summaryrefslogtreecommitdiff
path: root/drivers/usb/serial/mct_u232.c
blob: d8825e159aa5cfe9361b152489d79fe953f22889 (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
/*
 * MCT (Magic Control Technology Corp.) USB RS232 Converter Driver
 *
 *   Copyright (C) 2000 Wolfgang Grandegger (wolfgang@ces.ch)
 *
 *   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.
 *
 * This program is largely derived from the Belkin USB Serial Adapter Driver
 * (see belkin_sa.[ch]). All of the information about the device was acquired
 * by using SniffUSB on Windows98. For technical details see mct_u232.h.
 *
 * William G. Greathouse and Greg Kroah-Hartman provided great help on how to
 * do the reverse engineering and how to write a USB serial device driver.
 *
 * TO BE DONE, TO BE CHECKED:
 *   DTR/RTS signal handling may be incomplete or incorrect. I have mainly
 *   implemented what I have seen with SniffUSB or found in belkin_sa.c.
 *   For further TODOs check also belkin_sa.c.
 *
 * TEST STATUS:
 *   Basic tests have been performed with minicom/zmodem transfers and
 *   modem dialing under Linux 2.4.0-test10 (for me it works fine).
 *
 * 04-Nov-2003 Bill Marr <marr at flex dot com>
 *   - Mimic Windows driver by sending 2 USB 'device request' messages
 *     following normal 'baud rate change' message.  This allows data to be
 *     transmitted to RS-232 devices which don't assert the 'CTS' signal.
 *
 * 10-Nov-2001 Wolfgang Grandegger
 *   - Fixed an endianess problem with the baudrate selection for PowerPC.
 *
 * 06-Dec-2001 Martin Hamilton <martinh@gnu.org>
 *   - Added support for the Belkin F5U109 DB9 adaptor
 *
 * 30-May-2001 Greg Kroah-Hartman
 *   - switched from using spinlock to a semaphore, which fixes lots of
 *     problems.
 *
 * 04-May-2001 Stelian Pop
 *   - Set the maximum bulk output size for Sitecom U232-P25 model to 16 bytes
 *     instead of the device reported 32 (using 32 bytes causes many data
 *     loss, Windows driver uses 16 too).
 *
 * 02-May-2001 Stelian Pop
 *   - Fixed the baud calculation for Sitecom U232-P25 model
 *
 * 08-Apr-2001 gb
 *   - Identify version on module load.
 *
 * 06-Jan-2001 Cornel Ciocirlan
 *   - Added support for Sitecom U232-P25 model (Product Id 0x0230)
 *   - Added support for D-Link DU-H3SP USB BAY (Product Id 0x0200)
 *
 * 29-Nov-2000 Greg Kroah-Hartman
 *   - Added device id table to fit with 2.4.0-test11 structure.
 *   - took out DEAL_WITH_TWO_INT_IN_ENDPOINTS #define as it's not needed
 *     (lots of things will change if/when the usb-serial core changes to
 *     handle these issues.
 *
 * 27-Nov-2000 Wolfgang Grandegge
 *   A version for kernel 2.4.0-test10 released to the Linux community
 *   (via linux-usb-devel).
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include "mct_u232.h"

/*
 * Version Information
 */
#define DRIVER_VERSION "z2.1"		/* Linux in-kernel version */
#define DRIVER_AUTHOR "Wolfgang Grandegger <wolfgang@ces.ch>"
#define DRIVER_DESC "Magic Control Technology USB-RS232 converter driver"

static int debug;

/*
 * Function prototypes
 */
static int  mct_u232_startup(struct usb_serial *serial);
static void mct_u232_release(struct usb_serial *serial);
static int  mct_u232_open(struct tty_struct *tty,
			struct usb_serial_port *port, struct file *filp);
static void mct_u232_close(struct usb_serial_port *port);
static void mct_u232_dtr_rts(struct usb_serial_port *port, int on);
static void mct_u232_read_int_callback(struct urb *urb);
static void mct_u232_set_termios(struct tty_struct *tty,
			struct usb_serial_port *port, struct ktermios *old);
static void mct_u232_break_ctl(struct tty_struct *tty, int break_state);
static int  mct_u232_tiocmget(struct tty_struct *tty, struct file *file);
static int  mct_u232_tiocmset(struct tty_struct *tty, struct file *file,
			unsigned int set, unsigned int clear);
static void mct_u232_throttle(struct tty_struct *tty);
static void mct_u232_unthrottle(struct tty_struct *tty);


