Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1032 insertions, 0 deletions

diff --git a/drivers/hid/hid-ntrig.c b/drivers/hid/hid-ntrig.c
new file mode 100644
index 000000000..b5d26f03f
--- /dev/null
+++ b/drivers/hid/hid-ntrig.c
@@ -0,0 +1,1032 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for N-Trig touchscreens
+ *
+ *  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
+
+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 || report->maxfield < 1 ||
+	    report->field[0]->report_count < 1)
+		return -EINVAL;
+
+	hid_hw_request(hdev, report, HID_REQ_GET_REPORT);
+	hid_hw_wait(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;
+
+	hid_hw_request(hdev, report, HID_REQ_GET_REPORT);
+}
+
+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 = to_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 = to_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 = to_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 = to_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 = to_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 = to_hid_device(dev);
+	struct ntrig_data *nd = hid_get_drvdata(hdev);
+
+	unsigned long val;
+
+	if (kstrtoul(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 = to_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 = to_hid_device(dev);
+	struct ntrig_data *nd = hid_get_drvdata(hdev);
+
+	unsigned long val;
+
+	if (kstrtoul(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 = to_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 = to_hid_device(dev);
+	struct ntrig_data *nd = hid_get_drvdata(hdev);
+
+	unsigned long val;
+
+	if (kstrtoul(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 = to_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 = to_hid_device(dev);
+	struct ntrig_data *nd = hid_get_drvdata(hdev);
+
+	unsigned long val;
+
+	if (kstrtoul(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 = to_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 = to_hid_device(dev);
+	struct ntrig_data *nd = hid_get_drvdata(hdev);
+
+	unsigned long val;
+
+	if (kstrtoul(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 = to_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 = to_hid_device(dev);
+	struct ntrig_data *nd = hid_get_drvdata(hdev);
+
+	unsigned long val;
+
+	if (kstrtoul(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 const 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 = true;
+		nd->first_contact_touch = false;
+		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 = false;
+			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 = false;
+		} 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 = false;
+
+
+		/*
+		 * 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_input_configured(struct hid_device *hid,
+		struct hid_input *hidinput)
+
+{
+	struct input_dev *input = hidinput->input;
+
+	if (hidinput->report->maxfield < 1)
+		return 0;
+
+	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;
+	}
+
+	return 0;
+}
+
+static int ntrig_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	int ret;
+	struct ntrig_data *nd;
+	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 = false;
+	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;
+	}
+
+	/* 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 */
+		hid_hw_wait(hdev);
+		hid_hw_request(hdev, report, HID_REQ_GET_REPORT);
+
+		/*
+		 * 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);
+	if (ret)
+		hid_err(hdev, "cannot create sysfs group\n");
+
+	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,
+	.input_configured = ntrig_input_configured,
+	.usage_table = ntrig_grabbed_usages,
+	.event = ntrig_event,
+};
+module_hid_driver(ntrig_driver);
+
+MODULE_LICENSE("GPL");