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 bool debug;
  74
  75 static const struct usb_device_id id_table[] = {
  76         { USB_DEVICE(0x4348, 0x5523) },
  77         { USB_DEVICE(0x1a86, 0x7523) },
  78         { USB_DEVICE(0x1a86, 0x5523) },
  79         { },
  80 };
  81 MODULE_DEVICE_TABLE(usb, id_table);
  82
  83 struct ch341_private {
  84         spinlock_t lock; /* access lock */
  85         wait_queue_head_t delta_msr_wait; /* wait queue for modem status */
  86         unsigned baud_rate; /* set baud rate */
  87         u8 line_control; /* set line control value RTS/DTR */
  88         u8 line_status; /* active status of modem control inputs */
  89         u8 multi_status_change; /* status changed multiple since last call */
  90 };
  91
  92 static int ch341_control_out(struct usb_device *dev, u8 request,
  93                              u16 value, u16 index)
  94 {
  95         int r;
  96         dbg("ch341_control_out(%02x,%02x,%04x,%04x)", USB_DIR_OUT|0x40,
  97                 (int)request, (int)value, (int)index);
  98
  99         r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
 100                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
 101                             value, index, NULL, 0, DEFAULT_TIMEOUT);
 102
 103         return r;
 104 }
 105
 106 static int ch341_control_in(struct usb_device *dev,
 107                             u8 request, u16 value, u16 index,
 108                             char *buf, unsigned bufsize)
 109 {
 110         int r;
 111         dbg("ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)", USB_DIR_IN|0x40,
 112                 (int)request, (int)value, (int)index, buf, (int)bufsize);
 113
 114         r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
 115                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 116                             value, index, buf, bufsize, DEFAULT_TIMEOUT);
 117         return r;
 118 }
 119
 120 static int ch341_set_baudrate(struct usb_device *dev,
 121                               struct ch341_private *priv)
 122 {
 123         short a, b;
 124         int r;
 125         unsigned long factor;
 126         short divisor;
 127
 128         dbg("ch341_set_baudrate(%d)", priv->baud_rate);
 129
 130         if (!priv->baud_rate)
 131                 return -EINVAL;
 132         factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate);
 133         divisor = CH341_BAUDBASE_DIVMAX;
 134
 135         while ((factor > 0xfff0) && divisor) {
 136                 factor >>= 3;
 137                 divisor--;
 138         }
 139
 140         if (factor > 0xfff0)
 141                 return -EINVAL;
 142
 143         factor = 0x10000 - factor;
 144         a = (factor & 0xff00) | divisor;
 145         b = factor & 0xff;
 146
 147         r = ch341_control_out(dev, 0x9a, 0x1312, a);
 148         if (!r)
 149                 r = ch341_control_out(dev, 0x9a, 0x0f2c, b);
 150
 151         return r;
 152 }
 153
 154 static int ch341_set_handshake(struct usb_device *dev, u8 control)
 155 {
 156         dbg("ch341_set_handshake(0x%02x)", control);
 157         return ch341_control_out(dev, 0xa4, ~control, 0);
 158 }
 159
 160 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 161 {
 162         char *buffer;
 163         int r;
 164         const unsigned size = 8;
 165         unsigned long flags;
 166
 167         dbg("ch341_get_status()");
 168
 169         buffer = kmalloc(size, GFP_KERNEL);
 170         if (!buffer)
 171                 return -ENOMEM;
 172
 173         r = ch341_control_in(dev, 0x95, 0x0706, 0, buffer, size);
 174         if (r < 0)
 175                 goto out;
 176
 177         /* setup the private status if available */
 178         if (r == 2) {
 179                 r = 0;
 180                 spin_lock_irqsave(&priv->lock, flags);
 181                 priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
 182                 priv->multi_status_change = 0;
 183                 spin_unlock_irqrestore(&priv->lock, flags);
 184         } else
 185                 r = -EPROTO;
 186
 187 out:    kfree(buffer);
 188         return r;
 189 }
 190
 191 /* -------------------------------------------------------------------------- */
 192
 193 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 194 {
 195         char *buffer;
 196         int r;
 197         const unsigned size = 8;
 198
 199         dbg("ch341_configure()");
 200
 201         buffer = kmalloc(size, GFP_KERNEL);
 202         if (!buffer)
 203                 return -ENOMEM;
 204
 205         /* expect two bytes 0x27 0x00 */
 206         r = ch341_control_in(dev, 0x5f, 0, 0, buffer, size);
 207         if (r < 0)
 208                 goto out;
 209
 210         r = ch341_control_out(dev, 0xa1, 0, 0);
 211         if (r < 0)
 212                 goto out;
 213
 214         r = ch341_set_baudrate(dev, priv);
 215         if (r < 0)