/*
 * All of the device info needed for the MCT USB-RS232 converter.
 */
static struct usb_device_id id_table_combined [] = {
	{ USB_DEVICE(MCT_U232_VID, MCT_U232_PID) },
	{ USB_DEVICE(MCT_U232_VID, MCT_U232_SITECOM_PID) },
	{ USB_DEVICE(MCT_U232_VID, MCT_U232_DU_H3SP_PID) },
	{ USB_DEVICE(MCT_U232_BELKIN_F5U109_VID, MCT_U232_BELKIN_F5U109_PID) },
	{ }		/* Terminating entry */
};

MODULE_DEVICE_TABLE(usb, id_table_combined);

static struct usb_driver mct_u232_driver = {
	.name =		"mct_u232",
	.probe =	usb_serial_probe,
	.disconnect =	usb_serial_disconnect,
	.id_table =	id_table_combined,
	.no_dynamic_id = 	1,
};

static struct usb_serial_driver mct_u232_device = {
	.driver = {
		.owner =	THIS_MODULE,
		.name =		"mct_u232",
	},
	.description =	     "MCT U232",
	.usb_driver = 	     &mct_u232_driver,
	.id_table =	     id_table_combined,
	.num_ports =	     1,
	.open =		     mct_u232_open,
	.close =	     mct_u232_close,
	.dtr_rts =	     mct_u232_dtr_rts,
	.throttle =	     mct_u232_throttle,
	.unthrottle =	     mct_u232_unthrottle,
	.read_int_callback = mct_u232_read_int_callback,
	.set_termios =	     mct_u232_set_termios,
	.break_ctl =	     mct_u232_break_ctl,
	.tiocmget =	     mct_u232_tiocmget,
	.tiocmset =	     mct_u232_tiocmset,
	.attach =	     mct_u232_startup,
	.release =	     mct_u232_release,
};


struct mct_u232_private {
	spinlock_t lock;
	unsigned int	     control_state; /* Modem Line Setting (TIOCM) */
	unsigned char        last_lcr;      /* Line Control Register */
	unsigned char	     last_lsr;      /* Line Status Register */
	unsigned char	     last_msr;      /* Modem Status Register */
	unsigned int	     rx_flags;      /* Throttling flags */
};

#define THROTTLED		0x01

/*
 * Handle vendor specific USB requests
 */

#define WDR_TIMEOUT 5000 /* default urb timeout */

/*
 * Later day 2.6.0-test kernels have new baud rates like B230400 which
 * we do not know how to support. We ignore them for the moment.
 */
static int mct_u232_calculate_baud_rate(struct usb_serial *serial,
					speed_t value, speed_t *result)
{
	*result = value;

	if (le16_to_cpu(serial->dev->descriptor.idProduct) == MCT_U232_SITECOM_PID
		|| le16_to_cpu(serial->dev->descriptor.idProduct) == MCT_U232_BELKIN_F5U109_PID) {
		switch (value) {
		case 300:
			return 0x01;
		case 600:
			return 0x02; /* this one not tested */
		case 1200:
			return 0x03;
		case 2400:
			return 0x04;
		case 4800:
			return 0x06;
		case 9600:
			return 0x08;
		case 19200:
			return 0x09;
		case 38400:
			return 0x0a;
		case 57600:
			return 0x0b;
		case 115200:
			return 0x0c;
		default:
			*result = 9600;
			return 0x08;
		}
	} else {
		/* FIXME: Can we use any divider - should we do
		   divider = 115200/value;
		   real baud = 115200/divider */
		switch (value) {
		case 300: break;
		case 600: break;
		case 1200: break;
		case 2400: break;
		case 4800: break;
		case 9600: break;
		case 19200: break;
		case 38400: break;
		case 57600: break;
		case 115200: break;
		default:
			value = 9600;
			*result = 9600;
		}
		return 115200/value;
	}
}

static int mct_u232_set_baud_rate(struct tty_struct *tty,
	struct usb_serial *serial, struct usb_serial_port *port, speed_t value)
{
	__le32 divisor;
	int rc;
	unsigned char zero_byte = 0;
	unsigned char cts_enable_byte = 0;
	speed_t speed;

	divisor = cpu_to_le32(mct_u232_calculate_baud_rate(serial, value,
								&speed));

