e138f3c11324153441ff50b04e6bd077ca25b051
[pandora-kernel.git] / drivers / usb / serial / ch341.c
1 /*
2  * Copyright 2007, Frank A Kingswood <frank@kingswood-consulting.co.uk>
3  * Copyright 2007, Werner Cornelius <werner@cornelius-consult.de>
4  * Copyright 2009, Boris Hajduk <boris@hajduk.org>
5  *
6  * ch341.c implements a serial port driver for the Winchiphead CH341.
7  *
8  * The CH341 device can be used to implement an RS232 asynchronous
9  * serial port, an IEEE-1284 parallel printer port or a memory-like
10  * interface. In all cases the CH341 supports an I2C interface as well.
11  * This driver only supports the asynchronous serial interface.
12  *
13  * This program is free software; you can redistribute it and/or
14  * modify it under the terms of the GNU General Public License version
15  * 2 as published by the Free Software Foundation.
16  */
17
18 #include <linux/kernel.h>
19 #include <linux/init.h>
20 #include <linux/tty.h>
21 #include <linux/module.h>
22 #include <linux/slab.h>
23 #include <linux/usb.h>
24 #include <linux/usb/serial.h>
25 #include <linux/serial.h>
26 #include <asm/unaligned.h>
27
28 #define DEFAULT_BAUD_RATE 9600
29 #define DEFAULT_TIMEOUT   1000
30
31 /* flags for IO-Bits */
32 #define CH341_BIT_RTS (1 << 6)
33 #define CH341_BIT_DTR (1 << 5)
34
35 /******************************/
36 /* interrupt pipe definitions */
37 /******************************/
38 /* always 4 interrupt bytes */
39 /* first irq byte normally 0x08 */
40 /* second irq byte base 0x7d + below */
41 /* third irq byte base 0x94 + below */
42 /* fourth irq byte normally 0xee */
43
44 /* second interrupt byte */
45 #define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */
46
47 /* status returned in third interrupt answer byte, inverted in data
48    from irq */
49 #define CH341_BIT_CTS 0x01
50 #define CH341_BIT_DSR 0x02
51 #define CH341_BIT_RI  0x04
52 #define CH341_BIT_DCD 0x08
53 #define CH341_BITS_MODEM_STAT 0x0f /* all bits */
54
55 /*******************************/
56 /* baudrate calculation factor */
57 /*******************************/
58 #define CH341_BAUDBASE_FACTOR 1532620800
59 #define CH341_BAUDBASE_DIVMAX 3
60
61 /* Break support - the information used to implement this was gleaned from
62  * the Net/FreeBSD uchcom.c driver by Takanori Watanabe.  Domo arigato.
63  */
64
65 #define CH341_REQ_READ_VERSION 0x5F
66 #define CH341_REQ_WRITE_REG    0x9A
67 #define CH341_REQ_READ_REG     0x95
68 #define CH341_REQ_SERIAL_INIT  0xA1
69 #define CH341_REQ_MODEM_CTRL   0xA4
70
71 #define CH341_REG_BREAK        0x05
72 #define CH341_REG_LCR          0x18
73 #define CH341_NBREAK_BITS      0x01
74
75 #define CH341_LCR_ENABLE_RX    0x80
76 #define CH341_LCR_ENABLE_TX    0x40
77 #define CH341_LCR_MARK_SPACE   0x20
78 #define CH341_LCR_PAR_EVEN     0x10
79 #define CH341_LCR_ENABLE_PAR   0x08
80 #define CH341_LCR_STOP_BITS_2  0x04
81 #define CH341_LCR_CS8          0x03
82 #define CH341_LCR_CS7          0x02
83 #define CH341_LCR_CS6          0x01
84 #define CH341_LCR_CS5          0x00
85
86 static int debug;
87
88 static const struct usb_device_id id_table[] = {
89         { USB_DEVICE(0x4348, 0x5523) },
90         { USB_DEVICE(0x1a86, 0x7523) },
91         { USB_DEVICE(0x1a86, 0x5523) },
92         { },
93 };
94 MODULE_DEVICE_TABLE(usb, id_table);
95
96 struct ch341_private {
97         spinlock_t lock; /* access lock */
98         unsigned baud_rate; /* set baud rate */
99         u8 line_control; /* set line control value RTS/DTR */
100         u8 line_status; /* active status of modem control inputs */
101         u8 multi_status_change; /* status changed multiple since last call */
102 };
103
104 static void ch341_set_termios(struct tty_struct *tty,
105                               struct usb_serial_port *port,
106                               struct ktermios *old_termios);
107
108 static int ch341_control_out(struct usb_device *dev, u8 request,
109                              u16 value, u16 index)
110 {
111         int r;
112         dbg("ch341_control_out(%02x,%02x,%04x,%04x)", USB_DIR_OUT|0x40,
113                 (int)request, (int)value, (int)index);
114
115         r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
116                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
117                             value, index, NULL, 0, DEFAULT_TIMEOUT);
118
119         return r;
120 }
121
122 static int ch341_control_in(struct usb_device *dev,
123                             u8 request, u16 value, u16 index,
124                             char *buf, unsigned bufsize)
125 {
126         int r;
127         dbg("ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)", USB_DIR_IN|0x40,
128                 (int)request, (int)value, (int)index, buf, (int)bufsize);
129
130         r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
131                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
