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 #include <asm/unaligned.h>
  26
  27 #define DEFAULT_BAUD_RATE 9600
  28 #define DEFAULT_TIMEOUT   1000
  29
  30 /* flags for IO-Bits */
  31 #define CH341_BIT_RTS (1 << 6)
  32 #define CH341_BIT_DTR (1 << 5)
  33
  34 /******************************/
  35 /* interrupt pipe definitions */
  36 /******************************/
  37 /* always 4 interrupt bytes */
  38 /* first irq byte normally 0x08 */
  39 /* second irq byte base 0x7d + below */
  40 /* third irq byte base 0x94 + below */
  41 /* fourth irq byte normally 0xee */
  42
  43 /* second interrupt byte */
  44 #define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */
  45
  46 /* status returned in third interrupt answer byte, inverted in data
  47    from irq */
  48 #define CH341_BIT_CTS 0x01
  49 #define CH341_BIT_DSR 0x02
  50 #define CH341_BIT_RI  0x04
  51 #define CH341_BIT_DCD 0x08
  52 #define CH341_BITS_MODEM_STAT 0x0f /* all bits */
  53
  54 /*******************************/
  55 /* baudrate calculation factor */
  56 /*******************************/
  57 #define CH341_BAUDBASE_FACTOR 1532620800
  58 #define CH341_BAUDBASE_DIVMAX 3
  59
  60 /* Break support - the information used to implement this was gleaned from
  61  * the Net/FreeBSD uchcom.c driver by Takanori Watanabe.  Domo arigato.
  62  */
  63
  64 #define CH341_REQ_WRITE_REG    0x9A
  65 #define CH341_REQ_READ_REG     0x95
  66 #define CH341_REG_BREAK1       0x05
  67 #define CH341_REG_BREAK2       0x18
  68 #define CH341_NBREAK_BITS_REG1 0x01
  69 #define CH341_NBREAK_BITS_REG2 0x40
  70
  71
  72 static int debug;
  73
  74 static const struct usb_device_id id_table[] = {
  75         { USB_DEVICE(0x4348, 0x5523) },
  76         { USB_DEVICE(0x1a86, 0x7523) },
  77         { },
  78 };
  79 MODULE_DEVICE_TABLE(usb, id_table);
  80
  81 struct ch341_private {
  82         spinlock_t lock; /* access lock */
  83         wait_queue_head_t delta_msr_wait; /* wait queue for modem status */
  84         unsigned baud_rate; /* set baud rate */
  85         u8 line_control; /* set line control value RTS/DTR */
  86         u8 line_status; /* active status of modem control inputs */
  87         u8 multi_status_change; /* status changed multiple since last call */
  88 };
  89
  90 static int ch341_control_out(struct usb_device *dev, u8 request,
  91                              u16 value, u16 index)
  92 {
  93         int r;
  94         dbg("ch341_control_out(%02x,%02x,%04x,%04x)", USB_DIR_OUT|0x40,
  95                 (int)request, (int)value, (int)index);
  96
  97         r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
  98                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
  99                             value, index, NULL, 0, DEFAULT_TIMEOUT);
 100
 101         return r;
 102 }
 103
 104 static int ch341_control_in(struct usb_device *dev,
 105                             u8 request, u16 value, u16 index,
 106                             char *buf, unsigned bufsize)
 107 {
 108         int r;
 109         dbg("ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)", USB_DIR_IN|0x40,
 110                 (int)request, (int)value, (int)index, buf, (int)bufsize);
 111
 112         r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
 113                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 114                             value, index, buf, bufsize, DEFAULT_TIMEOUT);
 115         return r;
 116 }
 117
 118 static int ch341_set_baudrate(struct usb_device *dev,
 119                               struct ch341_private *priv)
 120 {
 121         short a, b;
 122         int r;
 123         unsigned long factor;
