aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/usb/class/cdc-wdm.c
blob: a0d284ef3f40ad369cc34f093bb15723124ef4a2 (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
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
// SPDX-License-Identifier: GPL-2.0
/*
 * cdc-wdm.c
 *
 * This driver supports USB CDC WCM Device Management.
 *
 * Copyright (c) 2007-2009 Oliver Neukum
 *
 * Some code taken from cdc-acm.c
 *
 * Released under the GPLv2.
 *
 * Many thanks to Carl Nordbeck
 */
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/ioctl.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/uaccess.h>
#include <linux/bitops.h>
#include <linux/poll.h>
#include <linux/usb.h>
#include <linux/usb/cdc.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>
#include <linux/usb/cdc-wdm.h>

#define DRIVER_AUTHOR "Oliver Neukum"
#define DRIVER_DESC "USB Abstract Control Model driver for USB WCM Device Management"

static const struct usb_device_id wdm_ids[] = {
	{
		.match_flags = USB_DEVICE_ID_MATCH_INT_CLASS |
				 USB_DEVICE_ID_MATCH_INT_SUBCLASS,
		.bInterfaceClass = USB_CLASS_COMM,
		.bInterfaceSubClass = USB_CDC_SUBCLASS_DMM
	},
	{ }
};

MODULE_DEVICE_TABLE (usb, wdm_ids);

#define WDM_MINOR_BASE	176


#define WDM_IN_USE		1
#define WDM_DISCONNECTING	2
#define WDM_RESULT		3
#define WDM_READ		4
#define WDM_INT_STALL		5
#define WDM_POLL_RUNNING	6
#define WDM_RESPONDING		7
#define WDM_SUSPENDING		8
#define WDM_RESETTING		9
#define WDM_OVERFLOW		10

#define WDM_MAX			16

/* CDC-WMC r1.1 requires wMaxCommand to be "at least 256 decimal (0x100)" */
#define WDM_DEFAULT_BUFSIZE	256

static DEFINE_MUTEX(wdm_mutex);
static DEFINE_SPINLOCK(wdm_device_list_lock);
static LIST_HEAD(wdm_device_list);

/* --- method tables --- */

struct wdm_device {
	u8			*inbuf; /* buffer for response */
	u8			*outbuf; /* buffer for command */
	u8			*sbuf; /* buffer for status */
	u8			*ubuf; /* buffer for copy to user space */

	struct urb		*command;
	struct urb		*response;
	struct urb		*validity;
	struct usb_interface	*intf;
	struct usb_ctrlrequest	*orq;
	struct usb_ctrlrequest	*irq;
	spinlock_t		iuspin;

	unsigned long		flags;
	u16			bufsize;
	u16			wMaxCommand;
	u16			wMaxPacketSize;
	__le16			inum;
	int			reslength;
	int			length;
	int			read;
	int			count;
	dma_addr_t		shandle;
	dma_addr_t		ihandle;
	struct mutex		wlock;
	struct mutex		rlock;
	wait_queue_head_t	wait;
	struct work_struct	rxwork;
	int			werr;
	int			rerr;
	int                     resp_count;

	struct list_head	device_list;
	int			(*manage_power)(struct usb_interface *, int);
};

static struct usb_driver wdm_driver;

/* return intfdata if we own the interface, else look up intf in the list */
static struct wdm_device *wdm_find_device(struct usb_interface *intf)
{
	struct wdm_device *desc;

	spin_lock(&wdm_device_list_lock);
	list_for_each_entry(desc, &wdm_device_list, device_list)
		if (desc->intf == intf)
			goto found;
	desc = NULL;
found:
	spin_unlock(&wdm_device_list_lock);

	return desc;
}

static struct wdm_device *wdm_find_device_by_minor(int minor)
{
	struct wdm_device *desc;

	spin_lock(&wdm_device_list_lock);
	list_for_each_entry(desc, &wdm_device_list, device_list)
		if (desc->intf->minor == minor)
			goto found;
	desc = NULL;
found:
	spin_unlock(&wdm_device_list_lock);

	return desc;
}

/* --- callbacks --- */
static void wdm_out_callback(struct urb *urb)
{
	struct wdm_device *desc;
	desc = urb->context;
	spin_lock(&desc->iuspin);
	desc->werr = urb->status;
	spin_unlock(&desc->iuspin);
	kfree(desc->outbuf);
	desc->outbuf = NULL;
	clear_bit(WDM_IN_USE, &desc->flags);
	wake_up(&desc->wait);
}

