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 /* Break support - the information used to implement this was gleaned from 52 * the Net/FreeBSD uchcom.c driver by Takanori Watanabe. Domo arigato. 53 */ 54 55 #define CH341_REQ_READ_VERSION 0x5F 56 #define CH341_REQ_WRITE_REG 0x9A 57 #define CH341_REQ_READ_REG 0x95 58 #define CH341_REQ_SERIAL_INIT 0xA1 59 #define CH341_REQ_MODEM_CTRL 0xA4 60 61 #define CH341_REG_BREAK 0x05 62 #define CH341_REG_LCR 0x18 63 #define CH341_NBREAK_BITS 0x01 64 65 #define CH341_LCR_ENABLE_RX 0x80 66 #define CH341_LCR_ENABLE_TX 0x40 67 #define CH341_LCR_MARK_SPACE 0x20 68 #define CH341_LCR_PAR_EVEN 0x10 69 #define CH341_LCR_ENABLE_PAR 0x08 70 #define CH341_LCR_STOP_BITS_2 0x04 71 #define CH341_LCR_CS8 0x03 72 #define CH341_LCR_CS7 0x02 73 #define CH341_LCR_CS6 0x01 74 #define CH341_LCR_CS5 0x00 75 76 static const struct usb_device_id id_table[] = { 77 { USB_DEVICE(0x4348, 0x5523) }, 78 { USB_DEVICE(0x1a86, 0x7523) }, 79 { USB_DEVICE(0x1a86, 0x5523) }, 80 { }, 81 }; 82 MODULE_DEVICE_TABLE(usb, id_table); 83 84 struct ch341_private { 85 spinlock_t lock; /* access lock */ 86 unsigned baud_rate; /* set baud rate */ 87 u8 mcr; 88 u8 msr; 89 u8 lcr; 90 }; 91 92 static void ch341_set_termios(struct tty_struct *tty, 93 struct usb_serial_port *port, 94 struct ktermios *old_termios); 95 96 static int ch341_control_out(struct usb_device *dev, u8 request, 97 u16 value, u16 index) 98 { 99 int r; 100 101 dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x)\n", __func__, 102 request, value, index); 103 104 r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request, 105 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT, 106 value, index, NULL, 0, DEFAULT_TIMEOUT); 107 if (r < 0) 108 dev_err(&dev->dev, "failed to send control message: %d\n", r); 109 110 return r; 111 } 112 113 static int ch341_control_in(struct usb_device *dev, 114 u8 request, u16 value, u16 index, 115 char *buf, unsigned bufsize) 116 { 117 int r; 118 119 dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x,%u)\n", __func__, 120 request, value, index, bufsize); 121 122 r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request, 123 USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN, 124 value, index, buf, bufsize, DEFAULT_TIMEOUT); 125 if (r < (int)bufsize) { 126 if (r >= 0) { 127 dev_err(&dev->dev, 128 "short control message received (%d < %u)\n", 129 r, bufsize); 130 r = -EIO; 131 } 132 133 dev_err(&dev->dev, "failed to receive control message: %d\n", 134 r); 135 return r; 136 } 137 138 return 0; 139 } 140 141 #define CH341_CLKRATE 48000000 142 #define CH341_CLK_DIV(ps, fact) (1 << (12 - 3 * (ps) - (fact))) 143 #define CH341_MIN_RATE(ps) (CH341_CLKRATE / (CH341_CLK_DIV((ps), 1) * 512)) 144 145 static const speed_t ch341_min_rates[] = { 146 CH341_MIN_RATE(0), 147 CH341_MIN_RATE(1), 148 CH341_MIN_RATE(2), 149 CH341_MIN_RATE(3), 150 }; 151 152 /* 153 * The device line speed is given by the following equation: 154 * 155 * baudrate = 48000000 / (2^(12 - 3 * ps - fact) * div), where 156 * 157 * 0 <= ps <= 3, 158 * 0 <= fact <= 1, 159 * 2 <= div <= 256 if fact = 0, or 160 * 9 <= div <= 256 if fact = 1 161 */ 162 static int ch341_get_divisor(speed_t speed) 163 { 164 unsigned int fact, div, clk_div; 165 int ps; 166 167 /* 168 * Clamp to supported range, this makes the (ps < 0) and (div < 2) 169 * sanity checks below redundant. 170 */ 171 speed = clamp(speed, 46U, 3000000U); 172 173 /* 174 * Start with highest possible base clock (fact = 1) that will give a 175 * divisor strictly less than 512. 