 124         short divisor;
 125
 126         dbg("ch341_set_baudrate(%d)", priv->baud_rate);
 127
 128         if (!priv->baud_rate)
 129                 return -EINVAL;
 130         factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate);
 131         divisor = CH341_BAUDBASE_DIVMAX;
 132
 133         while ((factor > 0xfff0) && divisor) {
 134                 factor >>= 3;
 135                 divisor--;
 136         }
 137
 138         if (factor > 0xfff0)
 139                 return -EINVAL;
 140
 141         factor = 0x10000 - factor;
 142         a = (factor & 0xff00) | divisor;
 143         b = factor & 0xff;
 144
 145         r = ch341_control_out(dev, 0x9a, 0x1312, a);
 146         if (!r)
 147                 r = ch341_control_out(dev, 0x9a, 0x0f2c, b);
 148
 149         return r;
 150 }
 151
 152 static int ch341_set_handshake(struct usb_device *dev, u8 control)
 153 {
 154         dbg("ch341_set_handshake(0x%02x)", control);
 155         return ch341_control_out(dev, 0xa4, ~control, 0);
 156 }
 157
 158 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 159 {
 160         char *buffer;
 161         int r;
 162         const unsigned size = 8;
 163         unsigned long flags;
 164
 165         dbg("ch341_get_status()");
 166
 167         buffer = kmalloc(size, GFP_KERNEL);
 168         if (!buffer)
 169                 return -ENOMEM;
 170
 171         r = ch341_control_in(dev, 0x95, 0x0706, 0, buffer, size);
 172         if (r < 0)
 173                 goto out;
 174
 175         /* setup the private status if available */
 176         if (r == 2) {
 177                 r = 0;
 178                 spin_lock_irqsave(&priv->lock, flags);
 179                 priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
 180                 priv->multi_status_change = 0;
 181                 spin_unlock_irqrestore(&priv->lock, flags);
 182         } else
 183                 r = -EPROTO;
 184
 185 out:    kfree(buffer);
 186         return r;
 187 }
 188
 189 /* -------------------------------------------------------------------------- */
 190
 191 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 192 {
 193         char *buffer;
 194         int r;
 195         const unsigned size = 8;
 196
 197         dbg("ch341_configure()");
 198
 199         buffer = kmalloc(size, GFP_KERNEL);
 200         if (!buffer)
 201                 return -ENOMEM;
 202
 203         /* expect two bytes 0x27 0x00 */
 204         r = ch341_control_in(dev, 0x5f, 0, 0, buffer, size);
 205         if (r < 0)
 206                 goto out;
 207
 208         r = ch341_control_out(dev, 0xa1, 0, 0);
 209         if (r < 0)
 210                 goto out;
 211
 212         r = ch341_set_baudrate(dev, priv);
 213         if (r < 0)
 214                 goto out;
 215
 216         /* expect two bytes 0x56 0x00 */
 217         r = ch341_control_in(dev, 0x95, 0x2518, 0, buffer, size);
 218         if (r < 0)
 219                 goto out;
 220
 221         r = ch341_control_out(dev, 0x9a, 0x2518, 0x0050);
 222         if (r < 0)
 223                 goto out;
 224
 225         /* expect 0xff 0xee */
 226         r = ch341_get_status(dev, priv);
 227         if (r < 0)
 228                 goto out;
 229
 230         r = ch341_control_out(dev, 0xa1, 0x501f, 0xd90a);
 231         if (r < 0)
 232                 goto out;
 233
 234         r = ch341_set_baudrate(dev, priv);
 235         if (r < 0)
 236                 goto out;
 237
 238         r = ch341_set_handshake(dev, priv->line_control);
 239         if (r < 0)
 240                 goto out;
 241
 242         /* expect 0x9f 0xee */
 243         r = ch341_get_status(dev, priv);
