/*

   *  HID driver for N-Trig touchscreens

   *

   *  Copyright (c) 2008-2010 Rafi Rubin
   *  Copyright (c) 2009-2010 Stephane Chatty

   *
   */
  
  /*
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License as published by the Free
   * Software Foundation; either version 2 of the License, or (at your option)
   * any later version.
   */
  
  #include <linux/device.h>
  #include <linux/hid.h>

  #include <linux/usb.h>
  #include "usbhid/usbhid.h"

  #include <linux/module.h>

  #include <linux/slab.h>

  
  #include "hid-ids.h"
  
  #define NTRIG_DUPLICATE_USAGES	0x001

  static unsigned int min_width;

  module_param(min_width, uint, 0644);
  MODULE_PARM_DESC(min_width, "Minimum touch contact width to accept.");

  static unsigned int min_height;

  module_param(min_height, uint, 0644);
  MODULE_PARM_DESC(min_height, "Minimum touch contact height to accept.");

  static unsigned int activate_slack = 1;

  module_param(activate_slack, uint, 0644);
  MODULE_PARM_DESC(activate_slack, "Number of touch frames to ignore at "
  		 "the start of touch input.");

  static unsigned int deactivate_slack = 4;

  module_param(deactivate_slack, uint, 0644);
  MODULE_PARM_DESC(deactivate_slack, "Number of empty frames to ignore before "
  		 "deactivating touch.");

  static unsigned int activation_width = 64;

  module_param(activation_width, uint, 0644);
  MODULE_PARM_DESC(activation_width, "Width threshold to immediately start "
  		 "processing touch events.");

  static unsigned int activation_height = 32;

  module_param(activation_height, uint, 0644);
  MODULE_PARM_DESC(activation_height, "Height threshold to immediately start "
  		 "processing touch events.");

  struct ntrig_data {

  	/* Incoming raw values for a single contact */
  	__u16 x, y, w, h;
  	__u16 id;

  
  	bool tipswitch;
  	bool confidence;
  	bool first_contact_touch;

  
  	bool reading_mt;

  
  	__u8 mt_footer[4];
  	__u8 mt_foot_count;

  
  	/* The current activation state. */
  	__s8 act_state;
  
  	/* Empty frames to ignore before recognizing the end of activity */
  	__s8 deactivate_slack;
  
  	/* Frames to ignore before acknowledging the start of activity */
  	__s8 activate_slack;
  
  	/* Minimum size contact to accept */
  	__u16 min_width;
  	__u16 min_height;
  
  	/* Threshold to override activation slack */
  	__u16 activation_width;
  	__u16 activation_height;
  
  	__u16 sensor_logical_width;
  	__u16 sensor_logical_height;
  	__u16 sensor_physical_width;
  	__u16 sensor_physical_height;

  };

  /*
   * This function converts the 4 byte raw firmware code into
   * a string containing 5 comma separated numbers.
   */
  static int ntrig_version_string(unsigned char *raw, char *buf)
  {
  	__u8 a =  (raw[1] & 0x0e) >> 1;
  	__u8 b =  (raw[0] & 0x3c) >> 2;
  	__u8 c = ((raw[0] & 0x03) << 3) | ((raw[3] & 0xe0) >> 5);
  	__u8 d = ((raw[3] & 0x07) << 3) | ((raw[2] & 0xe0) >> 5);
  	__u8 e =   raw[2] & 0x07;
  
