drivers/usb/serial/ch341.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright 2007, Frank A Kingswood <frank@kingswood-consulting.co.uk>
   4  * Copyright 2007, Werner Cornelius <werner@cornelius-consult.de>
   5  * Copyright 2009, Boris Hajduk <boris@hajduk.org>
   6  *
   7  * ch341.c implements a serial port driver for the Winchiphead CH341.
   8  *
   9  * The CH341 device can be used to implement an RS232 asynchronous
  10  * serial port, an IEEE-1284 parallel printer port or a memory-like
  11  * interface. In all cases the CH341 supports an I2C interface as well.
  12  * This driver only supports the asynchronous serial interface.
  13  */
  14
  15 #include <linux/kernel.h>
  16 #include <linux/tty.h>
  17 #include <linux/module.h>
  18 #include <linux/slab.h>
  19 #include <linux/usb.h>
  20 #include <linux/usb/serial.h>
  21 #include <linux/serial.h>
  22 #include <asm/unaligned.h>
  23
  24 #define DEFAULT_BAUD_RATE 9600
  25 #define DEFAULT_TIMEOUT   1000
  26
  27 /* flags for IO-Bits */
  28 #define CH341_BIT_RTS (1 << 6)
  29 #define CH341_BIT_DTR (1 << 5)
  30
  31 /******************************/
  32 /* interrupt pipe definitions */
  33 /******************************/
  34 /* always 4 interrupt bytes */
  35 /* first irq byte normally 0x08 */
  36 /* second irq byte base 0x7d + below */
  37 /* third irq byte base 0x94 + below */
  38 /* fourth irq byte normally 0xee */
  39
  40 /* second interrupt byte */
  41 #define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */
  42
  43 /* status returned in third interrupt answer byte, inverted in data
  44    from irq */
  45 #define CH341_BIT_CTS 0x01
  46 #define CH341_BIT_DSR 0x02
  47 #define CH341_BIT_RI  0x04
  48 #define CH341_BIT_DCD 0x08
  49 #define CH341_BITS_MODEM_STAT 0x0f /* all bits */
  50
  51 /*******************************/
  52 /* baudrate calculation factor */
  53 /*******************************/
  54 #define CH341_BAUDBASE_FACTOR 1532620800
  55 #define CH341_BAUDBASE_DIVMAX 3
  56
  57 /* Break support - the information used to implement this was gleaned from
  58  * the Net/FreeBSD uchcom.c driver by Takanori Watanabe.  Domo arigato.
  59  */
  60
  61 #define CH341_REQ_READ_VERSION 0x5F
  62 #define CH341_REQ_WRITE_REG    0x9A
  63 #define CH341_REQ_READ_REG     0x95
  64 #define CH341_REQ_SERIAL_INIT  0xA1
  65 #define CH341_REQ_MODEM_CTRL   0xA4
  66
  67 #define CH341_REG_BREAK        0x05
  68 #define CH341_REG_LCR          0x18
  69 #define CH341_NBREAK_BITS      0x01
  70
  71 #define CH341_LCR_ENABLE_RX    0x80
  72 #define CH341_LCR_ENABLE_TX    0x40
  73 #define CH341_LCR_MARK_SPACE   0x20
  74 #define CH341_LCR_PAR_EVEN     0x10
  75 #define CH341_LCR_ENABLE_PAR   0x08
  76 #define CH341_LCR_STOP_BITS_2  0x04
  77 #define CH341_LCR_CS8          0x03
  78 #define CH341_LCR_CS7          0x02
  79 #define CH341_LCR_CS6          0x01
  80 #define CH341_LCR_CS5          0x00
  81
  82 static const struct usb_device_id id_table[] = {
  83         { USB_DEVICE(0x4348, 0x5523) },
  84         { USB_DEVICE(0x1a86, 0x7523) },
  85         { USB_DEVICE(0x1a86, 0x5523) },
  86         { },
  87 };
  88 MODULE_DEVICE_TABLE(usb, id_table);
  89
  90 struct ch341_private {
  91         spinlock_t lock; /* access lock */
  92         unsigned baud_rate; /* set baud rate */
  93         u8 mcr;
  94         u8 msr;
  95         u8 lcr;
  96         unsigned long quirks;
  97 };
  98
  99 static void ch341_set_termios(struct tty_struct *tty,
 100                               struct usb_serial_port *port,
 101                               struct ktermios *old_termios);
 102
 103 static int ch341_control_out(struct usb_device *dev, u8 request,
 104                              u16 value, u16 index)
 105 {
 106         int r;
 107
 108         dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x)\n", __func__,
 109                 request, value, index);
 110
 111         r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
 112                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
 113                             value, index, NULL, 0, DEFAULT_TIMEOUT);
 114         if (r < 0)
