summaryrefslogtreecommitdiffstats
path: root/drivers/usb/serial/ch341.c
blob: aa0962b72f4ccb7d3ceaa8d9534505e5488d6acf (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
/*
 * Copyright 2007, Frank A Kingswood <frank@kingswood-consulting.co.uk>
 * Copyright 2007, Werner Cornelius <werner@cornelius-consult.de>
 * Copyright 2009, Boris Hajduk <boris@hajduk.org>
 *
 * ch341.c implements a serial port driver for the Winchiphead CH341.
 *
 * The CH341 device can be used to implement an RS232 asynchronous
 * serial port, an IEEE-1284 parallel printer port or a memory-like
 * interface. In all cases the CH341 supports an I2C interface as well.
 * This driver only supports the asynchronous serial interface.
 *
 * 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.
 */

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/tty.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>
#include <linux/serial.h>
#include <asm/unaligned.h>

#define DEFAULT_BAUD_RATE 9600
#define DEFAULT_TIMEOUT   1000

/* flags for IO-Bits */
#define CH341_BIT_RTS (1 << 6)
#define CH341_BIT_DTR (1 << 5)

/******************************/
/* interrupt pipe definitions */
/******************************/
/* always 4 interrupt bytes */
/* first irq byte normally 0x08 */
/* second irq byte base 0x7d + below */
/* third irq byte base 0x94 + below */
/* fourth irq byte normally 0xee */

/* second interrupt byte */
#define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */

/* status returned in third interrupt answer byte, inverted in data
   from irq */
#define CH341_BIT_CTS 0x01
#define CH341_BIT_DSR 0x02
#define CH341_BIT_RI  0x04
#define CH341_BIT_DCD 0x08
#define CH341_BITS_MODEM_STAT 0x0f /* all bits */

/*******************************/
/* baudrate calculation factor */
/*******************************/
#define CH341_BAUDBASE_FACTOR 1532620800
#define CH341_BAUDBASE_DIVMAX 3

/* Break support - the information used to implement this was gleaned from
 * the Net/FreeBSD uchcom.c driver by Takanori Watanabe.  Domo arigato.
 */

#define CH341_REQ_WRITE_REG    0x9A
#define CH341_REQ_READ_REG     0x95
#define CH341_REG_BREAK1       0x05
#define CH341_REG_BREAK2       0x18
#define CH341_NBREAK_BITS_REG1 0x01
#define CH341_NBREAK_BITS_REG2 0x40


static int debug;

static const struct usb_device_id id_table[] = {
	{ USB_DEVICE(0x4348, 0x5523) },
	{ USB_DEVICE(0x1a86, 0x7523) },
	{ },
};
MODULE_DEVICE_TABLE(usb, id_table);

struct ch341_private {
	spinlock_t lock; /* access lock */
	wait_queue_head_t delta_msr_wait; /* wait queue for modem status */
	unsigned baud_rate; /* set baud rate */
	u8 line_control; /* set line control value RTS/DTR */
	u8 line_status; /* active status of modem control inputs */
	u8 multi_status_change; /* status changed multiple since last call */
};

static int ch341_control_out(struct usb_device *dev, u8 request,
			     u16 value, u16 index)
{
	int r;
	dbg("ch341_control_out(%02x,%02x,%04x,%04x)", USB_DIR_OUT|0x40,
		(int)request, (int)value, (int)index);

	r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
			    USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
			    value, index, NULL, 0, DEFAULT_TIMEOUT);

	return r;
}

static int ch341_control_in(struct usb_device *dev,
			    u8 request, u16 value, u16 index,
			    char *buf, unsigned bufsize)
{
	int r;
	dbg("ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)", USB_DIR_IN|0x40,
		(int)request, (int)value, (int)index, buf, (int)bufsize);

	r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
			    USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
			    value, index, buf, bufsize, DEFAULT_TIMEOUT);
	return r;
}

static int ch341_set_baudrate(struct usb_device *dev,
			      struct ch341_private *priv)
{
	short a, b;
	int r;
	unsigned long factor;
	short divisor;

	dbg("ch341_set_baudrate(%d)", priv->baud_rate);

