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_WRITE_REG    0x9A
  66 #define CH341_REQ_READ_REG     0x95
  67 #define CH341_REG_BREAK1       0x05
  68 #define CH341_REG_BREAK2       0x18
  69 #define CH341_NBREAK_BITS_REG1 0x01
  70 #define CH341_NBREAK_BITS_REG2 0x40
  71
  72
  73 static int debug;
  74
  75 static const struct usb_device_id id_table[] = {
  76         { USB_DEVICE(0x4348, 0x5523) },
  77         { USB_DEVICE(0x1a86, 0x7523) },
  78         { },
  79 };
  80 MODULE_DEVICE_TABLE(usb, id_table);
  81
  82 struct ch341_private {
  83         spinlock_t lock; /* access lock */
  84         wait_queue_head_t delta_msr_wait; /* wait queue for modem status */
  85         unsigned baud_rate; /* set baud rate */
  86         u8 line_control; /* set line control value RTS/DTR */
  87         u8 line_status; /* active status of modem control inputs */
  88         u8 multi_status_change; /* status changed multiple since last call */
  89 };
  90
  91 static int ch341_control_out(struct usb_device *dev, u8 request,
  92                              u16 value, u16 index)
  93 {
  94         int r;
  95         dbg("ch341_control_out(%02x,%02x,%04x,%04x)", USB_DIR_OUT|0x40,
  96                 (int)request, (int)value, (int)index);
  97
  98         r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
  99                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
 100                             value, index, NULL, 0, DEFAULT_TIMEOUT);
 101
 102         return r;
 103 }
 104
 105 static int ch341_control_in(struct usb_device *dev,
 106                             u8 request, u16 value, u16 index,
 107                             char *buf, unsigned bufsize)
 108 {
 109         int r;
 110         dbg("ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)", USB_DIR_IN|0x40,
 111                 (int)request, (int)value, (int)index, buf, (int)bufsize);
 112
 113         r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
 114                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 115                             value, index, buf, bufsize, DEFAULT_TIMEOUT);
 116         return r;
 117 }
 118
 119 static int ch341_set_baudrate(struct usb_device *dev,
 120                               struct ch341_private *priv)
 121 {
 122         short a, b;
 123         int r;
 124         unsigned long factor;
 125         short divisor;
 126
 127         dbg("ch341_set_baudrate(%d)", priv->baud_rate);
 128
 129         if (!priv->baud_rate)
 130                 return -EINVAL;
 131         factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate);
 132         divisor = CH341_BAUDBASE_DIVMAX;
 133
 134         while ((factor > 0xfff0) && divisor) {
 135                 factor >>= 3;
 136                 divisor--;
 137         }
 138
 139         if (factor > 0xfff0)
 140                 return -EINVAL;
 141
 142         factor = 0x10000 - factor;
 143         a = (factor & 0xff00) | divisor;
 144         b = factor & 0xff;
 145
 146         r = ch341_control_out(dev, 0x9a, 0x1312, a);
 147         if (!r)
 148                 r = ch341_control_out(dev, 0x9a, 0x0f2c, b);
 149
 150         return r;
 151 }
 152
 153 static int ch341_set_handshake(struct usb_device *dev, u8 control)
 154 {
 155         dbg("ch341_set_handshake(0x%02x)", control);
 156         return ch341_control_out(dev, 0xa4, ~control, 0);
 157 }
 158
 159 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 160 {
 161         char *buffer;
 162         int r;
 163         const unsigned size = 8;
 164         unsigned long flags;
 165
 166         dbg("ch341_get_status()");
 167
 168         buffer = kmalloc(size, GFP_KERNEL);
 169         if (!buffer)
 170                 return -ENOMEM;
 171
 172         r = ch341_control_in(dev, 0x95, 0x0706, 0, buffer, size);
 173         if (r < 0)
 174                 goto out;
 175
 176         /* setup the private status if available */
 177         if (r == 2) {
 178                 r = 0;
 179                 spin_lock_irqsave(&priv->lock, flags);
 180                 priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
 181                 priv->multi_status_change = 0;
 182                 spin_unlock_irqrestore(&priv->lock, flags);
 183         } else
 184                 r = -EPROTO;
 185
 186 out:    kfree(buffer);
 187         return r;
 188 }
 189
 190 /* -------------------------------------------------------------------------- */
 191
 192 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 193 {
 194         char *buffer;
 195         int r;
 196         const unsigned size = 8;
 197
 198         dbg("ch341_configure()");
 199
 200         buffer = kmalloc(size, GFP_KERNEL);
 201         if (!buffer)
 202                 return -ENOMEM;
 203
