summaryrefslogtreecommitdiff
path: root/drivers/usb/misc/ldusb.c
blob: 8de32df5978a0756f7b63135e4b67f793259f4b4 (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
/**
 * Generic USB driver for report based interrupt in/out devices
 * like LD Didactic's USB devices. LD Didactic's USB devices are
 * HID devices which do not use HID report definitons (they use
 * raw interrupt in and our reports only for communication).
 *
 * This driver uses a ring buffer for time critical reading of
 * interrupt in reports and provides read and write methods for
 * raw interrupt reports (similar to the Windows HID driver).
 * Devices based on the book USB COMPLETE by Jan Axelson may need
 * such a compatibility to the Windows HID driver.
 *
 * Copyright (C) 2005 Michael Hund <mhund@ld-didactic.de>
 *
 *	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.
 *
 * Derived from Lego USB Tower driver
 * Copyright (C) 2003 David Glance <advidgsf@sourceforge.net>
 *		 2001-2004 Juergen Stuber <starblue@users.sourceforge.net>
 *
 * V0.1  (mh) Initial version
 * V0.11 (mh) Added raw support for HID 1.0 devices (no interrupt out endpoint)
 * V0.12 (mh) Added kmalloc check for string buffer
 * V0.13 (mh) Added support for LD X-Ray and Machine Test System
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/smp_lock.h>

#include <asm/uaccess.h>
#include <linux/input.h>
#include <linux/usb.h>
#include <linux/poll.h>

/* Define these values to match your devices */
#define USB_VENDOR_ID_LD		0x0f11	/* USB Vendor ID of LD Didactic GmbH */
#define USB_DEVICE_ID_LD_CASSY		0x1000	/* USB Product ID of CASSY-S */
#define USB_DEVICE_ID_LD_POCKETCASSY	0x1010	/* USB Product ID of Pocket-CASSY */
#define USB_DEVICE_ID_LD_MOBILECASSY	0x1020	/* USB Product ID of Mobile-CASSY */
#define USB_DEVICE_ID_LD_JWM		0x1080	/* USB Product ID of Joule and Wattmeter */
#define USB_DEVICE_ID_LD_DMMP		0x1081	/* USB Product ID of Digital Multimeter P (reserved) */
#define USB_DEVICE_ID_LD_UMIP		0x1090	/* USB Product ID of UMI P */
#define USB_DEVICE_ID_LD_XRAY1		0x1100	/* USB Product ID of X-Ray Apparatus */
#define USB_DEVICE_ID_LD_XRAY2		0x1101	/* USB Product ID of X-Ray Apparatus */
#define USB_DEVICE_ID_LD_VIDEOCOM	0x1200	/* USB Product ID of VideoCom */
#define USB_DEVICE_ID_LD_COM3LAB	0x2000	/* USB Product ID of COM3LAB */
#define USB_DEVICE_ID_LD_TELEPORT	0x2010	/* USB Product ID of Terminal Adapter */
#define USB_DEVICE_ID_LD_NETWORKANALYSER 0x2020	/* USB Product ID of Network Analyser */
#define USB_DEVICE_ID_LD_POWERCONTROL	0x2030	/* USB Product ID of Converter Control Unit */
#define USB_DEVICE_ID_LD_MACHINETEST	0x2040	/* USB Product ID of Machine Test System */

#define USB_VENDOR_ID_VERNIER		0x08f7
#define USB_DEVICE_ID_VERNIER_GOTEMP	0x0002
#define USB_DEVICE_ID_VERNIER_SKIP	0x0003
#define USB_DEVICE_ID_VERNIER_CYCLOPS	0x0004
#define USB_DEVICE_ID_VERNIER_LCSPEC	0x0006

#ifdef CONFIG_USB_DYNAMIC_MINORS
#define USB_LD_MINOR_BASE	0
#else
#define USB_LD_MINOR_BASE	176
#endif

