aboutsummaryrefslogtreecommitdiff
path: root/drivers/hid/hid-ntrig.c
blob: 7757e82416e7f2270a1ebba2ef44070161424985 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
/*
 *  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 void ntrig_input_configured(struct hid_device *hid,
		struct hid_input *hidinput)

{
	struct input_dev *input = hidinput->input;

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

	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;
	}
}

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 = 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;
	}

	/* 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,
	.input_configured = ntrig_input_configured,
	.usage_table = ntrig_grabbed_usages,
	.event = ntrig_event,
};
module_hid_driver(ntrig_driver);

MODULE_LICENSE("GPL");