 216                 goto out;
 217
 218         /* expect two bytes 0x56 0x00 */
 219         r = ch341_control_in(dev, 0x95, 0x2518, 0, buffer, size);
 220         if (r < 0)
 221                 goto out;
 222
 223         r = ch341_control_out(dev, 0x9a, 0x2518, 0x0050);
 224         if (r < 0)
 225                 goto out;
 226
 227         /* expect 0xff 0xee */
 228         r = ch341_get_status(dev, priv);
 229         if (r < 0)
 230                 goto out;
 231
 232         r = ch341_control_out(dev, 0xa1, 0x501f, 0xd90a);
 233         if (r < 0)
 234                 goto out;
 235
 236         r = ch341_set_baudrate(dev, priv);
 237         if (r < 0)
 238                 goto out;
 239
 240         r = ch341_set_handshake(dev, priv->line_control);
 241         if (r < 0)
 242                 goto out;
 243
 244         /* expect 0x9f 0xee */
 245         r = ch341_get_status(dev, priv);
 246
 247 out:    kfree(buffer);
 248         return r;
 249 }
 250
 251 /* allocate private data */
 252 static int ch341_attach(struct usb_serial *serial)
 253 {
 254         struct ch341_private *priv;
 255         int r;
 256
 257         dbg("ch341_attach()");
 258
 259         /* private data */
 260         priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
 261         if (!priv)
 262                 return -ENOMEM;
 263
 264         spin_lock_init(&priv->lock);
 265         init_waitqueue_head(&priv->delta_msr_wait);
 266         priv->baud_rate = DEFAULT_BAUD_RATE;
 267         priv->line_control = CH341_BIT_RTS | CH341_BIT_DTR;
 268
 269         r = ch341_configure(serial->dev, priv);
 270         if (r < 0)
 271                 goto error;
 272
 273         usb_set_serial_port_data(serial->port[0], priv);
 274         return 0;
 275
 276 error:  kfree(priv);
 277         return r;
 278 }
 279
 280 static int ch341_carrier_raised(struct usb_serial_port *port)
 281 {
 282         struct ch341_private *priv = usb_get_serial_port_data(port);
 283         if (priv->line_status & CH341_BIT_DCD)
 284                 return 1;
 285         return 0;
 286 }
 287
 288 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
 289 {
 290         struct ch341_private *priv = usb_get_serial_port_data(port);
 291         unsigned long flags;
 292
 293         dbg("%s - port %d", __func__, port->number);
 294         /* drop DTR and RTS */
 295         spin_lock_irqsave(&priv->lock, flags);
 296         if (on)
 297                 priv->line_control |= CH341_BIT_RTS | CH341_BIT_DTR;
 298         else
 299                 priv->line_control &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
 300         spin_unlock_irqrestore(&priv->lock, flags);
 301         ch341_set_handshake(port->serial->dev, priv->line_control);
 302         wake_up_interruptible(&priv->delta_msr_wait);
 303 }
 304
 305 static void ch341_close(struct usb_serial_port *port)
 306 {
 307         dbg("%s - port %d", __func__, port->number);
 308
 309         usb_serial_generic_close(port);
 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         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                 goto out;
 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,
 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                 u8 prev_line_status = priv->line_status;
 490
 491                 spin_lock_irqsave(&priv->lock, flags);
 492                 priv->line_status = (~(data[2])) & CH341_BITS_MODEM_STAT;
 493                 if ((data[1] & CH341_MULT_STAT))
 494                         priv->multi_status_change = 1;
 495                 spin_unlock_irqrestore(&priv->lock, flags);
 496
 497                 if ((priv->line_status ^ prev_line_status) & CH341_BIT_DCD) {
 498                         struct tty_struct *tty = tty_port_tty_get(&port->port);
 499                         if (tty)
 500                                 usb_serial_handle_dcd_change(port, tty,
 501                                             priv->line_status & CH341_BIT_DCD);
 502                         tty_kref_put(tty);
 503                 }
 504
 505                 wake_up_interruptible(&priv->delta_msr_wait);
 506         }
 507
 508 exit:
 509         status = usb_submit_urb(urb, GFP_ATOMIC);
 510         if (status)
 511                 dev_err(&urb->dev->dev,
 512                         "%s - usb_submit_urb failed with result %d\n",
 513                         __func__, status);
 514 }
 515
 516 static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
 517 {
 518         struct ch341_private *priv = usb_get_serial_port_data(port);
 519         unsigned long flags;
 520         u8 prevstatus;
 521         u8 status;
 522         u8 changed;
 523         u8 multi_change = 0;
 524
 525         spin_lock_irqsave(&priv->lock, flags);
 526         prevstatus = priv->line_status;
 527         priv->multi_status_change = 0;
 528         spin_unlock_irqrestore(&priv->lock, flags);