/* table of devices that work with this driver */
static const struct usb_device_id ld_usb_table[] = {
	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_CASSY) },
	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_POCKETCASSY) },
	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MOBILECASSY) },
	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_JWM) },
	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_DMMP) },
	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_UMIP) },
	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_XRAY1) },
	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_XRAY2) },
	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_VIDEOCOM) },
	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_COM3LAB) },
	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_TELEPORT) },
	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_NETWORKANALYSER) },
	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_POWERCONTROL) },
	{ USB_DEVICE(USB_VENDOR_ID_LD, USB_DEVICE_ID_LD_MACHINETEST) },
	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_GOTEMP) },
	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_SKIP) },
	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_CYCLOPS) },
	{ USB_DEVICE(USB_VENDOR_ID_VERNIER, USB_DEVICE_ID_VERNIER_LCSPEC) },
	{ }					/* Terminating entry */
};
MODULE_DEVICE_TABLE(usb, ld_usb_table);
MODULE_VERSION("V0.13");
MODULE_AUTHOR("Michael Hund <mhund@ld-didactic.de>");
MODULE_DESCRIPTION("LD USB Driver");
MODULE_LICENSE("GPL");
MODULE_SUPPORTED_DEVICE("LD USB Devices");

#ifdef CONFIG_USB_DEBUG
	static int debug = 1;
#else
	static int debug = 0;
#endif

/* Use our own dbg macro */
#define dbg_info(dev, format, arg...) do { if (debug) dev_info(dev , format , ## arg); } while (0)

/* Module parameters */
module_param(debug, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Debug enabled or not");

/* All interrupt in transfers are collected in a ring buffer to
 * avoid racing conditions and get better performance of the driver.
 */
static int ring_buffer_size = 128;
module_param(ring_buffer_size, int, 0);
MODULE_PARM_DESC(ring_buffer_size, "Read ring buffer size in reports");

/* The write_buffer can contain more than one interrupt out transfer.
 */
static int write_buffer_size = 10;
module_param(write_buffer_size, int, 0);
MODULE_PARM_DESC(write_buffer_size, "Write buffer size in reports");

/* As of kernel version 2.6.4 ehci-hcd uses an
 * "only one interrupt transfer per frame" shortcut
 * to simplify the scheduling of periodic transfers.
 * This conflicts with our standard 1ms intervals for in and out URBs.
 * We use default intervals of 2ms for in and 2ms for out transfers,
 * which should be fast enough.
 * Increase the interval to allow more devices that do interrupt transfers,
 * or set to 1 to use the standard interval from the endpoint descriptors.
 */
static int min_interrupt_in_interval = 2;
module_param(min_interrupt_in_interval, int, 0);
MODULE_PARM_DESC(min_interrupt_in_interval, "Minimum interrupt in interval in ms");

static int min_interrupt_out_interval = 2;
module_param(min_interrupt_out_interval, int, 0);
MODULE_PARM_DESC(min_interrupt_out_interval, "Minimum interrupt out interval in ms");

/* Structure to hold all of our device specific stuff */
struct ld_usb {
	struct mutex		mutex;		/* locks this structure */
	struct usb_interface*	intf;		/* save off the usb interface pointer */

	int			open_count;	/* number of times this port has been opened */

	char*			ring_buffer;
	unsigned int		ring_head;
	unsigned int		ring_tail;

	wait_queue_head_t	read_wait;
	wait_queue_head_t	write_wait;

	char*			interrupt_in_buffer;
	struct usb_endpoint_descriptor* interrupt_in_endpoint;
	struct urb*		interrupt_in_urb;
	int			interrupt_in_interval;
	size_t			interrupt_in_endpoint_size;
	int			interrupt_in_running;
	int			interrupt_in_done;
	int			buffer_overflow;
	spinlock_t		rbsl;

	char*			interrupt_out_buffer;
	struct usb_endpoint_descriptor* interrupt_out_endpoint;
	struct urb*		interrupt_out_urb;
	int			interrupt_out_interval;
	size_t			interrupt_out_endpoint_size;
	int			interrupt_out_busy;
};

static struct usb_driver ld_usb_driver;

/**
 *	ld_usb_abort_transfers
 *      aborts transfers and frees associated data structures
 */
static void ld_usb_abort_transfers(struct ld_usb *dev)
{
	/* shutdown transfer */
	if (dev->interrupt_in_running) {
		dev->interrupt_in_running = 0;
		if (dev->intf)
			usb_kill_urb(dev->interrupt_in_urb);
	}
	if (dev->interrupt_out_busy)
		if (dev->intf)
			usb_kill_urb(dev->interrupt_out_urb);
}

