aboutsummaryrefslogtreecommitdiff
path: root/drivers/staging/frontier/alphatrack.c
blob: 15aed87fe1bb5a0310d17684f5dcd6a47a4501f0 (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
/*
 * Frontier Designs Alphatrack driver
 *
 * Copyright (C) 2007 Michael Taht (m@taht.net)
 *
 * Based on the usbled driver and ldusb drivers by
 *
 * Copyright (C) 2004 Greg Kroah-Hartman (greg@kroah.com)
 * Copyright (C) 2005 Michael Hund <mhund@ld-didactic.de>
 *
 * The ldusb driver was, in turn, derived from Lego USB Tower driver
 * Copyright (C) 2003 David Glance <advidgsf@sourceforge.net>
 *		 2001-2004 Juergen Stuber <starblue@users.sourceforge.net>
 *
 *	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, version 2.
 *
 */

/**
 * This driver uses a ring buffer for time critical reading of
 * interrupt in reports and provides read and write methods for
 * raw interrupt reports.
 */

/* Note: this currently uses a dumb ringbuffer for reads and writes.
 * A more optimal driver would cache and kill off outstanding urbs that are
 * now invalid, and ignore ones that already were in the queue but valid
 * as we only have 30 commands for the alphatrack. In particular this is
 * key for getting lights to flash in time as otherwise many commands
 * can be buffered up before the light change makes it to the interface.
*/

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

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

#include "alphatrack.h"

#define VENDOR_ID	0x165b
#define PRODUCT_ID	0xfad1

#ifdef CONFIG_USB_DYNAMIC_MINORS
#define USB_ALPHATRACK_MINOR_BASE	0
#else
/* FIXME 176 - is another driver's minor - apply for that */
#define USB_ALPHATRACK_MINOR_BASE	176
#endif

/* table of devices that work with this driver */
static struct usb_device_id usb_alphatrack_table[] = {
	{USB_DEVICE(VENDOR_ID, PRODUCT_ID)},
	{}			/* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, usb_alphatrack_table);
MODULE_VERSION("0.41");
MODULE_AUTHOR("Mike Taht <m@taht.net>");
MODULE_DESCRIPTION("Alphatrack USB Driver");
MODULE_LICENSE("GPL");
MODULE_SUPPORTED_DEVICE("Frontier Designs Alphatrack Control Surface");

/* These aren't done yet */

#define SUPPRESS_EXTRA_ONLINE_EVENTS 0
#define BUFFERED_WRITES 0
#define SUPPRESS_EXTRA_OFFLINE_EVENTS 0
#define COMPRESS_FADER_EVENTS 0

#define BUFFERED_READS 1
#define RING_BUFFER_SIZE 512
#define WRITE_BUFFER_SIZE 34
#define ALPHATRACK_USB_TIMEOUT 10
#define OUTPUT_CMD_SIZE 8
#define INPUT_CMD_SIZE 12
#define ALPHATRACK_DEBUG 0

static int debug = ALPHATRACK_DEBUG;

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

#define alphatrack_ocmd_info(dev, cmd, format, arg...)

#define alphatrack_icmd_info(dev, cmd, format, arg...)

/* 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 = RING_BUFFER_SIZE;

module_param(ring_buffer_size, int, S_IRUGO);
MODULE_PARM_DESC(ring_buffer_size, "Read ring buffer size");

/* The write_buffer can one day contain more than one interrupt out transfer.
 */

static int write_buffer_size = WRITE_BUFFER_SIZE;
module_param(write_buffer_size, int, S_IRUGO);
MODULE_PARM_DESC(write_buffer_size, "Write buffer size");

/*
 * Increase the interval for debugging purposes.
 * or set to 1 to use the standard interval from the endpoint descriptors.
 */

static int min_interrupt_in_interval = ALPHATRACK_USB_TIMEOUT;
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 = ALPHATRACK_USB_TIMEOUT;
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 usb_alphatrack {
	struct semaphore sem;	/* locks this structure */
	struct usb_interface *intf;	/* save off the usb interface pointer */
	int open_count;		/* number of times this port has been opened */

	/* make gcc happy */
	struct alphatrack_icmd (*ring_buffer)[RING_BUFFER_SIZE];
	struct alphatrack_ocmd (*write_buffer)[WRITE_BUFFER_SIZE];
	unsigned int ring_head;
	unsigned int ring_tail;

	wait_queue_head_t read_wait;
	wait_queue_head_t write_wait;

	unsigned char *interrupt_in_buffer;
	unsigned char *oldi_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;