	if (!priv->baud_rate)
		return -EINVAL;
	factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate);
	divisor = CH341_BAUDBASE_DIVMAX;

	while ((factor > 0xfff0) && divisor) {
		factor >>= 3;
		divisor--;
	}

	if (factor > 0xfff0)
		return -EINVAL;

	factor = 0x10000 - factor;
	a = (factor & 0xff00) | divisor;
	b = factor & 0xff;

	r = ch341_control_out(dev, 0x9a, 0x1312, a);
	if (!r)
		r = ch341_control_out(dev, 0x9a, 0x0f2c, b);

	return r;
}

static int ch341_set_handshake(struct usb_device *dev, u8 control)
{
	dbg("ch341_set_handshake(0x%02x)", control);
	return ch341_control_out(dev, 0xa4, ~control, 0);
}

static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
{
	char *buffer;
	int r;
	const unsigned size = 8;
	unsigned long flags;

	dbg("ch341_get_status()");

	buffer = kmalloc(size, GFP_KERNEL);
	if (!buffer)
		return -ENOMEM;

	r = ch341_control_in(dev, 0x95, 0x0706, 0, buffer, size);
	if (r < 0)
		goto out;

	/* setup the private status if available */
	if (r == 2) {
		r = 0;
		spin_lock_irqsave(&priv->lock, flags);
		priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
		priv->multi_status_change = 0;
		spin_unlock_irqrestore(&priv->lock, flags);
	} else
		r = -EPROTO;

out:	kfree(buffer);
	return r;
}

/* -------------------------------------------------------------------------- */

static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
{
	char *buffer;
	int r;
	const unsigned size = 8;

	dbg("ch341_configure()");

	buffer = kmalloc(size, GFP_KERNEL);
	if (!buffer)
		return -ENOMEM;

	/* expect two bytes 0x27 0x00 */
	r = ch341_control_in(dev, 0x5f, 0, 0, buffer, size);
	if (r < 0)
		goto out;

	r = ch341_control_out(dev, 0xa1, 0, 0);
	if (r < 0)
		goto out;

	r = ch341_set_baudrate(dev, priv);
	if (r < 0)
		goto out;

	/* expect two bytes 0x56 0x00 */
	r = ch341_control_in(dev, 0x95, 0x2518, 0, buffer, size);
	if (r < 0)
		goto out;

	r = ch341_control_out(dev, 0x9a, 0x2518, 0x0050);
	if (r < 0)
		goto out;

	/* expect 0xff 0xee */
	r = ch341_get_status(dev, priv);
	if (r < 0)
		goto out;

	r = ch341_control_out(dev, 0xa1, 0x501f, 0xd90a);
	if (r < 0)
		goto out;

	r = ch341_set_baudrate(dev, priv);
	if (r < 0)
		goto out;

	r = ch341_set_handshake(dev, priv->line_control);
	if (r < 0)
		goto out;

	/* expect 0x9f 0xee */
	r = ch341_get_status(dev, priv);

out:	kfree(buffer);
	return r;
}

/* allocate private data */
static int ch341_attach(struct usb_serial *serial)
{
	struct ch341_private *priv;
	int r;

	dbg("ch341_attach()");

	/* private data */
	priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	spin_lock_init(&priv->lock);
	init_waitqueue_head(&priv->delta_msr_wait);
	priv->baud_rate = DEFAULT_BAUD_RATE;
	priv->line_control = CH341_BIT_RTS | CH341_BIT_DTR;

	r = ch341_configure(serial->dev, priv);
	if (r < 0)
		goto error;

	usb_set_serial_port_data(serial->port[0], priv);
	return 0;

error:	kfree(priv);
	return r;
}

static int ch341_carrier_raised(struct usb_serial_port *port)
{
	struct ch341_private *priv = usb_get_serial_port_data(port);
	if (priv->line_status & CH341_BIT_DCD)
		return 1;
	return 0;
}

static void ch341_dtr_rts(struct usb_serial_port *port, int on)
{
	struct ch341_private *priv = usb_get_serial_port_data(port);
	unsigned long flags;