/**
 *	ld_usb_delete
 */
static void ld_usb_delete(struct ld_usb *dev)
{
	ld_usb_abort_transfers(dev);

	/* free data structures */
	usb_free_urb(dev->interrupt_in_urb);
	usb_free_urb(dev->interrupt_out_urb);
	kfree(dev->ring_buffer);
	kfree(dev->interrupt_in_buffer);
	kfree(dev->interrupt_out_buffer);
	kfree(dev);
}

/**
 *	ld_usb_interrupt_in_callback
 */
static void ld_usb_interrupt_in_callback(struct urb *urb)
{
	struct ld_usb *dev = urb->context;
	size_t *actual_buffer;
	unsigned int next_ring_head;
	int status = urb->status;
	int retval;

	if (status) {
		if (status == -ENOENT ||
		    status == -ECONNRESET ||
		    status == -ESHUTDOWN) {
			goto exit;
		} else {
			dbg_info(&dev->intf->dev, "%s: nonzero status received: %d\n",
				 __func__, status);
			spin_lock(&dev->rbsl);
			goto resubmit; /* maybe we can recover */
		}
	}

	spin_lock(&dev->rbsl);
	if (urb->actual_length > 0) {
		next_ring_head = (dev->ring_head+1) % ring_buffer_size;
		if (next_ring_head != dev->ring_tail) {
			actual_buffer = (size_t*)(dev->ring_buffer + dev->ring_head*(sizeof(size_t)+dev->interrupt_in_endpoint_size));
			/* actual_buffer gets urb->actual_length + interrupt_in_buffer */
			*actual_buffer = urb->actual_length;
			memcpy(actual_buffer+1, dev->interrupt_in_buffer, urb->actual_length);
			dev->ring_head = next_ring_head;
			dbg_info(&dev->intf->dev, "%s: received %d bytes\n",
				 __func__, urb->actual_length);
		} else {
			dev_warn(&dev->intf->dev,
				 "Ring buffer overflow, %d bytes dropped\n",
				 urb->actual_length);
			dev->buffer_overflow = 1;
		}
	}

resubmit:
	/* resubmit if we're still running */
	if (dev->interrupt_in_running && !dev->buffer_overflow && dev->intf) {
		retval = usb_submit_urb(dev->interrupt_in_urb, GFP_ATOMIC);
		if (retval) {
			dev_err(&dev->intf->dev,
				"usb_submit_urb failed (%d)\n", retval);
			dev->buffer_overflow = 1;
		}
	}
	spin_unlock(&dev->rbsl);
exit:
	dev->interrupt_in_done = 1;
	wake_up_interruptible(&dev->read_wait);
}

/**
 *	ld_usb_interrupt_out_callback
 */
static void ld_usb_interrupt_out_callback(struct urb *urb)
{
	struct ld_usb *dev = urb->context;
	int status = urb->status;

	/* sync/async unlink faults aren't errors */
	if (status && !(status == -ENOENT ||
			status == -ECONNRESET ||
			status == -ESHUTDOWN))
		dbg_info(&dev->intf->dev,
			 "%s - nonzero write interrupt status received: %d\n",
			 __func__, status);

	dev->interrupt_out_busy = 0;
	wake_up_interruptible(&dev->write_wait);
}

/**
 *	ld_usb_open
 */
static int ld_usb_open(struct inode *inode, struct file *file)
{
	struct ld_usb *dev;
	int subminor;
	int retval;
	struct usb_interface *interface;

	lock_kernel();
	nonseekable_open(inode, file);
	subminor = iminor(inode);

	interface = usb_find_interface(&ld_usb_driver, subminor);

	if (!interface) {
		unlock_kernel();
		err("%s - error, can't find device for minor %d\n",
		     __func__, subminor);
		return -ENODEV;
	}

	dev = usb_get_intfdata(interface);

	if (!dev) {
		unlock_kernel();
		return -ENODEV;
	}

	/* lock this device */
	if (mutex_lock_interruptible(&dev->mutex)) {
		unlock_kernel();
		return -ERESTARTSYS;
	}