  	/*
  	 * As yet unmapped bits:
  	 * 0b11000000 0b11110001 0b00011000 0b00011000
  	 */
  
  	return sprintf(buf, "%u.%u.%u.%u.%u", a, b, c, d, e);
  }

  static inline int ntrig_get_mode(struct hid_device *hdev)
  {
  	struct hid_report *report = hdev->report_enum[HID_FEATURE_REPORT].
  				    report_id_hash[0x0d];
  
  	if (!report)
  		return -EINVAL;
  
  	usbhid_submit_report(hdev, report, USB_DIR_IN);
  	usbhid_wait_io(hdev);
  	return (int)report->field[0]->value[0];
  }
  
  static inline void ntrig_set_mode(struct hid_device *hdev, const int mode)
  {
  	struct hid_report *report;
  	__u8 mode_commands[4] = { 0xe, 0xf, 0x1b, 0x10 };
  
  	if (mode < 0 || mode > 3)
  		return;
  
  	report = hdev->report_enum[HID_FEATURE_REPORT].
  		 report_id_hash[mode_commands[mode]];
  
  	if (!report)
  		return;
  
  	usbhid_submit_report(hdev, report, USB_DIR_IN);
  }

  static void ntrig_report_version(struct hid_device *hdev)
  {
  	int ret;
  	char buf[20];
  	struct usb_device *usb_dev = hid_to_usb_dev(hdev);
  	unsigned char *data = kmalloc(8, GFP_KERNEL);
  
  	if (!data)
  		goto err_free;
  
  	ret = usb_control_msg(usb_dev, usb_rcvctrlpipe(usb_dev, 0),
  			      USB_REQ_CLEAR_FEATURE,
  			      USB_TYPE_CLASS | USB_RECIP_INTERFACE |
  			      USB_DIR_IN,
  			      0x30c, 1, data, 8,
  			      USB_CTRL_SET_TIMEOUT);
  
  	if (ret == 8) {
  		ret = ntrig_version_string(&data[2], buf);

  		hid_info(hdev, "Firmware version: %s (%02x%02x %02x%02x)
  ",

  			 buf, data[2], data[3], data[4], data[5]);
  	}
  
  err_free:
  	kfree(data);
  }

  static ssize_t show_phys_width(struct device *dev,
  			       struct device_attribute *attr,
  			       char *buf)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	return sprintf(buf, "%d
  ", nd->sensor_physical_width);
  }
  
  static DEVICE_ATTR(sensor_physical_width, S_IRUGO, show_phys_width, NULL);
  
  static ssize_t show_phys_height(struct device *dev,
  				struct device_attribute *attr,
  				char *buf)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	return sprintf(buf, "%d
  ", nd->sensor_physical_height);
  }
  
  static DEVICE_ATTR(sensor_physical_height, S_IRUGO, show_phys_height, NULL);
  
  static ssize_t show_log_width(struct device *dev,
  			      struct device_attribute *attr,
  			      char *buf)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	return sprintf(buf, "%d
  ", nd->sensor_logical_width);
  }
  
  static DEVICE_ATTR(sensor_logical_width, S_IRUGO, show_log_width, NULL);
  
  static ssize_t show_log_height(struct device *dev,
  			       struct device_attribute *attr,
  			       char *buf)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	return sprintf(buf, "%d
  ", nd->sensor_logical_height);
  }
  
  static DEVICE_ATTR(sensor_logical_height, S_IRUGO, show_log_height, NULL);
  
  static ssize_t show_min_width(struct device *dev,
  			      struct device_attribute *attr,
  			      char *buf)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	return sprintf(buf, "%d
  ", nd->min_width *
  				    nd->sensor_physical_width /
  				    nd->sensor_logical_width);
  }
  
  static ssize_t set_min_width(struct device *dev,
  			     struct device_attribute *attr,
  			     const char *buf, size_t count)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	unsigned long val;
  
  	if (strict_strtoul(buf, 0, &val))
  		return -EINVAL;
  
  	if (val > nd->sensor_physical_width)
  		return -EINVAL;
  
  	nd->min_width = val * nd->sensor_logical_width /
  			      nd->sensor_physical_width;
  
  	return count;
  }
  
  static DEVICE_ATTR(min_width, S_IWUSR | S_IRUGO, show_min_width, set_min_width);
  