/* forward declaration */
static int service_outstanding_interrupt(struct wdm_device *desc);

static void wdm_in_callback(struct urb *urb)
{
	struct wdm_device *desc = urb->context;
	int status = urb->status;
	int length = urb->actual_length;

	spin_lock(&desc->iuspin);
	clear_bit(WDM_RESPONDING, &desc->flags);

	if (status) {
		switch (status) {
		case -ENOENT:
			dev_dbg(&desc->intf->dev,
				"nonzero urb status received: -ENOENT\n");
			goto skip_error;
		case -ECONNRESET:
			dev_dbg(&desc->intf->dev,
				"nonzero urb status received: -ECONNRESET\n");
			goto skip_error;
		case -ESHUTDOWN:
			dev_dbg(&desc->intf->dev,
				"nonzero urb status received: -ESHUTDOWN\n");
			goto skip_error;
		case -EPIPE:
			dev_err(&desc->intf->dev,
				"nonzero urb status received: -EPIPE\n");
			break;
		default:
			dev_err(&desc->intf->dev,
				"Unexpected error %d\n", status);
			break;
		}
	}

	/*
	 * only set a new error if there is no previous error.
	 * Errors are only cleared during read/open
	 * Avoid propagating -EPIPE (stall) to userspace since it is
	 * better handled as an empty read
	 */
	if (desc->rerr == 0 && status != -EPIPE)
		desc->rerr = status;

	if (length + desc->length > desc->wMaxCommand) {
		/* The buffer would overflow */
		set_bit(WDM_OVERFLOW, &desc->flags);
	} else {
		/* we may already be in overflow */
		if (!test_bit(WDM_OVERFLOW, &desc->flags)) {
			memmove(desc->ubuf + desc->length, desc->inbuf, length);
			desc->length += length;
			desc->reslength = length;
		}
	}
skip_error:
	set_bit(WDM_READ, &desc->flags);
	wake_up(&desc->wait);

	if (desc->rerr) {
		/*
		 * Since there was an error, userspace may decide to not read
		 * any data after poll'ing.
		 * We should respond to further attempts from the device to send
		 * data, so that we can get unstuck.
		 */
		service_outstanding_interrupt(desc);
	}

	spin_unlock(&desc->iuspin);
}

static void wdm_int_callback(struct urb *urb)
{
	int rv = 0;
	int responding;
	int status = urb->status;
	struct wdm_device *desc;
	struct usb_cdc_notification *dr;

	desc = urb->context;
	dr = (struct usb_cdc_notification *)desc->sbuf;

	if (status) {
		switch (status) {
		case -ESHUTDOWN:
		case -ENOENT:
		case -ECONNRESET:
			return; /* unplug */
		case -EPIPE:
			set_bit(WDM_INT_STALL, &desc->flags);
			dev_err(&desc->intf->dev, "Stall on int endpoint\n");
			goto sw; /* halt is cleared in work */
		default:
			dev_err(&desc->intf->dev,
				"nonzero urb status received: %d\n", status);
			break;
		}
	}

	if (urb->actual_length < sizeof(struct usb_cdc_notification)) {
		dev_err(&desc->intf->dev, "wdm_int_callback - %d bytes\n",
			urb->actual_length);
		goto exit;
	}

	switch (dr->bNotificationType) {
	case USB_CDC_NOTIFY_RESPONSE_AVAILABLE:
		dev_dbg(&desc->intf->dev,
			"NOTIFY_RESPONSE_AVAILABLE received: index %d len %d\n",
			le16_to_cpu(dr->wIndex), le16_to_cpu(dr->wLength));
		break;

	case USB_CDC_NOTIFY_NETWORK_CONNECTION:

		dev_dbg(&desc->intf->dev,
			"NOTIFY_NETWORK_CONNECTION %s network\n",
			dr->wValue ? "connected to" : "disconnected from");
		goto exit;
	case USB_CDC_NOTIFY_SPEED_CHANGE:
		dev_dbg(&desc->intf->dev, "SPEED_CHANGE received (len %u)\n",
			urb->actual_length);
		goto exit;
	default:
		clear_bit(WDM_POLL_RUNNING, &desc->flags);
		dev_err(&desc->intf->dev,
			"unknown notification %d received: index %d len %d\n",
			dr->bNotificationType,
			le16_to_cpu(dr->wIndex),
			le16_to_cpu(dr->wLength));
		goto exit;
	}