132                             value, index, buf, bufsize, DEFAULT_TIMEOUT);
133         return r;
134 }
135
136 static int ch341_init_set_baudrate(struct usb_device *dev,
137                                    struct ch341_private *priv, unsigned ctrl)
138 {
139         short a;
140         int r;
141         unsigned long factor;
142         short divisor;
143
144         dbg("ch341_set_baudrate(%d)", priv->baud_rate);
145
146         if (!priv->baud_rate)
147                 return -EINVAL;
148         factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate);
149         divisor = CH341_BAUDBASE_DIVMAX;
150
151         while ((factor > 0xfff0) && divisor) {
152                 factor >>= 3;
153                 divisor--;
154         }
155
156         if (factor > 0xfff0)
157                 return -EINVAL;
158
159         factor = 0x10000 - factor;
160         a = (factor & 0xff00) | divisor;
161
162         /* 0x9c is "enable SFR_UART Control register and timer" */
163         r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT,
164                               0x9c | (ctrl << 8), a | 0x80);
165
166         return r;
167 }
168
169 static int ch341_set_handshake(struct usb_device *dev, u8 control)
170 {
171         dbg("ch341_set_handshake(0x%02x)", control);
172         return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0);
173 }
174
175 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
176 {
177         char *buffer;
178         int r;
179         const unsigned size = 8;
180         unsigned long flags;
181
182         dbg("ch341_get_status()");
183
184         buffer = kmalloc(size, GFP_KERNEL);
185         if (!buffer)
186                 return -ENOMEM;
187
188         r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
189         if (r < 0)
190                 goto out;
191
192         /* setup the private status if available */
193         if (r == 2) {
194                 r = 0;
195                 spin_lock_irqsave(&priv->lock, flags);
196                 priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
197                 priv->multi_status_change = 0;
198                 spin_unlock_irqrestore(&priv->lock, flags);
199         } else
200                 r = -EPROTO;
201
202 out:    kfree(buffer);
203         return r;
204 }
205
206 /* -------------------------------------------------------------------------- */
207
208 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
209 {
210         char *buffer;
211         int r;
212         const unsigned size = 8;
213
214         dbg("ch341_configure()");
215
216         buffer = kmalloc(size, GFP_KERNEL);
217         if (!buffer)
218                 return -ENOMEM;
219
220         /* expect two bytes 0x27 0x00 */
221         r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
222         if (r < 0)
223                 goto out;
224
225         r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
226         if (r < 0)
227                 goto out;
228
229         /* expect two bytes 0x56 0x00 */
230         r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x2518, 0, buffer, size);
231         if (r < 0)
232                 goto out;
233
234         r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, 0x0050);
235         if (r < 0)
236                 goto out;
237
238         /* expect 0xff 0xee */
239         r = ch341_get_status(dev, priv);
240         if (r < 0)
241                 goto out;
242
243         r = ch341_init_set_baudrate(dev, priv, 0);
244         if (r < 0)
245                 goto out;
246
247         r = ch341_set_handshake(dev, priv->line_control);
248         if (r < 0)
249                 goto out;
250
251         /* expect 0x9f 0xee */
252         r = ch341_get_status(dev, priv);
253
254 out:    kfree(buffer);
255         return r;
256 }
257
258 /* allocate private data */
259 static int ch341_attach(struct usb_serial *serial)
260 {
261         struct ch341_private *priv;
262         int r;
263
264         dbg("ch341_attach()");
265
266         /* private data */
267         priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
268         if (!priv)
269                 return -ENOMEM;
270
271         spin_lock_init(&priv->lock);
272         priv->baud_rate = DEFAULT_BAUD_RATE;
273
274         r = ch341_configure(serial->dev, priv);
275         if (r < 0)
276                 goto error;
277
278         usb_set_serial_port_data(serial->port[0], priv);
279         return 0;
280
281 error:  kfree(priv);
282         return r;
283 }
284
285 static int ch341_carrier_raised(struct usb_serial_port *port)
286 {
287         struct ch341_private *priv = usb_get_serial_port_data(port);
288         if (priv->line_status & CH341_BIT_DCD)
289                 return 1;
290         return 0;
291 }
292
293 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
294 {
295         struct ch341_private *priv = usb_get_serial_port_data(port);