	dbg("%s - port %d", __func__, port->number);
	/* drop DTR and RTS */
	spin_lock_irqsave(&priv->lock, flags);
	if (on)
		priv->line_control |= CH341_BIT_RTS | CH341_BIT_DTR;
	else
		priv->line_control &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
	spin_unlock_irqrestore(&priv->lock, flags);
	ch341_set_handshake(port->serial->dev, priv->line_control);
	wake_up_interruptible(&priv->delta_msr_wait);
}

static void ch341_close(struct usb_serial_port *port)
{
	dbg("%s - port %d", __func__, port->number);

	usb_serial_generic_close(port);
	usb_kill_urb(port->interrupt_in_urb);
}


/* open this device, set default parameters */
static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
{
	struct usb_serial *serial = port->serial;
	struct ch341_private *priv = usb_get_serial_port_data(serial->port[0]);
	int r;

	dbg("ch341_open()");

	priv->baud_rate = DEFAULT_BAUD_RATE;

	r = ch341_configure(serial->dev, priv);
	if (r)
		goto out;

	r = ch341_set_handshake(serial->dev, priv->line_control);
	if (r)
		goto out;

	r = ch341_set_baudrate(serial->dev, priv);
	if (r)
		goto out;

	dbg("%s - submitting interrupt urb", __func__);
	port->interrupt_in_urb->dev = serial->dev;
	r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
	if (r) {
		dev_err(&port->dev, "%s - failed submitting interrupt urb,"
			" error %d\n", __func__, r);
		ch341_close(port);
		return -EPROTO;
	}

	r = usb_serial_generic_open(tty, port);

out:	return r;
}

/* Old_termios contains the original termios settings and
 * tty->termios contains the new setting to be used.
 */
static void ch341_set_termios(struct tty_struct *tty,
		struct usb_serial_port *port, struct ktermios *old_termios)
{
	struct ch341_private *priv = usb_get_serial_port_data(port);
	unsigned baud_rate;
	unsigned long flags;

	dbg("ch341_set_termios()");

	baud_rate = tty_get_baud_rate(tty);

	priv->baud_rate = baud_rate;

	if (baud_rate) {
		spin_lock_irqsave(&priv->lock, flags);
		priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
		spin_unlock_irqrestore(&priv->lock, flags);
		ch341_set_baudrate(port->serial->dev, priv);
	} else {
		spin_lock_irqsave(&priv->lock, flags);
		priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
		spin_unlock_irqrestore(&priv->lock, flags);
	}

	ch341_set_handshake(port->serial->dev, priv->line_control);

	/* Unimplemented:
	 * (cflag & CSIZE) : data bits [5, 8]
	 * (cflag & PARENB) : parity {NONE, EVEN, ODD}
	 * (cflag & CSTOPB) : stop bits [1, 2]
	 */
}

static void ch341_break_ctl(struct tty_struct *tty, int break_state)
{
	const uint16_t ch341_break_reg =
		CH341_REG_BREAK1 | ((uint16_t) CH341_REG_BREAK2 << 8);
	struct usb_serial_port *port = tty->driver_data;
	int r;
	uint16_t reg_contents;
	uint8_t *break_reg;

	dbg("%s()", __func__);

	break_reg = kmalloc(2, GFP_KERNEL);
	if (!break_reg) {
		dev_err(&port->dev, "%s - kmalloc failed\n", __func__);
		return;
	}

	r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
			ch341_break_reg, 0, break_reg, 2);
	if (r < 0) {
		dev_err(&port->dev, "%s - USB control read error (%d)\n",
				__func__, r);
		goto out;
	}
	dbg("%s - initial ch341 break register contents - reg1: %x, reg2: %x",
			__func__, break_reg[0], break_reg[1]);
	if (break_state != 0) {
		dbg("%s - Enter break state requested", __func__);
		break_reg[0] &= ~CH341_NBREAK_BITS_REG1;
		break_reg[1] &= ~CH341_NBREAK_BITS_REG2;
	} else {
		dbg("%s - Leave break state requested", __func__);
		break_reg[0] |= CH341_NBREAK_BITS_REG1;
		break_reg[1] |= CH341_NBREAK_BITS_REG2;
	}
	dbg("%s - New ch341 break register contents - reg1: %x, reg2: %x",
			__func__, break_reg[0], break_reg[1]);
	reg_contents = get_unaligned_le16(break_reg);
	r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
			ch341_break_reg, reg_contents);
	if (r < 0)
		dev_err(&port->dev, "%s - USB control write error (%d)\n",
				__func__, r);
out:
	kfree(break_reg);
}