	/* allow opening only once */
	if (dev->open_count) {
		retval = -EBUSY;
		goto unlock_exit;
	}
	dev->open_count = 1;

	/* initialize in direction */
	dev->ring_head = 0;
	dev->ring_tail = 0;
	dev->buffer_overflow = 0;
	usb_fill_int_urb(dev->interrupt_in_urb,
			 interface_to_usbdev(interface),
			 usb_rcvintpipe(interface_to_usbdev(interface),
					dev->interrupt_in_endpoint->bEndpointAddress),
			 dev->interrupt_in_buffer,
			 dev->interrupt_in_endpoint_size,
			 ld_usb_interrupt_in_callback,
			 dev,
			 dev->interrupt_in_interval);

	dev->interrupt_in_running = 1;
	dev->interrupt_in_done = 0;

	retval = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
	if (retval) {
		dev_err(&interface->dev, "Couldn't submit interrupt_in_urb %d\n", retval);
		dev->interrupt_in_running = 0;
		dev->open_count = 0;
		goto unlock_exit;
	}

	/* save device in the file's private structure */
	file->private_data = dev;

unlock_exit:
	mutex_unlock(&dev->mutex);
	unlock_kernel();

	return retval;
}

/**
 *	ld_usb_release
 */
static int ld_usb_release(struct inode *inode, struct file *file)
{
	struct ld_usb *dev;
	int retval = 0;

	dev = file->private_data;

	if (dev == NULL) {
		retval = -ENODEV;
		goto exit;
	}

	if (mutex_lock_interruptible(&dev->mutex)) {
		retval = -ERESTARTSYS;
		goto exit;
	}

	if (dev->open_count != 1) {
		retval = -ENODEV;
		goto unlock_exit;
	}
	if (dev->intf == NULL) {
		/* the device was unplugged before the file was released */
		mutex_unlock(&dev->mutex);
		/* unlock here as ld_usb_delete frees dev */
		ld_usb_delete(dev);
		goto exit;
	}

	/* wait until write transfer is finished */
	if (dev->interrupt_out_busy)
		wait_event_interruptible_timeout(dev->write_wait, !dev->interrupt_out_busy, 2 * HZ);
	ld_usb_abort_transfers(dev);
	dev->open_count = 0;

unlock_exit:
	mutex_unlock(&dev->mutex);

exit:
	return retval;
}

/**
 *	ld_usb_poll
 */
static unsigned int ld_usb_poll(struct file *file, poll_table *wait)
{
	struct ld_usb *dev;
	unsigned int mask = 0;

	dev = file->private_data;

	if (!dev->intf)
		return POLLERR | POLLHUP;

	poll_wait(file, &dev->read_wait, wait);
	poll_wait(file, &dev->write_wait, wait);

	if (dev->ring_head != dev->ring_tail)
		mask |= POLLIN | POLLRDNORM;
	if (!dev->interrupt_out_busy)
		mask |= POLLOUT | POLLWRNORM;

	return mask;
}

/**
 *	ld_usb_read
 */
static ssize_t ld_usb_read(struct file *file, char __user *buffer, size_t count,
			   loff_t *ppos)
{
	struct ld_usb *dev;
	size_t *actual_buffer;
	size_t bytes_to_read;
	int retval = 0;
	int rv;

	dev = file->private_data;

	/* verify that we actually have some data to read */
	if (count == 0)
		goto exit;

	/* lock this object */
	if (mutex_lock_interruptible(&dev->mutex)) {
		retval = -ERESTARTSYS;
		goto exit;
	}

	/* verify that the device wasn't unplugged */
	if (dev->intf == NULL) {
		retval = -ENODEV;
		err("No device or device unplugged %d\n", retval);
		goto unlock_exit;
	}

	/* wait for data */
	spin_lock_irq(&dev->rbsl);
	if (dev->ring_head == dev->ring_tail) {
		dev->interrupt_in_done = 0;
		spin_unlock_irq(&dev->rbsl);
		if (file->f_flags & O_NONBLOCK) {
			retval = -EAGAIN;
			goto unlock_exit;
		}
		retval = wait_event_interruptible(dev->read_wait, dev->interrupt_in_done);
		if (retval < 0)
			goto unlock_exit;
	} else {
		spin_unlock_irq(&dev->rbsl);
	}