	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
				MCT_U232_SET_BAUD_RATE_REQUEST,
				MCT_U232_SET_REQUEST_TYPE,
				0, 0, &divisor, MCT_U232_SET_BAUD_RATE_SIZE,
				WDR_TIMEOUT);
	if (rc < 0)	/*FIXME: What value speed results */
		dev_err(&port->dev, "Set BAUD RATE %d failed (error = %d)\n",
			value, rc);
	else
		tty_encode_baud_rate(tty, speed, speed);
	dbg("set_baud_rate: value: 0x%x, divisor: 0x%x", value, divisor);

	/* Mimic the MCT-supplied Windows driver (version 1.21P.0104), which
	   always sends two extra USB 'device request' messages after the
	   'baud rate change' message.  The actual functionality of the
	   request codes in these messages is not fully understood but these
	   particular codes are never seen in any operation besides a baud
	   rate change.  Both of these messages send a single byte of data.
	   In the first message, the value of this byte is always zero.

	   The second message has been determined experimentally to control
	   whether data will be transmitted to a device which is not asserting
	   the 'CTS' signal.  If the second message's data byte is zero, data
	   will be transmitted even if 'CTS' is not asserted (i.e. no hardware
	   flow control).  if the second message's data byte is nonzero (a
	   value of 1 is used by this driver), data will not be transmitted to
	   a device which is not asserting 'CTS'.
	*/

	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
				MCT_U232_SET_UNKNOWN1_REQUEST,
				MCT_U232_SET_REQUEST_TYPE,
				0, 0, &zero_byte, MCT_U232_SET_UNKNOWN1_SIZE,
				WDR_TIMEOUT);
	if (rc < 0)
		dev_err(&port->dev, "Sending USB device request code %d "
			"failed (error = %d)\n", MCT_U232_SET_UNKNOWN1_REQUEST,
			rc);

	if (port && C_CRTSCTS(tty))
	   cts_enable_byte = 1;

	dbg("set_baud_rate: send second control message, data = %02X",
							cts_enable_byte);
	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
			MCT_U232_SET_CTS_REQUEST,
			MCT_U232_SET_REQUEST_TYPE,
			0, 0, &cts_enable_byte, MCT_U232_SET_CTS_SIZE,
			WDR_TIMEOUT);
	if (rc < 0)
		dev_err(&port->dev, "Sending USB device request code %d "
			"failed (error = %d)\n", MCT_U232_SET_CTS_REQUEST, rc);

	return rc;
} /* mct_u232_set_baud_rate */

static int mct_u232_set_line_ctrl(struct usb_serial *serial, unsigned char lcr)
{
	int rc;
	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
			MCT_U232_SET_LINE_CTRL_REQUEST,
			MCT_U232_SET_REQUEST_TYPE,
			0, 0, &lcr, MCT_U232_SET_LINE_CTRL_SIZE,
			WDR_TIMEOUT);
	if (rc < 0)
		dev_err(&serial->dev->dev,
			"Set LINE CTRL 0x%x failed (error = %d)\n", lcr, rc);
	dbg("set_line_ctrl: 0x%x", lcr);
	return rc;
} /* mct_u232_set_line_ctrl */

static int mct_u232_set_modem_ctrl(struct usb_serial *serial,
				   unsigned int control_state)
{
	int rc;
	unsigned char mcr = MCT_U232_MCR_NONE;

	if (control_state & TIOCM_DTR)
		mcr |= MCT_U232_MCR_DTR;
	if (control_state & TIOCM_RTS)
		mcr |= MCT_U232_MCR_RTS;

	rc = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
			MCT_U232_SET_MODEM_CTRL_REQUEST,
			MCT_U232_SET_REQUEST_TYPE,
			0, 0, &mcr, MCT_U232_SET_MODEM_CTRL_SIZE,
			WDR_TIMEOUT);
	if (rc < 0)
		dev_err(&serial->dev->dev,
			"Set MODEM CTRL 0x%x failed (error = %d)\n", mcr, rc);
	dbg("set_modem_ctrl: state=0x%x ==> mcr=0x%x", control_state, mcr);