static int ch341_tiocmset(struct tty_struct *tty, struct file *file,
			  unsigned int set, unsigned int clear)
{
	struct usb_serial_port *port = tty->driver_data;
	struct ch341_private *priv = usb_get_serial_port_data(port);
	unsigned long flags;
	u8 control;

	spin_lock_irqsave(&priv->lock, flags);
	if (set & TIOCM_RTS)
		priv->line_control |= CH341_BIT_RTS;
	if (set & TIOCM_DTR)
		priv->line_control |= CH341_BIT_DTR;
	if (clear & TIOCM_RTS)
		priv->line_control &= ~CH341_BIT_RTS;
	if (clear & TIOCM_DTR)
		priv->line_control &= ~CH341_BIT_DTR;
	control = priv->line_control;
	spin_unlock_irqrestore(&priv->lock, flags);

	return ch341_set_handshake(port->serial->dev, control);
}

static void ch341_read_int_callback(struct urb *urb)
{
	struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
	unsigned char *data = urb->transfer_buffer;
	unsigned int actual_length = urb->actual_length;
	int status;

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

	switch (urb->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__,
		    urb->status);
		return;
	default:
		dbg("%s - nonzero urb status received: %d", __func__,
		    urb->status);
		goto exit;
	}

	usb_serial_debug_data(debug, &port->dev, __func__,
			      urb->actual_length, urb->transfer_buffer);

	if (actual_length >= 4) {
		struct ch341_private *priv = usb_get_serial_port_data(port);
		unsigned long flags;
		u8 prev_line_status = priv->line_status;

		spin_lock_irqsave(&priv->lock, flags);
		priv->line_status = (~(data[2])) & CH341_BITS_MODEM_STAT;
		if ((data[1] & CH341_MULT_STAT))
			priv->multi_status_change = 1;
		spin_unlock_irqrestore(&priv->lock, flags);

		if ((priv->line_status ^ prev_line_status) & CH341_BIT_DCD) {
			struct tty_struct *tty = tty_port_tty_get(&port->port);
			if (tty)
				usb_serial_handle_dcd_change(port, tty,
					    priv->line_status & CH341_BIT_DCD);
			tty_kref_put(tty);
		}

		wake_up_interruptible(&priv->delta_msr_wait);
	}

exit:
	status = usb_submit_urb(urb, GFP_ATOMIC);
	if (status)
		dev_err(&urb->dev->dev,
			"%s - usb_submit_urb failed with result %d\n",
			__func__, status);
}

static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
{
	struct ch341_private *priv = usb_get_serial_port_data(port);
	unsigned long flags;
	u8 prevstatus;
	u8 status;
	u8 changed;
	u8 multi_change = 0;

	spin_lock_irqsave(&priv->lock, flags);
	prevstatus = priv->line_status;
	priv->multi_status_change = 0;
	spin_unlock_irqrestore(&priv->lock, flags);

	while (!multi_change) {
		interruptible_sleep_on(&priv->delta_msr_wait);
		/* see if a signal did it */
		if (signal_pending(current))
			return -ERESTARTSYS;

		spin_lock_irqsave(&priv->lock, flags);
		status = priv->line_status;
		multi_change = priv->multi_status_change;
		spin_unlock_irqrestore(&priv->lock, flags);

		changed = prevstatus ^ status;

		if (((arg & TIOCM_RNG) && (changed & CH341_BIT_RI)) ||
		    ((arg & TIOCM_DSR) && (changed & CH341_BIT_DSR)) ||
		    ((arg & TIOCM_CD)  && (changed & CH341_BIT_DCD)) ||
		    ((arg & TIOCM_CTS) && (changed & CH341_BIT_CTS))) {
			return 0;
		}
		prevstatus = status;
	}

