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         /* shutdown our urbs */
 309         dbg("%s - shutting down urbs", __func__);
 310         usb_kill_urb(port->write_urb);
 311         usb_kill_urb(port->read_urb);
 312         usb_kill_urb(port->interrupt_in_urb);
 313 }
 314
 315
 316 /* open this device, set default parameters */
 317 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
 318 {
 319         struct usb_serial *serial = port->serial;
 320         struct ch341_private *priv = usb_get_serial_port_data(serial->port[0]);
 321         int r;
 322
 323         dbg("ch341_open()");
 324
 325         priv->baud_rate = DEFAULT_BAUD_RATE;
 326
 327         r = ch341_configure(serial->dev, priv);
 328         if (r)
 329                 goto out;
 330
 331         r = ch341_set_handshake(serial->dev, priv->line_control);
 332         if (r)
 333                 goto out;
 334
 335         r = ch341_set_baudrate(serial->dev, priv);
 336         if (r)
 337                 goto out;
 338
 339         dbg("%s - submitting interrupt urb", __func__);
 340         port->interrupt_in_urb->dev = serial->dev;
 341         r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 342         if (r) {
 343                 dev_err(&port->dev, "%s - failed submitting interrupt urb,"
 344                         " error %d\n", __func__, r);
 345                 ch341_close(port);
 346                 return -EPROTO;
 347         }
 348
 349         r = usb_serial_generic_open(tty, port);
 350
 351 out:    return r;
 352 }
 353
 354 /* Old_termios contains the original termios settings and
 355  * tty->termios contains the new setting to be used.
 356  */
 357 static void ch341_set_termios(struct tty_struct *tty,
 358                 struct usb_serial_port *port, struct ktermios *old_termios)
 359 {
 360         struct ch341_private *priv = usb_get_serial_port_data(port);
 361         unsigned baud_rate;
 362         unsigned long flags;
 363
 364         dbg("ch341_set_termios()");
 365
 366         baud_rate = tty_get_baud_rate(tty);
 367
 368         priv->baud_rate = baud_rate;
 369
 370         if (baud_rate) {
 371                 spin_lock_irqsave(&priv->lock, flags);
 372                 priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
 373                 spin_unlock_irqrestore(&priv->lock, flags);
 374                 ch341_set_baudrate(port->serial->dev, priv);
 375         } else {
 376                 spin_lock_irqsave(&priv->lock, flags);
 377                 priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
 378                 spin_unlock_irqrestore(&priv->lock, flags);
 379         }
 380
 381         ch341_set_handshake(port->serial->dev, priv->line_control);
 382
 383         /* Unimplemented:
 384          * (cflag & CSIZE) : data bits [5, 8]
 385          * (cflag & PARENB) : parity {NONE, EVEN, ODD}
 386          * (cflag & CSTOPB) : stop bits [1, 2]
 387          */
 388 }
 389
 390 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 391 {
 392         const uint16_t ch341_break_reg =
 393                 CH341_REG_BREAK1 | ((uint16_t) CH341_REG_BREAK2 << 8);
 394         struct usb_serial_port *port = tty->driver_data;
 395         int r;
 396         uint16_t reg_contents;
 397         uint8_t *break_reg;
 398
 399         dbg("%s()", __func__);
 400
 401         break_reg = kmalloc(2, GFP_KERNEL);
 402         if (!break_reg) {
 403                 dev_err(&port->dev, "%s - kmalloc failed\n", __func__);
 404                 return;
 405         }
 406
 407         r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
 408                         ch341_break_reg, 0, break_reg, 2);
 409         if (r < 0) {
 410                 dev_err(&port->dev, "%s - USB control read error (%d)\n",
 411                                 __func__, r);
 412                 goto out;
 413         }
 414         dbg("%s - initial ch341 break register contents - reg1: %x, reg2: %x",
 415                         __func__, break_reg[0], break_reg[1]);
 416         if (break_state != 0) {
 417                 dbg("%s - Enter break state requested", __func__);
 418                 break_reg[0] &= ~CH341_NBREAK_BITS_REG1;
 419                 break_reg[1] &= ~CH341_NBREAK_BITS_REG2;
 420         } else {
 421                 dbg("%s - Leave break state requested", __func__);
 422                 break_reg[0] |= CH341_NBREAK_BITS_REG1;
 423                 break_reg[1] |= CH341_NBREAK_BITS_REG2;
 424         }
 425         dbg("%s - New ch341 break register contents - reg1: %x, reg2: %x",
 426                         __func__, break_reg[0], break_reg[1]);