	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;

	atomic_t writes_pending;
	int event;		/* alternate interface to events */
	int fader;		/* 10 bits */
	int lights;		/* 23 bits */
	unsigned char dump_state;	/* 0 if disabled 1 if enabled */
	unsigned char enable;	/* 0 if disabled 1 if enabled */
	unsigned char offline;	/* if the device is out of range or asleep */
	unsigned char verbose;	/* be verbose in error reporting */
	unsigned char last_cmd[OUTPUT_CMD_SIZE];
	unsigned char screen[32];
};

/* prevent races between open() and disconnect() */
static DEFINE_MUTEX(disconnect_mutex);

/* forward declaration */

static struct usb_driver usb_alphatrack_driver;

/**
 *	usb_alphatrack_abort_transfers
 *      aborts transfers and frees associated data structures
 */
static void usb_alphatrack_abort_transfers(struct usb_alphatrack *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);
}

/**
 *	usb_alphatrack_delete
 */
static void usb_alphatrack_delete(struct usb_alphatrack *dev)
{
	usb_alphatrack_abort_transfers(dev);
	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);		/* fixme oldi_buffer */
}

/**
 *	usb_alphatrack_interrupt_in_callback
 */

static void usb_alphatrack_interrupt_in_callback(struct urb *urb)
{
	struct usb_alphatrack *dev = urb->context;
	unsigned int next_ring_head;
	int retval = -1;

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

	if (urb->actual_length != INPUT_CMD_SIZE) {
		dev_warn(&dev->intf->dev,
			 "Urb length was %d bytes!!"
			 "Do something intelligent \n", urb->actual_length);
	} else {
		alphatrack_ocmd_info(&dev->intf->dev,
				     &(*dev->ring_buffer)[dev->ring_tail].cmd,
				     "%s", "bla");
		if (memcmp
		    (dev->interrupt_in_buffer, dev->oldi_buffer,
		     INPUT_CMD_SIZE) == 0) {
			goto resubmit;
		}
		memcpy(dev->oldi_buffer, dev->interrupt_in_buffer,
		       INPUT_CMD_SIZE);

#if SUPPRESS_EXTRA_OFFLINE_EVENTS
		if (dev->offline == 2 && dev->interrupt_in_buffer[1] == 0xff)
			goto resubmit;
		if (dev->offline == 1 && dev->interrupt_in_buffer[1] == 0xff) {
			dev->offline = 2;
			goto resubmit;
		}
/* Always pass one offline event up the stack */
		if (dev->offline > 0 && dev->interrupt_in_buffer[1] != 0xff)
			dev->offline = 0;
		if (dev->offline == 0 && dev->interrupt_in_buffer[1] == 0xff)
			dev->offline = 1;
#endif
		dbg_info(&dev->intf->dev, "%s: head, tail are %x, %x\n",
			 __func__, dev->ring_head, dev->ring_tail);
		next_ring_head = (dev->ring_head + 1) % ring_buffer_size;

		if (next_ring_head != dev->ring_tail) {
			memcpy(&((*dev->ring_buffer)[dev->ring_head]),
			       dev->interrupt_in_buffer, urb->actual_length);
			dev->ring_head = next_ring_head;
			retval = 0;
			memset(dev->interrupt_in_buffer, 0, urb->actual_length);
		} else {
			dev_warn(&dev->intf->dev,
				 "Ring buffer overflow, %d bytes dropped\n",
				 urb->actual_length);
			memset(dev->interrupt_in_buffer, 0, urb->actual_length);
		}
	}

resubmit:
	/* resubmit if we're still running */
	if (dev->interrupt_in_running && 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);
	}

exit:
	dev->interrupt_in_done = 1;
	wake_up_interruptible(&dev->read_wait);
}

/**
 *	usb_alphatrack_interrupt_out_callback
 */
static void usb_alphatrack_interrupt_out_callback(struct urb *urb)
{
	struct usb_alphatrack *dev = urb->context;

