linux/drivers/input/input-mt.c
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   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 */
  28int 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}
  52EXPORT_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 */
  61void 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}
  69EXPORT_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 */
  83void 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}
 102EXPORT_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 */
 115void 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}
 123EXPORT_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 */
 136void input_mt_report_pointer_emulation(struct input_dev *dev, bool use_count)
 137{
 138        struct input_mt_slot *oldest = NULL;
 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}
 172EXPORT_SYMBOL(input_mt_report_pointer_emulation);
 173
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