176 */ 177 fact = 1; 178 for (ps = 3; ps >= 0; ps--) { 179 if (speed > ch341_min_rates[ps]) 180 break; 181 } 182 183 if (ps < 0) 184 return -EINVAL; 185 186 /* Determine corresponding divisor, rounding down. */ 187 clk_div = CH341_CLK_DIV(ps, fact); 188 div = CH341_CLKRATE / (clk_div * speed); 189 190 /* Halve base clock (fact = 0) if required. */ 191 if (div < 9 || div > 255) { 192 div /= 2; 193 clk_div *= 2; 194 fact = 0; 195 } 196 197 if (div < 2) 198 return -EINVAL; 199 200 /* 201 * Pick next divisor if resulting rate is closer to the requested one, 202 * scale up to avoid rounding errors on low rates. 203 */ 204 if (16 * CH341_CLKRATE / (clk_div * div) - 16 * speed >= 205 16 * speed - 16 * CH341_CLKRATE / (clk_div * (div + 1))) 206 div++; 207 208 /* 209 * Prefer lower base clock (fact = 0) if even divisor. 210 * 211 * Note that this makes the receiver more tolerant to errors. 212 */ 213 if (fact == 1 && div % 2 == 0) { 214 div /= 2; 215 fact = 0; 216 } 217 218 return (0x100 - div) << 8 | fact << 2 | ps; 219 } 220 221 static int ch341_set_baudrate_lcr(struct usb_device *dev, 222 struct ch341_private *priv, u8 lcr) 223 { 224 int val; 225 int r; 226 227 if (!priv->baud_rate) 228 return -EINVAL; 229 230 val = ch341_get_divisor(priv->baud_rate); 231 if (val < 0) 232 return -EINVAL; 233 234 /* 235 * CH341A buffers data until a full endpoint-size packet (32 bytes) 236 * has been received unless bit 7 is set. 237 */ 238 val |= BIT(7); 239 240 r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x1312, val); 241 if (r) 242 return r; 243 244 r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, lcr); 245 if (r) 246 return r; 247 248 return r; 249 } 250 251 static int ch341_set_handshake(struct usb_device *dev, u8 control) 252 { 253 return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0); 254 } 255 256 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv) 257 { 258 const unsigned int size = 2; 259 char *buffer; 260 int r; 261 unsigned long flags; 262 263 buffer = kmalloc(size, GFP_KERNEL); 264 if (!buffer) 265 return -ENOMEM; 266 267 r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size); 268 if (r < 0) 269 goto out; 270 271 spin_lock_irqsave(&priv->lock, flags); 272 priv->msr = (~(*buffer)) & CH341_BITS_MODEM_STAT; 273 spin_unlock_irqrestore(&priv->lock, flags); 274 275 out: kfree(buffer); 276 return r; 277 } 278 279 /* -------------------------------------------------------------------------- */ 280 281 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv) 282 { 283 const unsigned int size = 2; 284 char *buffer; 285 int r; 286 287 buffer = kmalloc(size, GFP_KERNEL); 288 if (!buffer) 289 return -ENOMEM; 290 291 /* expect two bytes 0x27 0x00 */ 292 r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size); 293 if (r < 0) 294 goto out; 295 dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]); 296 297 r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0); 298 if (r < 0) 299 goto out; 300 301 r = ch341_set_baudrate_lcr(dev, priv, priv->lcr); 302 if (r < 0) 303 goto out; 304 305 r = ch341_set_handshake(dev, priv->mcr); 306 307 out: kfree(buffer); 308 return r; 309 } 310 311 static int ch341_port_probe(struct usb_serial_port *port) 312 { 313 struct ch341_private *priv; 314 int r; 315 316 priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL); 317 if (!priv) 318 return -ENOMEM; 319 320 spin_lock_init(&priv->lock); 321 priv->baud_rate = DEFAULT_BAUD_RATE; 322 /* 323 * Some CH340 devices appear unable to change the initial LCR 324 * settings, so set a sane 8N1 default. 