 115                 dev_err(&dev->dev, "failed to send control message: %d\n", r);
 116
 117         return r;
 118 }
 119
 120 static int ch341_control_in(struct usb_device *dev,
 121                             u8 request, u16 value, u16 index,
 122                             char *buf, unsigned bufsize)
 123 {
 124         int r;
 125
 126         dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x,%u)\n", __func__,
 127                 request, value, index, bufsize);
 128
 129         r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
 130                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 131                             value, index, buf, bufsize, DEFAULT_TIMEOUT);
 132         if (r < (int)bufsize) {
 133                 if (r >= 0) {
 134                         dev_err(&dev->dev,
 135                                 "short control message received (%d < %u)\n",
 136                                 r, bufsize);
 137                         r = -EIO;
 138                 }
 139
 140                 dev_err(&dev->dev, "failed to receive control message: %d\n",
 141                         r);
 142                 return r;
 143         }
 144
 145         return 0;
 146 }
 147
 148 static int ch341_set_baudrate_lcr(struct usb_device *dev,
 149                                   struct ch341_private *priv, u8 lcr)
 150 {
 151         short a;
 152         int r;
 153         unsigned long factor;
 154         short divisor;
 155
 156         if (!priv->baud_rate)
 157                 return -EINVAL;
 158         factor = (CH341_BAUDBASE_FACTOR / priv->baud_rate);
 159         divisor = CH341_BAUDBASE_DIVMAX;
 160
 161         while ((factor > 0xfff0) && divisor) {
 162                 factor >>= 3;
 163                 divisor--;
 164         }
 165
 166         if (factor > 0xfff0)
 167                 return -EINVAL;
 168
 169         factor = 0x10000 - factor;
 170         a = (factor & 0xff00) | divisor;
 171
 172         /*
 173          * CH341A buffers data until a full endpoint-size packet (32 bytes)
 174          * has been received unless bit 7 is set.
 175          */
 176         a |= BIT(7);
 177
 178         r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x1312, a);
 179         if (r)
 180                 return r;
 181
 182         r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, lcr);
 183         if (r)
 184                 return r;
 185
 186         return r;
 187 }
 188
 189 static int ch341_set_handshake(struct usb_device *dev, u8 control)
 190 {
 191         return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0);
 192 }
 193
 194 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 195 {
 196         const unsigned int size = 2;
 197         char *buffer;
 198         int r;
 199         unsigned long flags;
 200
 201         buffer = kmalloc(size, GFP_KERNEL);
 202         if (!buffer)
 203                 return -ENOMEM;
 204
 205         r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
 206         if (r < 0)
 207                 goto out;
 208
 209         spin_lock_irqsave(&priv->lock, flags);
 210         priv->msr = (~(*buffer)) & CH341_BITS_MODEM_STAT;
 211         spin_unlock_irqrestore(&priv->lock, flags);
 212
 213 out:    kfree(buffer);
 214         return r;
 215 }
 216
 217 /* -------------------------------------------------------------------------- */
 218
 219 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 220 {
 221         const unsigned int size = 2;
 222         char *buffer;
 223         int r;
 224
 225         buffer = kmalloc(size, GFP_KERNEL);
 226         if (!buffer)
 227                 return -ENOMEM;
 228
 229         /* expect two bytes 0x27 0x00 */
 230         r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
 231         if (r < 0)
 232                 goto out;
 233         dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]);
 234
 235         r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
 236         if (r < 0)
 237                 goto out;
 238
 239         r = ch341_set_baudrate_lcr(dev, priv, priv->lcr);
 240         if (r < 0)
 241                 goto out;
 242