 529
 530         while (!multi_change) {
 531                 interruptible_sleep_on(&priv->delta_msr_wait);
 532                 /* see if a signal did it */
 533                 if (signal_pending(current))
 534                         return -ERESTARTSYS;
 535
 536                 spin_lock_irqsave(&priv->lock, flags);
 537                 status = priv->line_status;
 538                 multi_change = priv->multi_status_change;
 539                 spin_unlock_irqrestore(&priv->lock, flags);
 540
 541                 changed = prevstatus ^ status;
 542
 543                 if (((arg & TIOCM_RNG) && (changed & CH341_BIT_RI)) ||
 544                     ((arg & TIOCM_DSR) && (changed & CH341_BIT_DSR)) ||
 545                     ((arg & TIOCM_CD)  && (changed & CH341_BIT_DCD)) ||
 546                     ((arg & TIOCM_CTS) && (changed & CH341_BIT_CTS))) {
 547                         return 0;
 548                 }
 549                 prevstatus = status;
 550         }
 551
 552         return 0;
 553 }
 554
 555 static int ch341_ioctl(struct tty_struct *tty,
 556                         unsigned int cmd, unsigned long arg)
 557 {
 558         struct usb_serial_port *port = tty->driver_data;
 559         dbg("%s (%d) cmd = 0x%04x", __func__, port->number, cmd);
 560
 561         switch (cmd) {
 562         case TIOCMIWAIT:
 563                 dbg("%s (%d) TIOCMIWAIT", __func__,  port->number);
 564                 return wait_modem_info(port, arg);
 565
 566         default:
 567                 dbg("%s not supported = 0x%04x", __func__, cmd);
 568                 break;
 569         }
 570
 571         return -ENOIOCTLCMD;
 572 }
 573
 574 static int ch341_tiocmget(struct tty_struct *tty)
 575 {
 576         struct usb_serial_port *port = tty->driver_data;
 577         struct ch341_private *priv = usb_get_serial_port_data(port);
 578         unsigned long flags;
 579         u8 mcr;
 580         u8 status;
 581         unsigned int result;
 582
 583         dbg("%s (%d)", __func__, port->number);
 584
 585         spin_lock_irqsave(&priv->lock, flags);
 586         mcr = priv->line_control;
 587         status = priv->line_status;
 588         spin_unlock_irqrestore(&priv->lock, flags);
 589
 590         result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
 591                   | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
 592                   | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
 593                   | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
 594                   | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
 595                   | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
 596
 597         dbg("%s - result = %x", __func__, result);
 598
 599         return result;
 600 }
 601
 602
 603 static int ch341_reset_resume(struct usb_interface *intf)
 604 {
 605         struct usb_device *dev = interface_to_usbdev(intf);
 606         struct usb_serial *serial = NULL;
 607         struct ch341_private *priv;
 608
 609         serial = usb_get_intfdata(intf);
 610         priv = usb_get_serial_port_data(serial->port[0]);
 611
 612         /*reconfigure ch341 serial port after bus-reset*/
 613         ch341_configure(dev, priv);
 614
 615         usb_serial_resume(intf);
 616
 617         return 0;
 618 }
 619
 620 static struct usb_driver ch341_driver = {
 621         .name           = "ch341",
 622         .probe          = usb_serial_probe,
 623         .disconnect     = usb_serial_disconnect,
 624         .suspend        = usb_serial_suspend,
 625         .resume         = usb_serial_resume,
 626         .reset_resume   = ch341_reset_resume,
 627         .id_table       = id_table,
 628         .supports_autosuspend = 1,
 629 };
 630
 631 static struct usb_serial_driver ch341_device = {
 632         .driver = {
 633                 .owner  = THIS_MODULE,
 634                 .name   = "ch341-uart",
 635         },
 636         .id_table          = id_table,
 637         .num_ports         = 1,
 638         .open              = ch341_open,
 639         .dtr_rts           = ch341_dtr_rts,
 640         .carrier_raised    = ch341_carrier_raised,
 641         .close             = ch341_close,
 642         .ioctl             = ch341_ioctl,
 643         .set_termios       = ch341_set_termios,
 644         .break_ctl         = ch341_break_ctl,
 645         .tiocmget          = ch341_tiocmget,
 646         .tiocmset          = ch341_tiocmset,
 647         .read_int_callback = ch341_read_int_callback,
 648         .attach            = ch341_attach,
 649 };
 650
 651 static struct usb_serial_driver * const serial_drivers[] = {
 652         &ch341_device, NULL
 653 };
 654
 655 module_usb_serial_driver(ch341_driver, serial_drivers);
 656
 657 MODULE_LICENSE("GPL");
 658
 659 module_param(debug, bool, S_IRUGO | S_IWUSR);
 660 MODULE_PARM_DESC(debug, "Debug enabled or not");