	spin_lock(&desc->iuspin);
	responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
	if (!desc->resp_count++ && !responding
		&& !test_bit(WDM_DISCONNECTING, &desc->flags)
		&& !test_bit(WDM_SUSPENDING, &desc->flags)) {
		rv = usb_submit_urb(desc->response, GFP_ATOMIC);
		dev_dbg(&desc->intf->dev, "submit response URB %d\n", rv);
	}
	spin_unlock(&desc->iuspin);
	if (rv < 0) {
		clear_bit(WDM_RESPONDING, &desc->flags);
		if (rv == -EPERM)
			return;
		if (rv == -ENOMEM) {
sw:
			rv = schedule_work(&desc->rxwork);
			if (rv)
				dev_err(&desc->intf->dev,
					"Cannot schedule work\n");
		}
	}
exit:
	rv = usb_submit_urb(urb, GFP_ATOMIC);
	if (rv)
		dev_err(&desc->intf->dev,
			"%s - usb_submit_urb failed with result %d\n",
			__func__, rv);

}

static void kill_urbs(struct wdm_device *desc)
{
	/* the order here is essential */
	usb_kill_urb(desc->command);
	usb_kill_urb(desc->validity);
	usb_kill_urb(desc->response);
}

static void free_urbs(struct wdm_device *desc)
{
	usb_free_urb(desc->validity);
	usb_free_urb(desc->response);
	usb_free_urb(desc->command);
}

static void cleanup(struct wdm_device *desc)
{
	kfree(desc->sbuf);
	kfree(desc->inbuf);
	kfree(desc->orq);
	kfree(desc->irq);
	kfree(desc->ubuf);
	free_urbs(desc);
	kfree(desc);
}

static ssize_t wdm_write
(struct file *file, const char __user *buffer, size_t count, loff_t *ppos)
{
	u8 *buf;
	int rv = -EMSGSIZE, r, we;
	struct wdm_device *desc = file->private_data;
	struct usb_ctrlrequest *req;

	if (count > desc->wMaxCommand)
		count = desc->wMaxCommand;

	spin_lock_irq(&desc->iuspin);
	we = desc->werr;
	desc->werr = 0;
	spin_unlock_irq(&desc->iuspin);
	if (we < 0)
		return usb_translate_errors(we);

	buf = memdup_user(buffer, count);
	if (IS_ERR(buf))
		return PTR_ERR(buf);

	/* concurrent writes and disconnect */
	r = mutex_lock_interruptible(&desc->wlock);
	rv = -ERESTARTSYS;
	if (r)
		goto out_free_mem;

	if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
		rv = -ENODEV;
		goto out_free_mem_lock;
	}

	r = usb_autopm_get_interface(desc->intf);
	if (r < 0) {
		rv = usb_translate_errors(r);
		goto out_free_mem_lock;
	}

	if (!(file->f_flags & O_NONBLOCK))
		r = wait_event_interruptible(desc->wait, !test_bit(WDM_IN_USE,
								&desc->flags));
	else
		if (test_bit(WDM_IN_USE, &desc->flags))
			r = -EAGAIN;

	if (test_bit(WDM_RESETTING, &desc->flags))
		r = -EIO;

	if (r < 0) {
		rv = r;
		goto out_free_mem_pm;
	}

	req = desc->orq;
	usb_fill_control_urb(
		desc->command,
		interface_to_usbdev(desc->intf),
		/* using common endpoint 0 */
		usb_sndctrlpipe(interface_to_usbdev(desc->intf), 0),
		(unsigned char *)req,
		buf,
		count,
		wdm_out_callback,
		desc
	);

	req->bRequestType = (USB_DIR_OUT | USB_TYPE_CLASS |
			     USB_RECIP_INTERFACE);
	req->bRequest = USB_CDC_SEND_ENCAPSULATED_COMMAND;
	req->wValue = 0;
	req->wIndex = desc->inum; /* already converted */
	req->wLength = cpu_to_le16(count);
	set_bit(WDM_IN_USE, &desc->flags);
	desc->outbuf = buf;

	rv = usb_submit_urb(desc->command, GFP_KERNEL);
	if (rv < 0) {
		desc->outbuf = NULL;
		clear_bit(WDM_IN_USE, &desc->flags);
		dev_err(&desc->intf->dev, "Tx URB error: %d\n", rv);
		rv = usb_translate_errors(rv);
		goto out_free_mem_pm;
	} else {
		dev_dbg(&desc->intf->dev, "Tx URB has been submitted index=%d\n",
			le16_to_cpu(req->wIndex));
	}

	usb_autopm_put_interface(desc->intf);
	mutex_unlock(&desc->wlock);
	return count;

out_free_mem_pm:
	usb_autopm_put_interface(desc->intf);
out_free_mem_lock:
	mutex_unlock(&desc->wlock);
out_free_mem:
	kfree(buf);
	return rv;
}