 243         r = ch341_set_handshake(dev, priv->mcr);
 244
 245 out:    kfree(buffer);
 246         return r;
 247 }
 248
 249 static int ch341_detect_quirks(struct usb_serial_port *port)
 250 {
 251         struct ch341_private *priv = usb_get_serial_port_data(port);
 252         struct usb_device *udev = port->serial->dev;
 253         const unsigned int size = 2;
 254         unsigned long quirks = 0;
 255         char *buffer;
 256         int r;
 257
 258         buffer = kmalloc(size, GFP_KERNEL);
 259         if (!buffer)
 260                 return -ENOMEM;
 261
 262         /*
 263          * A subset of CH34x devices does not support all features. The
 264          * prescaler is limited and there is no support for sending a RS232
 265          * break condition. A read failure when trying to set up the latter is
 266          * used to detect these devices.
 267          */
 268         r = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0), CH341_REQ_READ_REG,
 269                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 270                             CH341_REG_BREAK, 0, buffer, size, DEFAULT_TIMEOUT);
 271         if (r == -EPIPE) {
 272                 dev_dbg(&port->dev, "break control not supported\n");
 273                 r = 0;
 274                 goto out;
 275         }
 276
 277         if (r != size) {
 278                 if (r >= 0)
 279                         r = -EIO;
 280                 dev_err(&port->dev, "failed to read break control: %d\n", r);
 281                 goto out;
 282         }
 283
 284         r = 0;
 285 out:
 286         kfree(buffer);
 287
 288         if (quirks) {
 289                 dev_dbg(&port->dev, "enabling quirk flags: 0x%02lx\n", quirks);
 290                 priv->quirks |= quirks;
 291         }
 292
 293         return r;
 294 }
 295
 296 static int ch341_port_probe(struct usb_serial_port *port)
 297 {
 298         struct ch341_private *priv;
 299         int r;
 300
 301         priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
 302         if (!priv)
 303                 return -ENOMEM;
 304
 305         spin_lock_init(&priv->lock);
 306         priv->baud_rate = DEFAULT_BAUD_RATE;
 307         /*
 308          * Some CH340 devices appear unable to change the initial LCR
 309          * settings, so set a sane 8N1 default.
 310          */
 311         priv->lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
 312
 313         r = ch341_configure(port->serial->dev, priv);
 314         if (r < 0)
 315                 goto error;
 316
 317         usb_set_serial_port_data(port, priv);
 318
 319         r = ch341_detect_quirks(port);
 320         if (r < 0)
 321                 goto error;
 322
 323         return 0;
 324
 325 error:  kfree(priv);
 326         return r;
 327 }
 328
 329 static int ch341_port_remove(struct usb_serial_port *port)
 330 {
 331         struct ch341_private *priv;
 332
 333         priv = usb_get_serial_port_data(port);
 334         kfree(priv);
 335
 336         return 0;
 337 }
 338
 339 static int ch341_carrier_raised(struct usb_serial_port *port)
 340 {
 341         struct ch341_private *priv = usb_get_serial_port_data(port);
 342         if (priv->msr & CH341_BIT_DCD)
 343                 return 1;
 344         return 0;
 345 }
 346
 347 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
 348 {
 349         struct ch341_private *priv = usb_get_serial_port_data(port);
 350         unsigned long flags;
 351
 352         /* drop DTR and RTS */
 353         spin_lock_irqsave(&priv->lock, flags);
 354         if (on)
 355                 priv->mcr |= CH341_BIT_RTS | CH341_BIT_DTR;
 356         else
 357                 priv->mcr &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
 358         spin_unlock_irqrestore(&priv->lock, flags);
 359         ch341_set_handshake(port->serial->dev, priv->mcr);
 360 }
 361
 362 static void ch341_close(struct usb_serial_port *port)
 363 {
 364         usb_serial_generic_close(port);
 365         usb_kill_urb(port->interrupt_in_urb);
 366 }
 367
 368
 369 /* open this device, set default parameters */
 370 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
 371 {