 204         /* expect two bytes 0x27 0x00 */
 205         r = ch341_control_in(dev, 0x5f, 0, 0, buffer, size);
 206         if (r < 0)
 207                 goto out;
 208
 209         r = ch341_control_out(dev, 0xa1, 0, 0);
 210         if (r < 0)
 211                 goto out;
 212
 213         r = ch341_set_baudrate(dev, priv);
 214         if (r < 0)
 215                 goto out;
 216
 217         /* expect two bytes 0x56 0x00 */
 218         r = ch341_control_in(dev, 0x95, 0x2518, 0, buffer, size);
 219         if (r < 0)
 220                 goto out;
 221
 222         r = ch341_control_out(dev, 0x9a, 0x2518, 0x0050);
 223         if (r < 0)
 224                 goto out;
 225
 226         /* expect 0xff 0xee */
 227         r = ch341_get_status(dev, priv);
 228         if (r < 0)
 229                 goto out;
 230
 231         r = ch341_control_out(dev, 0xa1, 0x501f, 0xd90a);
 232         if (r < 0)
 233                 goto out;
 234
 235         r = ch341_set_baudrate(dev, priv);
 236         if (r < 0)
 237                 goto out;
 238
 239         r = ch341_set_handshake(dev, priv->line_control);
 240         if (r < 0)
 241                 goto out;
 242
 243         /* expect 0x9f 0xee */
 244         r = ch341_get_status(dev, priv);
 245
 246 out:    kfree(buffer);
 247         return r;
 248 }
 249
 250 /* allocate private data */
 251 static int ch341_attach(struct usb_serial *serial)
 252 {
 253         struct ch341_private *priv;
 254         int r;
 255
 256         dbg("ch341_attach()");
 257
 258         /* private data */
 259         priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
 260         if (!priv)
 261                 return -ENOMEM;
 262
 263         spin_lock_init(&priv->lock);
 264         init_waitqueue_head(&priv->delta_msr_wait);
 265         priv->baud_rate = DEFAULT_BAUD_RATE;
 266         priv->line_control = CH341_BIT_RTS | CH341_BIT_DTR;
 267
 268         r = ch341_configure(serial->dev, priv);
 269         if (r < 0)
 270                 goto error;
 271
 272         usb_set_serial_port_data(serial->port[0], priv);
 273         return 0;
 274
 275 error:  kfree(priv);
 276         return r;
 277 }
 278
 279 static int ch341_carrier_raised(struct usb_serial_port *port)
 280 {
 281         struct ch341_private *priv = usb_get_serial_port_data(port);
 282         if (priv->line_status & CH341_BIT_DCD)
 283                 return 1;
 284         return 0;
 285 }
 286
 287 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
 288 {
 289         struct ch341_private *priv = usb_get_serial_port_data(port);
 290         unsigned long flags;
 291
 292         dbg("%s - port %d", __func__, port->number);
 293         /* drop DTR and RTS */
 294         spin_lock_irqsave(&priv->lock, flags);
 295         if (on)
 296                 priv->line_control |= CH341_BIT_RTS | CH341_BIT_DTR;
 297         else
 298                 priv->line_control &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
 299         spin_unlock_irqrestore(&priv->lock, flags);
 300         ch341_set_handshake(port->serial->dev, priv->line_control);
 301         wake_up_interruptible(&priv->delta_msr_wait);
 302 }
 303
 304 static void ch341_close(struct usb_serial_port *port)
 305 {
 306         dbg("%s - port %d", __func__, port->number);
 307
 308         usb_serial_generic_close(port);
 309         usb_kill_urb(port->interrupt_in_urb);
 310 }
 311
 312
 313 /* open this device, set default parameters */
 314 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
 315 {
 316         struct usb_serial *serial = port->serial;
 317         struct ch341_private *priv = usb_get_serial_port_data(serial->port[0]);
 318         int r;
 319
 320         dbg("ch341_open()");
 321
 322         priv->baud_rate = DEFAULT_BAUD_RATE;
 323
 324         r = ch341_configure(serial->dev, priv);
 325         if (r)
 326                 goto out;
 327
 328         r = ch341_set_handshake(serial->dev, priv->line_control);
 329         if (r)
 330                 goto out;
 331
 332         r = ch341_set_baudrate(serial->dev, priv);
 333         if (r)
 334                 goto out;
 335
 336         dbg("%s - submitting interrupt urb", __func__);
 337         port->interrupt_in_urb->dev = serial->dev;
 338         r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 339         if (r) {
 340                 dev_err(&port->dev, "%s - failed submitting interrupt urb,"
 341                         " error %d\n", __func__, r);
 342                 ch341_close(port);
 343                 return -EPROTO;
 344         }
 345
 346         r = usb_serial_generic_open(tty, port);
 347
 348 out:    return r;
 349 }
 350
 351 /* Old_termios contains the original termios settings and
 352  * tty->termios contains the new setting to be used.