/*
 * Submit the read urb if resp_count is non-zero.
 *
 * Called with desc->iuspin locked
 */
static int service_outstanding_interrupt(struct wdm_device *desc)
{
	int rv = 0;

	/* submit read urb only if the device is waiting for it */
	if (!desc->resp_count || !--desc->resp_count)
		goto out;

	set_bit(WDM_RESPONDING, &desc->flags);
	spin_unlock_irq(&desc->iuspin);
	rv = usb_submit_urb(desc->response, GFP_KERNEL);
	spin_lock_irq(&desc->iuspin);
	if (rv) {
		dev_err(&desc->intf->dev,
			"usb_submit_urb failed with result %d\n", rv);

		/* make sure the next notification trigger a submit */
		clear_bit(WDM_RESPONDING, &desc->flags);
		desc->resp_count = 0;
	}
out:
	return rv;
}

static ssize_t wdm_read
(struct file *file, char __user *buffer, size_t count, loff_t *ppos)
{
	int rv, cntr;
	int i = 0;
	struct wdm_device *desc = file->private_data;


	rv = mutex_lock_interruptible(&desc->rlock); /*concurrent reads */
	if (rv < 0)
		return -ERESTARTSYS;

	cntr = READ_ONCE(desc->length);
	if (cntr == 0) {
		desc->read = 0;
retry:
		if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
			rv = -ENODEV;
			goto err;
		}
		if (test_bit(WDM_OVERFLOW, &desc->flags)) {
			clear_bit(WDM_OVERFLOW, &desc->flags);
			rv = -ENOBUFS;
			goto err;
		}
		i++;
		if (file->f_flags & O_NONBLOCK) {
			if (!test_bit(WDM_READ, &desc->flags)) {
				rv = -EAGAIN;
				goto err;
			}
			rv = 0;
		} else {
			rv = wait_event_interruptible(desc->wait,
				test_bit(WDM_READ, &desc->flags));
		}

		/* may have happened while we slept */
		if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
			rv = -ENODEV;
			goto err;
		}
		if (test_bit(WDM_RESETTING, &desc->flags)) {
			rv = -EIO;
			goto err;
		}
		usb_mark_last_busy(interface_to_usbdev(desc->intf));
		if (rv < 0) {
			rv = -ERESTARTSYS;
			goto err;
		}

		spin_lock_irq(&desc->iuspin);

		if (desc->rerr) { /* read completed, error happened */
			rv = usb_translate_errors(desc->rerr);
			desc->rerr = 0;
			spin_unlock_irq(&desc->iuspin);
			goto err;
		}
		/*
		 * recheck whether we've lost the race
		 * against the completion handler
		 */
		if (!test_bit(WDM_READ, &desc->flags)) { /* lost race */
			spin_unlock_irq(&desc->iuspin);
			goto retry;
		}

		if (!desc->reslength) { /* zero length read */
			dev_dbg(&desc->intf->dev, "zero length - clearing WDM_READ\n");
			clear_bit(WDM_READ, &desc->flags);
			rv = service_outstanding_interrupt(desc);
			spin_unlock_irq(&desc->iuspin);
			if (rv < 0)
				goto err;
			goto retry;
		}
		cntr = desc->length;
		spin_unlock_irq(&desc->iuspin);
	}

	if (cntr > count)
		cntr = count;
	rv = copy_to_user(buffer, desc->ubuf, cntr);
	if (rv > 0) {
		rv = -EFAULT;
		goto err;
	}

	spin_lock_irq(&desc->iuspin);

	for (i = 0; i < desc->length - cntr; i++)
		desc->ubuf[i] = desc->ubuf[i + cntr];

	desc->length -= cntr;
	/* in case we had outstanding data */
	if (!desc->length) {
		clear_bit(WDM_READ, &desc->flags);
		service_outstanding_interrupt(desc);
	}
	spin_unlock_irq(&desc->iuspin);
	rv = cntr;

err:
	mutex_unlock(&desc->rlock);
	return rv;
}

static int wdm_flush(struct file *file, fl_owner_t id)
{
	struct wdm_device *desc = file->private_data;

	wait_event(desc->wait, !test_bit(WDM_IN_USE, &desc->flags));

