summaryrefslogtreecommitdiffstats
path: root/drivers/usb/serial/cp2101.c
blob: dc0ea08ed2315773b0f85fbcaf25848d83d69be9 (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
/*
 * Silicon Laboratories CP2101/CP2102 USB to RS232 serial adaptor driver
 *
 * Copyright (C) 2005 Craig Shelley (craig@microtron.org.uk)
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License version
 *	2 as published by the Free Software Foundation.
 *
 * Support to set flow control line levels using TIOCMGET and TIOCMSET
 * thanks to Karl Hiramoto karl@hiramoto.org. RTSCTS hardware flow
 * control thanks to Munir Nassar nassarmu@real-time.com
 *
 * Outstanding Issues:
 *  Buffers are not flushed when the port is opened.
 *  Multiple calls to write() may fail with "Resource temporarily unavailable"
 *
 */

#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/usb.h>
#include <asm/uaccess.h>
#include <linux/usb/serial.h>

/*
 * Version Information
 */
#define DRIVER_VERSION "v0.07"
#define DRIVER_DESC "Silicon Labs CP2101/CP2102 RS232 serial adaptor driver"

/*
 * Function Prototypes
 */
static int cp2101_open(struct usb_serial_port*, struct file*);
static void cp2101_cleanup(struct usb_serial_port*);
static void cp2101_close(struct usb_serial_port*, struct file*);
static void cp2101_get_termios(struct usb_serial_port*);
static void cp2101_set_termios(struct usb_serial_port*, struct ktermios*);
static int cp2101_tiocmget (struct usb_serial_port *, struct file *);
static int cp2101_tiocmset (struct usb_serial_port *, struct file *,
		unsigned int, unsigned int);
static void cp2101_break_ctl(struct usb_serial_port*, int);
static int cp2101_startup (struct usb_serial *);
static void cp2101_shutdown(struct usb_serial*);


static int debug;

static struct usb_device_id id_table [] = {
	{ USB_DEVICE(0x0489, 0xE000) }, /* Pirelli Broadband S.p.A, DP-L10 SIP/GSM Mobile */
	{ USB_DEVICE(0x08e6, 0x5501) }, /* Gemalto Prox-PU/CU contactless smartcard reader */
	{ USB_DEVICE(0x0FCF, 0x1003) }, /* Dynastream ANT development board */
	{ USB_DEVICE(0x0FCF, 0x1004) }, /* Dynastream ANT2USB */
	{ USB_DEVICE(0x0FCF, 0x1006) }, /* Dynastream ANT development board */
	{ USB_DEVICE(0x10A6, 0xAA26) }, /* Knock-off DCU-11 cable */
	{ USB_DEVICE(0x10AB, 0x10C5) }, /* Siemens MC60 Cable */
	{ USB_DEVICE(0x10B5, 0xAC70) }, /* Nokia CA-42 USB */
	{ USB_DEVICE(0x10C4, 0x800A) }, /* SPORTident BSM7-D-USB main station */
	{ USB_DEVICE(0x10C4, 0x803B) }, /* Pololu USB-serial converter */
	{ USB_DEVICE(0x10C4, 0x8053) }, /* Enfora EDG1228 */
	{ USB_DEVICE(0x10C4, 0x8066) }, /* Argussoft In-System Programmer */
	{ USB_DEVICE(0x10C4, 0x807A) }, /* Crumb128 board */
	{ USB_DEVICE(0x10C4, 0x80CA) }, /* Degree Controls Inc */
	{ USB_DEVICE(0x10C4, 0x80DD) }, /* Tracient RFID */
	{ USB_DEVICE(0x10C4, 0x80F6) }, /* Suunto sports instrument */
	{ USB_DEVICE(0x10C4, 0x813D) }, /* Burnside Telecom Deskmobile */
	{ USB_DEVICE(0x10C4, 0x814A) }, /* West Mountain Radio RIGblaster P&P */
	{ USB_DEVICE(0x10C4, 0x814B) }, /* West Mountain Radio RIGtalk */
	{ USB_DEVICE(0x10C4, 0x815E) }, /* Helicomm IP-Link 1220-DVM */
	{ USB_DEVICE(0x10C4, 0x81AC) }, /* MSD Dash Hawk */
	{ USB_DEVICE(0x10C4, 0x81C8) }, /* Lipowsky Industrie Elektronik GmbH, Baby-JTAG */
	{ USB_DEVICE(0x10C4, 0x81E2) }, /* Lipowsky Industrie Elektronik GmbH, Baby-LIN */
	{ USB_DEVICE(0x10C4, 0x81E7) }, /* Aerocomm Radio */
	{ USB_DEVICE(0x10C4, 0x8218) }, /* Lipowsky Industrie Elektronik GmbH, HARP-1 */
	{ USB_DEVICE(0x10c4, 0x8293) }, /* Telegesys ETRX2USB */
	{ USB_DEVICE(0x10C4, 0xEA60) }, /* Silicon Labs factory default */
	{ USB_DEVICE(0x10C4, 0xEA61) }, /* Silicon Labs factory default */
	{ USB_DEVICE(0x10C4, 0xF001) }, /* Elan Digital Systems USBscope50 */
	{ USB_DEVICE(0x10C4, 0xF002) }, /* Elan Digital Systems USBwave12 */
	{ USB_DEVICE(0x10C4, 0xF003) }, /* Elan Digital Systems USBpulse100 */
	{ USB_DEVICE(0x10C4, 0xF004) }, /* Elan Digital Systems USBcount50 */
	{ USB_DEVICE(0x10C5, 0xEA61) }, /* Silicon Labs MobiData GPRS USB Modem */
	{ USB_DEVICE(0x13AD, 0x9999) }, /* Baltech card reader */
	{ USB_DEVICE(0x166A, 0x0303) }, /* Clipsal 5500PCU C-Bus USB interface */
	{ USB_DEVICE(0x16D6, 0x0001) }, /* Jablotron serial interface */
	{ } /* Terminating Entry */
};