 353  */
 354 static void ch341_set_termios(struct tty_struct *tty,
 355                 struct usb_serial_port *port, struct ktermios *old_termios)
 356 {
 357         struct ch341_private *priv = usb_get_serial_port_data(port);
 358         unsigned baud_rate;
 359         unsigned long flags;
 360
 361         dbg("ch341_set_termios()");
 362
 363         baud_rate = tty_get_baud_rate(tty);
 364
 365         priv->baud_rate = baud_rate;
 366
 367         if (baud_rate) {
 368                 spin_lock_irqsave(&priv->lock, flags);
 369                 priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
 370                 spin_unlock_irqrestore(&priv->lock, flags);
 371                 ch341_set_baudrate(port->serial->dev, priv);
 372         } else {
 373                 spin_lock_irqsave(&priv->lock, flags);
 374                 priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
 375                 spin_unlock_irqrestore(&priv->lock, flags);
 376         }
 377
 378         ch341_set_handshake(port->serial->dev, priv->line_control);
 379
 380         /* Unimplemented:
 381          * (cflag & CSIZE) : data bits [5, 8]
 382          * (cflag & PARENB) : parity {NONE, EVEN, ODD}
 383          * (cflag & CSTOPB) : stop bits [1, 2]
 384          */
 385 }
 386
 387 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 388 {
 389         const uint16_t ch341_break_reg =
 390                 CH341_REG_BREAK1 | ((uint16_t) CH341_REG_BREAK2 << 8);
 391         struct usb_serial_port *port = tty->driver_data;
 392         int r;
 393         uint16_t reg_contents;
 394         uint8_t *break_reg;
 395
 396         dbg("%s()", __func__);
 397
 398         break_reg = kmalloc(2, GFP_KERNEL);
 399         if (!break_reg) {
 400                 dev_err(&port->dev, "%s - kmalloc failed\n", __func__);
 401                 return;
 402         }
 403
 404         r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
 405                         ch341_break_reg, 0, break_reg, 2);
 406         if (r < 0) {
 407                 dev_err(&port->dev, "%s - USB control read error (%d)\n",
 408                                 __func__, r);
 409                 goto out;
 410         }
 411         dbg("%s - initial ch341 break register contents - reg1: %x, reg2: %x",
 412                         __func__, break_reg[0], break_reg[1]);
 413         if (break_state != 0) {
 414                 dbg("%s - Enter break state requested", __func__);
 415                 break_reg[0] &= ~CH341_NBREAK_BITS_REG1;
 416                 break_reg[1] &= ~CH341_NBREAK_BITS_REG2;
 417         } else {
 418                 dbg("%s - Leave break state requested", __func__);
 419                 break_reg[0] |= CH341_NBREAK_BITS_REG1;
 420                 break_reg[1] |= CH341_NBREAK_BITS_REG2;
 421         }
 422         dbg("%s - New ch341 break register contents - reg1: %x, reg2: %x",
 423                         __func__, break_reg[0], break_reg[1]);
 424         reg_contents = get_unaligned_le16(break_reg);
 425         r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
 426                         ch341_break_reg, reg_contents);
 427         if (r < 0)
 428                 dev_err(&port->dev, "%s - USB control write error (%d)\n",
 429                                 __func__, r);
 430 out:
 431         kfree(break_reg);
 432 }
 433
 434 static int ch341_tiocmset(struct tty_struct *tty, struct file *file,
 435                           unsigned int set, unsigned int clear)
 436 {
 437         struct usb_serial_port *port = tty->driver_data;
 438         struct ch341_private *priv = usb_get_serial_port_data(port);
 439         unsigned long flags;
 440         u8 control;
 441
 442         spin_lock_irqsave(&priv->lock, flags);
 443         if (set & TIOCM_RTS)
 444                 priv->line_control |= CH341_BIT_RTS;
 445         if (set & TIOCM_DTR)
 446                 priv->line_control |= CH341_BIT_DTR;
 447         if (clear & TIOCM_RTS)
 448                 priv->line_control &= ~CH341_BIT_RTS;
 449         if (clear & TIOCM_DTR)