	return rc;
} /* mct_u232_set_modem_ctrl */

static int mct_u232_get_modem_stat(struct usb_serial *serial,
						unsigned char *msr)
{
	int rc;
	rc = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
			MCT_U232_GET_MODEM_STAT_REQUEST,
			MCT_U232_GET_REQUEST_TYPE,
			0, 0, msr, MCT_U232_GET_MODEM_STAT_SIZE,
			WDR_TIMEOUT);
	if (rc < 0) {
		dev_err(&serial->dev->dev,
			"Get MODEM STATus failed (error = %d)\n", rc);
		*msr = 0;
	}
	dbg("get_modem_stat: 0x%x", *msr);
	return rc;
} /* mct_u232_get_modem_stat */

static void mct_u232_msr_to_state(unsigned int *control_state,
						unsigned char msr)
{
	/* Translate Control Line states */
	if (msr & MCT_U232_MSR_DSR)
		*control_state |=  TIOCM_DSR;
	else
		*control_state &= ~TIOCM_DSR;
	if (msr & MCT_U232_MSR_CTS)
		*control_state |=  TIOCM_CTS;
	else
		*control_state &= ~TIOCM_CTS;
	if (msr & MCT_U232_MSR_RI)
		*control_state |=  TIOCM_RI;
	else
		*control_state &= ~TIOCM_RI;
	if (msr & MCT_U232_MSR_CD)
		*control_state |=  TIOCM_CD;
	else
		*control_state &= ~TIOCM_CD;
	dbg("msr_to_state: msr=0x%x ==> state=0x%x", msr, *control_state);
} /* mct_u232_msr_to_state */

/*
 * Driver's tty interface functions
 */

static int mct_u232_startup(struct usb_serial *serial)
{
	struct mct_u232_private *priv;
	struct usb_serial_port *port, *rport;

	priv = kzalloc(sizeof(struct mct_u232_private), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;
	spin_lock_init(&priv->lock);
	usb_set_serial_port_data(serial->port[0], priv);

	init_waitqueue_head(&serial->port[0]->write_wait);

	/* Puh, that's dirty */
	port = serial->port[0];
	rport = serial->port[1];
	/* No unlinking, it wasn't submitted yet. */
	usb_free_urb(port->read_urb);
	port->read_urb = rport->interrupt_in_urb;
	rport->interrupt_in_urb = NULL;
	port->read_urb->context = port;

	return 0;
} /* mct_u232_startup */


static void mct_u232_release(struct usb_serial *serial)
{
	struct mct_u232_private *priv;
	int i;

	dbg("%s", __func__);

	for (i = 0; i < serial->num_ports; ++i) {
		/* My special items, the standard routines free my urbs */
		priv = usb_get_serial_port_data(serial->port[i]);
		kfree(priv);
	}
} /* mct_u232_release */

static int  mct_u232_open(struct tty_struct *tty,
			struct usb_serial_port *port, struct file *filp)
{
	struct usb_serial *serial = port->serial;
	struct mct_u232_private *priv = usb_get_serial_port_data(port);
	int retval = 0;
	unsigned int control_state;
	unsigned long flags;
	unsigned char last_lcr;
	unsigned char last_msr;

	dbg("%s port %d", __func__, port->number);

	/* Compensate for a hardware bug: although the Sitecom U232-P25
	 * device reports a maximum output packet size of 32 bytes,
	 * it seems to be able to accept only 16 bytes (and that's what
	 * SniffUSB says too...)
	 */
	if (le16_to_cpu(serial->dev->descriptor.idProduct)
						== MCT_U232_SITECOM_PID)
		port->bulk_out_size = 16;

	/* Do a defined restart: the normal serial device seems to
	 * always turn on DTR and RTS here, so do the same. I'm not
	 * sure if this is really necessary. But it should not harm
	 * either.
	 */
	spin_lock_irqsave(&priv->lock, flags);
	if (tty && (tty->termios->c_cflag & CBAUD))
		priv->control_state = TIOCM_DTR | TIOCM_RTS;
	else
		priv->control_state = 0;

	priv->last_lcr = (MCT_U232_DATA_BITS_8 |
			  MCT_U232_PARITY_NONE |
			  MCT_U232_STOP_BITS_1);
	control_state = priv->control_state;
	last_lcr = priv->last_lcr;
	spin_unlock_irqrestore(&priv->lock, flags);
	mct_u232_set_modem_ctrl(serial, control_state);
	mct_u232_set_line_ctrl(serial, last_lcr);