	/* cannot dereference desc->intf if WDM_DISCONNECTING */
	if (desc->werr < 0 && !test_bit(WDM_DISCONNECTING, &desc->flags))
		dev_err(&desc->intf->dev, "Error in flush path: %d\n",
			desc->werr);

	return usb_translate_errors(desc->werr);
}

static __poll_t wdm_poll(struct file *file, struct poll_table_struct *wait)
{
	struct wdm_device *desc = file->private_data;
	unsigned long flags;
	__poll_t mask = 0;

	spin_lock_irqsave(&desc->iuspin, flags);
	if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
		mask = EPOLLHUP | EPOLLERR;
		spin_unlock_irqrestore(&desc->iuspin, flags);
		goto desc_out;
	}
	if (test_bit(WDM_READ, &desc->flags))
		mask = EPOLLIN | EPOLLRDNORM;
	if (desc->rerr || desc->werr)
		mask |= EPOLLERR;
	if (!test_bit(WDM_IN_USE, &desc->flags))
		mask |= EPOLLOUT | EPOLLWRNORM;
	spin_unlock_irqrestore(&desc->iuspin, flags);

	poll_wait(file, &desc->wait, wait);

desc_out:
	return mask;
}

static int wdm_open(struct inode *inode, struct file *file)
{
	int minor = iminor(inode);
	int rv = -ENODEV;
	struct usb_interface *intf;
	struct wdm_device *desc;

	mutex_lock(&wdm_mutex);
	desc = wdm_find_device_by_minor(minor);
	if (!desc)
		goto out;

	intf = desc->intf;
	if (test_bit(WDM_DISCONNECTING, &desc->flags))
		goto out;
	file->private_data = desc;

	rv = usb_autopm_get_interface(desc->intf);
	if (rv < 0) {
		dev_err(&desc->intf->dev, "Error autopm - %d\n", rv);
		goto out;
	}

	/* using write lock to protect desc->count */
	mutex_lock(&desc->wlock);
	if (!desc->count++) {
		desc->werr = 0;
		desc->rerr = 0;
		rv = usb_submit_urb(desc->validity, GFP_KERNEL);
		if (rv < 0) {
			desc->count--;
			dev_err(&desc->intf->dev,
				"Error submitting int urb - %d\n", rv);
			rv = usb_translate_errors(rv);
		}
	} else {
		rv = 0;
	}
	mutex_unlock(&desc->wlock);
	if (desc->count == 1)
		desc->manage_power(intf, 1);
	usb_autopm_put_interface(desc->intf);
out:
	mutex_unlock(&wdm_mutex);
	return rv;
}

static int wdm_release(struct inode *inode, struct file *file)
{
	struct wdm_device *desc = file->private_data;

	mutex_lock(&wdm_mutex);

	/* using write lock to protect desc->count */
	mutex_lock(&desc->wlock);
	desc->count--;
	mutex_unlock(&desc->wlock);

	if (!desc->count) {
		if (!test_bit(WDM_DISCONNECTING, &desc->flags)) {
			dev_dbg(&desc->intf->dev, "wdm_release: cleanup\n");
			kill_urbs(desc);
			spin_lock_irq(&desc->iuspin);
			desc->resp_count = 0;
			spin_unlock_irq(&desc->iuspin);
			desc->manage_power(desc->intf, 0);
		} else {
			/* must avoid dev_printk here as desc->intf is invalid */
			pr_debug(KBUILD_MODNAME " %s: device gone - cleaning up\n", __func__);
			cleanup(desc);
		}
	}
	mutex_unlock(&wdm_mutex);
	return 0;
}

static long wdm_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	struct wdm_device *desc = file->private_data;
	int rv = 0;

	switch (cmd) {
	case IOCTL_WDM_MAX_COMMAND:
		if (copy_to_user((void __user *)arg, &desc->wMaxCommand, sizeof(desc->wMaxCommand)))
			rv = -EFAULT;
		break;
	default:
		rv = -ENOTTY;
	}
	return rv;
}

static const struct file_operations wdm_fops = {
	.owner =	THIS_MODULE,
	.read =		wdm_read,
	.write =	wdm_write,
	.open =		wdm_open,
	.flush =	wdm_flush,
	.release =	wdm_release,
	.poll =		wdm_poll,
	.unlocked_ioctl = wdm_ioctl,
	.compat_ioctl = wdm_ioctl,
	.llseek =	noop_llseek,
};

static struct usb_class_driver wdm_class = {
	.name =		"cdc-wdm%d",
	.fops =		&wdm_fops,
	.minor_base =	WDM_MINOR_BASE,
};