MODULE_DEVICE_TABLE (usb, id_table);

static struct usb_driver cp2101_driver = {
	.name		= "cp2101",
	.probe		= usb_serial_probe,
	.disconnect	= usb_serial_disconnect,
	.id_table	= id_table,
	.no_dynamic_id	= 	1,
};

static struct usb_serial_driver cp2101_device = {
	.driver = {
		.owner =	THIS_MODULE,
		.name = 	"cp2101",
	},
	.usb_driver		= &cp2101_driver,
	.id_table		= id_table,
	.num_ports		= 1,
	.open			= cp2101_open,
	.close			= cp2101_close,
	.break_ctl		= cp2101_break_ctl,
	.set_termios		= cp2101_set_termios,
	.tiocmget 		= cp2101_tiocmget,
	.tiocmset		= cp2101_tiocmset,
	.attach			= cp2101_startup,
	.shutdown		= cp2101_shutdown,
};

/* Config request types */
#define REQTYPE_HOST_TO_DEVICE	0x41
#define REQTYPE_DEVICE_TO_HOST	0xc1

/* Config SET requests. To GET, add 1 to the request number */
#define CP2101_UART 		0x00	/* Enable / Disable */
#define CP2101_BAUDRATE		0x01	/* (BAUD_RATE_GEN_FREQ / baudrate) */
#define CP2101_BITS		0x03	/* 0x(0)(databits)(parity)(stopbits) */
#define CP2101_BREAK		0x05	/* On / Off */
#define CP2101_CONTROL		0x07	/* Flow control line states */
#define CP2101_MODEMCTL		0x13	/* Modem controls */
#define CP2101_CONFIG_6		0x19	/* 6 bytes of config data ??? */

/* CP2101_UART */
#define UART_ENABLE		0x0001
#define UART_DISABLE		0x0000

/* CP2101_BAUDRATE */
#define BAUD_RATE_GEN_FREQ	0x384000

/* CP2101_BITS */
#define BITS_DATA_MASK		0X0f00
#define BITS_DATA_5		0X0500
#define BITS_DATA_6		0X0600
#define BITS_DATA_7		0X0700
#define BITS_DATA_8		0X0800
#define BITS_DATA_9		0X0900