296         unsigned long flags;
297
298         dbg("%s - port %d", __func__, port->number);
299         /* drop DTR and RTS */
300         spin_lock_irqsave(&priv->lock, flags);
301         if (on)
302                 priv->line_control |= CH341_BIT_RTS | CH341_BIT_DTR;
303         else
304                 priv->line_control &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
305         spin_unlock_irqrestore(&priv->lock, flags);
306         ch341_set_handshake(port->serial->dev, priv->line_control);
307         wake_up_interruptible(&port->delta_msr_wait);
308 }
309
310 static void ch341_close(struct usb_serial_port *port)
311 {
312         dbg("%s - port %d", __func__, port->number);
313
314         usb_serial_generic_close(port);
315         usb_kill_urb(port->interrupt_in_urb);
316 }
317
318
319 /* open this device, set default parameters */
320 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
321 {
322         struct usb_serial *serial = port->serial;
323         struct ch341_private *priv = usb_get_serial_port_data(serial->port[0]);
324         int r;
325
326         dbg("ch341_open()");
327
328         r = ch341_configure(serial->dev, priv);
329         if (r)
330                 goto out;
331
332         if (tty)
333                 ch341_set_termios(tty, port, NULL);
334
335         dbg("%s - submitting interrupt urb", __func__);
336         port->interrupt_in_urb->dev = serial->dev;
337         r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
338         if (r) {
339                 dev_err(&port->dev, "%s - failed submitting interrupt urb,"
340                         " error %d\n", __func__, r);
341                 goto out;
342         }
343
344         r = usb_serial_generic_open(tty, port);
345
346 out:    return r;
347 }
348
349 /* Old_termios contains the original termios settings and
350  * tty->termios contains the new setting to be used.
351  */
352 static void ch341_set_termios(struct tty_struct *tty,
353                 struct usb_serial_port *port, struct ktermios *old_termios)
354 {
355         struct ch341_private *priv = usb_get_serial_port_data(port);
356         unsigned baud_rate;
357         unsigned long flags;
358         unsigned char ctrl;
359         int r;
360
361         /* redundant changes may cause the chip to lose bytes */
362         if (old_termios && !tty_termios_hw_change(tty->termios, old_termios))
363                 return;
364
365         dbg("ch341_set_termios()");
366
367         baud_rate = tty_get_baud_rate(tty);
368
369         ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
370
371         if (baud_rate) {
372                 priv->baud_rate = baud_rate;
373
374                 r = ch341_init_set_baudrate(port->serial->dev, priv, ctrl);
375                 if (r < 0 && old_termios) {
376                         priv->baud_rate = tty_termios_baud_rate(old_termios);
377                         tty_termios_copy_hw(tty->termios, old_termios);
378                 }
379         }
380
381         spin_lock_irqsave(&priv->lock, flags);
382         if (C_BAUD(tty) == B0)
383                 priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
384         else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
385                 priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
386         spin_unlock_irqrestore(&priv->lock, flags);
387
388         /* Unimplemented:
389          * (cflag & CSIZE) : data bits [5, 8]
390          * (cflag & PARENB) : parity {NONE, EVEN, ODD}
391          * (cflag & CSTOPB) : stop bits [1, 2]
392          */
393 }
394
395 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
396 {
397         const uint16_t ch341_break_reg =
398                         ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
399         struct usb_serial_port *port = tty->driver_data;
400         int r;
401         uint16_t reg_contents;
402         uint8_t *break_reg;
403
404         dbg("%s()", __func__);
405
406         break_reg = kmalloc(2, GFP_KERNEL);
407         if (!break_reg) {
408                 dev_err(&port->dev, "%s - kmalloc failed\n", __func__);
409                 return;
410         }
411
412         r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
413                         ch341_break_reg, 0, break_reg, 2);
414         if (r < 0) {
415                 dev_err(&port->dev, "%s - USB control read error (%d)\n",
416                                 __func__, r);
417                 goto out;
418         }
419         dbg("%s - initial ch341 break register contents - reg1: %x, reg2: %x",
420                         __func__, break_reg[0], break_reg[1]);
421         if (break_state != 0) {
422                 dbg("%s - Enter break state requested", __func__);
423                 break_reg[0] &= ~CH341_NBREAK_BITS;
424                 break_reg[1] &= ~CH341_LCR_ENABLE_TX;
425         } else {
426                 dbg("%s - Leave break state requested", __func__);
