summaryrefslogtreecommitdiffstats
path: root/drivers/usb/serial/oti6858.c
blob: ae9cb15ee02dce660cf0aa5da2a8d31268bca878 (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
// SPDX-License-Identifier: GPL-2.0
/*
 * Ours Technology Inc. OTi-6858 USB to serial adapter driver.
 *
 * Copyleft  (C) 2007 Kees Lemmens (adapted for kernel 2.6.20)
 * Copyright (C) 2006 Tomasz Michal Lukaszewski (FIXME: add e-mail)
 * Copyright (C) 2001-2004 Greg Kroah-Hartman (greg@kroah.com)
 * Copyright (C) 2003 IBM Corp.
 *
 * Many thanks to the authors of pl2303 driver: all functions in this file
 * are heavily based on pl2303 code, buffering code is a 1-to-1 copy.
 *
 * Warning! You use this driver on your own risk! The only official
 * description of this device I have is datasheet from manufacturer,
 * and it doesn't contain almost any information needed to write a driver.
 * Almost all knowlegde used while writing this driver was gathered by:
 *  - analyzing traffic between device and the M$ Windows 2000 driver,
 *  - trying different bit combinations and checking pin states
 *    with a voltmeter,
 *  - receiving malformed frames and producing buffer overflows
 *    to learn how errors are reported,
 * So, THIS CODE CAN DESTROY OTi-6858 AND ANY OTHER DEVICES, THAT ARE
 * CONNECTED TO IT!
 *
 * See Documentation/usb/usb-serial.txt for more information on using this
 * driver
 *
 * TODO:
 *  - implement correct flushing for ioctls and oti6858_close()
 *  - check how errors (rx overflow, parity error, framing error) are reported
 *  - implement oti6858_break_ctl()
 *  - implement more ioctls
 *  - test/implement flow control
 *  - allow setting custom baud rates
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/spinlock.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <linux/uaccess.h>
#include <linux/kfifo.h>
#include "oti6858.h"

#define OTI6858_DESCRIPTION \
	"Ours Technology Inc. OTi-6858 USB to serial adapter driver"
#define OTI6858_AUTHOR "Tomasz Michal Lukaszewski <FIXME@FIXME>"

static const struct usb_device_id id_table[] = {
	{ USB_DEVICE(OTI6858_VENDOR_ID, OTI6858_PRODUCT_ID) },
	{ }
};

MODULE_DEVICE_TABLE(usb, id_table);

/* requests */
#define	OTI6858_REQ_GET_STATUS		(USB_DIR_IN | USB_TYPE_VENDOR | 0x00)
#define	OTI6858_REQ_T_GET_STATUS	0x01

#define	OTI6858_REQ_SET_LINE		(USB_DIR_OUT | USB_TYPE_VENDOR | 0x00)
#define	OTI6858_REQ_T_SET_LINE		0x00

#define	OTI6858_REQ_CHECK_TXBUFF	(USB_DIR_IN | USB_TYPE_VENDOR | 0x01)
#define	OTI6858_REQ_T_CHECK_TXBUFF	0x00

/* format of the control packet */
struct oti6858_control_pkt {
	__le16	divisor;	/* baud rate = 96000000 / (16 * divisor), LE */
#define OTI6858_MAX_BAUD_RATE	3000000
	u8	frame_fmt;
#define FMT_STOP_BITS_MASK	0xc0
#define FMT_STOP_BITS_1		0x00
#define FMT_STOP_BITS_2		0x40	/* 1.5 stop bits if FMT_DATA_BITS_5 */
#define FMT_PARITY_MASK		0x38
#define FMT_PARITY_NONE		0x00
#define FMT_PARITY_ODD		0x08
#define FMT_PARITY_EVEN		0x18
#define FMT_PARITY_MARK		0x28
#define FMT_PARITY_SPACE	0x38
#define FMT_DATA_BITS_MASK	0x03
#define FMT_DATA_BITS_5		0x00
#define FMT_DATA_BITS_6		0x01
#define FMT_DATA_BITS_7		0x02
#define FMT_DATA_BITS_8		0x03
	u8	something;	/* always equals 0x43 */
	u8	control;	/* settings of flow control lines */
#define CONTROL_MASK		0x0c
#define CONTROL_DTR_HIGH	0x08
#define CONTROL_RTS_HIGH	0x04
	u8	tx_status;
#define	TX_BUFFER_EMPTIED	0x09
	u8	pin_state;
#define PIN_MASK		0x3f
#define PIN_MSR_MASK		0x1b
#define PIN_RTS			0x20	/* output pin */
#define PIN_CTS			0x10	/* input pin, active low */
#define PIN_DSR			0x08	/* input pin, active low */
#define PIN_DTR			0x04	/* output pin */
#define PIN_RI			0x02	/* input pin, active low */
#define PIN_DCD			0x01	/* input pin, active low */
	u8	rx_bytes_avail;		/* number of bytes in rx buffer */;
};