	/* sync/async unlink faults aren't errors */
	if (urb->status && !(urb->status == -ENOENT ||
			     urb->status == -ECONNRESET ||
			     urb->status == -ESHUTDOWN))
		dbg_info(&dev->intf->dev,
			 "%s - nonzero write interrupt status received: %d\n",
			 __func__, urb->status);
	atomic_dec(&dev->writes_pending);
	dev->interrupt_out_busy = 0;
	wake_up_interruptible(&dev->write_wait);
}

/**
 *	usb_alphatrack_open
 */
static int usb_alphatrack_open(struct inode *inode, struct file *file)
{
	struct usb_alphatrack *dev;
	int subminor;
	int retval = 0;
	struct usb_interface *interface;

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

	mutex_lock(&disconnect_mutex);

	interface = usb_find_interface(&usb_alphatrack_driver, subminor);

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

	dev = usb_get_intfdata(interface);

	if (!dev) {
		retval = -ENODEV;
		goto unlock_disconnect_exit;
	}

	/* lock this device */
	if (down_interruptible(&dev->sem)) {
		retval = -ERESTARTSYS;
		goto unlock_disconnect_exit;
	}

	/* 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;
	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,
			 usb_alphatrack_interrupt_in_callback, dev,
			 dev->interrupt_in_interval);

	dev->interrupt_in_running = 1;
	dev->interrupt_in_done = 0;
	dev->enable = 1;
	dev->offline = 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:
	up(&dev->sem);

unlock_disconnect_exit:
	mutex_unlock(&disconnect_mutex);

	return retval;
}

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

	dev = file->private_data;

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

	if (down_interruptible(&dev->sem)) {
		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 */
		up(&dev->sem);
		/* unlock here as usb_alphatrack_delete frees dev */
		usb_alphatrack_delete(dev);
		retval = -ENODEV;
		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);
	usb_alphatrack_abort_transfers(dev);
	dev->open_count = 0;

unlock_exit:
	up(&dev->sem);

exit:
	return retval;
}

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

	dev = file->private_data;

	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;
}

/**
 *	usb_alphatrack_read
 */
static ssize_t usb_alphatrack_read(struct file *file, char __user *buffer,
				   size_t count, loff_t *ppos)
{
	struct usb_alphatrack *dev;
	int retval = 0;

	int c = 0;

	dev = file->private_data;

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

	/* lock this object */
	if (down_interruptible(&dev->sem)) {
		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;
	}

	while (dev->ring_head == dev->ring_tail) {
		if (file->f_flags & O_NONBLOCK) {
			retval = -EAGAIN;
			goto unlock_exit;
		}
		dev->interrupt_in_done = 0;
		retval =
		    wait_event_interruptible(dev->read_wait,
					     dev->interrupt_in_done);
		if (retval < 0)
			goto unlock_exit;
	}

	alphatrack_ocmd_info(&dev->intf->dev,
			     &(*dev->ring_buffer)[dev->ring_tail].cmd, "%s",
			     ": copying to userspace");

	c = 0;
	while ((c < count) && (dev->ring_tail != dev->ring_head)) {
		if (copy_to_user
		    (&buffer[c], &(*dev->ring_buffer)[dev->ring_tail],
		     INPUT_CMD_SIZE)) {
			retval = -EFAULT;
			goto unlock_exit;
		}
		dev->ring_tail = (dev->ring_tail + 1) % ring_buffer_size;
		c += INPUT_CMD_SIZE;
		dbg_info(&dev->intf->dev, "%s: head, tail are %x, %x\n",
			 __func__, dev->ring_head, dev->ring_tail);
	}
	retval = c;

unlock_exit:
	/* unlock the device */
	up(&dev->sem);

exit:
	return retval;
}

/**
 *	usb_alphatrack_write
 */
static ssize_t usb_alphatrack_write(struct file *file,
				    const char __user *buffer, size_t count,
				    loff_t *ppos)
{
	struct usb_alphatrack *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 (down_interruptible(&dev->sem)) {
		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 */
	/* FIXME - if you write more than 12 bytes this breaks */
	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) {
		err("Endpoint should not be be null! \n");
		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,
			 usb_alphatrack_interrupt_out_callback, dev,
			 dev->interrupt_out_interval);
	dev->interrupt_out_busy = 1;
	atomic_inc(&dev->writes_pending);
	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);
		atomic_dec(&dev->writes_pending);
		goto unlock_exit;
	}
	retval = bytes_to_write;

unlock_exit:
	/* unlock the device */
	up(&dev->sem);

exit:
	return retval;
}

/* file operations needed when we register this driver */
static const struct file_operations usb_alphatrack_fops = {
	.owner = THIS_MODULE,
	.read = usb_alphatrack_read,
	.write = usb_alphatrack_write,
	.open = usb_alphatrack_open,
	.release = usb_alphatrack_release,
	.poll = usb_alphatrack_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 usb_alphatrack_class = {
	.name = "alphatrack%d",
	.fops = &usb_alphatrack_fops,
	.minor_base = USB_ALPHATRACK_MINOR_BASE,
};