/* --- error handling --- */
static void wdm_rxwork(struct work_struct *work)
{
	struct wdm_device *desc = container_of(work, struct wdm_device, rxwork);
	unsigned long flags;
	int rv = 0;
	int responding;

	spin_lock_irqsave(&desc->iuspin, flags);
	if (test_bit(WDM_DISCONNECTING, &desc->flags)) {
		spin_unlock_irqrestore(&desc->iuspin, flags);
	} else {
		responding = test_and_set_bit(WDM_RESPONDING, &desc->flags);
		spin_unlock_irqrestore(&desc->iuspin, flags);
		if (!responding)
			rv = usb_submit_urb(desc->response, GFP_KERNEL);
		if (rv < 0 && rv != -EPERM) {
			spin_lock_irqsave(&desc->iuspin, flags);
			clear_bit(WDM_RESPONDING, &desc->flags);
			if (!test_bit(WDM_DISCONNECTING, &desc->flags))
				schedule_work(&desc->rxwork);
			spin_unlock_irqrestore(&desc->iuspin, flags);
		}
	}
}

/* --- hotplug --- */

static int wdm_create(struct usb_interface *intf, struct usb_endpoint_descriptor *ep,
		u16 bufsize, int (*manage_power)(struct usb_interface *, int))
{
	int rv = -ENOMEM;
	struct wdm_device *desc;

	desc = kzalloc(sizeof(struct wdm_device), GFP_KERNEL);
	if (!desc)
		goto out;
	INIT_LIST_HEAD(&desc->device_list);
	mutex_init(&desc->rlock);
	mutex_init(&desc->wlock);
	spin_lock_init(&desc->iuspin);
	init_waitqueue_head(&desc->wait);
	desc->wMaxCommand = bufsize;
	/* this will be expanded and needed in hardware endianness */
	desc->inum = cpu_to_le16((u16)intf->cur_altsetting->desc.bInterfaceNumber);
	desc->intf = intf;
	INIT_WORK(&desc->rxwork, wdm_rxwork);

	rv = -EINVAL;
	if (!usb_endpoint_is_int_in(ep))
		goto err;

	desc->wMaxPacketSize = usb_endpoint_maxp(ep);

	desc->orq = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL);
	if (!desc->orq)
		goto err;
	desc->irq = kmalloc(sizeof(struct usb_ctrlrequest), GFP_KERNEL);
	if (!desc->irq)
		goto err;

	desc->validity = usb_alloc_urb(0, GFP_KERNEL);
	if (!desc->validity)
		goto err;

	desc->response = usb_alloc_urb(0, GFP_KERNEL);
	if (!desc->response)
		goto err;

	desc->command = usb_alloc_urb(0, GFP_KERNEL);
	if (!desc->command)
		goto err;

	desc->ubuf = kmalloc(desc->wMaxCommand, GFP_KERNEL);
	if (!desc->ubuf)
		goto err;

	desc->sbuf = kmalloc(desc->wMaxPacketSize, GFP_KERNEL);
	if (!desc->sbuf)
		goto err;

	desc->inbuf = kmalloc(desc->wMaxCommand, GFP_KERNEL);
	if (!desc->inbuf)
		goto err;

	usb_fill_int_urb(
		desc->validity,
		interface_to_usbdev(intf),
		usb_rcvintpipe(interface_to_usbdev(intf), ep->bEndpointAddress),
		desc->sbuf,
		desc->wMaxPacketSize,
		wdm_int_callback,
		desc,
		ep->bInterval
	);

	desc->irq->bRequestType = (USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_INTERFACE);
	desc->irq->bRequest = USB_CDC_GET_ENCAPSULATED_RESPONSE;
	desc->irq->wValue = 0;
	desc->irq->wIndex = desc->inum; /* already converted */
	desc->irq->wLength = cpu_to_le16(desc->wMaxCommand);

