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/usb.h>
  23 #include <linux/usb/serial.h>
  24 #include <linux/serial.h>
  25
  26 #define DEFAULT_BAUD_RATE 9600
  27 #define DEFAULT_TIMEOUT   1000
  28
  29 /* flags for IO-Bits */
  30 #define CH341_BIT_RTS (1 << 6)
  31 #define CH341_BIT_DTR (1 << 5)
  32
  33 /******************************/
  34 /* interrupt pipe definitions */
  35 /******************************/
  36 /* always 4 interrupt bytes */
  37 /* first irq byte normally 0x08 */
  38 /* second irq byte base 0x7d + below */
  39 /* third irq byte base 0x94 + below */
  40 /* fourth irq byte normally 0xee */
  41
  42 /* second interrupt byte */
  43 #define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */
  44
  45 /* status returned in third interrupt answer byte, inverted in data
  46    from irq */
  47 #define CH341_BIT_CTS 0x01
  48 #define CH341_BIT_DSR 0x02
  49 #define CH341_BIT_RI  0x04
  50 #define CH341_BIT_DCD 0x08
  51 #define CH341_BITS_MODEM_STAT 0x0f /* all bits */
  52
  53 /*******************************/
  54 /* baudrate calculation factor */
  55 /*******************************/
  56 #define CH341_BAUDBASE_FACTOR 1532620800
  57 #define CH341_BAUDBASE_DIVMAX 3
  58
  59 /* Break support - the information used to implement this was gleaned from
  60  * the Net/FreeBSD uchcom.c driver by Takanori Watanabe.  Domo arigato.
  61  */
  62
  63 #define CH341_REQ_WRITE_REG    0x9A
  64 #define CH341_REQ_READ_REG     0x95
  65 #define CH341_REG_BREAK1       0x05
  66 #define CH341_REG_BREAK2       0x18
  67 #define CH341_NBREAK_BITS_REG1 0x01
  68 #define CH341_NBREAK_BITS_REG2 0x40
  69
  70
  71 static int debug;
  72
  73 static struct usb_device_id id_table [] = {
  74         { USB_DEVICE(0x4348, 0x5523) },
  75         { USB_DEVICE(0x1a86, 0x7523) },
  76         { },
  77 };
  78 MODULE_DEVICE_TABLE(usb, id_table);
  79
  80 struct ch341_private {
  81         spinlock_t lock; /* access lock */
  82         wait_queue_head_t delta_msr_wait; /* wait queue for modem status */
  83         unsigned baud_rate; /* set baud rate */
  84         u8 line_control; /* set line control value RTS/DTR */
  85         u8 line_status; /* active status of modem control inputs */
  86         u8 multi_status_change; /* status changed multiple since last call */
  87 };
  88
  89 static int ch341_control_out(struct usb_device *dev, u8 request,
  90                              u16 value, u16 index)
  91 {
  92         int r;
  93         dbg("ch341_control_out(%02x,%02x,%04x,%04x)", USB_DIR_OUT|0x40,
  94                 (int)request, (int)value, (int)index);
  95
  96         r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
  97                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
  98                             value, index, NULL, 0, DEFAULT_TIMEOUT);
  99
 100         return r;
 101 }
 102
 103 static int ch341_control_in(struct usb_device *dev,
 104                             u8 request, u16 value, u16 index,
 105                             char *buf, unsigned bufsize)
 106 {
 107         int r;
 108         dbg("ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)", USB_DIR_IN|0x40,
 109                 (int)request, (int)value, (int)index, buf, (int)bufsize);
 110
 111         r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
 112                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 113                             value, index, buf, bufsize, DEFAULT_TIMEOUT);
 114         return r;
 115 }
 116
 117 static int ch341_set_baudrate(struct usb_device *dev,
 118                               struct ch341_private *priv)
 119 {
 120         short a, b;
 121         int r;