#define OTI6858_CTRL_PKT_SIZE	sizeof(struct oti6858_control_pkt)
#define OTI6858_CTRL_EQUALS_PENDING(a, priv) \
	(((a)->divisor == (priv)->pending_setup.divisor) \
	  && ((a)->control == (priv)->pending_setup.control) \
	  && ((a)->frame_fmt == (priv)->pending_setup.frame_fmt))

/* function prototypes */
static int oti6858_open(struct tty_struct *tty, struct usb_serial_port *port);
static void oti6858_close(struct usb_serial_port *port);
static void oti6858_set_termios(struct tty_struct *tty,
			struct usb_serial_port *port, struct ktermios *old);
static void oti6858_init_termios(struct tty_struct *tty);
static void oti6858_read_int_callback(struct urb *urb);
static void oti6858_read_bulk_callback(struct urb *urb);
static void oti6858_write_bulk_callback(struct urb *urb);
static int oti6858_write(struct tty_struct *tty, struct usb_serial_port *port,
			const unsigned char *buf, int count);
static int oti6858_write_room(struct tty_struct *tty);
static int oti6858_chars_in_buffer(struct tty_struct *tty);
static int oti6858_tiocmget(struct tty_struct *tty);
static int oti6858_tiocmset(struct tty_struct *tty,
				unsigned int set, unsigned int clear);
static int oti6858_port_probe(struct usb_serial_port *port);
static int oti6858_port_remove(struct usb_serial_port *port);

/* device info */
static struct usb_serial_driver oti6858_device = {
	.driver = {
		.owner =	THIS_MODULE,
		.name =		"oti6858",
	},
	.id_table =		id_table,
	.num_ports =		1,
	.num_bulk_in =		1,
	.num_bulk_out =		1,
	.num_interrupt_in =	1,
	.open =			oti6858_open,
	.close =		oti6858_close,
	.write =		oti6858_write,
	.set_termios =		oti6858_set_termios,
	.init_termios = 	oti6858_init_termios,
	.tiocmget =		oti6858_tiocmget,
	.tiocmset =		oti6858_tiocmset,
	.tiocmiwait =		usb_serial_generic_tiocmiwait,
	.read_bulk_callback =	oti6858_read_bulk_callback,
	.read_int_callback =	oti6858_read_int_callback,
	.write_bulk_callback =	oti6858_write_bulk_callback,
	.write_room =		oti6858_write_room,
	.chars_in_buffer =	oti6858_chars_in_buffer,
	.port_probe =		oti6858_port_probe,
	.port_remove =		oti6858_port_remove,
};

static struct usb_serial_driver * const serial_drivers[] = {
	&oti6858_device, NULL
};

struct oti6858_private {
	spinlock_t lock;

	struct oti6858_control_pkt status;

	struct {
		u8 read_urb_in_use;
		u8 write_urb_in_use;
	} flags;
	struct delayed_work delayed_write_work;

	struct {
		__le16 divisor;
		u8 frame_fmt;
		u8 control;
	} pending_setup;
	u8 transient;
	u8 setup_done;
	struct delayed_work delayed_setup_work;

	struct usb_serial_port *port;   /* USB port with which associated */
};

static void setup_line(struct work_struct *work)
{
	struct oti6858_private *priv = container_of(work,
			struct oti6858_private, delayed_setup_work.work);
	struct usb_serial_port *port = priv->port;
	struct oti6858_control_pkt *new_setup;
	unsigned long flags;
	int result;

	new_setup = kmalloc(OTI6858_CTRL_PKT_SIZE, GFP_KERNEL);
	if (!new_setup) {
		/* we will try again */
		schedule_delayed_work(&priv->delayed_setup_work,
						msecs_to_jiffies(2));
		return;
	}