 450                 priv->line_control &= ~CH341_BIT_DTR;
 451         control = priv->line_control;
 452         spin_unlock_irqrestore(&priv->lock, flags);
 453
 454         return ch341_set_handshake(port->serial->dev, control);
 455 }
 456
 457 static void ch341_read_int_callback(struct urb *urb)
 458 {
 459         struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
 460         unsigned char *data = urb->transfer_buffer;
 461         unsigned int actual_length = urb->actual_length;
 462         int status;
 463
 464         dbg("%s (%d)", __func__, port->number);
 465
 466         switch (urb->status) {
 467         case 0:
 468                 /* success */
 469                 break;
 470         case -ECONNRESET:
 471         case -ENOENT:
 472         case -ESHUTDOWN:
 473                 /* this urb is terminated, clean up */
 474                 dbg("%s - urb shutting down with status: %d", __func__,
 475                     urb->status);
 476                 return;
 477         default:
 478                 dbg("%s - nonzero urb status received: %d", __func__,
 479                     urb->status);
 480                 goto exit;
 481         }
 482
 483         usb_serial_debug_data(debug, &port->dev, __func__,
 484                               urb->actual_length, urb->transfer_buffer);
 485
 486         if (actual_length >= 4) {
 487                 struct ch341_private *priv = usb_get_serial_port_data(port);
 488                 unsigned long flags;
 489
 490                 spin_lock_irqsave(&priv->lock, flags);
 491                 priv->line_status = (~(data[2])) & CH341_BITS_MODEM_STAT;
 492                 if ((data[1] & CH341_MULT_STAT))
 493                         priv->multi_status_change = 1;
 494                 spin_unlock_irqrestore(&priv->lock, flags);
 495                 wake_up_interruptible(&priv->delta_msr_wait);
 496         }
 497
 498 exit:
 499         status = usb_submit_urb(urb, GFP_ATOMIC);
 500         if (status)
 501                 dev_err(&urb->dev->dev,
 502                         "%s - usb_submit_urb failed with result %d\n",
 503                         __func__, status);
 504 }
 505
 506 static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
 507 {
 508         struct ch341_private *priv = usb_get_serial_port_data(port);
 509         unsigned long flags;
 510         u8 prevstatus;
 511         u8 status;
 512         u8 changed;
 513         u8 multi_change = 0;
 514
 515         spin_lock_irqsave(&priv->lock, flags);
 516         prevstatus = priv->line_status;
 517         priv->multi_status_change = 0;
 518         spin_unlock_irqrestore(&priv->lock, flags);
 519
 520         while (!multi_change) {
 521                 interruptible_sleep_on(&priv->delta_msr_wait);
 522                 /* see if a signal did it */
 523                 if (signal_pending(current))
 524                         return -ERESTARTSYS;
 525
 526                 spin_lock_irqsave(&priv->lock, flags);
 527                 status = priv->line_status;
 528                 multi_change = priv->multi_status_change;
 529                 spin_unlock_irqrestore(&priv->lock, flags);
 530
 531                 changed = prevstatus ^ status;
 532
 533                 if (((arg & TIOCM_RNG) && (changed & CH341_BIT_RI)) ||
 534                     ((arg & TIOCM_DSR) && (changed & CH341_BIT_DSR)) ||
 535                     ((arg & TIOCM_CD)  && (changed & CH341_BIT_DCD)) ||
 536                     ((arg & TIOCM_CTS) && (changed & CH341_BIT_CTS))) {
 537                         return 0;
 538                 }
 539                 prevstatus = status;
 540         }
 541
 542         return 0;
 543 }
 544
 545 /*static int ch341_ioctl(struct usb_serial_port *port, struct file *file,*/
 546 static int ch341_ioctl(struct tty_struct *tty, struct file *file,
 547                         unsigned int cmd, unsigned long arg)
 548 {
 549         struct usb_serial_port *port = tty->driver_data;
 550         dbg("%s (%d) cmd = 0x%04x", __func__, port->number, cmd);
 551
 552         switch (cmd) {
 553         case TIOCMIWAIT:
 554                 dbg("%s (%d) TIOCMIWAIT", __func__,  port->number);
 555                 return wait_modem_info(port, arg);
 556
 557         default:
 558                 dbg("%s not supported = 0x%04x", __func__, cmd);
 559                 break;
 560         }
 561
 562         return -ENOIOCTLCMD;
 563 }
 564
 565 static int ch341_tiocmget(struct tty_struct *tty, struct file *file)
 566 {
 567         struct usb_serial_port *port = tty->driver_data;
 568         struct ch341_private *priv = usb_get_serial_port_data(port);
 569         unsigned long flags;
 570         u8 mcr;
 571         u8 status;
 572         unsigned int result;
 573
 574         dbg("%s (%d)", __func__, port->number);
 575
 576         spin_lock_irqsave(&priv->lock, flags);
 577         mcr = priv->line_control;
 578         status = priv->line_status;
 579         spin_unlock_irqrestore(&priv->lock, flags);
 580
 581         result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
 582                   | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
 583                   | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
 584                   | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
 585                   | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
 586                   | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
 587
 588         dbg("%s - result = %x", __func__, result);
 589
 590         return result;
 591 }
 592
 593
 594 static int ch341_reset_resume(struct usb_interface *intf)
 595 {
 596         struct usb_device *dev = interface_to_usbdev(intf);
 597         struct usb_serial *serial = NULL;
 598         struct ch341_private *priv;
 599
 600         serial = usb_get_intfdata(intf);
 601         priv = usb_get_serial_port_data(serial->port[0]);
 602
 603         /*reconfigure ch341 serial port after bus-reset*/
 604         ch341_configure(dev, priv);
 605
 606         usb_serial_resume(intf);
 607
 608         return 0;
 609 }
 610
 611 static struct usb_driver ch341_driver = {
 612         .name           = "ch341",
 613         .probe          = usb_serial_probe,
 614         .disconnect     = usb_serial_disconnect,
 615         .suspend        = usb_serial_suspend,
 616         .resume         = usb_serial_resume,
 617         .reset_resume   = ch341_reset_resume,
 618         .id_table       = id_table,
 619         .no_dynamic_id  = 1,
 620         .supports_autosuspend = 1,
 621 };
 622
 623 static struct usb_serial_driver ch341_device = {
 624         .driver = {
 625                 .owner  = THIS_MODULE,
 626                 .name   = "ch341-uart",
 627         },
 628         .id_table          = id_table,
 629         .usb_driver        = &ch341_driver,
 630         .num_ports         = 1,
 631         .open              = ch341_open,
 632         .dtr_rts           = ch341_dtr_rts,
 633         .carrier_raised    = ch341_carrier_raised,
 634         .close             = ch341_close,
 635         .ioctl             = ch341_ioctl,
 636         .set_termios       = ch341_set_termios,
 637         .break_ctl         = ch341_break_ctl,
 638         .tiocmget          = ch341_tiocmget,
 639         .tiocmset          = ch341_tiocmset,
 640         .read_int_callback = ch341_read_int_callback,
 641         .attach            = ch341_attach,
 642 };
 643
 644 static int __init ch341_init(void)
 645 {
 646         int retval;
 647
 648         retval = usb_serial_register(&ch341_device);
 649         if (retval)
 650                 return retval;
 651         retval = usb_register(&ch341_driver);
 652         if (retval)
 653                 usb_serial_deregister(&ch341_device);
 654         return retval;
 655 }
 656
 657 static void __exit ch341_exit(void)
 658 {
 659         usb_deregister(&ch341_driver);
 660         usb_serial_deregister(&ch341_device);
 661 }
 662
 663 module_init(ch341_init);
 664 module_exit(ch341_exit);
 665 MODULE_LICENSE("GPL");
 666
 667 module_param(debug, bool, S_IRUGO | S_IWUSR);
 668 MODULE_PARM_DESC(debug, "Debug enabled or not");
 669
 670 /* EOF ch341.c */