 122         unsigned long factor;
 123         short divisor;
 124
 125         dbg("ch341_set_baudrate(%d)", priv->baud_rate);
 126
 127         if (!priv->baud_rate)
 128                 return -EINVAL;
 129         factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate);
 130         divisor = CH341_BAUDBASE_DIVMAX;
 131
 132         while ((factor > 0xfff0) && divisor) {
 133                 factor >>= 3;
 134                 divisor--;
 135         }
 136
 137         if (factor > 0xfff0)
 138                 return -EINVAL;
 139
 140         factor = 0x10000 - factor;
 141         a = (factor & 0xff00) | divisor;
 142         b = factor & 0xff;
 143
 144         r = ch341_control_out(dev, 0x9a, 0x1312, a);
 145         if (!r)
 146                 r = ch341_control_out(dev, 0x9a, 0x0f2c, b);
 147
 148         return r;
 149 }
 150
 151 static int ch341_set_handshake(struct usb_device *dev, u8 control)
 152 {
 153         dbg("ch341_set_handshake(0x%02x)", control);
 154         return ch341_control_out(dev, 0xa4, ~control, 0);
 155 }
 156
 157 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 158 {
 159         char *buffer;
 160         int r;
 161         const unsigned size = 8;
 162         unsigned long flags;
 163
 164         dbg("ch341_get_status()");
 165
 166         buffer = kmalloc(size, GFP_KERNEL);
 167         if (!buffer)
 168                 return -ENOMEM;
 169
 170         r = ch341_control_in(dev, 0x95, 0x0706, 0, buffer, size);
 171         if (r < 0)
 172                 goto out;
 173
 174         /* setup the private status if available */
 175         if (r == 2) {
 176                 r = 0;
 177                 spin_lock_irqsave(&priv->lock, flags);
 178                 priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
 179                 priv->multi_status_change = 0;
 180                 spin_unlock_irqrestore(&priv->lock, flags);
 181         } else
 182                 r = -EPROTO;
 183
 184 out:    kfree(buffer);
 185         return r;
 186 }
 187
 188 /* -------------------------------------------------------------------------- */
 189
 190 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 191 {
 192         char *buffer;
 193         int r;
 194         const unsigned size = 8;
 195
 196         dbg("ch341_configure()");
 197
 198         buffer = kmalloc(size, GFP_KERNEL);
 199         if (!buffer)
 200                 return -ENOMEM;
 201
 202         /* expect two bytes 0x27 0x00 */
 203         r = ch341_control_in(dev, 0x5f, 0, 0, buffer, size);
 204         if (r < 0)
 205                 goto out;
 206
 207         r = ch341_control_out(dev, 0xa1, 0, 0);
 208         if (r < 0)
 209                 goto out;
 210
 211         r = ch341_set_baudrate(dev, priv);
 212         if (r < 0)
 213                 goto out;
 214
 215         /* expect two bytes 0x56 0x00 */
 216         r = ch341_control_in(dev, 0x95, 0x2518, 0, buffer, size);
 217         if (r < 0)
 218                 goto out;
 219
 220         r = ch341_control_out(dev, 0x9a, 0x2518, 0x0050);
 221         if (r < 0)
 222                 goto out;
 223
 224         /* expect 0xff 0xee */
 225         r = ch341_get_status(dev, priv);
 226         if (r < 0)
 227                 goto out;
 228
 229         r = ch341_control_out(dev, 0xa1, 0x501f, 0xd90a);
 230         if (r < 0)
 231                 goto out;
 232
 233         r = ch341_set_baudrate(dev, priv);
 234         if (r < 0)
 235                 goto out;
 236
 237         r = ch341_set_handshake(dev, priv->line_control);
 238         if (r < 0)
 239                 goto out;
 240
 241         /* expect 0x9f 0xee */
 242         r = ch341_get_status(dev, priv);