 244
 245 out:    kfree(buffer);
 246         return r;
 247 }
 248
 249 /* allocate private data */
 250 static int ch341_attach(struct usb_serial *serial)
 251 {
 252         struct ch341_private *priv;
 253         int r;
 254
 255         dbg("ch341_attach()");
 256
 257         /* private data */
 258         priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
 259         if (!priv)
 260                 return -ENOMEM;
 261
 262         spin_lock_init(&priv->lock);
 263         init_waitqueue_head(&priv->delta_msr_wait);
 264         priv->baud_rate = DEFAULT_BAUD_RATE;
 265         priv->line_control = CH341_BIT_RTS | CH341_BIT_DTR;
 266
 267         r = ch341_configure(serial->dev, priv);
 268         if (r < 0)
 269                 goto error;
 270
 271         usb_set_serial_port_data(serial->port[0], priv);
 272         return 0;
 273
 274 error:  kfree(priv);
 275         return r;
 276 }
 277
 278 static int ch341_carrier_raised(struct usb_serial_port *port)
 279 {
 280         struct ch341_private *priv = usb_get_serial_port_data(port);
 281         if (priv->line_status & CH341_BIT_DCD)
 282                 return 1;
 283         return 0;
 284 }
 285
 286 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
 287 {
 288         struct ch341_private *priv = usb_get_serial_port_data(port);
 289         unsigned long flags;
 290
 291         dbg("%s - port %d", __func__, port->number);
 292         /* drop DTR and RTS */
 293         spin_lock_irqsave(&priv->lock, flags);
 294         if (on)
 295                 priv->line_control |= CH341_BIT_RTS | CH341_BIT_DTR;
 296         else
 297                 priv->line_control &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
 298         spin_unlock_irqrestore(&priv->lock, flags);
 299         ch341_set_handshake(port->serial->dev, priv->line_control);
 300         wake_up_interruptible(&priv->delta_msr_wait);
 301 }
 302
 303 static void ch341_close(struct usb_serial_port *port)
 304 {
 305         dbg("%s - port %d", __func__, port->number);
 306
 307         /* shutdown our urbs */
 308         dbg("%s - shutting down urbs", __func__);
 309         usb_kill_urb(port->write_urb);
 310         usb_kill_urb(port->read_urb);
 311         usb_kill_urb(port->interrupt_in_urb);
 312 }
 313
 314
 315 /* open this device, set default parameters */
 316 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
 317 {
 318         struct usb_serial *serial = port->serial;
 319         struct ch341_private *priv = usb_get_serial_port_data(serial->port[0]);
 320         int r;
 321
 322         dbg("ch341_open()");
 323
 324         priv->baud_rate = DEFAULT_BAUD_RATE;
 325
 326         r = ch341_configure(serial->dev, priv);
 327         if (r)
 328                 goto out;
 329
 330         r = ch341_set_handshake(serial->dev, priv->line_control);
 331         if (r)
 332                 goto out;
 333
 334         r = ch341_set_baudrate(serial->dev, priv);
 335         if (r)
 336                 goto out;
 337
 338         dbg("%s - submitting interrupt urb", __func__);
 339         port->interrupt_in_urb->dev = serial->dev;
 340         r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 341         if (r) {
 342                 dev_err(&port->dev, "%s - failed submitting interrupt urb,"
 343                         " error %d\n", __func__, r);
 344                 ch341_close(port);
 345                 return -EPROTO;
 346         }
 347
 348         r = usb_serial_generic_open(tty, port);
 349
 350 out:    return r;
 351 }
 352
 353 /* Old_termios contains the original termios settings and
 354  * tty->termios contains the new setting to be used.