	/* actual_buffer contains actual_length + interrupt_in_buffer */
	actual_buffer = (size_t*)(dev->ring_buffer + dev->ring_tail*(sizeof(size_t)+dev->interrupt_in_endpoint_size));
	bytes_to_read = min(count, *actual_buffer);
	if (bytes_to_read < *actual_buffer)
		dev_warn(&dev->intf->dev, "Read buffer overflow, %zd bytes dropped\n",
			 *actual_buffer-bytes_to_read);

	/* copy one interrupt_in_buffer from ring_buffer into userspace */
	if (copy_to_user(buffer, actual_buffer+1, bytes_to_read)) {
		retval = -EFAULT;
		goto unlock_exit;
	}
	dev->ring_tail = (dev->ring_tail+1) % ring_buffer_size;

	retval = bytes_to_read;

	spin_lock_irq(&dev->rbsl);
	if (dev->buffer_overflow) {
		dev->buffer_overflow = 0;
		spin_unlock_irq(&dev->rbsl);
		rv = usb_submit_urb(dev->interrupt_in_urb, GFP_KERNEL);
		if (rv < 0)
			dev->buffer_overflow = 1;
	} else {
		spin_unlock_irq(&dev->rbsl);
	}

unlock_exit:
	/* unlock the device */
	mutex_unlock(&dev->mutex);

exit:
	return retval;
}

/**
 *	ld_usb_write
 */
static ssize_t ld_usb_write(struct file *file, const char __user *buffer,
			    size_t count, loff_t *ppos)
{
	struct ld_usb *dev;
	size_t bytes_to_write;
	int retval = 0;

	dev = file->private_data;

	/* verify that we actually have some data to write */
	if (count == 0)
		goto exit;

	/* lock this object */
	if (mutex_lock_interruptible(&dev->mutex)) {
		retval = -ERESTARTSYS;
		goto exit;
	}

	/* verify that the device wasn't unplugged */
	if (dev->intf == NULL) {
		retval = -ENODEV;
		err("No device or device unplugged %d\n", retval);
		goto unlock_exit;
	}

	/* wait until previous transfer is finished */
	if (dev->interrupt_out_busy) {
		if (file->f_flags & O_NONBLOCK) {
			retval = -EAGAIN;
			goto unlock_exit;
		}
		retval = wait_event_interruptible(dev->write_wait, !dev->interrupt_out_busy);
		if (retval < 0) {
			goto unlock_exit;
		}
	}

	/* write the data into interrupt_out_buffer from userspace */
	bytes_to_write = min(count, write_buffer_size*dev->interrupt_out_endpoint_size);
	if (bytes_to_write < count)
		dev_warn(&dev->intf->dev, "Write buffer overflow, %zd bytes dropped\n",count-bytes_to_write);
	dbg_info(&dev->intf->dev, "%s: count = %zd, bytes_to_write = %zd\n", __func__, count, bytes_to_write);

	if (copy_from_user(dev->interrupt_out_buffer, buffer, bytes_to_write)) {
		retval = -EFAULT;
		goto unlock_exit;
	}

	if (dev->interrupt_out_endpoint == NULL) {
		/* try HID_REQ_SET_REPORT=9 on control_endpoint instead of interrupt_out_endpoint */
		retval = usb_control_msg(interface_to_usbdev(dev->intf),
					 usb_sndctrlpipe(interface_to_usbdev(dev->intf), 0),
					 9,
					 USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_OUT,
					 1 << 8, 0,
					 dev->interrupt_out_buffer,
					 bytes_to_write,
					 USB_CTRL_SET_TIMEOUT * HZ);
		if (retval < 0)
			err("Couldn't submit HID_REQ_SET_REPORT %d\n", retval);
		goto unlock_exit;
	}