 372         struct ch341_private *priv = usb_get_serial_port_data(port);
 373         int r;
 374
 375         if (tty)
 376                 ch341_set_termios(tty, port, NULL);
 377
 378         dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
 379         r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 380         if (r) {
 381                 dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n",
 382                         __func__, r);
 383                 return r;
 384         }
 385
 386         r = ch341_get_status(port->serial->dev, priv);
 387         if (r < 0) {
 388                 dev_err(&port->dev, "failed to read modem status: %d\n", r);
 389                 goto err_kill_interrupt_urb;
 390         }
 391
 392         r = usb_serial_generic_open(tty, port);
 393         if (r)
 394                 goto err_kill_interrupt_urb;
 395
 396         return 0;
 397
 398 err_kill_interrupt_urb:
 399         usb_kill_urb(port->interrupt_in_urb);
 400
 401         return r;
 402 }
 403
 404 /* Old_termios contains the original termios settings and
 405  * tty->termios contains the new setting to be used.
 406  */
 407 static void ch341_set_termios(struct tty_struct *tty,
 408                 struct usb_serial_port *port, struct ktermios *old_termios)
 409 {
 410         struct ch341_private *priv = usb_get_serial_port_data(port);
 411         unsigned baud_rate;
 412         unsigned long flags;
 413         u8 lcr;
 414         int r;
 415
 416         /* redundant changes may cause the chip to lose bytes */
 417         if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
 418                 return;
 419
 420         baud_rate = tty_get_baud_rate(tty);
 421
 422         lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
 423
 424         switch (C_CSIZE(tty)) {
 425         case CS5:
 426                 lcr |= CH341_LCR_CS5;
 427                 break;
 428         case CS6:
 429                 lcr |= CH341_LCR_CS6;
 430                 break;
 431         case CS7:
 432                 lcr |= CH341_LCR_CS7;
 433                 break;
 434         case CS8:
 435                 lcr |= CH341_LCR_CS8;
 436                 break;
 437         }
 438
 439         if (C_PARENB(tty)) {
 440                 lcr |= CH341_LCR_ENABLE_PAR;
 441                 if (C_PARODD(tty) == 0)
 442                         lcr |= CH341_LCR_PAR_EVEN;
 443                 if (C_CMSPAR(tty))
 444                         lcr |= CH341_LCR_MARK_SPACE;
 445         }
 446
 447         if (C_CSTOPB(tty))
 448                 lcr |= CH341_LCR_STOP_BITS_2;
 449
 450         if (baud_rate) {
 451                 priv->baud_rate = baud_rate;
 452
 453                 r = ch341_set_baudrate_lcr(port->serial->dev, priv, lcr);
 454                 if (r < 0 && old_termios) {
 455                         priv->baud_rate = tty_termios_baud_rate(old_termios);
 456                         tty_termios_copy_hw(&tty->termios, old_termios);
 457                 } else if (r == 0) {
 458                         priv->lcr = lcr;
 459                 }
 460         }
 461
 462         spin_lock_irqsave(&priv->lock, flags);
 463         if (C_BAUD(tty) == B0)
 464                 priv->mcr &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
 465         else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
 466                 priv->mcr |= (CH341_BIT_DTR | CH341_BIT_RTS);
 467         spin_unlock_irqrestore(&priv->lock, flags);
 468
 469         ch341_set_handshake(port->serial->dev, priv->mcr);
 470 }
 471
 472 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 473 {
 474         const uint16_t ch341_break_reg =
 475                         ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
 476         struct usb_serial_port *port = tty->driver_data;
 477         int r;
 478         uint16_t reg_contents;
 479         uint8_t *break_reg;
 480
 481         break_reg = kmalloc(2, GFP_KERNEL);
 482         if (!break_reg)
 483                 return;
 484
 485         r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
 486                         ch341_break_reg, 0, break_reg, 2);
 487         if (r < 0) {