325 */ 326 priv->lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8; 327 328 r = ch341_configure(port->serial->dev, priv); 329 if (r < 0) 330 goto error; 331 332 usb_set_serial_port_data(port, priv); 333 return 0; 334 335 error: kfree(priv); 336 return r; 337 } 338 339 static int ch341_port_remove(struct usb_serial_port *port) 340 { 341 struct ch341_private *priv; 342 343 priv = usb_get_serial_port_data(port); 344 kfree(priv); 345 346 return 0; 347 } 348 349 static int ch341_carrier_raised(struct usb_serial_port *port) 350 { 351 struct ch341_private *priv = usb_get_serial_port_data(port); 352 if (priv->msr & CH341_BIT_DCD) 353 return 1; 354 return 0; 355 } 356 357 static void ch341_dtr_rts(struct usb_serial_port *port, int on) 358 { 359 struct ch341_private *priv = usb_get_serial_port_data(port); 360 unsigned long flags; 361 362 /* drop DTR and RTS */ 363 spin_lock_irqsave(&priv->lock, flags); 364 if (on) 365 priv->mcr |= CH341_BIT_RTS | CH341_BIT_DTR; 366 else 367 priv->mcr &= ~(CH341_BIT_RTS | CH341_BIT_DTR); 368 spin_unlock_irqrestore(&priv->lock, flags); 369 ch341_set_handshake(port->serial->dev, priv->mcr); 370 } 371 372 static void ch341_close(struct usb_serial_port *port) 373 { 374 usb_serial_generic_close(port); 375 usb_kill_urb(port->interrupt_in_urb); 376 } 377 378 379 /* open this device, set default parameters */ 380 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port) 381 { 382 struct ch341_private *priv = usb_get_serial_port_data(port); 383 int r; 384 385 if (tty) 386 ch341_set_termios(tty, port, NULL); 387 388 dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__); 389 r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL); 390 if (r) { 391 dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n", 392 __func__, r); 393 return r; 394 } 395 396 r = ch341_get_status(port->serial->dev, priv); 397 if (r < 0) { 398 dev_err(&port->dev, "failed to read modem status: %d\n", r); 399 goto err_kill_interrupt_urb; 400 } 401 402 r = usb_serial_generic_open(tty, port); 403 if (r) 404 goto err_kill_interrupt_urb; 405 406 return 0; 407 408 err_kill_interrupt_urb: 409 usb_kill_urb(port->interrupt_in_urb); 410 411 return r; 412 } 413 414 /* Old_termios contains the original termios settings and 415 * tty->termios contains the new setting to be used. 416 */ 417 static void ch341_set_termios(struct tty_struct *tty, 418 struct usb_serial_port *port, struct ktermios *old_termios) 419 { 420 struct ch341_private *priv = usb_get_serial_port_data(port); 421 unsigned baud_rate; 422 unsigned long flags; 423 u8 lcr; 424 int r; 425 426 /* redundant changes may cause the chip to lose bytes */ 427 if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios)) 428 return; 429 430 baud_rate = tty_get_baud_rate(tty); 431 432 lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX; 433 434 switch (C_CSIZE(tty)) { 435 case CS5: 436 lcr |= CH341_LCR_CS5; 437 break; 438 case CS6: 439 lcr |= CH341_LCR_CS6; 440 break; 441 case CS7: 442 lcr |= CH341_LCR_CS7; 443 break; 444 case CS8: 445 lcr |= CH341_LCR_CS8; 446 break; 447 } 448 449 if (C_PARENB(tty)) { 450 lcr |= CH341_LCR_ENABLE_PAR; 451 if (C_PARODD(tty) == 0) 452 lcr |= CH341_LCR_PAR_EVEN; 453 if (C_CMSPAR(tty)) 454 lcr |= CH341_LCR_MARK_SPACE; 455 } 456 457 if (C_CSTOPB(tty)) 458 lcr |= CH341_LCR_STOP_BITS_2; 459 460 if (baud_rate) { 461 priv->baud_rate = baud_rate; 462 463 r = ch341_set_baudrate_lcr(port->serial->dev, priv, lcr); 464 if (r < 0 && old_termios) { 