	/* send off the urb */
	usb_fill_int_urb(dev->interrupt_out_urb,
			 interface_to_usbdev(dev->intf),
			 usb_sndintpipe(interface_to_usbdev(dev->intf),
					dev->interrupt_out_endpoint->bEndpointAddress),
			 dev->interrupt_out_buffer,
			 bytes_to_write,
			 ld_usb_interrupt_out_callback,
			 dev,
			 dev->interrupt_out_interval);

	dev->interrupt_out_busy = 1;
	wmb();

	retval = usb_submit_urb(dev->interrupt_out_urb, GFP_KERNEL);
	if (retval) {
		dev->interrupt_out_busy = 0;
		err("Couldn't submit interrupt_out_urb %d\n", retval);
		goto unlock_exit;
	}
	retval = bytes_to_write;

unlock_exit:
	/* unlock the device */
	mutex_unlock(&dev->mutex);

exit:
	return retval;
}

/* file operations needed when we register this driver */
static const struct file_operations ld_usb_fops = {
	.owner =	THIS_MODULE,
	.read  =	ld_usb_read,
	.write =	ld_usb_write,
	.open =		ld_usb_open,
	.release =	ld_usb_release,
	.poll =		ld_usb_poll,
};

/*
 * usb class driver info in order to get a minor number from the usb core,
 * and to have the device registered with the driver core
 */
static struct usb_class_driver ld_usb_class = {
	.name =		"ldusb%d",
	.fops =		&ld_usb_fops,
	.minor_base =	USB_LD_MINOR_BASE,
};

/**
 *	ld_usb_probe
 *
 *	Called by the usb core when a new device is connected that it thinks
 *	this driver might be interested in.
 */
static int ld_usb_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
	struct usb_device *udev = interface_to_usbdev(intf);
	struct ld_usb *dev = NULL;
	struct usb_host_interface *iface_desc;
	struct usb_endpoint_descriptor *endpoint;
	char *buffer;
	int i;
	int retval = -ENOMEM;

	/* allocate memory for our device state and intialize it */

	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (dev == NULL) {
		dev_err(&intf->dev, "Out of memory\n");
		goto exit;
	}
	mutex_init(&dev->mutex);
	spin_lock_init(&dev->rbsl);
	dev->intf = intf;
	init_waitqueue_head(&dev->read_wait);
	init_waitqueue_head(&dev->write_wait);

	/* workaround for early firmware versions on fast computers */
	if ((le16_to_cpu(udev->descriptor.idVendor) == USB_VENDOR_ID_LD) &&
	    ((le16_to_cpu(udev->descriptor.idProduct) == USB_DEVICE_ID_LD_CASSY) ||
	     (le16_to_cpu(udev->descriptor.idProduct) == USB_DEVICE_ID_LD_COM3LAB)) &&
	    (le16_to_cpu(udev->descriptor.bcdDevice) <= 0x103)) {
		buffer = kmalloc(256, GFP_KERNEL);
		if (buffer == NULL) {
			dev_err(&intf->dev, "Couldn't allocate string buffer\n");
			goto error;
		}
		/* usb_string makes SETUP+STALL to leave always ControlReadLoop */
		usb_string(udev, 255, buffer, 256);
		kfree(buffer);
	}

	iface_desc = intf->cur_altsetting;

	/* set up the endpoint information */
	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
		endpoint = &iface_desc->endpoint[i].desc;

		if (usb_endpoint_is_int_in(endpoint))
			dev->interrupt_in_endpoint = endpoint;

		if (usb_endpoint_is_int_out(endpoint))
			dev->interrupt_out_endpoint = endpoint;
	}
	if (dev->interrupt_in_endpoint == NULL) {
		dev_err(&intf->dev, "Interrupt in endpoint not found\n");
		goto error;
	}
	if (dev->interrupt_out_endpoint == NULL)
		dev_warn(&intf->dev, "Interrupt out endpoint not found (using control endpoint instead)\n");