 427         reg_contents = get_unaligned_le16(break_reg);
 428         r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
 429                         ch341_break_reg, reg_contents);
 430         if (r < 0)
 431                 dev_err(&port->dev, "%s - USB control write error (%d)\n",
 432                                 __func__, r);
 433 out:
 434         kfree(break_reg);
 435 }
 436
 437 static int ch341_tiocmset(struct tty_struct *tty, struct file *file,
 438                           unsigned int set, unsigned int clear)
 439 {
 440         struct usb_serial_port *port = tty->driver_data;
 441         struct ch341_private *priv = usb_get_serial_port_data(port);
 442         unsigned long flags;
 443         u8 control;
 444
 445         spin_lock_irqsave(&priv->lock, flags);
 446         if (set & TIOCM_RTS)
 447                 priv->line_control |= CH341_BIT_RTS;
 448         if (set & TIOCM_DTR)
 449                 priv->line_control |= CH341_BIT_DTR;
 450         if (clear & TIOCM_RTS)
 451                 priv->line_control &= ~CH341_BIT_RTS;
 452         if (clear & TIOCM_DTR)
 453                 priv->line_control &= ~CH341_BIT_DTR;
 454         control = priv->line_control;
 455         spin_unlock_irqrestore(&priv->lock, flags);
 456
 457         return ch341_set_handshake(port->serial->dev, control);
 458 }
 459
 460 static void ch341_read_int_callback(struct urb *urb)
 461 {
 462         struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
 463         unsigned char *data = urb->transfer_buffer;
 464         unsigned int actual_length = urb->actual_length;
 465         int status;
 466
 467         dbg("%s (%d)", __func__, port->number);
 468
 469         switch (urb->status) {
 470         case 0:
 471                 /* success */
 472                 break;
 473         case -ECONNRESET:
 474         case -ENOENT:
 475         case -ESHUTDOWN:
 476                 /* this urb is terminated, clean up */
 477                 dbg("%s - urb shutting down with status: %d", __func__,
 478                     urb->status);
 479                 return;
 480         default:
 481                 dbg("%s - nonzero urb status received: %d", __func__,
 482                     urb->status);
 483                 goto exit;
 484         }
 485
 486         usb_serial_debug_data(debug, &port->dev, __func__,
 487                               urb->actual_length, urb->transfer_buffer);
 488
 489         if (actual_length >= 4) {
 490                 struct ch341_private *priv = usb_get_serial_port_data(port);
 491                 unsigned long flags;
 492
 493                 spin_lock_irqsave(&priv->lock, flags);
 494                 priv->line_status = (~(data[2])) & CH341_BITS_MODEM_STAT;
 495                 if ((data[1] & CH341_MULT_STAT))
 496                         priv->multi_status_change = 1;
 497                 spin_unlock_irqrestore(&priv->lock, flags);
 498                 wake_up_interruptible(&priv->delta_msr_wait);
 499         }
 500
 501 exit:
 502         status = usb_submit_urb(urb, GFP_ATOMIC);
 503         if (status)
 504                 dev_err(&urb->dev->dev,
 505                         "%s - usb_submit_urb failed with result %d\n",
 506                         __func__, status);
 507 }
 508
 509 static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
 510 {
 511         struct ch341_private *priv = usb_get_serial_port_data(port);
 512         unsigned long flags;
 513         u8 prevstatus;
 514         u8 status;
 515         u8 changed;
 516         u8 multi_change = 0;
 517
 518         spin_lock_irqsave(&priv->lock, flags);
 519         prevstatus = priv->line_status;
 520         priv->multi_status_change = 0;
 521         spin_unlock_irqrestore(&priv->lock, flags);
 522
 523         while (!multi_change) {
 524                 interruptible_sleep_on(&priv->delta_msr_wait);
 525                 /* see if a signal did it */
 526                 if (signal_pending(current))
 527                         return -ERESTARTSYS;
 528
 529                 spin_lock_irqsave(&priv->lock, flags);
 530                 status = priv->line_status;
 531                 multi_change = priv->multi_status_change;
 532                 spin_unlock_irqrestore(&priv->lock, flags);
 533
 534                 changed = prevstatus ^ status;
 535
 536                 if (((arg & TIOCM_RNG) && (changed & CH341_BIT_RI)) ||
 537                     ((arg & TIOCM_DSR) && (changed & CH341_BIT_DSR)) ||
 538                     ((arg & TIOCM_CD)  && (changed & CH341_BIT_DCD)) ||
 539                     ((arg & TIOCM_CTS) && (changed & CH341_BIT_CTS))) {
 540                         return 0;