 243
 244 out:    kfree(buffer);
 245         return r;
 246 }
 247
 248 /* allocate private data */
 249 static int ch341_attach(struct usb_serial *serial)
 250 {
 251         struct ch341_private *priv;
 252         int r;
 253
 254         dbg("ch341_attach()");
 255
 256         /* private data */
 257         priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
 258         if (!priv)
 259                 return -ENOMEM;
 260
 261         spin_lock_init(&priv->lock);
 262         init_waitqueue_head(&priv->delta_msr_wait);
 263         priv->baud_rate = DEFAULT_BAUD_RATE;
 264         priv->line_control = CH341_BIT_RTS | CH341_BIT_DTR;
 265
 266         r = ch341_configure(serial->dev, priv);
 267         if (r < 0)
 268                 goto error;
 269
 270         usb_set_serial_port_data(serial->port[0], priv);
 271         return 0;
 272
 273 error:  kfree(priv);
 274         return r;
 275 }
 276
 277 static int ch341_carrier_raised(struct usb_serial_port *port)
 278 {
 279         struct ch341_private *priv = usb_get_serial_port_data(port);
 280         if (priv->line_status & CH341_BIT_DCD)
 281                 return 1;
 282         return 0;
 283 }
 284
 285 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
 286 {
 287         struct ch341_private *priv = usb_get_serial_port_data(port);
 288         unsigned long flags;
 289
 290         dbg("%s - port %d", __func__, port->number);
 291         /* drop DTR and RTS */
 292         spin_lock_irqsave(&priv->lock, flags);
 293         if (on)
 294                 priv->line_control |= CH341_BIT_RTS | CH341_BIT_DTR;
 295         else
 296                 priv->line_control &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
 297         spin_unlock_irqrestore(&priv->lock, flags);
 298         ch341_set_handshake(port->serial->dev, priv->line_control);
 299         wake_up_interruptible(&priv->delta_msr_wait);
 300 }
 301
 302 static void ch341_close(struct usb_serial_port *port)
 303 {
 304         dbg("%s - port %d", __func__, port->number);
 305
 306         /* shutdown our urbs */
 307         dbg("%s - shutting down urbs", __func__);
 308         usb_kill_urb(port->write_urb);
 309         usb_kill_urb(port->read_urb);
 310         usb_kill_urb(port->interrupt_in_urb);
 311 }
 312
 313
 314 /* open this device, set default parameters */
 315 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
 316 {
 317         struct usb_serial *serial = port->serial;
 318         struct ch341_private *priv = usb_get_serial_port_data(serial->port[0]);
 319         int r;
 320
 321         dbg("ch341_open()");
 322
 323         priv->baud_rate = DEFAULT_BAUD_RATE;
 324
 325         r = ch341_configure(serial->dev, priv);
 326         if (r)
 327                 goto out;
 328
 329         r = ch341_set_handshake(serial->dev, priv->line_control);
 330         if (r)
 331                 goto out;
 332
 333         r = ch341_set_baudrate(serial->dev, priv);
 334         if (r)
 335                 goto out;
 336
 337         dbg("%s - submitting interrupt urb", __func__);
 338         port->interrupt_in_urb->dev = serial->dev;
 339         r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 340         if (r) {
 341                 dev_err(&port->dev, "%s - failed submitting interrupt urb,"
 342                         " error %d\n", __func__, r);
 343                 ch341_close(port);
 344                 return -EPROTO;
 345         }
 346
 347         r = usb_serial_generic_open(tty, port);
 348
 349 out:    return r;
 350 }
 351
 352 /* Old_termios contains the original termios settings and
 353  * tty->termios contains the new setting to be used.