 355  */
 356 static void ch341_set_termios(struct tty_struct *tty,
 357                 struct usb_serial_port *port, struct ktermios *old_termios)
 358 {
 359         struct ch341_private *priv = usb_get_serial_port_data(port);
 360         unsigned baud_rate;
 361         unsigned long flags;
 362
 363         dbg("ch341_set_termios()");
 364
 365         baud_rate = tty_get_baud_rate(tty);
 366
 367         priv->baud_rate = baud_rate;
 368
 369         if (baud_rate) {
 370                 spin_lock_irqsave(&priv->lock, flags);
 371                 priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
 372                 spin_unlock_irqrestore(&priv->lock, flags);
 373                 ch341_set_baudrate(port->serial->dev, priv);
 374         } else {
 375                 spin_lock_irqsave(&priv->lock, flags);
 376                 priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
 377                 spin_unlock_irqrestore(&priv->lock, flags);
 378         }
 379
 380         ch341_set_handshake(port->serial->dev, priv->line_control);
 381
 382         /* Unimplemented:
 383          * (cflag & CSIZE) : data bits [5, 8]
 384          * (cflag & PARENB) : parity {NONE, EVEN, ODD}
 385          * (cflag & CSTOPB) : stop bits [1, 2]
 386          */
 387 }
 388
 389 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 390 {
 391         const uint16_t ch341_break_reg =
 392                 CH341_REG_BREAK1 | ((uint16_t) CH341_REG_BREAK2 << 8);
 393         struct usb_serial_port *port = tty->driver_data;
 394         int r;
 395         uint16_t reg_contents;
 396         uint8_t *break_reg;
 397
 398         dbg("%s()", __func__);
 399
 400         break_reg = kmalloc(2, GFP_KERNEL);
 401         if (!break_reg) {
 402                 dev_err(&port->dev, "%s - kmalloc failed\n", __func__);
 403                 return;
 404         }
 405
 406         r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
 407                         ch341_break_reg, 0, break_reg, 2);
 408         if (r < 0) {
 409                 dev_err(&port->dev, "%s - USB control read error (%d)\n",
 410                                 __func__, r);
 411                 goto out;
 412         }
 413         dbg("%s - initial ch341 break register contents - reg1: %x, reg2: %x",
 414                         __func__, break_reg[0], break_reg[1]);
 415         if (break_state != 0) {
 416                 dbg("%s - Enter break state requested", __func__);
 417                 break_reg[0] &= ~CH341_NBREAK_BITS_REG1;
 418                 break_reg[1] &= ~CH341_NBREAK_BITS_REG2;
 419         } else {
 420                 dbg("%s - Leave break state requested", __func__);
 421                 break_reg[0] |= CH341_NBREAK_BITS_REG1;
 422                 break_reg[1] |= CH341_NBREAK_BITS_REG2;
 423         }
 424         dbg("%s - New ch341 break register contents - reg1: %x, reg2: %x",
 425                         __func__, break_reg[0], break_reg[1]);
 426         reg_contents = get_unaligned_le16(break_reg);
 427         r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
 428                         ch341_break_reg, reg_contents);
 429         if (r < 0)
 430                 dev_err(&port->dev, "%s - USB control write error (%d)\n",
 431                                 __func__, r);
 432 out:
 433         kfree(break_reg);
 434 }
 435
 436 static int ch341_tiocmset(struct tty_struct *tty, struct file *file,
 437                           unsigned int set, unsigned int clear)
 438 {
 439         struct usb_serial_port *port = tty->driver_data;
 440         struct ch341_private *priv = usb_get_serial_port_data(port);
 441         unsigned long flags;
 442         u8 control;
 443
 444         spin_lock_irqsave(&priv->lock, flags);
 445         if (set & TIOCM_RTS)
 446                 priv->line_control |= CH341_BIT_RTS;
 447         if (set & TIOCM_DTR)
 448                 priv->line_control |= CH341_BIT_DTR;
 449         if (clear & TIOCM_RTS)
 450                 priv->line_control &= ~CH341_BIT_RTS;
 451         if (clear & TIOCM_DTR)