	result = usb_control_msg(port->serial->dev,
				usb_rcvctrlpipe(port->serial->dev, 0),
				OTI6858_REQ_T_GET_STATUS,
				OTI6858_REQ_GET_STATUS,
				0, 0,
				new_setup, OTI6858_CTRL_PKT_SIZE,
				100);

	if (result != OTI6858_CTRL_PKT_SIZE) {
		dev_err(&port->dev, "%s(): error reading status\n", __func__);
		kfree(new_setup);
		/* we will try again */
		schedule_delayed_work(&priv->delayed_setup_work,
							msecs_to_jiffies(2));
		return;
	}

	spin_lock_irqsave(&priv->lock, flags);
	if (!OTI6858_CTRL_EQUALS_PENDING(new_setup, priv)) {
		new_setup->divisor = priv->pending_setup.divisor;
		new_setup->control = priv->pending_setup.control;
		new_setup->frame_fmt = priv->pending_setup.frame_fmt;

		spin_unlock_irqrestore(&priv->lock, flags);
		result = usb_control_msg(port->serial->dev,
					usb_sndctrlpipe(port->serial->dev, 0),
					OTI6858_REQ_T_SET_LINE,
					OTI6858_REQ_SET_LINE,
					0, 0,
					new_setup, OTI6858_CTRL_PKT_SIZE,
					100);
	} else {
		spin_unlock_irqrestore(&priv->lock, flags);
		result = 0;
	}
	kfree(new_setup);

	spin_lock_irqsave(&priv->lock, flags);
	if (result != OTI6858_CTRL_PKT_SIZE)
		priv->transient = 0;
	priv->setup_done = 1;
	spin_unlock_irqrestore(&priv->lock, flags);

	dev_dbg(&port->dev, "%s(): submitting interrupt urb\n", __func__);
	result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
	if (result != 0) {
		dev_err(&port->dev, "%s(): usb_submit_urb() failed with error %d\n",
			__func__, result);
	}
}

static void send_data(struct work_struct *work)
{
	struct oti6858_private *priv = container_of(work,
			struct oti6858_private, delayed_write_work.work);
	struct usb_serial_port *port = priv->port;
	int count = 0, result;
	unsigned long flags;
	u8 *allow;

	spin_lock_irqsave(&priv->lock, flags);
	if (priv->flags.write_urb_in_use) {
		spin_unlock_irqrestore(&priv->lock, flags);
		schedule_delayed_work(&priv->delayed_write_work,
						msecs_to_jiffies(2));
		return;
	}
	priv->flags.write_urb_in_use = 1;
	spin_unlock_irqrestore(&priv->lock, flags);

	spin_lock_irqsave(&port->lock, flags);
	count = kfifo_len(&port->write_fifo);
	spin_unlock_irqrestore(&port->lock, flags);

	if (count > port->bulk_out_size)
		count = port->bulk_out_size;

	if (count != 0) {
		allow = kmalloc(1, GFP_KERNEL);
		if (!allow)
			return;

		result = usb_control_msg(port->serial->dev,
				usb_rcvctrlpipe(port->serial->dev, 0),
				OTI6858_REQ_T_CHECK_TXBUFF,
				OTI6858_REQ_CHECK_TXBUFF,
				count, 0, allow, 1, 100);
		if (result != 1 || *allow != 0)
			count = 0;
		kfree(allow);
	}

	if (count == 0) {
		priv->flags.write_urb_in_use = 0;

		dev_dbg(&port->dev, "%s(): submitting interrupt urb\n", __func__);
		result = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO);
		if (result != 0) {
			dev_err(&port->dev, "%s(): usb_submit_urb() failed with error %d\n",
				__func__, result);
		}
		return;
	}

	count = kfifo_out_locked(&port->write_fifo,
					port->write_urb->transfer_buffer,
					count, &port->lock);
	port->write_urb->transfer_buffer_length = count;
	result = usb_submit_urb(port->write_urb, GFP_NOIO);
	if (result != 0) {
		dev_err_console(port, "%s(): usb_submit_urb() failed with error %d\n",
				__func__, result);
		priv->flags.write_urb_in_use = 0;
	}

	usb_serial_port_softint(port);
}

static int oti6858_port_probe(struct usb_serial_port *port)
{
	struct oti6858_private *priv;