 354  */
 355 static void ch341_set_termios(struct tty_struct *tty,
 356                 struct usb_serial_port *port, struct ktermios *old_termios)
 357 {
 358         struct ch341_private *priv = usb_get_serial_port_data(port);
 359         unsigned baud_rate;
 360         unsigned long flags;
 361
 362         dbg("ch341_set_termios()");
 363
 364         baud_rate = tty_get_baud_rate(tty);
 365
 366         priv->baud_rate = baud_rate;
 367
 368         if (baud_rate) {
 369                 spin_lock_irqsave(&priv->lock, flags);
 370                 priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
 371                 spin_unlock_irqrestore(&priv->lock, flags);
 372                 ch341_set_baudrate(port->serial->dev, priv);
 373         } else {
 374                 spin_lock_irqsave(&priv->lock, flags);
 375                 priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
 376                 spin_unlock_irqrestore(&priv->lock, flags);
 377         }
 378
 379         ch341_set_handshake(port->serial->dev, priv->line_control);
 380
 381         /* Unimplemented:
 382          * (cflag & CSIZE) : data bits [5, 8]
 383          * (cflag & PARENB) : parity {NONE, EVEN, ODD}
 384          * (cflag & CSTOPB) : stop bits [1, 2]
 385          */
 386 }
 387
 388 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 389 {
 390         const uint16_t ch341_break_reg =
 391                 CH341_REG_BREAK1 | ((uint16_t) CH341_REG_BREAK2 << 8);
 392         struct usb_serial_port *port = tty->driver_data;
 393         int r;
 394         uint16_t reg_contents;
 395         uint8_t break_reg[2];
 396
 397         dbg("%s()", __func__);
 398
 399         r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
 400                         ch341_break_reg, 0, break_reg, sizeof(break_reg));
 401         if (r < 0) {
 402                 printk(KERN_WARNING "%s: USB control read error whilst getting"
 403                                 " break register contents.\n", __FILE__);
 404                 return;
 405         }
 406         dbg("%s - initial ch341 break register contents - reg1: %x, reg2: %x",
 407                         __func__, break_reg[0], break_reg[1]);
 408         if (break_state != 0) {
 409                 dbg("%s - Enter break state requested", __func__);
 410                 break_reg[0] &= ~CH341_NBREAK_BITS_REG1;
 411                 break_reg[1] &= ~CH341_NBREAK_BITS_REG2;
 412         } else {
 413                 dbg("%s - Leave break state requested", __func__);
 414                 break_reg[0] |= CH341_NBREAK_BITS_REG1;
 415                 break_reg[1] |= CH341_NBREAK_BITS_REG2;
 416         }
 417         dbg("%s - New ch341 break register contents - reg1: %x, reg2: %x",
 418                         __func__, break_reg[0], break_reg[1]);
 419         reg_contents = (uint16_t)break_reg[0] | ((uint16_t)break_reg[1] << 8);
 420         r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
 421                         ch341_break_reg, reg_contents);
 422         if (r < 0)
 423                 printk(KERN_WARNING "%s: USB control write error whilst setting"
 424                                 " break register contents.\n", __FILE__);
 425 }
 426
 427 static int ch341_tiocmset(struct tty_struct *tty, struct file *file,
 428                           unsigned int set, unsigned int clear)
 429 {
 430         struct usb_serial_port *port = tty->driver_data;
 431         struct ch341_private *priv = usb_get_serial_port_data(port);
 432         unsigned long flags;
 433         u8 control;
 434
 435         spin_lock_irqsave(&priv->lock, flags);
 436         if (set & TIOCM_RTS)
 437                 priv->line_control |= CH341_BIT_RTS;
 438         if (set & TIOCM_DTR)
 439                 priv->line_control |= CH341_BIT_DTR;
 440         if (clear & TIOCM_RTS)
 441                 priv->line_control &= ~CH341_BIT_RTS;
 442         if (clear & TIOCM_DTR)
 443                 priv->line_control &= ~CH341_BIT_DTR;
 444         control = priv->line_control;