	usb_fill_control_urb(
		desc->response,
		interface_to_usbdev(intf),
		/* using common endpoint 0 */
		usb_rcvctrlpipe(interface_to_usbdev(desc->intf), 0),
		(unsigned char *)desc->irq,
		desc->inbuf,
		desc->wMaxCommand,
		wdm_in_callback,
		desc
	);

	desc->manage_power = manage_power;

	spin_lock(&wdm_device_list_lock);
	list_add(&desc->device_list, &wdm_device_list);
	spin_unlock(&wdm_device_list_lock);

	rv = usb_register_dev(intf, &wdm_class);
	if (rv < 0)
		goto err;
	else
		dev_info(&intf->dev, "%s: USB WDM device\n", dev_name(intf->usb_dev));
out:
	return rv;
err:
	spin_lock(&wdm_device_list_lock);
	list_del(&desc->device_list);
	spin_unlock(&wdm_device_list_lock);
	cleanup(desc);
	return rv;
}

static int wdm_manage_power(struct usb_interface *intf, int on)
{
	/* need autopm_get/put here to ensure the usbcore sees the new value */
	int rv = usb_autopm_get_interface(intf);

	intf->needs_remote_wakeup = on;
	if (!rv)
		usb_autopm_put_interface(intf);
	return 0;
}

static int wdm_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
	int rv = -EINVAL;
	struct usb_host_interface *iface;
	struct usb_endpoint_descriptor *ep;
	struct usb_cdc_parsed_header hdr;
	u8 *buffer = intf->altsetting->extra;
	int buflen = intf->altsetting->extralen;
	u16 maxcom = WDM_DEFAULT_BUFSIZE;

	if (!buffer)
		goto err;

	cdc_parse_cdc_header(&hdr, intf, buffer, buflen);

	if (hdr.usb_cdc_dmm_desc)
		maxcom = le16_to_cpu(hdr.usb_cdc_dmm_desc->wMaxCommand);

	iface = intf->cur_altsetting;
	if (iface->desc.bNumEndpoints != 1)
		goto err;
	ep = &iface->endpoint[0].desc;

	rv = wdm_create(intf, ep, maxcom, &wdm_manage_power);

err:
	return rv;
}

/**
 * usb_cdc_wdm_register - register a WDM subdriver
 * @intf: usb interface the subdriver will associate with
 * @ep: interrupt endpoint to monitor for notifications
 * @bufsize: maximum message size to support for read/write
 *
 * Create WDM usb class character device and associate it with intf
 * without binding, allowing another driver to manage the interface.
 *
 * The subdriver will manage the given interrupt endpoint exclusively
 * and will issue control requests referring to the given intf. It
 * will otherwise avoid interferring, and in particular not do
 * usb_set_intfdata/usb_get_intfdata on intf.
 *
 * The return value is a pointer to the subdriver's struct usb_driver.
 * The registering driver is responsible for calling this subdriver's
 * disconnect, suspend, resume, pre_reset and post_reset methods from
 * its own.
 */
struct usb_driver *usb_cdc_wdm_register(struct usb_interface *intf,
					struct usb_endpoint_descriptor *ep,
					int bufsize,
					int (*manage_power)(struct usb_interface *, int))
{
	int rv = -EINVAL;

	rv = wdm_create(intf, ep, bufsize, manage_power);
	if (rv < 0)
		goto err;

	return &wdm_driver;
err:
	return ERR_PTR(rv);
}
EXPORT_SYMBOL(usb_cdc_wdm_register);

static void wdm_disconnect(struct usb_interface *intf)
{
	struct wdm_device *desc;
	unsigned long flags;

	usb_deregister_dev(intf, &wdm_class);
	desc = wdm_find_device(intf);
	mutex_lock(&wdm_mutex);

	/* the spinlock makes sure no new urbs are generated in the callbacks */
	spin_lock_irqsave(&desc->iuspin, flags);
	set_bit(WDM_DISCONNECTING, &desc->flags);
	set_bit(WDM_READ, &desc->flags);
	/* to terminate pending flushes */
	clear_bit(WDM_IN_USE, &desc->flags);
	spin_unlock_irqrestore(&desc->iuspin, flags);
	wake_up_all(&desc->wait);
	mutex_lock(&desc->rlock);
	mutex_lock(&desc->wlock);
	kill_urbs(desc);
	cancel_work_sync(&desc->rxwork);
	mutex_unlock(&desc->wlock);
	mutex_unlock(&desc->rlock);