#define BITS_PARITY_MASK	0x00f0
#define BITS_PARITY_NONE	0x0000
#define BITS_PARITY_ODD		0x0010
#define BITS_PARITY_EVEN	0x0020
#define BITS_PARITY_MARK	0x0030
#define BITS_PARITY_SPACE	0x0040

#define BITS_STOP_MASK		0x000f
#define BITS_STOP_1		0x0000
#define BITS_STOP_1_5		0x0001
#define BITS_STOP_2		0x0002

/* CP2101_BREAK */
#define BREAK_ON		0x0000
#define BREAK_OFF		0x0001

/* CP2101_CONTROL */
#define CONTROL_DTR		0x0001
#define CONTROL_RTS		0x0002
#define CONTROL_CTS		0x0010
#define CONTROL_DSR		0x0020
#define CONTROL_RING		0x0040
#define CONTROL_DCD		0x0080
#define CONTROL_WRITE_DTR	0x0100
#define CONTROL_WRITE_RTS	0x0200

/*
 * cp2101_get_config
 * Reads from the CP2101 configuration registers
 * 'size' is specified in bytes.
 * 'data' is a pointer to a pre-allocated array of integers large
 * enough to hold 'size' bytes (with 4 bytes to each integer)
 */
static int cp2101_get_config(struct usb_serial_port* port, u8 request,
		unsigned int *data, int size)
{
	struct usb_serial *serial = port->serial;
	__le32 *buf;
	int result, i, length;

	/* Number of integers required to contain the array */
	length = (((size - 1) | 3) + 1)/4;

	buf = kcalloc(length, sizeof(__le32), GFP_KERNEL);
	if (!buf) {
		dev_err(&port->dev, "%s - out of memory.\n", __func__);
		return -ENOMEM;
	}

	/* For get requests, the request number must be incremented */
	request++;

	/* Issue the request, attempting to read 'size' bytes */
	result = usb_control_msg (serial->dev,usb_rcvctrlpipe (serial->dev, 0),
				request, REQTYPE_DEVICE_TO_HOST, 0x0000,
				0, buf, size, 300);

	/* Convert data into an array of integers */
	for (i=0; i<length; i++)
		data[i] = le32_to_cpu(buf[i]);

	kfree(buf);

	if (result != size) {
		dev_err(&port->dev, "%s - Unable to send config request, "
				"request=0x%x size=%d result=%d\n",
				__func__, request, size, result);
		return -EPROTO;
	}

	return 0;
}

/*
 * cp2101_set_config
 * Writes to the CP2101 configuration registers
 * Values less than 16 bits wide are sent directly
 * 'size' is specified in bytes.
 */
static int cp2101_set_config(struct usb_serial_port* port, u8 request,
		unsigned int *data, int size)
{
	struct usb_serial *serial = port->serial;
	__le32 *buf;
	int result, i, length;

	/* Number of integers required to contain the array */
	length = (((size - 1) | 3) + 1)/4;

	buf = kmalloc(length * sizeof(__le32), GFP_KERNEL);
	if (!buf) {
		dev_err(&port->dev, "%s - out of memory.\n",
				__func__);
		return -ENOMEM;
	}

	/* Array of integers into bytes */
	for (i = 0; i < length; i++)
		buf[i] = cpu_to_le32(data[i]);

	if (size > 2) {
		result = usb_control_msg (serial->dev,
				usb_sndctrlpipe(serial->dev, 0),
				request, REQTYPE_HOST_TO_DEVICE, 0x0000,
				0, buf, size, 300);
	} else {
		result = usb_control_msg (serial->dev,
				usb_sndctrlpipe(serial->dev, 0),
				request, REQTYPE_HOST_TO_DEVICE, data[0],
				0, NULL, 0, 300);
	}

	kfree(buf);

	if ((size > 2 && result != size) || result < 0) {
		dev_err(&port->dev, "%s - Unable to send request, "
				"request=0x%x size=%d result=%d\n",
				__func__, request, size, result);
		return -EPROTO;
	}

