HID: ntrig: add filtering module parameters
[safe/jmp/linux-2.6] / drivers / hid / hid-ntrig.c
index 38b2364..b6b0cae 100644 (file)
@@ -1,8 +1,8 @@
 /*
  *  HID driver for N-Trig touchscreens
  *
- *  Copyright (c) 2008 Rafi Rubin
- *  Copyright (c) 2009 Stephane Chatty
+ *  Copyright (c) 2008-2010 Rafi Rubin
+ *  Copyright (c) 2009-2010 Stephane Chatty
  *
  */
 
 
 #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
 
-#define nt_map_key_clear(c)    hid_map_usage_clear(hi, usage, bit, max, \
-                                       EV_KEY, (c))
+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 {
-       __s32 x, y, id, w, h;
-       bool reading_a_point, found_contact_id;
-       bool pen_active;
-       bool finger_active;
-       bool inverted;
+       /* 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;
+};
+
+
+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
 };
 
 /*
@@ -42,12 +380,13 @@ 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)
 {
-       /* No special mappings needed for the pen */
-       if (field->application == HID_DG_PEN)
+       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:
@@ -56,6 +395,21 @@ static int ntrig_input_mapping(struct hid_device *hdev, struct hid_input *hi,
                        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,
@@ -63,6 +417,21 @@ static int ntrig_input_mapping(struct hid_device *hdev, struct hid_input *hi,
                        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;
@@ -70,18 +439,12 @@ static int ntrig_input_mapping(struct hid_device *hdev, struct hid_input *hi,
        case HID_UP_DIGITIZER:
                switch (usage->hid) {
                /* we do not want to map these for now */
-               case HID_DG_CONTACTID: /* value is useless */
+               case HID_DG_CONTACTID: /* Not trustworthy, squelch for now */
                case HID_DG_INPUTMODE:
                case HID_DG_DEVICEINDEX:
-               case HID_DG_CONTACTCOUNT:
                case HID_DG_CONTACTMAX:
                        return -1;
 
-               /* original mapping by Rafi Rubin */
-               case HID_DG_CONFIDENCE:
-                       nt_map_key_clear(BTN_TOOL_DOUBLETAP);
-                       return 1;
-
                /* width/height mapped on TouchMajor/TouchMinor/Orientation */
                case HID_DG_WIDTH:
                        hid_map_usage(hi, usage, bit, max,
@@ -108,9 +471,10 @@ 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 */
-       if (field->application == HID_DG_PEN)
+       /* 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);
@@ -136,29 +500,28 @@ static int ntrig_event (struct hid_device *hid, struct hid_field *field,
 
         if (hid->claimed & HID_CLAIMED_INPUT) {
                switch (usage->hid) {
-
-               case HID_DG_INRANGE:
-                       if (field->application & 0x3)
-                               nd->pen_active = (value != 0);
-                       else
-                               nd->finger_active = (value != 0);
-                       return 0;
-
-               case HID_DG_INVERT:
-                       nd->inverted = value;
-                       return 0;
-
+               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;
-                       nd->reading_a_point = 1;
+                       /* 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;
-                       /* we receive this only when in multitouch mode */
-                       nd->found_contact_id = 1;
                        break;
                case HID_DG_WIDTH:
                        nd->w = value;
@@ -170,35 +533,19 @@ static int ntrig_event (struct hid_device *hid, struct hid_field *field,
                         * report received in a finger event. We want
                         * to emit a normal (X, Y) position
                         */
-                       if (!nd->found_contact_id) {
-                               if (nd->pen_active && nd->finger_active) {
-                                       input_report_key(input, BTN_TOOL_DOUBLETAP, 0);
-                                       input_report_key(input, BTN_TOOL_DOUBLETAP, 1);
-                               }
+                       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 HID_DG_TIPPRESSURE:
-                       /*
-                        * when in single touch mode, this is the last
-                        * report received in a pen event. We want
-                        * to emit a normal (X, Y) position
-                        */
-                       if (! nd->found_contact_id) {
-                               if (nd->pen_active && nd->finger_active) {
-                                       input_report_key(input,
-                                                       nd->inverted ? BTN_TOOL_RUBBER : BTN_TOOL_PEN
-                                                       , 0);
-                                       input_report_key(input,
-                                                       nd->inverted ? BTN_TOOL_RUBBER : BTN_TOOL_PEN
-                                                       , 1);
-                               }
-                               input_event(input, EV_ABS, ABS_X, nd->x);
-                               input_event(input, EV_ABS, ABS_Y, nd->y);
-                               input_event(input, EV_ABS, ABS_PRESSURE, value);
-                       }
-                       break;
                case 0xff000002:
                        /*
                         * we receive this when the device is in multitouch
@@ -206,15 +553,100 @@ static int ntrig_event (struct hid_device *hid, struct hid_field *field,
                         * this usage tells if the contact point is real
                         * or a placeholder
                         */
-                       if (!nd->reading_a_point || value != 1)
+
+                       /* 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);
@@ -231,12 +663,101 @@ static int ntrig_event (struct hid_device *hid, struct hid_field *field,
                                                ABS_MT_TOUCH_MINOR, nd->w);
                        }
                        input_mt_sync(field->hidinput->input);
-                       nd->reading_a_point = 0;
-                       nd->found_contact_id = 0;
+                       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:
-                       /* fallback to the generic hidinput handling */
+                       /* fall-back to the generic hidinput handling */
                        return 0;
                }
        }
@@ -254,6 +775,7 @@ static int ntrig_probe(struct hid_device *hdev, const struct hid_device_id *id)
        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;
@@ -263,8 +785,18 @@ static int ntrig_probe(struct hid_device *hdev, const struct hid_device_id *id)
                dev_err(&hdev->dev, "cannot allocate N-Trig data\n");
                return -ENOMEM;
        }
-       nd->reading_a_point = 0;
-       nd->found_contact_id = 0;
+
+       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);
@@ -281,12 +813,21 @@ static int ntrig_probe(struct hid_device *hdev, const struct hid_device_id *id)
 
 
        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
@@ -302,6 +843,14 @@ static int ntrig_probe(struct hid_device *hdev, const struct hid_device_id *id)
                }
        }
 
+       /* This is needed for devices with more recent firmware versions */
+       report = hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0x0a];
+       if (report)
+               usbhid_submit_report(hdev, report, USB_DIR_OUT);
+
+       ret = sysfs_create_group(&hdev->dev.kobj,
+                       &ntrig_attribute_group);
+
        return 0;
 err_free:
        kfree(nd);
@@ -310,6 +859,8 @@ err_free:
 
 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));
 }