/*
 *  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)\n",
                         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\n", 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\n", 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\n", 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\n", 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\n", 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\n", 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\n", 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\n", 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\n", 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\n", -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\n");
                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 = 1;
        nd->sensor_logical_height = 1;
        nd->sensor_physical_width = 1;
        nd->sensor_physical_height = 1;

        hid_set_drvdata(hdev, nd);

        ret = hid_parse(hdev);
        if (ret) {
                hid_err(hdev, "parse failed\n");
                goto err_free;
        }

        ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT & ~HID_CONNECT_FF);
        if (ret) {
                hid_err(hdev, "hw start failed\n");
                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");