	/* Single data value */
	result = usb_control_msg (serial->dev,
			usb_sndctrlpipe(serial->dev, 0),
			request, REQTYPE_HOST_TO_DEVICE, data[0],
			0, NULL, 0, 300);
	return 0;
}

/*
 * cp2101_set_config_single
 * Convenience function for calling cp2101_set_config on single data values
 * without requiring an integer pointer
 */
static inline int cp2101_set_config_single(struct usb_serial_port* port,
		u8 request, unsigned int data)
{
	return cp2101_set_config(port, request, &data, 2);
}

static int cp2101_open (struct usb_serial_port *port, struct file *filp)
{
	struct usb_serial *serial = port->serial;
	int result;

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

	if (cp2101_set_config_single(port, CP2101_UART, UART_ENABLE)) {
		dev_err(&port->dev, "%s - Unable to enable UART\n",
				__func__);
		return -EPROTO;
	}

	/* Start reading from the device */
	usb_fill_bulk_urb (port->read_urb, serial->dev,
			usb_rcvbulkpipe(serial->dev,
			port->bulk_in_endpointAddress),
			port->read_urb->transfer_buffer,
			port->read_urb->transfer_buffer_length,
			serial->type->read_bulk_callback,
			port);
	result = usb_submit_urb(port->read_urb, GFP_KERNEL);
	if (result) {
		dev_err(&port->dev, "%s - failed resubmitting read urb, "
				"error %d\n", __func__, result);
		return result;
	}

	/* Configure the termios structure */
	cp2101_get_termios(port);

	/* Set the DTR and RTS pins low */
	cp2101_tiocmset(port, NULL, TIOCM_DTR | TIOCM_RTS, 0);

	return 0;
}

static void cp2101_cleanup (struct usb_serial_port *port)
{
	struct usb_serial *serial = port->serial;

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

	if (serial->dev) {
		/* shutdown any bulk reads that might be going on */
		if (serial->num_bulk_out)
			usb_kill_urb(port->write_urb);
		if (serial->num_bulk_in)
			usb_kill_urb(port->read_urb);
	}
}

static void cp2101_close (struct usb_serial_port *port, struct file * filp)
{
	dbg("%s - port %d", __func__, port->number);

	/* shutdown our urbs */
	dbg("%s - shutting down urbs", __func__);
	usb_kill_urb(port->write_urb);
	usb_kill_urb(port->read_urb);

	mutex_lock(&port->serial->disc_mutex);
	if (!port->serial->disconnected)
		cp2101_set_config_single(port, CP2101_UART, UART_DISABLE);
	mutex_unlock(&port->serial->disc_mutex);
}

/*
 * cp2101_get_termios
 * Reads the baud rate, data bits, parity, stop bits and flow control mode
 * from the device, corrects any unsupported values, and configures the
 * termios structure to reflect the state of the device
 */
static void cp2101_get_termios (struct usb_serial_port *port)
{
	unsigned int cflag, modem_ctl[4];
	int baud;
	int bits;

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

	if (!port->tty || !port->tty->termios) {
		dbg("%s - no tty structures", __func__);
		return;
	}

	cp2101_get_config(port, CP2101_BAUDRATE, &baud, 2);
	/* Convert to baudrate */
	if (baud)
		baud = BAUD_RATE_GEN_FREQ / baud;

	dbg("%s - baud rate = %d", __func__, baud);

	tty_encode_baud_rate(port->tty, baud, baud);
	cflag = port->tty->termios->c_cflag;