 445         spin_unlock_irqrestore(&priv->lock, flags);
 446
 447         return ch341_set_handshake(port->serial->dev, control);
 448 }
 449
 450 static void ch341_read_int_callback(struct urb *urb)
 451 {
 452         struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
 453         unsigned char *data = urb->transfer_buffer;
 454         unsigned int actual_length = urb->actual_length;
 455         int status;
 456
 457         dbg("%s (%d)", __func__, port->number);
 458
 459         switch (urb->status) {
 460         case 0:
 461                 /* success */
 462                 break;
 463         case -ECONNRESET:
 464         case -ENOENT:
 465         case -ESHUTDOWN:
 466                 /* this urb is terminated, clean up */
 467                 dbg("%s - urb shutting down with status: %d", __func__,
 468                     urb->status);
 469                 return;
 470         default:
 471                 dbg("%s - nonzero urb status received: %d", __func__,
 472                     urb->status);
 473                 goto exit;
 474         }
 475
 476         usb_serial_debug_data(debug, &port->dev, __func__,
 477                               urb->actual_length, urb->transfer_buffer);
 478
 479         if (actual_length >= 4) {
 480                 struct ch341_private *priv = usb_get_serial_port_data(port);
 481                 unsigned long flags;
 482
 483                 spin_lock_irqsave(&priv->lock, flags);
 484                 priv->line_status = (~(data[2])) & CH341_BITS_MODEM_STAT;
 485                 if ((data[1] & CH341_MULT_STAT))
 486                         priv->multi_status_change = 1;
 487                 spin_unlock_irqrestore(&priv->lock, flags);
 488                 wake_up_interruptible(&priv->delta_msr_wait);
 489         }
 490
 491 exit:
 492         status = usb_submit_urb(urb, GFP_ATOMIC);
 493         if (status)
 494                 dev_err(&urb->dev->dev,
 495                         "%s - usb_submit_urb failed with result %d\n",
 496                         __func__, status);
 497 }
 498
 499 static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
 500 {
 501         struct ch341_private *priv = usb_get_serial_port_data(port);
 502         unsigned long flags;
 503         u8 prevstatus;
 504         u8 status;
 505         u8 changed;
 506         u8 multi_change = 0;
 507
 508         spin_lock_irqsave(&priv->lock, flags);
 509         prevstatus = priv->line_status;
 510         priv->multi_status_change = 0;
 511         spin_unlock_irqrestore(&priv->lock, flags);
 512
 513         while (!multi_change) {
 514                 interruptible_sleep_on(&priv->delta_msr_wait);
 515                 /* see if a signal did it */
 516                 if (signal_pending(current))
 517                         return -ERESTARTSYS;
 518
 519                 spin_lock_irqsave(&priv->lock, flags);
 520                 status = priv->line_status;
 521                 multi_change = priv->multi_status_change;
 522                 spin_unlock_irqrestore(&priv->lock, flags);
 523
 524                 changed = prevstatus ^ status;
 525
 526                 if (((arg & TIOCM_RNG) && (changed & CH341_BIT_RI)) ||
 527                     ((arg & TIOCM_DSR) && (changed & CH341_BIT_DSR)) ||
 528                     ((arg & TIOCM_CD)  && (changed & CH341_BIT_DCD)) ||
 529                     ((arg & TIOCM_CTS) && (changed & CH341_BIT_CTS))) {
 530                         return 0;
 531                 }
 532                 prevstatus = status;
 533         }
 534
 535         return 0;
 536 }
 537
 538 /*static int ch341_ioctl(struct usb_serial_port *port, struct file *file,*/
 539 static int ch341_ioctl(struct tty_struct *tty, struct file *file,
 540                         unsigned int cmd, unsigned long arg)
 541 {
 542         struct usb_serial_port *port = tty->driver_data;
 543         dbg("%s (%d) cmd = 0x%04x", __func__, port->number, cmd);
 544
 545         switch (cmd) {
 546         case TIOCMIWAIT:
 547                 dbg("%s (%d) TIOCMIWAIT", __func__,  port->number);