	return 0;
}

/*static int ch341_ioctl(struct usb_serial_port *port, struct file *file,*/
static int ch341_ioctl(struct tty_struct *tty, struct file *file,
			unsigned int cmd, unsigned long arg)
{
	struct usb_serial_port *port = tty->driver_data;
	dbg("%s (%d) cmd = 0x%04x", __func__, port->number, cmd);

	switch (cmd) {
	case TIOCMIWAIT:
		dbg("%s (%d) TIOCMIWAIT", __func__,  port->number);
		return wait_modem_info(port, arg);

	default:
		dbg("%s not supported = 0x%04x", __func__, cmd);
		break;
	}

	return -ENOIOCTLCMD;
}

static int ch341_tiocmget(struct tty_struct *tty)
{
	struct usb_serial_port *port = tty->driver_data;
	struct ch341_private *priv = usb_get_serial_port_data(port);
	unsigned long flags;
	u8 mcr;
	u8 status;
	unsigned int result;

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

	spin_lock_irqsave(&priv->lock, flags);
	mcr = priv->line_control;
	status = priv->line_status;
	spin_unlock_irqrestore(&priv->lock, flags);

	result = ((mcr & CH341_BIT_DTR)		? TIOCM_DTR : 0)
		  | ((mcr & CH341_BIT_RTS)	? TIOCM_RTS : 0)
		  | ((status & CH341_BIT_CTS)	? TIOCM_CTS : 0)
		  | ((status & CH341_BIT_DSR)	? TIOCM_DSR : 0)
		  | ((status & CH341_BIT_RI)	? TIOCM_RI  : 0)
		  | ((status & CH341_BIT_DCD)	? TIOCM_CD  : 0);

	dbg("%s - result = %x", __func__, result);

	return result;
}


static int ch341_reset_resume(struct usb_interface *intf)
{
	struct usb_device *dev = interface_to_usbdev(intf);
	struct usb_serial *serial = NULL;
	struct ch341_private *priv;

	serial = usb_get_intfdata(intf);
	priv = usb_get_serial_port_data(serial->port[0]);

	/*reconfigure ch341 serial port after bus-reset*/
	ch341_configure(dev, priv);

	usb_serial_resume(intf);

	return 0;
}

static struct usb_driver ch341_driver = {
	.name		= "ch341",
	.probe		= usb_serial_probe,
	.disconnect	= usb_serial_disconnect,
	.suspend	= usb_serial_suspend,
	.resume		= usb_serial_resume,
	.reset_resume	= ch341_reset_resume,
	.id_table	= id_table,
	.no_dynamic_id	= 1,
	.supports_autosuspend =	1,
};

static struct usb_serial_driver ch341_device = {
	.driver = {
		.owner	= THIS_MODULE,
		.name	= "ch341-uart",
	},
	.id_table          = id_table,
	.usb_driver        = &ch341_driver,
	.num_ports         = 1,
	.open              = ch341_open,
	.dtr_rts	   = ch341_dtr_rts,
	.carrier_raised	   = ch341_carrier_raised,
	.close             = ch341_close,
	.ioctl             = ch341_ioctl,
	.set_termios       = ch341_set_termios,
	.break_ctl         = ch341_break_ctl,
	.tiocmget          = ch341_tiocmget,
	.tiocmset          = ch341_tiocmset,
	.read_int_callback = ch341_read_int_callback,
	.attach            = ch341_attach,
};

static int __init ch341_init(void)
{
	int retval;

	retval = usb_serial_register(&ch341_device);
	if (retval)
		return retval;
	retval = usb_register(&ch341_driver);
	if (retval)
		usb_serial_deregister(&ch341_device);
	return retval;
}

static void __exit ch341_exit(void)
{
	usb_deregister(&ch341_driver);
	usb_serial_deregister(&ch341_device);
}

module_init(ch341_init);
module_exit(ch341_exit);
MODULE_LICENSE("GPL");

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

/* EOF ch341.c */
OpenPOWER on IntegriCloud