	cp2101_get_config(port, CP2101_BITS, &bits, 2);
	cflag &= ~CSIZE;
	switch(bits & BITS_DATA_MASK) {
		case BITS_DATA_5:
			dbg("%s - data bits = 5", __func__);
			cflag |= CS5;
			break;
		case BITS_DATA_6:
			dbg("%s - data bits = 6", __func__);
			cflag |= CS6;
			break;
		case BITS_DATA_7:
			dbg("%s - data bits = 7", __func__);
			cflag |= CS7;
			break;
		case BITS_DATA_8:
			dbg("%s - data bits = 8", __func__);
			cflag |= CS8;
			break;
		case BITS_DATA_9:
			dbg("%s - data bits = 9 (not supported, "
					"using 8 data bits)", __func__);
			cflag |= CS8;
			bits &= ~BITS_DATA_MASK;
			bits |= BITS_DATA_8;
			cp2101_set_config(port, CP2101_BITS, &bits, 2);
			break;
		default:
			dbg("%s - Unknown number of data bits, "
					"using 8", __func__);
			cflag |= CS8;
			bits &= ~BITS_DATA_MASK;
			bits |= BITS_DATA_8;
			cp2101_set_config(port, CP2101_BITS, &bits, 2);
			break;
	}

	switch(bits & BITS_PARITY_MASK) {
		case BITS_PARITY_NONE:
			dbg("%s - parity = NONE", __func__);
			cflag &= ~PARENB;
			break;
		case BITS_PARITY_ODD:
			dbg("%s - parity = ODD", __func__);
			cflag |= (PARENB|PARODD);
			break;
		case BITS_PARITY_EVEN:
			dbg("%s - parity = EVEN", __func__);
			cflag &= ~PARODD;
			cflag |= PARENB;
			break;
		case BITS_PARITY_MARK:
			dbg("%s - parity = MARK (not supported, "
					"disabling parity)", __func__);
			cflag &= ~PARENB;
			bits &= ~BITS_PARITY_MASK;
			cp2101_set_config(port, CP2101_BITS, &bits, 2);
			break;
		case BITS_PARITY_SPACE:
			dbg("%s - parity = SPACE (not supported, "
					"disabling parity)", __func__);
			cflag &= ~PARENB;
			bits &= ~BITS_PARITY_MASK;
			cp2101_set_config(port, CP2101_BITS, &bits, 2);
			break;
		default:
			dbg("%s - Unknown parity mode, "
					"disabling parity", __func__);
			cflag &= ~PARENB;
			bits &= ~BITS_PARITY_MASK;
			cp2101_set_config(port, CP2101_BITS, &bits, 2);
			break;
	}

	cflag &= ~CSTOPB;
	switch(bits & BITS_STOP_MASK) {
		case BITS_STOP_1:
			dbg("%s - stop bits = 1", __func__);
			break;
		case BITS_STOP_1_5:
			dbg("%s - stop bits = 1.5 (not supported, "
					"using 1 stop bit)", __func__);
			bits &= ~BITS_STOP_MASK;
			cp2101_set_config(port, CP2101_BITS, &bits, 2);
			break;
		case BITS_STOP_2:
			dbg("%s - stop bits = 2", __func__);
			cflag |= CSTOPB;
			break;
		default:
			dbg("%s - Unknown number of stop bits, "
					"using 1 stop bit", __func__);
			bits &= ~BITS_STOP_MASK;
			cp2101_set_config(port, CP2101_BITS, &bits, 2);
			break;
	}

	cp2101_get_config(port, CP2101_MODEMCTL, modem_ctl, 16);
	if (modem_ctl[0] & 0x0008) {
		dbg("%s - flow control = CRTSCTS", __func__);
		cflag |= CRTSCTS;
	} else {
		dbg("%s - flow control = NONE", __func__);
		cflag &= ~CRTSCTS;
	}

	port->tty->termios->c_cflag = cflag;
}

static void cp2101_set_termios (struct usb_serial_port *port,
		struct ktermios *old_termios)
{
	unsigned int cflag, old_cflag;
	int baud=0, bits;
	unsigned int modem_ctl[4];

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

	if (!port->tty || !port->tty->termios) {
		dbg("%s - no tty structures", __func__);
		return;
	}
	port->tty->termios->c_cflag &= ~CMSPAR;

	cflag = port->tty->termios->c_cflag;
	old_cflag = old_termios->c_cflag;
	baud = tty_get_baud_rate(port->tty);