	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	spin_lock_init(&priv->lock);
	priv->port = port;
	INIT_DELAYED_WORK(&priv->delayed_setup_work, setup_line);
	INIT_DELAYED_WORK(&priv->delayed_write_work, send_data);

	usb_set_serial_port_data(port, priv);

	port->port.drain_delay = 256;	/* FIXME: check the FIFO length */

	return 0;
}

static int oti6858_port_remove(struct usb_serial_port *port)
{
	struct oti6858_private *priv;

	priv = usb_get_serial_port_data(port);
	kfree(priv);

	return 0;
}

static int oti6858_write(struct tty_struct *tty, struct usb_serial_port *port,
			const unsigned char *buf, int count)
{
	if (!count)
		return count;

	count = kfifo_in_locked(&port->write_fifo, buf, count, &port->lock);

	return count;
}

static int oti6858_write_room(struct tty_struct *tty)
{
	struct usb_serial_port *port = tty->driver_data;
	int room = 0;
	unsigned long flags;

	spin_lock_irqsave(&port->lock, flags);
	room = kfifo_avail(&port->write_fifo);
	spin_unlock_irqrestore(&port->lock, flags);

	return room;
}

static int oti6858_chars_in_buffer(struct tty_struct *tty)
{
	struct usb_serial_port *port = tty->driver_data;
	int chars = 0;
	unsigned long flags;

	spin_lock_irqsave(&port->lock, flags);
	chars = kfifo_len(&port->write_fifo);
	spin_unlock_irqrestore(&port->lock, flags);

	return chars;
}

static void oti6858_init_termios(struct tty_struct *tty)
{
	tty->termios = tty_std_termios;
	tty->termios.c_cflag = B38400 | CS8 | CREAD | HUPCL | CLOCAL;
	tty->termios.c_ispeed = 38400;
	tty->termios.c_ospeed = 38400;
}

static void oti6858_set_termios(struct tty_struct *tty,
		struct usb_serial_port *port, struct ktermios *old_termios)
{
	struct oti6858_private *priv = usb_get_serial_port_data(port);
	unsigned long flags;
	unsigned int cflag;
	u8 frame_fmt, control;
	__le16 divisor;
	int br;

	cflag = tty->termios.c_cflag;

	spin_lock_irqsave(&priv->lock, flags);
	divisor = priv->pending_setup.divisor;
	frame_fmt = priv->pending_setup.frame_fmt;
	control = priv->pending_setup.control;
	spin_unlock_irqrestore(&priv->lock, flags);

	frame_fmt &= ~FMT_DATA_BITS_MASK;
	switch (cflag & CSIZE) {
	case CS5:
		frame_fmt |= FMT_DATA_BITS_5;
		break;
	case CS6:
		frame_fmt |= FMT_DATA_BITS_6;
		break;
	case CS7:
		frame_fmt |= FMT_DATA_BITS_7;
		break;
	default:
	case CS8:
		frame_fmt |= FMT_DATA_BITS_8;
		break;
	}

	/* manufacturer claims that this device can work with baud rates
	 * up to 3 Mbps; I've tested it only on 115200 bps, so I can't
	 * guarantee that any other baud rate will work (especially
	 * the higher ones)
	 */
	br = tty_get_baud_rate(tty);
	if (br == 0) {
		divisor = 0;
	} else {
		int real_br;
		int new_divisor;
		br = min(br, OTI6858_MAX_BAUD_RATE);

		new_divisor = (96000000 + 8 * br) / (16 * br);
		real_br = 96000000 / (16 * new_divisor);
		divisor = cpu_to_le16(new_divisor);
		tty_encode_baud_rate(tty, real_br, real_br);
	}

	frame_fmt &= ~FMT_STOP_BITS_MASK;
	if ((cflag & CSTOPB) != 0)
		frame_fmt |= FMT_STOP_BITS_2;
	else
		frame_fmt |= FMT_STOP_BITS_1;

	frame_fmt &= ~FMT_PARITY_MASK;
	if ((cflag & PARENB) != 0) {
		if ((cflag & PARODD) != 0)
			frame_fmt |= FMT_PARITY_ODD;
		else
			frame_fmt |= FMT_PARITY_EVEN;
	} else {
		frame_fmt |= FMT_PARITY_NONE;
	}

	control &= ~CONTROL_MASK;
	if ((cflag & CRTSCTS) != 0)
		control |= (CONTROL_DTR_HIGH | CONTROL_RTS_HIGH);