 452                 priv->line_control &= ~CH341_BIT_DTR;
 453         control = priv->line_control;
 454         spin_unlock_irqrestore(&priv->lock, flags);
 455
 456         return ch341_set_handshake(port->serial->dev, control);
 457 }
 458
 459 static void ch341_read_int_callback(struct urb *urb)
 460 {
 461         struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
 462         unsigned char *data = urb->transfer_buffer;
 463         unsigned int actual_length = urb->actual_length;
 464         int status;
 465
 466         dbg("%s (%d)", __func__, port->number);
 467
 468         switch (urb->status) {
 469         case 0:
 470                 /* success */
 471                 break;
 472         case -ECONNRESET:
 473         case -ENOENT:
 474         case -ESHUTDOWN:
 475                 /* this urb is terminated, clean up */
 476                 dbg("%s - urb shutting down with status: %d", __func__,
 477                     urb->status);
 478                 return;
 479         default:
 480                 dbg("%s - nonzero urb status received: %d", __func__,
 481                     urb->status);
 482                 goto exit;
 483         }
 484
 485         usb_serial_debug_data(debug, &port->dev, __func__,
 486                               urb->actual_length, urb->transfer_buffer);
 487
 488         if (actual_length >= 4) {
 489                 struct ch341_private *priv = usb_get_serial_port_data(port);
 490                 unsigned long flags;
 491
 492                 spin_lock_irqsave(&priv->lock, flags);
 493                 priv->line_status = (~(data[2])) & CH341_BITS_MODEM_STAT;
 494                 if ((data[1] & CH341_MULT_STAT))
 495                         priv->multi_status_change = 1;
 496                 spin_unlock_irqrestore(&priv->lock, flags);
 497                 wake_up_interruptible(&priv->delta_msr_wait);
 498         }
 499
 500 exit:
 501         status = usb_submit_urb(urb, GFP_ATOMIC);
 502         if (status)
 503                 dev_err(&urb->dev->dev,
 504                         "%s - usb_submit_urb failed with result %d\n",
 505                         __func__, status);
 506 }
 507
 508 static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
 509 {
 510         struct ch341_private *priv = usb_get_serial_port_data(port);
 511         unsigned long flags;
 512         u8 prevstatus;
 513         u8 status;
 514         u8 changed;
 515         u8 multi_change = 0;
 516
 517         spin_lock_irqsave(&priv->lock, flags);
 518         prevstatus = priv->line_status;
 519         priv->multi_status_change = 0;
 520         spin_unlock_irqrestore(&priv->lock, flags);
 521
 522         while (!multi_change) {
 523                 interruptible_sleep_on(&priv->delta_msr_wait);
 524                 /* see if a signal did it */
 525                 if (signal_pending(current))
 526                         return -ERESTARTSYS;
 527
 528                 spin_lock_irqsave(&priv->lock, flags);
 529                 status = priv->line_status;
 530                 multi_change = priv->multi_status_change;
 531                 spin_unlock_irqrestore(&priv->lock, flags);
 532
 533                 changed = prevstatus ^ status;
 534
 535                 if (((arg & TIOCM_RNG) && (changed & CH341_BIT_RI)) ||
 536                     ((arg & TIOCM_DSR) && (changed & CH341_BIT_DSR)) ||
 537                     ((arg & TIOCM_CD)  && (changed & CH341_BIT_DCD)) ||
 538                     ((arg & TIOCM_CTS) && (changed & CH341_BIT_CTS))) {
 539                         return 0;
 540                 }
 541                 prevstatus = status;
 542         }
 543
 544         return 0;
 545 }
 546
 547 /*static int ch341_ioctl(struct usb_serial_port *port, struct file *file,*/
 548 static int ch341_ioctl(struct tty_struct *tty, struct file *file,
 549                         unsigned int cmd, unsigned long arg)
 550 {
 551         struct usb_serial_port *port = tty->driver_data;
 552         dbg("%s (%d) cmd = 0x%04x", __func__, port->number, cmd);
 553
 554         switch (cmd) {
 555         case TIOCMIWAIT:
 556                 dbg("%s (%d) TIOCMIWAIT", __func__,  port->number);
 557                 return wait_modem_info(port, arg);
 558
 559         default:
 560                 dbg("%s not supported = 0x%04x", __func__, cmd);
 561                 break;
 562         }
 563
 564         return -ENOIOCTLCMD;
 565 }
 566
 567 static int ch341_tiocmget(struct tty_struct *tty, struct file *file)
 568 {
 569         struct usb_serial_port *port = tty->driver_data;
 570         struct ch341_private *priv = usb_get_serial_port_data(port);
 571         unsigned long flags;
 572         u8 mcr;
 573         u8 status;
 574         unsigned int result;
 575
 576         dbg("%s (%d)", __func__, port->number);
 577
 578         spin_lock_irqsave(&priv->lock, flags);
 579         mcr = priv->line_control;
 580         status = priv->line_status;
 581         spin_unlock_irqrestore(&priv->lock, flags);
 582
 583         result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
 584                   | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
 585                   | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
 586                   | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
 587                   | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
 588                   | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
 589
 590         dbg("%s - result = %x", __func__, result);
 591
 592         return result;
 593 }
 594
 595
 596 static int ch341_reset_resume(struct usb_interface *intf)
 597 {
 598         struct usb_device *dev = interface_to_usbdev(intf);
 599         struct usb_serial *serial = NULL;
 600         struct ch341_private *priv;
 601
 602         serial = usb_get_intfdata(intf);
 603         priv = usb_get_serial_port_data(serial->port[0]);
 604
 605         /*reconfigure ch341 serial port after bus-reset*/
 606         ch341_configure(dev, priv);
 607
 608         usb_serial_resume(intf);
 609
 610         return 0;
 611 }
 612
 613 static struct usb_driver ch341_driver = {
 614         .name           = "ch341",
 615         .probe          = usb_serial_probe,
 616         .disconnect     = usb_serial_disconnect,
 617         .suspend        = usb_serial_suspend,
 618         .resume         = usb_serial_resume,
 619         .reset_resume   = ch341_reset_resume,
 620         .id_table       = id_table,
 621         .no_dynamic_id  = 1,
 622         .supports_autosuspend = 1,
 623 };
 624
 625 static struct usb_serial_driver ch341_device = {
 626         .driver = {
 627                 .owner  = THIS_MODULE,
 628                 .name   = "ch341-uart",
 629         },
 630         .id_table          = id_table,
 631         .usb_driver        = &ch341_driver,
 632         .num_ports         = 1,
 633         .open              = ch341_open,
 634         .dtr_rts           = ch341_dtr_rts,
 635         .carrier_raised    = ch341_carrier_raised,
 636         .close             = ch341_close,
 637         .ioctl             = ch341_ioctl,
 638         .set_termios       = ch341_set_termios,
 639         .break_ctl         = ch341_break_ctl,
 640         .tiocmget          = ch341_tiocmget,
 641         .tiocmset          = ch341_tiocmset,
 642         .read_int_callback = ch341_read_int_callback,
 643         .attach            = ch341_attach,
 644 };
 645
 646 static int __init ch341_init(void)
 647 {
 648         int retval;
 649
 650         retval = usb_serial_register(&ch341_device);
 651         if (retval)
 652                 return retval;
 653         retval = usb_register(&ch341_driver);
 654         if (retval)
 655                 usb_serial_deregister(&ch341_device);
 656         return retval;
 657 }
 658
 659 static void __exit ch341_exit(void)
 660 {
 661         usb_deregister(&ch341_driver);
 662         usb_serial_deregister(&ch341_device);
 663 }
 664
 665 module_init(ch341_init);
 666 module_exit(ch341_exit);
 667 MODULE_LICENSE("GPL");
 668
 669 module_param(debug, bool, S_IRUGO | S_IWUSR);
 670 MODULE_PARM_DESC(debug, "Debug enabled or not");
 671
 672 /* EOF ch341.c */