  static ssize_t show_min_height(struct device *dev,
  			       struct device_attribute *attr,
  			       char *buf)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	return sprintf(buf, "%d
  ", nd->min_height *
  				    nd->sensor_physical_height /
  				    nd->sensor_logical_height);
  }
  
  static ssize_t set_min_height(struct device *dev,
  			      struct device_attribute *attr,
  			      const char *buf, size_t count)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	unsigned long val;
  
  	if (strict_strtoul(buf, 0, &val))
  		return -EINVAL;
  
  	if (val > nd->sensor_physical_height)
  		return -EINVAL;
  
  	nd->min_height = val * nd->sensor_logical_height /
  			       nd->sensor_physical_height;
  
  	return count;
  }
  
  static DEVICE_ATTR(min_height, S_IWUSR | S_IRUGO, show_min_height,
  		   set_min_height);
  
  static ssize_t show_activate_slack(struct device *dev,
  				   struct device_attribute *attr,
  				   char *buf)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	return sprintf(buf, "%d
  ", nd->activate_slack);
  }
  
  static ssize_t set_activate_slack(struct device *dev,
  				  struct device_attribute *attr,
  				  const char *buf, size_t count)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	unsigned long val;
  
  	if (strict_strtoul(buf, 0, &val))
  		return -EINVAL;
  
  	if (val > 0x7f)
  		return -EINVAL;
  
  	nd->activate_slack = val;
  
  	return count;
  }
  
  static DEVICE_ATTR(activate_slack, S_IWUSR | S_IRUGO, show_activate_slack,
  		   set_activate_slack);
  
  static ssize_t show_activation_width(struct device *dev,
  				     struct device_attribute *attr,
  				     char *buf)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	return sprintf(buf, "%d
  ", nd->activation_width *
  				    nd->sensor_physical_width /
  				    nd->sensor_logical_width);
  }
  
  static ssize_t set_activation_width(struct device *dev,
  				    struct device_attribute *attr,
  				    const char *buf, size_t count)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	unsigned long val;
  
  	if (strict_strtoul(buf, 0, &val))
  		return -EINVAL;
  
  	if (val > nd->sensor_physical_width)
  		return -EINVAL;
  
  	nd->activation_width = val * nd->sensor_logical_width /
  				     nd->sensor_physical_width;
  
  	return count;
  }
  
  static DEVICE_ATTR(activation_width, S_IWUSR | S_IRUGO, show_activation_width,
  		   set_activation_width);
  
  static ssize_t show_activation_height(struct device *dev,
  				      struct device_attribute *attr,
  				      char *buf)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	return sprintf(buf, "%d
  ", nd->activation_height *
  				    nd->sensor_physical_height /
  				    nd->sensor_logical_height);
  }
  
  static ssize_t set_activation_height(struct device *dev,
  				     struct device_attribute *attr,
  				     const char *buf, size_t count)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	unsigned long val;
  
  	if (strict_strtoul(buf, 0, &val))
  		return -EINVAL;
  
  	if (val > nd->sensor_physical_height)
  		return -EINVAL;
  
  	nd->activation_height = val * nd->sensor_logical_height /
  				      nd->sensor_physical_height;
  
  	return count;
  }
  
  static DEVICE_ATTR(activation_height, S_IWUSR | S_IRUGO,
  		   show_activation_height, set_activation_height);
  
  static ssize_t show_deactivate_slack(struct device *dev,
  				     struct device_attribute *attr,
  				     char *buf)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	return sprintf(buf, "%d
  ", -nd->deactivate_slack);
  }
  
  static ssize_t set_deactivate_slack(struct device *dev,
  				    struct device_attribute *attr,
  				    const char *buf, size_t count)
  {
  	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
  	struct ntrig_data *nd = hid_get_drvdata(hdev);
  
  	unsigned long val;
  
  	if (strict_strtoul(buf, 0, &val))
  		return -EINVAL;
  