	dev->interrupt_in_endpoint_size = le16_to_cpu(dev->interrupt_in_endpoint->wMaxPacketSize);
	dev->ring_buffer = kmalloc(ring_buffer_size*(sizeof(size_t)+dev->interrupt_in_endpoint_size), GFP_KERNEL);
	if (!dev->ring_buffer) {
		dev_err(&intf->dev, "Couldn't allocate ring_buffer\n");
		goto error;
	}
	dev->interrupt_in_buffer = kmalloc(dev->interrupt_in_endpoint_size, GFP_KERNEL);
	if (!dev->interrupt_in_buffer) {
		dev_err(&intf->dev, "Couldn't allocate interrupt_in_buffer\n");
		goto error;
	}
	dev->interrupt_in_urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!dev->interrupt_in_urb) {
		dev_err(&intf->dev, "Couldn't allocate interrupt_in_urb\n");
		goto error;
	}
	dev->interrupt_out_endpoint_size = dev->interrupt_out_endpoint ? le16_to_cpu(dev->interrupt_out_endpoint->wMaxPacketSize) :
									 udev->descriptor.bMaxPacketSize0;
	dev->interrupt_out_buffer = kmalloc(write_buffer_size*dev->interrupt_out_endpoint_size, GFP_KERNEL);
	if (!dev->interrupt_out_buffer) {
		dev_err(&intf->dev, "Couldn't allocate interrupt_out_buffer\n");
		goto error;
	}
	dev->interrupt_out_urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!dev->interrupt_out_urb) {
		dev_err(&intf->dev, "Couldn't allocate interrupt_out_urb\n");
		goto error;
	}
	dev->interrupt_in_interval = min_interrupt_in_interval > dev->interrupt_in_endpoint->bInterval ? min_interrupt_in_interval : dev->interrupt_in_endpoint->bInterval;
	if (dev->interrupt_out_endpoint)
		dev->interrupt_out_interval = min_interrupt_out_interval > dev->interrupt_out_endpoint->bInterval ? min_interrupt_out_interval : dev->interrupt_out_endpoint->bInterval;

	/* we can register the device now, as it is ready */
	usb_set_intfdata(intf, dev);

	retval = usb_register_dev(intf, &ld_usb_class);
	if (retval) {
		/* something prevented us from registering this driver */
		dev_err(&intf->dev, "Not able to get a minor for this device.\n");
		usb_set_intfdata(intf, NULL);
		goto error;
	}

	/* let the user know what node this device is now attached to */
	dev_info(&intf->dev, "LD USB Device #%d now attached to major %d minor %d\n",
		(intf->minor - USB_LD_MINOR_BASE), USB_MAJOR, intf->minor);

exit:
	return retval;

error:
	ld_usb_delete(dev);

	return retval;
}

/**
 *	ld_usb_disconnect
 *
 *	Called by the usb core when the device is removed from the system.
 */
static void ld_usb_disconnect(struct usb_interface *intf)
{
	struct ld_usb *dev;
	int minor;

	dev = usb_get_intfdata(intf);
	usb_set_intfdata(intf, NULL);

	minor = intf->minor;

	/* give back our minor */
	usb_deregister_dev(intf, &ld_usb_class);

	mutex_lock(&dev->mutex);

	/* if the device is not opened, then we clean up right now */
	if (!dev->open_count) {
		mutex_unlock(&dev->mutex);
		ld_usb_delete(dev);
	} else {
		dev->intf = NULL;
		/* wake up pollers */
		wake_up_interruptible_all(&dev->read_wait);
		wake_up_interruptible_all(&dev->write_wait);
		mutex_unlock(&dev->mutex);
	}

	dev_info(&intf->dev, "LD USB Device #%d now disconnected\n",
		 (minor - USB_LD_MINOR_BASE));
}

/* usb specific object needed to register this driver with the usb subsystem */
static struct usb_driver ld_usb_driver = {
	.name =		"ldusb",
	.probe =	ld_usb_probe,
	.disconnect =	ld_usb_disconnect,
	.id_table =	ld_usb_table,
};

/**
 *	ld_usb_init
 */
static int __init ld_usb_init(void)
{
	int retval;

	/* register this driver with the USB subsystem */
	retval = usb_register(&ld_usb_driver);
	if (retval)
		err("usb_register failed for the "__FILE__" driver. Error number %d\n", retval);

	return retval;
}

/**
 *	ld_usb_exit
 */
static void __exit ld_usb_exit(void)
{
	/* deregister this driver with the USB subsystem */
	usb_deregister(&ld_usb_driver);
}

module_init(ld_usb_init);
module_exit(ld_usb_exit);