	/* the desc->intf pointer used as list key is now invalid */
	spin_lock(&wdm_device_list_lock);
	list_del(&desc->device_list);
	spin_unlock(&wdm_device_list_lock);

	if (!desc->count)
		cleanup(desc);
	else
		dev_dbg(&intf->dev, "%d open files - postponing cleanup\n", desc->count);
	mutex_unlock(&wdm_mutex);
}

#ifdef CONFIG_PM
static int wdm_suspend(struct usb_interface *intf, pm_message_t message)
{
	struct wdm_device *desc = wdm_find_device(intf);
	int rv = 0;

	dev_dbg(&desc->intf->dev, "wdm%d_suspend\n", intf->minor);

	/* if this is an autosuspend the caller does the locking */
	if (!PMSG_IS_AUTO(message)) {
		mutex_lock(&desc->rlock);
		mutex_lock(&desc->wlock);
	}
	spin_lock_irq(&desc->iuspin);

	if (PMSG_IS_AUTO(message) &&
			(test_bit(WDM_IN_USE, &desc->flags)
			|| test_bit(WDM_RESPONDING, &desc->flags))) {
		spin_unlock_irq(&desc->iuspin);
		rv = -EBUSY;
	} else {

		set_bit(WDM_SUSPENDING, &desc->flags);
		spin_unlock_irq(&desc->iuspin);
		/* callback submits work - order is essential */
		kill_urbs(desc);
		cancel_work_sync(&desc->rxwork);
	}
	if (!PMSG_IS_AUTO(message)) {
		mutex_unlock(&desc->wlock);
		mutex_unlock(&desc->rlock);
	}

	return rv;
}
#endif

static int recover_from_urb_loss(struct wdm_device *desc)
{
	int rv = 0;

	if (desc->count) {
		rv = usb_submit_urb(desc->validity, GFP_NOIO);
		if (rv < 0)
			dev_err(&desc->intf->dev,
				"Error resume submitting int urb - %d\n", rv);
	}
	return rv;
}

#ifdef CONFIG_PM
static int wdm_resume(struct usb_interface *intf)
{
	struct wdm_device *desc = wdm_find_device(intf);
	int rv;

	dev_dbg(&desc->intf->dev, "wdm%d_resume\n", intf->minor);

	clear_bit(WDM_SUSPENDING, &desc->flags);
	rv = recover_from_urb_loss(desc);

	return rv;
}
#endif

static int wdm_pre_reset(struct usb_interface *intf)
{
	struct wdm_device *desc = wdm_find_device(intf);

	/*
	 * we notify everybody using poll of
	 * an exceptional situation
	 * must be done before recovery lest a spontaneous
	 * message from the device is lost
	 */
	spin_lock_irq(&desc->iuspin);
	set_bit(WDM_RESETTING, &desc->flags);	/* inform read/write */
	set_bit(WDM_READ, &desc->flags);	/* unblock read */
	clear_bit(WDM_IN_USE, &desc->flags);	/* unblock write */
	desc->rerr = -EINTR;
	spin_unlock_irq(&desc->iuspin);
	wake_up_all(&desc->wait);
	mutex_lock(&desc->rlock);
	mutex_lock(&desc->wlock);
	kill_urbs(desc);
	cancel_work_sync(&desc->rxwork);
	return 0;
}

static int wdm_post_reset(struct usb_interface *intf)
{
	struct wdm_device *desc = wdm_find_device(intf);
	int rv;

	clear_bit(WDM_OVERFLOW, &desc->flags);
	clear_bit(WDM_RESETTING, &desc->flags);
	rv = recover_from_urb_loss(desc);
	mutex_unlock(&desc->wlock);
	mutex_unlock(&desc->rlock);
	return 0;
}

static struct usb_driver wdm_driver = {
	.name =		"cdc_wdm",
	.probe =	wdm_probe,
	.disconnect =	wdm_disconnect,
#ifdef CONFIG_PM
	.suspend =	wdm_suspend,
	.resume =	wdm_resume,
	.reset_resume =	wdm_resume,
#endif
	.pre_reset =	wdm_pre_reset,
	.post_reset =	wdm_post_reset,
	.id_table =	wdm_ids,
	.supports_autosuspend = 1,
	.disable_hub_initiated_lpm = 1,
};

module_usb_driver(wdm_driver);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

Privacy Policy