  	/*
  	 * No more than 8 terminal frames have been observed so far
  	 * and higher slack is highly likely to leave the single
  	 * touch emulation stuck down.
  	 */
  	if (val > 7)
  		return -EINVAL;
  
  	nd->deactivate_slack = -val;
  
  	return count;
  }
  
  static DEVICE_ATTR(deactivate_slack, S_IWUSR | S_IRUGO, show_deactivate_slack,
  		   set_deactivate_slack);
  
  static struct attribute *sysfs_attrs[] = {
  	&dev_attr_sensor_physical_width.attr,
  	&dev_attr_sensor_physical_height.attr,
  	&dev_attr_sensor_logical_width.attr,
  	&dev_attr_sensor_logical_height.attr,
  	&dev_attr_min_height.attr,
  	&dev_attr_min_width.attr,
  	&dev_attr_activate_slack.attr,
  	&dev_attr_activation_width.attr,
  	&dev_attr_activation_height.attr,
  	&dev_attr_deactivate_slack.attr,
  	NULL
  };
  
  static struct attribute_group ntrig_attribute_group = {
  	.attrs = sysfs_attrs
  };

  /*
   * this driver is aimed at two firmware versions in circulation:
   *  - dual pen/finger single touch
   *  - finger multitouch, pen not working
   */

  static int ntrig_input_mapping(struct hid_device *hdev, struct hid_input *hi,

  			       struct hid_field *field, struct hid_usage *usage,
  			       unsigned long **bit, int *max)

  {

  	struct ntrig_data *nd = hid_get_drvdata(hdev);

  	/* No special mappings needed for the pen and single touch */
  	if (field->physical)

  		return 0;

  	switch (usage->hid & HID_USAGE_PAGE) {

  	case HID_UP_GENDESK:
  		switch (usage->hid) {
  		case HID_GD_X:
  			hid_map_usage(hi, usage, bit, max,
  					EV_ABS, ABS_MT_POSITION_X);
  			input_set_abs_params(hi->input, ABS_X,
  					field->logical_minimum,
  					field->logical_maximum, 0, 0);

  
  			if (!nd->sensor_logical_width) {
  				nd->sensor_logical_width =
  					field->logical_maximum -
  					field->logical_minimum;
  				nd->sensor_physical_width =
  					field->physical_maximum -
  					field->physical_minimum;
  				nd->activation_width = activation_width *
  					nd->sensor_logical_width /
  					nd->sensor_physical_width;
  				nd->min_width = min_width *
  					nd->sensor_logical_width /
  					nd->sensor_physical_width;
  			}

  			return 1;
  		case HID_GD_Y:
  			hid_map_usage(hi, usage, bit, max,
  					EV_ABS, ABS_MT_POSITION_Y);
  			input_set_abs_params(hi->input, ABS_Y,
  					field->logical_minimum,
  					field->logical_maximum, 0, 0);

  
  			if (!nd->sensor_logical_height) {
  				nd->sensor_logical_height =
  					field->logical_maximum -
  					field->logical_minimum;
  				nd->sensor_physical_height =
  					field->physical_maximum -
  					field->physical_minimum;
  				nd->activation_height = activation_height *
  					nd->sensor_logical_height /
  					nd->sensor_physical_height;
  				nd->min_height = min_height *
  					nd->sensor_logical_height /
  					nd->sensor_physical_height;
  			}

  			return 1;
  		}
  		return 0;
  
  	case HID_UP_DIGITIZER:
  		switch (usage->hid) {
  		/* we do not want to map these for now */

  		case HID_DG_CONTACTID: /* Not trustworthy, squelch for now */

  		case HID_DG_INPUTMODE:
  		case HID_DG_DEVICEINDEX:

  		case HID_DG_CONTACTMAX:
  			return -1;

  		/* width/height mapped on TouchMajor/TouchMinor/Orientation */
  		case HID_DG_WIDTH:
  			hid_map_usage(hi, usage, bit, max,