465 priv->baud_rate = tty_termios_baud_rate(old_termios); 466 tty_termios_copy_hw(&tty->termios, old_termios); 467 } else if (r == 0) { 468 priv->lcr = lcr; 469 } 470 } 471 472 spin_lock_irqsave(&priv->lock, flags); 473 if (C_BAUD(tty) == B0) 474 priv->mcr &= ~(CH341_BIT_DTR | CH341_BIT_RTS); 475 else if (old_termios && (old_termios->c_cflag & CBAUD) == B0) 476 priv->mcr |= (CH341_BIT_DTR | CH341_BIT_RTS); 477 spin_unlock_irqrestore(&priv->lock, flags); 478 479 ch341_set_handshake(port->serial->dev, priv->mcr); 480 } 481 482 static void ch341_break_ctl(struct tty_struct *tty, int break_state) 483 { 484 const uint16_t ch341_break_reg = 485 ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK; 486 struct usb_serial_port *port = tty->driver_data; 487 int r; 488 uint16_t reg_contents; 489 uint8_t *break_reg; 490 491 break_reg = kmalloc(2, GFP_KERNEL); 492 if (!break_reg) 493 return; 494 495 r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG, 496 ch341_break_reg, 0, break_reg, 2); 497 if (r < 0) { 498 dev_err(&port->dev, "%s - USB control read error (%d)\n", 499 __func__, r); 500 goto out; 501 } 502 dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n", 503 __func__, break_reg[0], break_reg[1]); 504 if (break_state != 0) { 505 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__); 506 break_reg[0] &= ~CH341_NBREAK_BITS; 507 break_reg[1] &= ~CH341_LCR_ENABLE_TX; 508 } else { 509 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__); 510 break_reg[0] |= CH341_NBREAK_BITS; 511 break_reg[1] |= CH341_LCR_ENABLE_TX; 512 } 513 dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n", 514 __func__, break_reg[0], break_reg[1]); 515 reg_contents = get_unaligned_le16(break_reg); 516 r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG, 517 ch341_break_reg, reg_contents); 518 if (r < 0) 519 dev_err(&port->dev, "%s - USB control write error (%d)\n", 520 __func__, r); 521 out: 522 kfree(break_reg); 523 } 524 525 static int ch341_tiocmset(struct tty_struct *tty, 526 unsigned int set, unsigned int clear) 527 { 528 struct usb_serial_port *port = tty->driver_data; 529 struct ch341_private *priv = usb_get_serial_port_data(port); 530 unsigned long flags; 531 u8 control; 532 533 spin_lock_irqsave(&priv->lock, flags); 534 if (set & TIOCM_RTS) 535 priv->mcr |= CH341_BIT_RTS; 536 if (set & TIOCM_DTR) 537 priv->mcr |= CH341_BIT_DTR; 538 if (clear & TIOCM_RTS) 539 priv->mcr &= ~CH341_BIT_RTS; 540 if (clear & TIOCM_DTR) 541 priv->mcr &= ~CH341_BIT_DTR; 542 control = priv->mcr; 543 spin_unlock_irqrestore(&priv->lock, flags); 544 545 return ch341_set_handshake(port->serial->dev, control); 546 } 547 548 static void ch341_update_status(struct usb_serial_port *port, 549 unsigned char *data, size_t len) 550 { 551 struct ch341_private *priv = usb_get_serial_port_data(port); 552 struct tty_struct *tty; 553 unsigned long flags; 554 u8 status; 555 u8 delta; 556 557 if (len < 4) 558 return; 559 560 status = ~data[2] & CH341_BITS_MODEM_STAT; 561 562 spin_lock_irqsave(&priv->lock, flags); 563 delta = status ^ priv->msr; 564 priv->msr = status; 565 spin_unlock_irqrestore(&priv->lock, flags); 566 567 if (data[1] & CH341_MULT_STAT) 568 dev_dbg(&port->dev, "%s - multiple status change\n", __func__); 569 570 if (!delta) 571 return; 572 573 if (delta & CH341_BIT_CTS) 574 port->icount.cts++; 575 if (delta & CH341_BIT_DSR) 576 port->icount.dsr++; 577 if (delta & CH341_BIT_RI) 578 port->icount.rng++; 579 if (delta & CH341_BIT_DCD) { 580 port->icount.dcd++; 581 tty = tty_port_tty_get(&port->port); 