 488                 dev_err(&port->dev, "%s - USB control read error (%d)\n",
 489                                 __func__, r);
 490                 goto out;
 491         }
 492         dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
 493                 __func__, break_reg[0], break_reg[1]);
 494         if (break_state != 0) {
 495                 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
 496                 break_reg[0] &= ~CH341_NBREAK_BITS;
 497                 break_reg[1] &= ~CH341_LCR_ENABLE_TX;
 498         } else {
 499                 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
 500                 break_reg[0] |= CH341_NBREAK_BITS;
 501                 break_reg[1] |= CH341_LCR_ENABLE_TX;
 502         }
 503         dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
 504                 __func__, break_reg[0], break_reg[1]);
 505         reg_contents = get_unaligned_le16(break_reg);
 506         r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
 507                         ch341_break_reg, reg_contents);
 508         if (r < 0)
 509                 dev_err(&port->dev, "%s - USB control write error (%d)\n",
 510                                 __func__, r);
 511 out:
 512         kfree(break_reg);
 513 }
 514
 515 static int ch341_tiocmset(struct tty_struct *tty,
 516                           unsigned int set, unsigned int clear)
 517 {
 518         struct usb_serial_port *port = tty->driver_data;
 519         struct ch341_private *priv = usb_get_serial_port_data(port);
 520         unsigned long flags;
 521         u8 control;
 522
 523         spin_lock_irqsave(&priv->lock, flags);
 524         if (set & TIOCM_RTS)
 525                 priv->mcr |= CH341_BIT_RTS;
 526         if (set & TIOCM_DTR)
 527                 priv->mcr |= CH341_BIT_DTR;
 528         if (clear & TIOCM_RTS)
 529                 priv->mcr &= ~CH341_BIT_RTS;
 530         if (clear & TIOCM_DTR)
 531                 priv->mcr &= ~CH341_BIT_DTR;
 532         control = priv->mcr;
 533         spin_unlock_irqrestore(&priv->lock, flags);
 534
 535         return ch341_set_handshake(port->serial->dev, control);
 536 }
 537
 538 static void ch341_update_status(struct usb_serial_port *port,
 539                                         unsigned char *data, size_t len)
 540 {
 541         struct ch341_private *priv = usb_get_serial_port_data(port);
 542         struct tty_struct *tty;
 543         unsigned long flags;
 544         u8 status;
 545         u8 delta;
 546
 547         if (len < 4)
 548                 return;
 549
 550         status = ~data[2] & CH341_BITS_MODEM_STAT;
 551
 552         spin_lock_irqsave(&priv->lock, flags);
 553         delta = status ^ priv->msr;
 554         priv->msr = status;
 555         spin_unlock_irqrestore(&priv->lock, flags);
 556
 557         if (data[1] & CH341_MULT_STAT)
 558                 dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
 559
 560         if (!delta)
 561                 return;
 562
 563         if (delta & CH341_BIT_CTS)
 564                 port->icount.cts++;
 565         if (delta & CH341_BIT_DSR)
 566                 port->icount.dsr++;
 567         if (delta & CH341_BIT_RI)
 568                 port->icount.rng++;
 569         if (delta & CH341_BIT_DCD) {
 570                 port->icount.dcd++;
 571                 tty = tty_port_tty_get(&port->port);
 572                 if (tty) {
 573                         usb_serial_handle_dcd_change(port, tty,
 574                                                 status & CH341_BIT_DCD);
 575                         tty_kref_put(tty);
 576                 }
 577         }
 578
 579         wake_up_interruptible(&port->port.delta_msr_wait);
 580 }
 581
 582 static void ch341_read_int_callback(struct urb *urb)
 583 {
 584         struct usb_serial_port *port = urb->context;
 585         unsigned char *data = urb->transfer_buffer;
 586         unsigned int len = urb->actual_length;
 587         int status;
 588
 589         switch (urb->status) {
 590         case 0:
 591                 /* success */
 592                 break;
 593         case -ECONNRESET:
 594         case -ENOENT:
 595         case -ESHUTDOWN:
 596                 /* this urb is terminated, clean up */
 597                 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
 598                         __func__, urb->status);
 599                 return;
 600         default:
 601                 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
 602                         __func__, urb->status);
 603                 goto exit;
 604         }
 605
 606         usb_serial_debug_data(&port->dev, __func__, len, data);
 607         ch341_update_status(port, data, len);
 608 exit:
 609         status = usb_submit_urb(urb, GFP_ATOMIC);
 610         if (status) {
 611                 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
 612                         __func__, status);
 613         }
 614 }
 615
 616 static int ch341_tiocmget(struct tty_struct *tty)
 617 {
 618         struct usb_serial_port *port = tty->driver_data;
 619         struct ch341_private *priv = usb_get_serial_port_data(port);
 620         unsigned long flags;
 621         u8 mcr;
 622         u8 status;
 623         unsigned int result;
 624
 625         spin_lock_irqsave(&priv->lock, flags);
 626         mcr = priv->mcr;
 627         status = priv->msr;
 628         spin_unlock_irqrestore(&priv->lock, flags);
 629
 630         result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
 631                   | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
 632                   | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
 633                   | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
 634                   | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
 635                   | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
 636
 637         dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
 638
 639         return result;
 640 }
 641
 642 static int ch341_reset_resume(struct usb_serial *serial)
 643 {
 644         struct usb_serial_port *port = serial->port[0];
 645         struct ch341_private *priv;
 646         int ret;
 647
 648         priv = usb_get_serial_port_data(port);
 649         if (!priv)
 650                 return 0;
 651
 652         /* reconfigure ch341 serial port after bus-reset */
 653         ch341_configure(serial->dev, priv);
 654
 655         if (tty_port_initialized(&port->port)) {
 656                 ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO);
 657                 if (ret) {
 658                         dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
 659                                 ret);
 660                         return ret;
 661                 }
 662
 663                 ret = ch341_get_status(port->serial->dev, priv);
 664                 if (ret < 0) {
 665                         dev_err(&port->dev, "failed to read modem status: %d\n",
 666                                 ret);
 667                 }
 668         }
 669
 670         return usb_serial_generic_resume(serial);
 671 }
 672
 673 static struct usb_serial_driver ch341_device = {
 674         .driver = {
 675                 .owner  = THIS_MODULE,
 676                 .name   = "ch341-uart",
 677         },
 678         .id_table          = id_table,
 679         .num_ports         = 1,
 680         .open              = ch341_open,
 681         .dtr_rts           = ch341_dtr_rts,
 682         .carrier_raised    = ch341_carrier_raised,
 683         .close             = ch341_close,
 684         .set_termios       = ch341_set_termios,
 685         .break_ctl         = ch341_break_ctl,
 686         .tiocmget          = ch341_tiocmget,
 687         .tiocmset          = ch341_tiocmset,
 688         .tiocmiwait        = usb_serial_generic_tiocmiwait,
 689         .read_int_callback = ch341_read_int_callback,
 690         .port_probe        = ch341_port_probe,
 691         .port_remove       = ch341_port_remove,
 692         .reset_resume      = ch341_reset_resume,
 693 };
 694
 695 static struct usb_serial_driver * const serial_drivers[] = {
 696         &ch341_device, NULL
 697 };
 698
 699 module_usb_serial_driver(serial_drivers, id_table);
 700
 701 MODULE_LICENSE("GPL v2");