  				      EV_ABS, ABS_MT_TOUCH_MAJOR);

  			return 1;
  		case HID_DG_HEIGHT:
  			hid_map_usage(hi, usage, bit, max,

  				      EV_ABS, ABS_MT_TOUCH_MINOR);

  			input_set_abs_params(hi->input, ABS_MT_ORIENTATION,

  					     0, 1, 0, 0);

  			return 1;
  		}
  		return 0;
  
  	case 0xff000000:
  		/* we do not want to map these: no input-oriented meaning */
  		return -1;

  	}

  	return 0;
  }
  
  static int ntrig_input_mapped(struct hid_device *hdev, struct hid_input *hi,

  			      struct hid_field *field, struct hid_usage *usage,
  			      unsigned long **bit, int *max)

  {

  	/* No special mappings needed for the pen and single touch */
  	if (field->physical)

  		return 0;

  	if (usage->type == EV_KEY || usage->type == EV_REL
  			|| usage->type == EV_ABS)
  		clear_bit(usage->code, *bit);
  
  	return 0;
  }

  
  /*
   * this function is called upon all reports
   * so that we can filter contact point information,
   * decide whether we are in multi or single touch mode
   * and call input_mt_sync after each point if necessary
   */
  static int ntrig_event (struct hid_device *hid, struct hid_field *field,

  			struct hid_usage *usage, __s32 value)

  {

  	struct ntrig_data *nd = hid_get_drvdata(hid);

  	struct input_dev *input;
  
  	/* Skip processing if not a claimed input */
  	if (!(hid->claimed & HID_CLAIMED_INPUT))
  		goto not_claimed_input;
  
  	/* This function is being called before the structures are fully
  	 * initialized */
  	if(!(field->hidinput && field->hidinput->input))
  		return -EINVAL;
  
  	input = field->hidinput->input;

  	/* No special handling needed for the pen */
  	if (field->application == HID_DG_PEN)
  		return 0;

  	switch (usage->hid) {
  	case 0xff000001:
  		/* Tag indicating the start of a multitouch group */
  		nd->reading_mt = 1;
  		nd->first_contact_touch = 0;
  		break;
  	case HID_DG_TIPSWITCH:
  		nd->tipswitch = value;
  		/* Prevent emission of touch until validated */
  		return 1;
  	case HID_DG_CONFIDENCE:
  		nd->confidence = value;
  		break;
  	case HID_GD_X:
  		nd->x = value;
  		/* Clear the contact footer */
  		nd->mt_foot_count = 0;
  		break;
  	case HID_GD_Y:
  		nd->y = value;
  		break;
  	case HID_DG_CONTACTID:
  		nd->id = value;
  		break;
  	case HID_DG_WIDTH:
  		nd->w = value;
  		break;
  	case HID_DG_HEIGHT:
  		nd->h = value;
  		/*
  		 * when in single touch mode, this is the last
  		 * report received in a finger event. We want
  		 * to emit a normal (X, Y) position
  		 */
  		if (!nd->reading_mt) {

  			/*

  			 * TipSwitch indicates the presence of a
  			 * finger in single touch mode.

  			 */

  			input_report_key(input, BTN_TOUCH,
  					 nd->tipswitch);
  			input_report_key(input, BTN_TOOL_DOUBLETAP,
  					 nd->tipswitch);
  			input_event(input, EV_ABS, ABS_X, nd->x);
  			input_event(input, EV_ABS, ABS_Y, nd->y);
  		}
  		break;
  	case 0xff000002:
  		/*
  		 * we receive this when the device is in multitouch
  		 * mode. The first of the three values tagged with
  		 * this usage tells if the contact point is real
  		 * or a placeholder
  		 */
  
  		/* Shouldn't get more than 4 footer packets, so skip */
  		if (nd->mt_foot_count >= 4)

  			break;

  		nd->mt_footer[nd->mt_foot_count++] = value;