	/* Read modem status and update control state */
	mct_u232_get_modem_stat(serial, &last_msr);
	spin_lock_irqsave(&priv->lock, flags);
	priv->last_msr = last_msr;
	mct_u232_msr_to_state(&priv->control_state, priv->last_msr);
	spin_unlock_irqrestore(&priv->lock, flags);

	port->read_urb->dev = port->serial->dev;
	retval = usb_submit_urb(port->read_urb, GFP_KERNEL);
	if (retval) {
		dev_err(&port->dev,
			"usb_submit_urb(read bulk) failed pipe 0x%x err %d\n",
			port->read_urb->pipe, retval);
		goto error;
	}

	port->interrupt_in_urb->dev = port->serial->dev;
	retval = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
	if (retval) {
		usb_kill_urb(port->read_urb);
		dev_err(&port->dev,
			"usb_submit_urb(read int) failed pipe 0x%x err %d",
			port->interrupt_in_urb->pipe, retval);
		goto error;
	}
	return 0;

error:
	return retval;
} /* mct_u232_open */

static void mct_u232_dtr_rts(struct usb_serial_port *port, int on)
{
	unsigned int control_state;
	struct mct_u232_private *priv = usb_get_serial_port_data(port);

	mutex_lock(&port->serial->disc_mutex);
	if (!port->serial->disconnected) {
		/* drop DTR and RTS */
		spin_lock_irq(&priv->lock);
		if (on)
			priv->control_state |= TIOCM_DTR | TIOCM_RTS;
		else
			priv->control_state &= ~(TIOCM_DTR | TIOCM_RTS);
		control_state = priv->control_state;
		spin_unlock_irq(&priv->lock);
		mct_u232_set_modem_ctrl(port->serial, control_state);
	}
	mutex_unlock(&port->serial->disc_mutex);
}

static void mct_u232_close(struct usb_serial_port *port)
{
	dbg("%s port %d", __func__, port->number);

	if (port->serial->dev) {
		/* shutdown our urbs */
		usb_kill_urb(port->write_urb);
		usb_kill_urb(port->read_urb);
		usb_kill_urb(port->interrupt_in_urb);
	}
} /* mct_u232_close */


static void mct_u232_read_int_callback(struct urb *urb)
{
	struct usb_serial_port *port = urb->context;
	struct mct_u232_private *priv = usb_get_serial_port_data(port);
	struct usb_serial *serial = port->serial;
	struct tty_struct *tty;
	unsigned char *data = urb->transfer_buffer;
	int retval;
	int status = urb->status;
	unsigned long flags;

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

	if (!serial) {
		dbg("%s - bad serial pointer, exiting", __func__);
		return;
	}

	dbg("%s - port %d", __func__, port->number);
	usb_serial_debug_data(debug, &port->dev, __func__,
					urb->actual_length, data);

	/*
	 * Work-a-round: handle the 'usual' bulk-in pipe here
	 */
	if (urb->transfer_buffer_length > 2) {
		tty = tty_port_tty_get(&port->port);
		if (urb->actual_length) {
			tty_insert_flip_string(tty, data, urb->actual_length);
			tty_flip_buffer_push(tty);
			tty_kref_put(tty);
		}
		goto exit;
	}

	/*
	 * The interrupt-in pipe signals exceptional conditions (modem line
	 * signal changes and errors). data[0] holds MSR, data[1] holds LSR.
	 */
	spin_lock_irqsave(&priv->lock, flags);
	priv->last_msr = data[MCT_U232_MSR_INDEX];

	/* Record Control Line states */
	mct_u232_msr_to_state(&priv->control_state, priv->last_msr);