427                 break_reg[0] |= CH341_NBREAK_BITS;
428                 break_reg[1] |= CH341_LCR_ENABLE_TX;
429         }
430         dbg("%s - New ch341 break register contents - reg1: %x, reg2: %x",
431                         __func__, break_reg[0], break_reg[1]);
432         reg_contents = get_unaligned_le16(break_reg);
433         r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
434                         ch341_break_reg, reg_contents);
435         if (r < 0)
436                 dev_err(&port->dev, "%s - USB control write error (%d)\n",
437                                 __func__, r);
438 out:
439         kfree(break_reg);
440 }
441
442 static int ch341_tiocmset(struct tty_struct *tty,
443                           unsigned int set, unsigned int clear)
444 {
445         struct usb_serial_port *port = tty->driver_data;
446         struct ch341_private *priv = usb_get_serial_port_data(port);
447         unsigned long flags;
448         u8 control;
449
450         spin_lock_irqsave(&priv->lock, flags);
451         if (set & TIOCM_RTS)
452                 priv->line_control |= CH341_BIT_RTS;
453         if (set & TIOCM_DTR)
454                 priv->line_control |= CH341_BIT_DTR;
455         if (clear & TIOCM_RTS)
456                 priv->line_control &= ~CH341_BIT_RTS;
457         if (clear & TIOCM_DTR)
458                 priv->line_control &= ~CH341_BIT_DTR;
459         control = priv->line_control;
460         spin_unlock_irqrestore(&priv->lock, flags);
461
462         return ch341_set_handshake(port->serial->dev, control);
463 }
464
465 static void ch341_read_int_callback(struct urb *urb)
466 {
467         struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
468         unsigned char *data = urb->transfer_buffer;
469         unsigned int actual_length = urb->actual_length;
470         int status;
471
472         dbg("%s (%d)", __func__, port->number);
473
474         switch (urb->status) {
475         case 0:
476                 /* success */
477                 break;
478         case -ECONNRESET:
479         case -ENOENT:
480         case -ESHUTDOWN:
481                 /* this urb is terminated, clean up */
482                 dbg("%s - urb shutting down with status: %d", __func__,
483                     urb->status);
484                 return;
485         default:
486                 dbg("%s - nonzero urb status received: %d", __func__,
487                     urb->status);
488                 goto exit;
489         }
490
491         usb_serial_debug_data(debug, &port->dev, __func__,
492                               urb->actual_length, urb->transfer_buffer);
493
494         if (actual_length >= 4) {
495                 struct ch341_private *priv = usb_get_serial_port_data(port);
496                 unsigned long flags;
497                 u8 prev_line_status = priv->line_status;
498
499                 spin_lock_irqsave(&priv->lock, flags);
500                 priv->line_status = (~(data[2])) & CH341_BITS_MODEM_STAT;
501                 if ((data[1] & CH341_MULT_STAT))
502                         priv->multi_status_change = 1;
503                 spin_unlock_irqrestore(&priv->lock, flags);
504
505                 if ((priv->line_status ^ prev_line_status) & CH341_BIT_DCD) {
506                         struct tty_struct *tty = tty_port_tty_get(&port->port);
507                         if (tty)
508                                 usb_serial_handle_dcd_change(port, tty,
509                                             priv->line_status & CH341_BIT_DCD);
510                         tty_kref_put(tty);
511                 }
512
513                 wake_up_interruptible(&port->delta_msr_wait);
514         }
515
516 exit:
517         status = usb_submit_urb(urb, GFP_ATOMIC);
518         if (status)
519                 dev_err(&urb->dev->dev,
520                         "%s - usb_submit_urb failed with result %d\n",
521                         __func__, status);
522 }
523
524 static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
525 {
526         struct ch341_private *priv = usb_get_serial_port_data(port);
527         unsigned long flags;
528         u8 prevstatus;
529         u8 status;
530         u8 changed;
531         u8 multi_change = 0;
532
533         spin_lock_irqsave(&priv->lock, flags);
534         prevstatus = priv->line_status;
535         priv->multi_status_change = 0;
536         spin_unlock_irqrestore(&priv->lock, flags);
537
538         while (!multi_change) {
539                 interruptible_sleep_on(&port->delta_msr_wait);
540                 /* see if a signal did it */
541                 if (signal_pending(current))
542                         return -ERESTARTSYS;
543
544                 if (port->serial->disconnected)
545                         return -EIO;
546
547                 spin_lock_irqsave(&priv->lock, flags);
548                 status = priv->line_status;
