/*
   * Input Multitouch Library
   *
   * Copyright (c) 2008-2010 Henrik Rydberg
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 as published by
   * the Free Software Foundation.
   */
  
  #include <linux/input/mt.h>

  #include <linux/export.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, 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)

  {
  	int i;
  
  	if (!num_slots)
  		return 0;

  	if (dev->mt)
  		return dev->mtsize != num_slots ? -EINVAL : 0;

  
  	dev->mt = kcalloc(num_slots, sizeof(struct input_mt_slot), GFP_KERNEL);
  	if (!dev->mt)
  		return -ENOMEM;
  
  	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' */
  	for (i = 0; i < num_slots; i++)
  		input_mt_set_value(&dev->mt[i], ABS_MT_TRACKING_ID, -1);
  
  	return 0;
  }

  EXPORT_SYMBOL(input_mt_init_slots);

  
  /**
   * input_mt_destroy_slots() - frees the MT slots of the input device
   * @dev: input device with allocated MT slots
   *
   * This function is only needed in error path as the input core will
   * automatically free the MT slots when the device is destroyed.
   */
  void input_mt_destroy_slots(struct input_dev *dev)
  {
  	kfree(dev->mt);
  	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);

  	input_event(dev, EV_KEY, BTN_TOOL_QUINTTAP, count == 5);

  }
  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);