582 if (tty) { 583 usb_serial_handle_dcd_change(port, tty, 584 status & CH341_BIT_DCD); 585 tty_kref_put(tty); 586 } 587 } 588 589 wake_up_interruptible(&port->port.delta_msr_wait); 590 } 591 592 static void ch341_read_int_callback(struct urb *urb) 593 { 594 struct usb_serial_port *port = urb->context; 595 unsigned char *data = urb->transfer_buffer; 596 unsigned int len = urb->actual_length; 597 int status; 598 599 switch (urb->status) { 600 case 0: 601 /* success */ 602 break; 603 case -ECONNRESET: 604 case -ENOENT: 605 case -ESHUTDOWN: 606 /* this urb is terminated, clean up */ 607 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n", 608 __func__, urb->status); 609 return; 610 default: 611 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n", 612 __func__, urb->status); 613 goto exit; 614 } 615 616 usb_serial_debug_data(&port->dev, __func__, len, data); 617 ch341_update_status(port, data, len); 618 exit: 619 status = usb_submit_urb(urb, GFP_ATOMIC); 620 if (status) { 621 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n", 622 __func__, status); 623 } 624 } 625 626 static int ch341_tiocmget(struct tty_struct *tty) 627 { 628 struct usb_serial_port *port = tty->driver_data; 629 struct ch341_private *priv = usb_get_serial_port_data(port); 630 unsigned long flags; 631 u8 mcr; 632 u8 status; 633 unsigned int result; 634 635 spin_lock_irqsave(&priv->lock, flags); 636 mcr = priv->mcr; 637 status = priv->msr; 638 spin_unlock_irqrestore(&priv->lock, flags); 639 640 result = ((mcr & CH341_BIT_DTR) ? TIOCM_DTR : 0) 641 | ((mcr & CH341_BIT_RTS) ? TIOCM_RTS : 0) 642 | ((status & CH341_BIT_CTS) ? TIOCM_CTS : 0) 643 | ((status & CH341_BIT_DSR) ? TIOCM_DSR : 0) 644 | ((status & CH341_BIT_RI) ? TIOCM_RI : 0) 645 | ((status & CH341_BIT_DCD) ? TIOCM_CD : 0); 646 647 dev_dbg(&port->dev, "%s - result = %x\n", __func__, result); 648 649 return result; 650 } 651 652 static int ch341_reset_resume(struct usb_serial *serial) 653 { 654 struct usb_serial_port *port = serial->port[0]; 655 struct ch341_private *priv; 656 int ret; 657 658 priv = usb_get_serial_port_data(port); 659 if (!priv) 660 return 0; 661 662 /* reconfigure ch341 serial port after bus-reset */ 663 ch341_configure(serial->dev, priv); 664 665 if (tty_port_initialized(&port->port)) { 666 ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO); 667 if (ret) { 668 dev_err(&port->dev, "failed to submit interrupt urb: %d\n", 669 ret); 670 return ret; 671 } 672 673 ret = ch341_get_status(port->serial->dev, priv); 674 if (ret < 0) { 675 dev_err(&port->dev, "failed to read modem status: %d\n", 676 ret); 677 } 678 } 679 680 return usb_serial_generic_resume(serial); 681 } 682 683 static struct usb_serial_driver ch341_device = { 684 .driver = { 685 .owner = THIS_MODULE, 686 .name = "ch341-uart", 687 }, 688 .id_table = id_table, 689 .num_ports = 1, 690 .open = ch341_open, 691 .dtr_rts = ch341_dtr_rts, 692 .carrier_raised = ch341_carrier_raised, 693 .close = ch341_close, 694 .set_termios = ch341_set_termios, 695 .break_ctl = ch341_break_ctl, 696 .tiocmget = ch341_tiocmget, 697 .tiocmset = ch341_tiocmset, 698 .tiocmiwait = usb_serial_generic_tiocmiwait, 699 .read_int_callback = ch341_read_int_callback, 700 .port_probe = ch341_port_probe, 701 .port_remove = ch341_port_remove, 702 .reset_resume = ch341_reset_resume, 703 }; 704 705 static struct usb_serial_driver * const serial_drivers[] = { 706 &ch341_device, NULL 707 }; 708 709 module_usb_serial_driver(serial_drivers, id_table); 710 711 MODULE_LICENSE("GPL v2"); 712