 148                         continue;
 149                 if ((id - oldid) & TRKID_SGN) {
 150                         oldest = ps;
 151                         oldid = id;
 152                 }
 153                 count++;
 154         }
 155
 156         input_event(dev, EV_KEY, BTN_TOUCH, count > 0);
 157         if (use_count)
 158                 input_mt_report_finger_count(dev, count);
 159
 160         if (oldest) {
 161                 int x = input_mt_get_value(oldest, ABS_MT_POSITION_X);
 162                 int y = input_mt_get_value(oldest, ABS_MT_POSITION_Y);
 163                 int p = input_mt_get_value(oldest, ABS_MT_PRESSURE);
 164
 165                 input_event(dev, EV_ABS, ABS_X, x);
 166                 input_event(dev, EV_ABS, ABS_Y, y);
 167                 input_event(dev, EV_ABS, ABS_PRESSURE, p);
 168         } else {
 169                 input_event(dev, EV_ABS, ABS_PRESSURE, 0);
 170         }
 171 }
 172 EXPORT_SYMBOL(input_mt_report_pointer_emulation);