	/* If the baud rate is to be updated*/
	if (baud != tty_termios_baud_rate(old_termios)) {
		switch (baud) {
			case 0:
			case 600:
			case 1200:
			case 1800:
			case 2400:
			case 4800:
			case 7200:
			case 9600:
			case 14400:
			case 19200:
			case 28800:
			case 38400:
			case 55854:
			case 57600:
			case 115200:
			case 127117:
			case 230400:
			case 460800:
			case 921600:
			case 3686400:
				break;
			default:
				baud = 9600;
				break;
		}

		if (baud) {
			dbg("%s - Setting baud rate to %d baud", __func__,
					baud);
			if (cp2101_set_config_single(port, CP2101_BAUDRATE,
						(BAUD_RATE_GEN_FREQ / baud))) {
				dev_err(&port->dev, "Baud rate requested not "
						"supported by device\n");
				baud = tty_termios_baud_rate(old_termios);
			}
		}
	}
	/* Report back the resulting baud rate */
	tty_encode_baud_rate(port->tty, baud, baud);

	/* If the number of data bits is to be updated */
	if ((cflag & CSIZE) != (old_cflag & CSIZE)) {
		cp2101_get_config(port, CP2101_BITS, &bits, 2);
		bits &= ~BITS_DATA_MASK;
		switch (cflag & CSIZE) {
			case CS5:
				bits |= BITS_DATA_5;
				dbg("%s - data bits = 5", __func__);
				break;
			case CS6:
				bits |= BITS_DATA_6;
				dbg("%s - data bits = 6", __func__);
				break;
			case CS7:
				bits |= BITS_DATA_7;
				dbg("%s - data bits = 7", __func__);
				break;
			case CS8:
				bits |= BITS_DATA_8;
				dbg("%s - data bits = 8", __func__);
				break;
			/*case CS9:
			 	bits |= BITS_DATA_9;
				dbg("%s - data bits = 9", __func__);
				break;*/
			default:
				dev_err(&port->dev, "cp2101 driver does not "
					"support the number of bits requested,"
					" using 8 bit mode\n");
				bits |= BITS_DATA_8;
				break;
		}
		if (cp2101_set_config(port, CP2101_BITS, &bits, 2))
			dev_err(&port->dev, "Number of data bits requested "
					"not supported by device\n");
	}

	if ((cflag & (PARENB|PARODD)) != (old_cflag & (PARENB|PARODD))) {
		cp2101_get_config(port, CP2101_BITS, &bits, 2);
		bits &= ~BITS_PARITY_MASK;
		if (cflag & PARENB) {
			if (cflag & PARODD) {
				bits |= BITS_PARITY_ODD;
				dbg("%s - parity = ODD", __func__);
			} else {
				bits |= BITS_PARITY_EVEN;
				dbg("%s - parity = EVEN", __func__);
			}
		}
		if (cp2101_set_config(port, CP2101_BITS, &bits, 2))
			dev_err(&port->dev, "Parity mode not supported "
					"by device\n");
	}

	if ((cflag & CSTOPB) != (old_cflag & CSTOPB)) {
		cp2101_get_config(port, CP2101_BITS, &bits, 2);
		bits &= ~BITS_STOP_MASK;
		if (cflag & CSTOPB) {
			bits |= BITS_STOP_2;
			dbg("%s - stop bits = 2", __func__);
		} else {
			bits |= BITS_STOP_1;
			dbg("%s - stop bits = 1", __func__);
		}
		if (cp2101_set_config(port, CP2101_BITS, &bits, 2))
			dev_err(&port->dev, "Number of stop bits requested "
					"not supported by device\n");
	}

	if ((cflag & CRTSCTS) != (old_cflag & CRTSCTS)) {
		cp2101_get_config(port, CP2101_MODEMCTL, modem_ctl, 16);
		dbg("%s - read modem controls = 0x%.4x 0x%.4x 0x%.4x 0x%.4x",
				__func__, modem_ctl[0], modem_ctl[1],
				modem_ctl[2], modem_ctl[3]);