 541                 }
 542                 prevstatus = status;
 543         }
 544
 545         return 0;
 546 }
 547
 548 /*static int ch341_ioctl(struct usb_serial_port *port, struct file *file,*/
 549 static int ch341_ioctl(struct tty_struct *tty, struct file *file,
 550                         unsigned int cmd, unsigned long arg)
 551 {
 552         struct usb_serial_port *port = tty->driver_data;
 553         dbg("%s (%d) cmd = 0x%04x", __func__, port->number, cmd);
 554
 555         switch (cmd) {
 556         case TIOCMIWAIT:
 557                 dbg("%s (%d) TIOCMIWAIT", __func__,  port->number);
 558                 return wait_modem_info(port, arg);
 559
 560         default:
 561                 dbg("%s not supported = 0x%04x", __func__, cmd);
 562                 break;
 563         }
 564
 565         return -ENOIOCTLCMD;
 566 }
 567
 568 static int ch341_tiocmget(struct tty_struct *tty, struct file *file)
 569 {
 570         struct usb_serial_port *port = tty->driver_data;
 571         struct ch341_private *priv = usb_get_serial_port_data(port);
 572         unsigned long flags;
 573         u8 mcr;
 574         u8 status;
 575         unsigned int result;
 576
 577         dbg("%s (%d)", __func__, port->number);
 578
 579         spin_lock_irqsave(&priv->lock, flags);
 580         mcr = priv->line_control;
 581         status = priv->line_status;
 582         spin_unlock_irqrestore(&priv->lock, flags);
 583
 584         result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
 585                   | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
 586                   | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
 587                   | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
 588                   | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
 589                   | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
 590
 591         dbg("%s - result = %x", __func__, result);
 592
 593         return result;
 594 }
 595
 596
 597 static int ch341_reset_resume(struct usb_interface *intf)
 598 {
 599         struct usb_device *dev = interface_to_usbdev(intf);
 600         struct usb_serial *serial = NULL;
 601         struct ch341_private *priv;
 602
 603         serial = usb_get_intfdata(intf);
 604         priv = usb_get_serial_port_data(serial->port[0]);
 605
 606         /*reconfigure ch341 serial port after bus-reset*/
 607         ch341_configure(dev, priv);
 608
 609         usb_serial_resume(intf);
 610
 611         return 0;
 612 }
 613
 614 static struct usb_driver ch341_driver = {
 615         .name           = "ch341",
 616         .probe          = usb_serial_probe,
 617         .disconnect     = usb_serial_disconnect,
 618         .suspend        = usb_serial_suspend,
 619         .resume         = usb_serial_resume,
 620         .reset_resume   = ch341_reset_resume,
 621         .id_table       = id_table,
 622         .no_dynamic_id  = 1,
 623         .supports_autosuspend = 1,
 624 };
 625
 626 static struct usb_serial_driver ch341_device = {
 627         .driver = {
 628                 .owner  = THIS_MODULE,
 629                 .name   = "ch341-uart",
 630         },
 631         .id_table          = id_table,
 632         .usb_driver        = &ch341_driver,
 633         .num_ports         = 1,
 634         .open              = ch341_open,
 635         .dtr_rts           = ch341_dtr_rts,
 636         .carrier_raised    = ch341_carrier_raised,
 637         .close             = ch341_close,
 638         .ioctl             = ch341_ioctl,
 639         .set_termios       = ch341_set_termios,
 640         .break_ctl         = ch341_break_ctl,
 641         .tiocmget          = ch341_tiocmget,
 642         .tiocmset          = ch341_tiocmset,
 643         .read_int_callback = ch341_read_int_callback,
 644         .attach            = ch341_attach,
 645 };
 646
 647 static int __init ch341_init(void)
 648 {
 649         int retval;
 650
 651         retval = usb_serial_register(&ch341_device);
 652         if (retval)
 653                 return retval;
 654         retval = usb_register(&ch341_driver);
 655         if (retval)
 656                 usb_serial_deregister(&ch341_device);
 657         return retval;
 658 }
 659
 660 static void __exit ch341_exit(void)
 661 {
 662         usb_deregister(&ch341_driver);
 663         usb_serial_deregister(&ch341_device);
 664 }
 665
 666 module_init(ch341_init);
 667 module_exit(ch341_exit);
 668 MODULE_LICENSE("GPL");
 669
 670 module_param(debug, bool, S_IRUGO | S_IWUSR);
 671 MODULE_PARM_DESC(debug, "Debug enabled or not");
 672
 673 /* EOF ch341.c */