#if 0
	/* Not yet handled. See belkin_sa.c for further information */
	/* Now to report any errors */
	priv->last_lsr = data[MCT_U232_LSR_INDEX];
	/*
	 * fill in the flip buffer here, but I do not know the relation
	 * to the current/next receive buffer or characters.  I need
	 * to look in to this before committing any code.
	 */
	if (priv->last_lsr & MCT_U232_LSR_ERR) {
		tty = tty_port_tty_get(&port->port);
		/* Overrun Error */
		if (priv->last_lsr & MCT_U232_LSR_OE) {
		}
		/* Parity Error */
		if (priv->last_lsr & MCT_U232_LSR_PE) {
		}
		/* Framing Error */
		if (priv->last_lsr & MCT_U232_LSR_FE) {
		}
		/* Break Indicator */
		if (priv->last_lsr & MCT_U232_LSR_BI) {
		}
		tty_kref_put(tty);
	}
#endif
	spin_unlock_irqrestore(&priv->lock, flags);
exit:
	retval = usb_submit_urb(urb, GFP_ATOMIC);
	if (retval)
		dev_err(&port->dev,
			"%s - usb_submit_urb failed with result %d\n",
			__func__, retval);
} /* mct_u232_read_int_callback */

static void mct_u232_set_termios(struct tty_struct *tty,
				 struct usb_serial_port *port,
				 struct ktermios *old_termios)
{
	struct usb_serial *serial = port->serial;
	struct mct_u232_private *priv = usb_get_serial_port_data(port);
	struct ktermios *termios = tty->termios;
	unsigned int cflag = termios->c_cflag;
	unsigned int old_cflag = old_termios->c_cflag;
	unsigned long flags;
	unsigned int control_state;
	unsigned char last_lcr;

	/* get a local copy of the current port settings */
	spin_lock_irqsave(&priv->lock, flags);
	control_state = priv->control_state;
	spin_unlock_irqrestore(&priv->lock, flags);
	last_lcr = 0;

	/*
	 * Update baud rate.
	 * Do not attempt to cache old rates and skip settings,
	 * disconnects screw such tricks up completely.
	 * Premature optimization is the root of all evil.
	 */

	/* reassert DTR and RTS on transition from B0 */
	if ((old_cflag & CBAUD) == B0) {
		dbg("%s: baud was B0", __func__);
		control_state |= TIOCM_DTR | TIOCM_RTS;
		mct_u232_set_modem_ctrl(serial, control_state);
	}

	mct_u232_set_baud_rate(tty, serial, port, tty_get_baud_rate(tty));

	if ((cflag & CBAUD) == B0) {
		dbg("%s: baud is B0", __func__);
		/* Drop RTS and DTR */
		control_state &= ~(TIOCM_DTR | TIOCM_RTS);
		mct_u232_set_modem_ctrl(serial, control_state);
	}

	/*
	 * Update line control register (LCR)
	 */

	/* set the parity */
	if (cflag & PARENB)
		last_lcr |= (cflag & PARODD) ?
			MCT_U232_PARITY_ODD : MCT_U232_PARITY_EVEN;
	else
		last_lcr |= MCT_U232_PARITY_NONE;

	/* set the number of data bits */
	switch (cflag & CSIZE) {
	case CS5:
		last_lcr |= MCT_U232_DATA_BITS_5; break;
	case CS6:
		last_lcr |= MCT_U232_DATA_BITS_6; break;
	case CS7:
		last_lcr |= MCT_U232_DATA_BITS_7; break;
	case CS8:
		last_lcr |= MCT_U232_DATA_BITS_8; break;
	default:
		dev_err(&port->dev,
			"CSIZE was not CS5-CS8, using default of 8\n");
		last_lcr |= MCT_U232_DATA_BITS_8;
		break;
	}

	termios->c_cflag &= ~CMSPAR;

	/* set the number of stop bits */
	last_lcr |= (cflag & CSTOPB) ?
		MCT_U232_STOP_BITS_2 : MCT_U232_STOP_BITS_1;

	mct_u232_set_line_ctrl(serial, last_lcr);