	/* change control lines if we are switching to or from B0 */
	/* FIXME:
	spin_lock_irqsave(&priv->lock, flags);
	control = priv->line_control;
	if ((cflag & CBAUD) == B0)
		priv->line_control &= ~(CONTROL_DTR | CONTROL_RTS);
	else
		priv->line_control |= (CONTROL_DTR | CONTROL_RTS);
	if (control != priv->line_control) {
		control = priv->line_control;
		spin_unlock_irqrestore(&priv->lock, flags);
		set_control_lines(serial->dev, control);
	} else {
		spin_unlock_irqrestore(&priv->lock, flags);
	}
	*/

	spin_lock_irqsave(&priv->lock, flags);
	if (divisor != priv->pending_setup.divisor
			|| control != priv->pending_setup.control
			|| frame_fmt != priv->pending_setup.frame_fmt) {
		priv->pending_setup.divisor = divisor;
		priv->pending_setup.control = control;
		priv->pending_setup.frame_fmt = frame_fmt;
	}
	spin_unlock_irqrestore(&priv->lock, flags);
}

static int oti6858_open(struct tty_struct *tty, struct usb_serial_port *port)
{
	struct oti6858_private *priv = usb_get_serial_port_data(port);
	struct usb_serial *serial = port->serial;
	struct oti6858_control_pkt *buf;
	unsigned long flags;
	int result;

	usb_clear_halt(serial->dev, port->write_urb->pipe);
	usb_clear_halt(serial->dev, port->read_urb->pipe);

	buf = kmalloc(OTI6858_CTRL_PKT_SIZE, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	result = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
				OTI6858_REQ_T_GET_STATUS,
				OTI6858_REQ_GET_STATUS,
				0, 0,
				buf, OTI6858_CTRL_PKT_SIZE,
				100);
	if (result != OTI6858_CTRL_PKT_SIZE) {
		/* assume default (after power-on reset) values */
		buf->divisor = cpu_to_le16(0x009c);	/* 38400 bps */
		buf->frame_fmt = 0x03;	/* 8N1 */
		buf->something = 0x43;
		buf->control = 0x4c;	/* DTR, RTS */
		buf->tx_status = 0x00;
		buf->pin_state = 0x5b;	/* RTS, CTS, DSR, DTR, RI, DCD */
		buf->rx_bytes_avail = 0x00;
	}

	spin_lock_irqsave(&priv->lock, flags);
	memcpy(&priv->status, buf, OTI6858_CTRL_PKT_SIZE);
	priv->pending_setup.divisor = buf->divisor;
	priv->pending_setup.frame_fmt = buf->frame_fmt;
	priv->pending_setup.control = buf->control;
	spin_unlock_irqrestore(&priv->lock, flags);
	kfree(buf);

	dev_dbg(&port->dev, "%s(): submitting interrupt urb\n", __func__);
	result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
	if (result != 0) {
		dev_err(&port->dev, "%s(): usb_submit_urb() failed with error %d\n",
			__func__, result);
		oti6858_close(port);
		return result;
	}

	/* setup termios */
	if (tty)
		oti6858_set_termios(tty, port, NULL);

	return 0;
}

static void oti6858_close(struct usb_serial_port *port)
{
	struct oti6858_private *priv = usb_get_serial_port_data(port);
	unsigned long flags;

	spin_lock_irqsave(&port->lock, flags);
	/* clear out any remaining data in the buffer */
	kfifo_reset_out(&port->write_fifo);
	spin_unlock_irqrestore(&port->lock, flags);

	dev_dbg(&port->dev, "%s(): after buf_clear()\n", __func__);

	/* cancel scheduled setup */
	cancel_delayed_work_sync(&priv->delayed_setup_work);
	cancel_delayed_work_sync(&priv->delayed_write_work);

	/* shutdown our urbs */
	dev_dbg(&port->dev, "%s(): shutting down urbs\n", __func__);
	usb_kill_urb(port->write_urb);
	usb_kill_urb(port->read_urb);
	usb_kill_urb(port->interrupt_in_urb);
}

static int oti6858_tiocmset(struct tty_struct *tty,
				unsigned int set, unsigned int clear)
{
	struct usb_serial_port *port = tty->driver_data;
	struct oti6858_private *priv = usb_get_serial_port_data(port);
	unsigned long flags;
	u8 control;

	dev_dbg(&port->dev, "%s(set = 0x%08x, clear = 0x%08x)\n",
		__func__, set, clear);