  		/* if the footer isn't complete break */
  		if (nd->mt_foot_count != 4)
  			break;

  		/* Pen activity signal. */
  		if (nd->mt_footer[2]) {
  			/*
  			 * When the pen deactivates touch, we see a
  			 * bogus frame with ContactCount > 0.
  			 * We can
  			 * save a bit of work by ensuring act_state < 0
  			 * even if deactivation slack is turned off.
  			 */
  			nd->act_state = deactivate_slack - 1;
  			nd->confidence = 0;
  			break;
  		}

  		/*
  		 * The first footer value indicates the presence of a
  		 * finger.
  		 */
  		if (nd->mt_footer[0]) {
  			/*
  			 * We do not want to process contacts under
  			 * the size threshold, but do not want to
  			 * ignore them for activation state
  			 */
  			if (nd->w < nd->min_width ||
  			    nd->h < nd->min_height)

  				nd->confidence = 0;

  		} else
  			break;

  		if (nd->act_state > 0) {

  			/*

  			 * Contact meets the activation size threshold

  			 */

  			if (nd->w >= nd->activation_width &&
  			    nd->h >= nd->activation_height) {
  				if (nd->id)

  					/*

  					 * first contact, activate now

  					 */

  					nd->act_state = 0;
  				else {
  					/*
  					 * avoid corrupting this frame
  					 * but ensure next frame will
  					 * be active
  					 */
  					nd->act_state = 1;

  					break;

  				}
  			} else

  				/*

  				 * Defer adjusting the activation state
  				 * until the end of the frame.

  				 */

  				break;
  		}

  		/* Discarding this contact */
  		if (!nd->confidence)
  			break;

  		/* emit a normal (X, Y) for the first point only */
  		if (nd->id == 0) {

  			/*

  			 * TipSwitch is superfluous in multitouch
  			 * mode.  The footer events tell us
  			 * if there is a finger on the screen or
  			 * not.

  			 */

  			nd->first_contact_touch = nd->confidence;
  			input_event(input, EV_ABS, ABS_X, nd->x);
  			input_event(input, EV_ABS, ABS_Y, nd->y);
  		}

  		/* Emit MT events */
  		input_event(input, EV_ABS, ABS_MT_POSITION_X, nd->x);
  		input_event(input, EV_ABS, ABS_MT_POSITION_Y, nd->y);
  
  		/*
  		 * Translate from height and width to size
  		 * and orientation.
  		 */
  		if (nd->w > nd->h) {
  			input_event(input, EV_ABS,
  					ABS_MT_ORIENTATION, 1);
  			input_event(input, EV_ABS,
  					ABS_MT_TOUCH_MAJOR, nd->w);
  			input_event(input, EV_ABS,
  					ABS_MT_TOUCH_MINOR, nd->h);
  		} else {
  			input_event(input, EV_ABS,
  					ABS_MT_ORIENTATION, 0);
  			input_event(input, EV_ABS,
  					ABS_MT_TOUCH_MAJOR, nd->h);
  			input_event(input, EV_ABS,
  					ABS_MT_TOUCH_MINOR, nd->w);
  		}
  		input_mt_sync(field->hidinput->input);
  		break;

  	case HID_DG_CONTACTCOUNT: /* End of a multitouch group */
  		if (!nd->reading_mt) /* Just to be sure */
  			break;

  		nd->reading_mt = 0;
  