 548                 return wait_modem_info(port, arg);
 549
 550         default:
 551                 dbg("%s not supported = 0x%04x", __func__, cmd);
 552                 break;
 553         }
 554
 555         return -ENOIOCTLCMD;
 556 }
 557
 558 static int ch341_tiocmget(struct tty_struct *tty, struct file *file)
 559 {
 560         struct usb_serial_port *port = tty->driver_data;
 561         struct ch341_private *priv = usb_get_serial_port_data(port);
 562         unsigned long flags;
 563         u8 mcr;
 564         u8 status;
 565         unsigned int result;
 566
 567         dbg("%s (%d)", __func__, port->number);
 568
 569         spin_lock_irqsave(&priv->lock, flags);
 570         mcr = priv->line_control;
 571         status = priv->line_status;
 572         spin_unlock_irqrestore(&priv->lock, flags);
 573
 574         result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
 575                   | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
 576                   | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
 577                   | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
 578                   | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
 579                   | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
 580
 581         dbg("%s - result = %x", __func__, result);
 582
 583         return result;
 584 }
 585
 586
 587 static int ch341_reset_resume(struct usb_interface *intf)
 588 {
 589         struct usb_device *dev = interface_to_usbdev(intf);
 590         struct usb_serial *serial = NULL;
 591         struct ch341_private *priv;
 592
 593         serial = usb_get_intfdata(intf);
 594         priv = usb_get_serial_port_data(serial->port[0]);
 595
 596         /*reconfigure ch341 serial port after bus-reset*/
 597         ch341_configure(dev, priv);
 598
 599         usb_serial_resume(intf);
 600
 601         return 0;
 602 }
 603
 604 static struct usb_driver ch341_driver = {
 605         .name           = "ch341",
 606         .probe          = usb_serial_probe,
 607         .disconnect     = usb_serial_disconnect,
 608         .suspend        = usb_serial_suspend,
 609         .resume         = usb_serial_resume,
 610         .reset_resume   = ch341_reset_resume,
 611         .id_table       = id_table,
 612         .no_dynamic_id  = 1,
 613         .supports_autosuspend = 1,
 614 };
 615
 616 static struct usb_serial_driver ch341_device = {
 617         .driver = {
 618                 .owner  = THIS_MODULE,
 619                 .name   = "ch341-uart",
 620         },
 621         .id_table          = id_table,
 622         .usb_driver        = &ch341_driver,
 623         .num_ports         = 1,
 624         .open              = ch341_open,
 625         .dtr_rts           = ch341_dtr_rts,
 626         .carrier_raised    = ch341_carrier_raised,
 627         .close             = ch341_close,
 628         .ioctl             = ch341_ioctl,
 629         .set_termios       = ch341_set_termios,
 630         .break_ctl         = ch341_break_ctl,
 631         .tiocmget          = ch341_tiocmget,
 632         .tiocmset          = ch341_tiocmset,
 633         .read_int_callback = ch341_read_int_callback,
 634         .attach            = ch341_attach,
 635 };
 636
 637 static int __init ch341_init(void)
 638 {
 639         int retval;
 640
 641         retval = usb_serial_register(&ch341_device);
 642         if (retval)
 643                 return retval;
 644         retval = usb_register(&ch341_driver);
 645         if (retval)
 646                 usb_serial_deregister(&ch341_device);
 647         return retval;
 648 }
 649
 650 static void __exit ch341_exit(void)
 651 {
 652         usb_deregister(&ch341_driver);
 653         usb_serial_deregister(&ch341_device);
 654 }
 655
 656 module_init(ch341_init);
 657 module_exit(ch341_exit);
 658 MODULE_LICENSE("GPL");
 659
 660 module_param(debug, bool, S_IRUGO | S_IWUSR);
 661 MODULE_PARM_DESC(debug, "Debug enabled or not");
 662
 663 /* EOF ch341.c */