	/* FIXME: check if this is correct (active high/low) */
	spin_lock_irqsave(&priv->lock, flags);
	control = priv->pending_setup.control;
	if ((set & TIOCM_RTS) != 0)
		control |= CONTROL_RTS_HIGH;
	if ((set & TIOCM_DTR) != 0)
		control |= CONTROL_DTR_HIGH;
	if ((clear & TIOCM_RTS) != 0)
		control &= ~CONTROL_RTS_HIGH;
	if ((clear & TIOCM_DTR) != 0)
		control &= ~CONTROL_DTR_HIGH;

	if (control != priv->pending_setup.control)
		priv->pending_setup.control = control;

	spin_unlock_irqrestore(&priv->lock, flags);
	return 0;
}

static int oti6858_tiocmget(struct tty_struct *tty)
{
	struct usb_serial_port *port = tty->driver_data;
	struct oti6858_private *priv = usb_get_serial_port_data(port);
	unsigned long flags;
	unsigned pin_state;
	unsigned result = 0;

	spin_lock_irqsave(&priv->lock, flags);
	pin_state = priv->status.pin_state & PIN_MASK;
	spin_unlock_irqrestore(&priv->lock, flags);

	/* FIXME: check if this is correct (active high/low) */
	if ((pin_state & PIN_RTS) != 0)
		result |= TIOCM_RTS;
	if ((pin_state & PIN_CTS) != 0)
		result |= TIOCM_CTS;
	if ((pin_state & PIN_DSR) != 0)
		result |= TIOCM_DSR;
	if ((pin_state & PIN_DTR) != 0)
		result |= TIOCM_DTR;
	if ((pin_state & PIN_RI) != 0)
		result |= TIOCM_RI;
	if ((pin_state & PIN_DCD) != 0)
		result |= TIOCM_CD;

	dev_dbg(&port->dev, "%s() = 0x%08x\n", __func__, result);

	return result;
}

static void oti6858_read_int_callback(struct urb *urb)
{
	struct usb_serial_port *port =  urb->context;
	struct oti6858_private *priv = usb_get_serial_port_data(port);
	int transient = 0, can_recv = 0, resubmit = 1;
	int status = urb->status;

	switch (status) {
	case 0:
		/* success */
		break;
	case -ECONNRESET:
	case -ENOENT:
	case -ESHUTDOWN:
		/* this urb is terminated, clean up */
		dev_dbg(&urb->dev->dev, "%s(): urb shutting down with status: %d\n",
			__func__, status);
		return;
	default:
		dev_dbg(&urb->dev->dev, "%s(): nonzero urb status received: %d\n",
			__func__, status);
		break;
	}

	if (status == 0 && urb->actual_length == OTI6858_CTRL_PKT_SIZE) {
		struct oti6858_control_pkt *xs = urb->transfer_buffer;
		unsigned long flags;

		spin_lock_irqsave(&priv->lock, flags);

		if (!priv->transient) {
			if (!OTI6858_CTRL_EQUALS_PENDING(xs, priv)) {
				if (xs->rx_bytes_avail == 0) {
					priv->transient = 4;
					priv->setup_done = 0;
					resubmit = 0;
					dev_dbg(&port->dev, "%s(): scheduling setup_line()\n", __func__);
					schedule_delayed_work(&priv->delayed_setup_work, 0);
				}
			}
		} else {
			if (OTI6858_CTRL_EQUALS_PENDING(xs, priv)) {
				priv->transient = 0;
			} else if (!priv->setup_done) {
				resubmit = 0;
			} else if (--priv->transient == 0) {
				if (xs->rx_bytes_avail == 0) {
					priv->transient = 4;
					priv->setup_done = 0;
					resubmit = 0;
					dev_dbg(&port->dev, "%s(): scheduling setup_line()\n", __func__);
					schedule_delayed_work(&priv->delayed_setup_work, 0);
				}
			}
		}

		if (!priv->transient) {
			u8 delta = xs->pin_state ^ priv->status.pin_state;

			if (delta & PIN_MSR_MASK) {
				if (delta & PIN_CTS)
					port->icount.cts++;
				if (delta & PIN_DSR)
					port->icount.dsr++;
				if (delta & PIN_RI)
					port->icount.rng++;
				if (delta & PIN_DCD)
					port->icount.dcd++;