		if (cflag & CRTSCTS) {
			modem_ctl[0] &= ~0x7B;
			modem_ctl[0] |= 0x09;
			modem_ctl[1] = 0x80;
			dbg("%s - flow control = CRTSCTS", __func__);
		} else {
			modem_ctl[0] &= ~0x7B;
			modem_ctl[0] |= 0x01;
			modem_ctl[1] |= 0x40;
			dbg("%s - flow control = NONE", __func__);
		}

		dbg("%s - write modem controls = 0x%.4x 0x%.4x 0x%.4x 0x%.4x",
				__func__, modem_ctl[0], modem_ctl[1],
				modem_ctl[2], modem_ctl[3]);
		cp2101_set_config(port, CP2101_MODEMCTL, modem_ctl, 16);
	}

}

static int cp2101_tiocmset (struct usb_serial_port *port, struct file *file,
		unsigned int set, unsigned int clear)
{
	int control = 0;

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

	if (set & TIOCM_RTS) {
		control |= CONTROL_RTS;
		control |= CONTROL_WRITE_RTS;
	}
	if (set & TIOCM_DTR) {
		control |= CONTROL_DTR;
		control |= CONTROL_WRITE_DTR;
	}
	if (clear & TIOCM_RTS) {
		control &= ~CONTROL_RTS;
		control |= CONTROL_WRITE_RTS;
	}
	if (clear & TIOCM_DTR) {
		control &= ~CONTROL_DTR;
		control |= CONTROL_WRITE_DTR;
	}

	dbg("%s - control = 0x%.4x", __func__, control);

	return cp2101_set_config(port, CP2101_CONTROL, &control, 2);

}

static int cp2101_tiocmget (struct usb_serial_port *port, struct file *file)
{
	int control, result;

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

	cp2101_get_config(port, CP2101_CONTROL, &control, 1);

	result = ((control & CONTROL_DTR) ? TIOCM_DTR : 0)
		|((control & CONTROL_RTS) ? TIOCM_RTS : 0)
		|((control & CONTROL_CTS) ? TIOCM_CTS : 0)
		|((control & CONTROL_DSR) ? TIOCM_DSR : 0)
		|((control & CONTROL_RING)? TIOCM_RI  : 0)
		|((control & CONTROL_DCD) ? TIOCM_CD  : 0);

	dbg("%s - control = 0x%.2x", __func__, control);

	return result;
}

static void cp2101_break_ctl (struct usb_serial_port *port, int break_state)
{
	int state;

	dbg("%s - port %d", __func__, port->number);
	if (break_state == 0)
		state = BREAK_OFF;
	else
		state = BREAK_ON;
	dbg("%s - turning break %s", __func__,
			state==BREAK_OFF ? "off" : "on");
	cp2101_set_config(port, CP2101_BREAK, &state, 2);
}

static int cp2101_startup (struct usb_serial *serial)
{
	/* CP2101 buffers behave strangely unless device is reset */
	usb_reset_device(serial->dev);
	return 0;
}

static void cp2101_shutdown (struct usb_serial *serial)
{
	int i;

	dbg("%s", __func__);

	/* Stop reads and writes on all ports */
	for (i=0; i < serial->num_ports; ++i) {
		cp2101_cleanup(serial->port[i]);
	}
}

static int __init cp2101_init (void)
{
	int retval;

	retval = usb_serial_register(&cp2101_device);
	if (retval)
		return retval; /* Failed to register */

	retval = usb_register(&cp2101_driver);
	if (retval) {
		/* Failed to register */
		usb_serial_deregister(&cp2101_device);
		return retval;
	}

	/* Success */
	info(DRIVER_DESC " " DRIVER_VERSION);
	return 0;
}

static void __exit cp2101_exit (void)
{
	usb_deregister (&cp2101_driver);
	usb_serial_deregister (&cp2101_device);
}

module_init(cp2101_init);
module_exit(cp2101_exit);

MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_VERSION(DRIVER_VERSION);
MODULE_LICENSE("GPL");

module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Enable verbose debugging messages");