/**
 *	usb_alphatrack_probe
 *
 *	Called by the usb core when a new device is connected that it thinks
 *	this driver might be interested in.
 */
static int usb_alphatrack_probe(struct usb_interface *intf,
				const struct usb_device_id *id)
{
	struct usb_device *udev = interface_to_usbdev(intf);
	struct usb_alphatrack *dev = NULL;
	struct usb_host_interface *iface_desc;
	struct usb_endpoint_descriptor *endpoint;
	int i;
	int true_size;
	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;
	}
	init_MUTEX(&dev->sem);
	dev->intf = intf;
	init_waitqueue_head(&dev->read_wait);
	init_waitqueue_head(&dev->write_wait);

	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);

	if (dev->interrupt_in_endpoint_size != 64)
		dev_warn(&intf->dev, "Interrupt in endpoint size is not 64!\n");

	if (ring_buffer_size == 0)
		ring_buffer_size = RING_BUFFER_SIZE;

	true_size = min(ring_buffer_size, RING_BUFFER_SIZE);

	/* FIXME - there are more usb_alloc routines for dma correctness.
	   Needed? */
	dev->ring_buffer =
	    kmalloc((true_size * sizeof(struct alphatrack_icmd)), GFP_KERNEL);

	if (!dev->ring_buffer) {
		dev_err(&intf->dev,
			"Couldn't allocate input ring_buffer of size %d\n",
			true_size);
		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->oldi_buffer = kmalloc(dev->interrupt_in_endpoint_size, GFP_KERNEL);
	if (!dev->oldi_buffer) {
		dev_err(&intf->dev, "Couldn't allocate old 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;

	if (dev->interrupt_out_endpoint_size != 64)
		dev_warn(&intf->dev,
			 "Interrupt out endpoint size is not 64!)\n");

	if (write_buffer_size == 0)
		write_buffer_size = WRITE_BUFFER_SIZE;
	true_size = min(write_buffer_size, WRITE_BUFFER_SIZE);

	dev->interrupt_out_buffer =
	    kmalloc(true_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->write_buffer =
	    kmalloc(sizeof(struct alphatrack_ocmd) * true_size, GFP_KERNEL);

	if (!dev->write_buffer) {
		dev_err(&intf->dev, "Couldn't allocate write_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);

	atomic_set(&dev->writes_pending, 0);
	retval = usb_register_dev(intf, &usb_alphatrack_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,
		 "Alphatrack Device #%d now attached to major %d minor %d\n",
		 (intf->minor - USB_ALPHATRACK_MINOR_BASE), USB_MAJOR,
		 intf->minor);

exit:
	return retval;

error:
	usb_alphatrack_delete(dev);

	return retval;
}

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

	mutex_lock(&disconnect_mutex);

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

	down(&dev->sem);

	minor = intf->minor;

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

	/* if the device is not opened, then we clean up right now */
	if (!dev->open_count) {
		up(&dev->sem);
		usb_alphatrack_delete(dev);
	} else {
		dev->intf = NULL;
		up(&dev->sem);
	}

	atomic_set(&dev->writes_pending, 0);
	mutex_unlock(&disconnect_mutex);

	dev_info(&intf->dev, "Alphatrack Surface #%d now disconnected\n",
		 (minor - USB_ALPHATRACK_MINOR_BASE));
}

/* usb specific object needed to register this driver with the usb subsystem */
static struct usb_driver usb_alphatrack_driver = {
	.name = "alphatrack",
	.probe = usb_alphatrack_probe,
	.disconnect = usb_alphatrack_disconnect,
	.id_table = usb_alphatrack_table,
};

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

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

	return retval;
}

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

module_init(usb_alphatrack_init);
module_exit(usb_alphatrack_exit);