				wake_up_interruptible(&port->port.delta_msr_wait);
			}

			memcpy(&priv->status, xs, OTI6858_CTRL_PKT_SIZE);
		}

		if (!priv->transient && xs->rx_bytes_avail != 0) {
			can_recv = xs->rx_bytes_avail;
			priv->flags.read_urb_in_use = 1;
		}

		transient = priv->transient;
		spin_unlock_irqrestore(&priv->lock, flags);
	}

	if (can_recv) {
		int result;

		result = usb_submit_urb(port->read_urb, GFP_ATOMIC);
		if (result != 0) {
			priv->flags.read_urb_in_use = 0;
			dev_err(&port->dev, "%s(): usb_submit_urb() failed,"
					" error %d\n", __func__, result);
		} else {
			resubmit = 0;
		}
	} else if (!transient) {
		unsigned long flags;
		int count;

		spin_lock_irqsave(&port->lock, flags);
		count = kfifo_len(&port->write_fifo);
		spin_unlock_irqrestore(&port->lock, flags);

		spin_lock_irqsave(&priv->lock, flags);
		if (priv->flags.write_urb_in_use == 0 && count != 0) {
			schedule_delayed_work(&priv->delayed_write_work, 0);
			resubmit = 0;
		}
		spin_unlock_irqrestore(&priv->lock, flags);
	}

	if (resubmit) {
		int result;

/*		dev_dbg(&urb->dev->dev, "%s(): submitting interrupt urb\n", __func__); */
		result = usb_submit_urb(urb, GFP_ATOMIC);
		if (result != 0) {
			dev_err(&urb->dev->dev,
					"%s(): usb_submit_urb() failed with"
					" error %d\n", __func__, result);
		}
	}
}

static void oti6858_read_bulk_callback(struct urb *urb)
{
	struct usb_serial_port *port =  urb->context;
	struct oti6858_private *priv = usb_get_serial_port_data(port);
	unsigned char *data = urb->transfer_buffer;
	unsigned long flags;
	int status = urb->status;
	int result;

	spin_lock_irqsave(&priv->lock, flags);
	priv->flags.read_urb_in_use = 0;
	spin_unlock_irqrestore(&priv->lock, flags);

	if (status != 0) {
		dev_dbg(&urb->dev->dev, "%s(): unable to handle the error, exiting\n", __func__);
		return;
	}

	if (urb->actual_length > 0) {
		tty_insert_flip_string(&port->port, data, urb->actual_length);
		tty_flip_buffer_push(&port->port);
	}

	/* schedule the interrupt urb */
	result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
	if (result != 0 && result != -EPERM) {
		dev_err(&port->dev, "%s(): usb_submit_urb() failed,"
				" error %d\n", __func__, result);
	}
}

static void oti6858_write_bulk_callback(struct urb *urb)
{
	struct usb_serial_port *port =  urb->context;
	struct oti6858_private *priv = usb_get_serial_port_data(port);
	int status = urb->status;
	int result;

	switch (status) {
	case 0:
		/* success */
		break;
	case -ECONNRESET:
	case -ENOENT:
	case -ESHUTDOWN:
		/* this urb is terminated, clean up */
		dev_dbg(&urb->dev->dev, "%s(): urb shutting down with status: %d\n", __func__, status);
		priv->flags.write_urb_in_use = 0;
		return;
	default:
		/* error in the urb, so we have to resubmit it */
		dev_dbg(&urb->dev->dev, "%s(): nonzero write bulk status received: %d\n", __func__, status);
		dev_dbg(&urb->dev->dev, "%s(): overflow in write\n", __func__);

		port->write_urb->transfer_buffer_length = 1;
		result = usb_submit_urb(port->write_urb, GFP_ATOMIC);
		if (result) {
			dev_err_console(port, "%s(): usb_submit_urb() failed,"
					" error %d\n", __func__, result);
		} else {
			return;
		}
	}

	priv->flags.write_urb_in_use = 0;

	/* schedule the interrupt urb if we are still open */
	dev_dbg(&port->dev, "%s(): submitting interrupt urb\n", __func__);
	result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
	if (result != 0) {
		dev_err(&port->dev, "%s(): failed submitting int urb,"
					" error %d\n", __func__, result);
	}
}

module_usb_serial_driver(serial_drivers, id_table);

MODULE_DESCRIPTION(OTI6858_DESCRIPTION);
MODULE_AUTHOR(OTI6858_AUTHOR);
MODULE_LICENSE("GPL v2");