	/* save off the modified port settings */
	spin_lock_irqsave(&priv->lock, flags);
	priv->control_state = control_state;
	priv->last_lcr = last_lcr;
	spin_unlock_irqrestore(&priv->lock, flags);
} /* mct_u232_set_termios */

static void mct_u232_break_ctl(struct tty_struct *tty, int break_state)
{
	struct usb_serial_port *port = tty->driver_data;
	struct usb_serial *serial = port->serial;
	struct mct_u232_private *priv = usb_get_serial_port_data(port);
	unsigned char lcr;
	unsigned long flags;

	dbg("%sstate=%d", __func__, break_state);

	spin_lock_irqsave(&priv->lock, flags);
	lcr = priv->last_lcr;

	if (break_state)
		lcr |= MCT_U232_SET_BREAK;
	spin_unlock_irqrestore(&priv->lock, flags);

	mct_u232_set_line_ctrl(serial, lcr);
} /* mct_u232_break_ctl */


static int mct_u232_tiocmget(struct tty_struct *tty, struct file *file)
{
	struct usb_serial_port *port = tty->driver_data;
	struct mct_u232_private *priv = usb_get_serial_port_data(port);
	unsigned int control_state;
	unsigned long flags;

	dbg("%s", __func__);

	spin_lock_irqsave(&priv->lock, flags);
	control_state = priv->control_state;
	spin_unlock_irqrestore(&priv->lock, flags);

	return control_state;
}

static int mct_u232_tiocmset(struct tty_struct *tty, struct file *file,
			      unsigned int set, unsigned int clear)
{
	struct usb_serial_port *port = tty->driver_data;
	struct usb_serial *serial = port->serial;
	struct mct_u232_private *priv = usb_get_serial_port_data(port);
	unsigned int control_state;
	unsigned long flags;

	dbg("%s", __func__);

	spin_lock_irqsave(&priv->lock, flags);
	control_state = priv->control_state;

	if (set & TIOCM_RTS)
		control_state |= TIOCM_RTS;
	if (set & TIOCM_DTR)
		control_state |= TIOCM_DTR;
	if (clear & TIOCM_RTS)
		control_state &= ~TIOCM_RTS;
	if (clear & TIOCM_DTR)
		control_state &= ~TIOCM_DTR;

	priv->control_state = control_state;
	spin_unlock_irqrestore(&priv->lock, flags);
	return mct_u232_set_modem_ctrl(serial, control_state);
}

static void mct_u232_throttle(struct tty_struct *tty)
{
	struct usb_serial_port *port = tty->driver_data;
	struct mct_u232_private *priv = usb_get_serial_port_data(port);
	unsigned long flags;
	unsigned int control_state;

	dbg("%s - port %d", __func__, port->number);

	spin_lock_irqsave(&priv->lock, flags);
	priv->rx_flags |= THROTTLED;
	if (C_CRTSCTS(tty)) {
		priv->control_state &= ~TIOCM_RTS;
		control_state = priv->control_state;
		spin_unlock_irqrestore(&priv->lock, flags);
		(void) mct_u232_set_modem_ctrl(port->serial, control_state);
	} else {
		spin_unlock_irqrestore(&priv->lock, flags);
	}
}


static void mct_u232_unthrottle(struct tty_struct *tty)
{
	struct usb_serial_port *port = tty->driver_data;
	struct mct_u232_private *priv = usb_get_serial_port_data(port);
	unsigned long flags;
	unsigned int control_state;

	dbg("%s - port %d", __func__, port->number);

	spin_lock_irqsave(&priv->lock, flags);
	if ((priv->rx_flags & THROTTLED) && C_CRTSCTS(tty)) {
		priv->rx_flags &= ~THROTTLED;
		priv->control_state |= TIOCM_RTS;
		control_state = priv->control_state;
		spin_unlock_irqrestore(&priv->lock, flags);
		(void) mct_u232_set_modem_ctrl(port->serial, control_state);
	} else {
		spin_unlock_irqrestore(&priv->lock, flags);
	}
}

static int __init mct_u232_init(void)
{
	int retval;
	retval = usb_serial_register(&mct_u232_device);
	if (retval)
		goto failed_usb_serial_register;
	retval = usb_register(&mct_u232_driver);
	if (retval)
		goto failed_usb_register;
	printk(KERN_INFO KBUILD_MODNAME ": " DRIVER_VERSION ":"
	       DRIVER_DESC "\n");
	return 0;
failed_usb_register:
	usb_serial_deregister(&mct_u232_device);
failed_usb_serial_register:
	return retval;
}


static void __exit mct_u232_exit(void)
{
	usb_deregister(&mct_u232_driver);
	usb_serial_deregister(&mct_u232_device);
}

module_init(mct_u232_init);
module_exit(mct_u232_exit);

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

module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Debug enabled or not");