  
  		/*
  		 * Activation state machine logic:
  		 *
  		 * Fundamental states:
  		 *	state >  0: Inactive
  		 *	state <= 0: Active
  		 *	state <  -deactivate_slack:
  		 *		 Pen termination of touch
  		 *
  		 * Specific values of interest
  		 *	state == activate_slack
  		 *		 no valid input since the last reset
  		 *
  		 *	state == 0
  		 *		 general operational state
  		 *
  		 *	state == -deactivate_slack
  		 *		 read sufficient empty frames to accept
  		 *		 the end of input and reset
  		 */
  
  		if (nd->act_state > 0) { /* Currently inactive */
  			if (value)
  				/*
  				 * Consider each live contact as
  				 * evidence of intentional activity.
  				 */
  				nd->act_state = (nd->act_state > value)
  						? nd->act_state - value
  						: 0;
  			else
  				/*
  				 * Empty frame before we hit the
  				 * activity threshold, reset.
  				 */
  				nd->act_state = nd->activate_slack;

  
  			/*

  			 * Entered this block inactive and no
  			 * coordinates sent this frame, so hold off
  			 * on button state.

  			 */

  			break;
  		} else { /* Currently active */
  			if (value && nd->act_state >=
  				     nd->deactivate_slack)

  				/*

  				 * Live point: clear accumulated
  				 * deactivation count.

  				 */

  				nd->act_state = 0;
  			else if (nd->act_state <= nd->deactivate_slack)

  				/*

  				 * We've consumed the deactivation
  				 * slack, time to deactivate and reset.

  				 */

  				nd->act_state =
  					nd->activate_slack;
  			else { /* Move towards deactivation */
  				nd->act_state--;
  				break;

  			}

  		}

  		if (nd->first_contact_touch && nd->act_state <= 0) {
  			/*
  			 * Check to see if we're ready to start
  			 * emitting touch events.
  			 *
  			 * Note: activation slack will decrease over
  			 * the course of the frame, and it will be
  			 * inconsistent from the start to the end of
  			 * the frame.  However if the frame starts
  			 * with slack, first_contact_touch will still
  			 * be 0 and we will not get to this point.
  			 */
  			input_report_key(input, BTN_TOOL_DOUBLETAP, 1);
  			input_report_key(input, BTN_TOUCH, 1);
  		} else {
  			input_report_key(input, BTN_TOOL_DOUBLETAP, 0);
  			input_report_key(input, BTN_TOUCH, 0);

  		}

  		break;
  
  	default:
  		/* fall-back to the generic hidinput handling */
  		return 0;

  	}

  not_claimed_input:

  	/* we have handled the hidinput part, now remains hiddev */

  	if ((hid->claimed & HID_CLAIMED_HIDDEV) && hid->hiddev_hid_event)
  		hid->hiddev_hid_event(hid, field, usage, value);

  
  	return 1;
  }
  
  static int ntrig_probe(struct hid_device *hdev, const struct hid_device_id *id)
  {
  	int ret;
  	struct ntrig_data *nd;

  	struct hid_input *hidinput;
  	struct input_dev *input;

  	struct hid_report *report;

  
  	if (id->driver_data)

  		hdev->quirks |= HID_QUIRK_MULTI_INPUT
  				| HID_QUIRK_NO_INIT_REPORTS;

  
  	nd = kmalloc(sizeof(struct ntrig_data), GFP_KERNEL);
  	if (!nd) {

  		hid_err(hdev, "cannot allocate N-Trig data
  ");

  		return -ENOMEM;
  	}

  
  	nd->reading_mt = 0;

  	nd->min_width = 0;
  	nd->min_height = 0;
  	nd->activate_slack = activate_slack;
  	nd->act_state = activate_slack;
  	nd->deactivate_slack = -deactivate_slack;
  	nd->sensor_logical_width = 0;
  	nd->sensor_logical_height = 0;
  	nd->sensor_physical_width = 0;
  	nd->sensor_physical_height = 0;

  	hid_set_drvdata(hdev, nd);
  
  	ret = hid_parse(hdev);

  	if (ret) {

  		hid_err(hdev, "parse failed
  ");

  		goto err_free;
  	}
  
  	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT & ~HID_CONNECT_FF);
  	if (ret) {

  		hid_err(hdev, "hw start failed
  ");

  		goto err_free;
  	}

  	list_for_each_entry(hidinput, &hdev->inputs, list) {

  		if (hidinput->report->maxfield < 1)
  			continue;

  		input = hidinput->input;
  		switch (hidinput->report->field[0]->application) {
  		case HID_DG_PEN:
  			input->name = "N-Trig Pen";
  			break;
  		case HID_DG_TOUCHSCREEN:

  			/* These keys are redundant for fingers, clear them
  			 * to prevent incorrect identification */

  			__clear_bit(BTN_TOOL_PEN, input->keybit);

  			__clear_bit(BTN_TOOL_FINGER, input->keybit);
  			__clear_bit(BTN_0, input->keybit);

  			__set_bit(BTN_TOOL_DOUBLETAP, input->keybit);

  			/*
  			 * The physical touchscreen (single touch)
  			 * input has a value for physical, whereas
  			 * the multitouch only has logical input
  			 * fields.
  			 */
  			input->name =
  				(hidinput->report->field[0]
  				 ->physical) ?
  				"N-Trig Touchscreen" :
  				"N-Trig MultiTouch";
  			break;
  		}
  	}

  	/* This is needed for devices with more recent firmware versions */
  	report = hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0x0a];

  	if (report) {
  		/* Let the device settle to ensure the wakeup message gets
  		 * through */
  		usbhid_wait_io(hdev);
  		usbhid_submit_report(hdev, report, USB_DIR_IN);
  
  		/*
  		 * Sanity check: if the current mode is invalid reset it to
  		 * something reasonable.
  		 */
  		if (ntrig_get_mode(hdev) >= 4)
  			ntrig_set_mode(hdev, 3);
  	}

  	ntrig_report_version(hdev);

  	ret = sysfs_create_group(&hdev->dev.kobj,
  			&ntrig_attribute_group);

  	return 0;
  err_free:
  	kfree(nd);

  	return ret;
  }
  
  static void ntrig_remove(struct hid_device *hdev)
  {

  	sysfs_remove_group(&hdev->dev.kobj,

  			   &ntrig_attribute_group);

  	hid_hw_stop(hdev);
  	kfree(hid_get_drvdata(hdev));
  }

  static const struct hid_device_id ntrig_devices[] = {
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN),
  		.driver_data = NTRIG_DUPLICATE_USAGES },

  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_1),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_2),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_3),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_4),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_5),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_6),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_7),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_8),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_9),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_10),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_11),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_12),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_13),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_14),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_15),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_16),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_17),
  		.driver_data = NTRIG_DUPLICATE_USAGES },
  	{ HID_USB_DEVICE(USB_VENDOR_ID_NTRIG, USB_DEVICE_ID_NTRIG_TOUCH_SCREEN_18),
  		.driver_data = NTRIG_DUPLICATE_USAGES },

  	{ }
  };
  MODULE_DEVICE_TABLE(hid, ntrig_devices);

  static const struct hid_usage_id ntrig_grabbed_usages[] = {
  	{ HID_ANY_ID, HID_ANY_ID, HID_ANY_ID },

  	{ HID_ANY_ID - 1, HID_ANY_ID - 1, HID_ANY_ID - 1 }

  };

  static struct hid_driver ntrig_driver = {
  	.name = "ntrig",
  	.id_table = ntrig_devices,

  	.probe = ntrig_probe,
  	.remove = ntrig_remove,

  	.input_mapping = ntrig_input_mapping,
  	.input_mapped = ntrig_input_mapped,

  	.usage_table = ntrig_grabbed_usages,
  	.event = ntrig_event,

  };

  static int __init ntrig_init(void)

  {
  	return hid_register_driver(&ntrig_driver);
  }

  static void __exit ntrig_exit(void)

  {
  	hid_unregister_driver(&ntrig_driver);
  }
  
  module_init(ntrig_init);
  module_exit(ntrig_exit);
  MODULE_LICENSE("GPL");