549                 multi_change = priv->multi_status_change;
550                 spin_unlock_irqrestore(&priv->lock, flags);
551
552                 changed = prevstatus ^ status;
553
554                 if (((arg & TIOCM_RNG) && (changed & CH341_BIT_RI)) ||
555                     ((arg & TIOCM_DSR) && (changed & CH341_BIT_DSR)) ||
556                     ((arg & TIOCM_CD)  && (changed & CH341_BIT_DCD)) ||
557                     ((arg & TIOCM_CTS) && (changed & CH341_BIT_CTS))) {
558                         return 0;
559                 }
560                 prevstatus = status;
561         }
562
563         return 0;
564 }
565
566 static int ch341_ioctl(struct tty_struct *tty,
567                         unsigned int cmd, unsigned long arg)
568 {
569         struct usb_serial_port *port = tty->driver_data;
570         dbg("%s (%d) cmd = 0x%04x", __func__, port->number, cmd);
571
572         switch (cmd) {
573         case TIOCMIWAIT:
574                 dbg("%s (%d) TIOCMIWAIT", __func__,  port->number);
575                 return wait_modem_info(port, arg);
576
577         default:
578                 dbg("%s not supported = 0x%04x", __func__, cmd);
579                 break;
580         }
581
582         return -ENOIOCTLCMD;
583 }
584
585 static int ch341_tiocmget(struct tty_struct *tty)
586 {
587         struct usb_serial_port *port = tty->driver_data;
588         struct ch341_private *priv = usb_get_serial_port_data(port);
589         unsigned long flags;
590         u8 mcr;
591         u8 status;
592         unsigned int result;
593
594         dbg("%s (%d)", __func__, port->number);
595
596         spin_lock_irqsave(&priv->lock, flags);
597         mcr = priv->line_control;
598         status = priv->line_status;
599         spin_unlock_irqrestore(&priv->lock, flags);
600
601         result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
602                   | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
603                   | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
604                   | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
605                   | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
606                   | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
607
608         dbg("%s - result = %x", __func__, result);
609
610         return result;
611 }
612
613
614 static int ch341_reset_resume(struct usb_interface *intf)
615 {
616         struct usb_device *dev = interface_to_usbdev(intf);
617         struct usb_serial *serial = NULL;
618         struct ch341_private *priv;
619
620         serial = usb_get_intfdata(intf);
621         priv = usb_get_serial_port_data(serial->port[0]);
622
623         /*reconfigure ch341 serial port after bus-reset*/
624         ch341_configure(dev, priv);
625
626         usb_serial_resume(intf);
627
628         return 0;
629 }
630
631 static struct usb_driver ch341_driver = {
632         .name           = "ch341",
633         .probe          = usb_serial_probe,
634         .disconnect     = usb_serial_disconnect,
635         .suspend        = usb_serial_suspend,
636         .resume         = usb_serial_resume,
637         .reset_resume   = ch341_reset_resume,
638         .id_table       = id_table,
639         .no_dynamic_id  = 1,
640         .supports_autosuspend = 1,
641 };
642
643 static struct usb_serial_driver ch341_device = {
644         .driver = {
645                 .owner  = THIS_MODULE,
646                 .name   = "ch341-uart",
647         },
648         .id_table          = id_table,
649         .usb_driver        = &ch341_driver,
650         .num_ports         = 1,
651         .open              = ch341_open,
652         .dtr_rts           = ch341_dtr_rts,
653         .carrier_raised    = ch341_carrier_raised,
654         .close             = ch341_close,
655         .ioctl             = ch341_ioctl,
656         .set_termios       = ch341_set_termios,
657         .break_ctl         = ch341_break_ctl,
658         .tiocmget          = ch341_tiocmget,
659         .tiocmset          = ch341_tiocmset,
660         .read_int_callback = ch341_read_int_callback,
661         .attach            = ch341_attach,
662 };
663
664 static int __init ch341_init(void)
665 {
666         int retval;
667
668         retval = usb_serial_register(&ch341_device);
669         if (retval)
670                 return retval;
671         retval = usb_register(&ch341_driver);
672         if (retval)
673                 usb_serial_deregister(&ch341_device);
674         return retval;
675 }
676
677 static void __exit ch341_exit(void)
678 {
679         usb_deregister(&ch341_driver);
680         usb_serial_deregister(&ch341_device);
681 }
682
683 module_init(ch341_init);
684 module_exit(ch341_exit);
685 MODULE_LICENSE("GPL");
686
687 module_param(debug, bool, S_IRUGO | S_IWUSR);
688 MODULE_PARM_DESC(debug, "Debug enabled or not");
689
690 /* EOF ch341.c */