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 /* 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 #define CH341_QUIRK_LIMITED_PRESCALER   BIT(0)
  77
  78 static const struct usb_device_id id_table[] = {
  79         { USB_DEVICE(0x4348, 0x5523) },
  80         { USB_DEVICE(0x1a86, 0x7523) },
  81         { USB_DEVICE(0x1a86, 0x5523) },
  82         { },
  83 };
  84 MODULE_DEVICE_TABLE(usb, id_table);
  85
  86 struct ch341_private {
  87         spinlock_t lock; /* access lock */
  88         unsigned baud_rate; /* set baud rate */
  89         u8 mcr;
  90         u8 msr;
  91         u8 lcr;
  92         unsigned long quirks;
  93 };
  94
  95 static void ch341_set_termios(struct tty_struct *tty,
  96                               struct usb_serial_port *port,
  97                               struct ktermios *old_termios);
  98
  99 static int ch341_control_out(struct usb_device *dev, u8 request,
 100                              u16 value, u16 index)
 101 {
 102         int r;
 103
 104         dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x)\n", __func__,
 105                 request, value, index);
 106
 107         r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
 108                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_OUT,
 109                             value, index, NULL, 0, DEFAULT_TIMEOUT);
 110         if (r < 0)
 111                 dev_err(&dev->dev, "failed to send control message: %d\n", r);
 112
 113         return r;
 114 }
 115
 116 static int ch341_control_in(struct usb_device *dev,
 117                             u8 request, u16 value, u16 index,
 118                             char *buf, unsigned bufsize)
 119 {
 120         int r;
 121
 122         dev_dbg(&dev->dev, "%s - (%02x,%04x,%04x,%u)\n", __func__,
 123                 request, value, index, bufsize);
 124
 125         r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
 126                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 127                             value, index, buf, bufsize, DEFAULT_TIMEOUT);
 128         if (r < (int)bufsize) {
 129                 if (r >= 0) {
 130                         dev_err(&dev->dev,
 131                                 "short control message received (%d < %u)\n",
 132                                 r, bufsize);
 133                         r = -EIO;
 134                 }
 135
 136                 dev_err(&dev->dev, "failed to receive control message: %d\n",
 137                         r);
 138                 return r;
 139         }
 140
 141         return 0;
 142 }
 143
 144 #define CH341_CLKRATE           48000000
 145 #define CH341_CLK_DIV(ps, fact) (1 << (12 - 3 * (ps) - (fact)))
 146 #define CH341_MIN_RATE(ps)      (CH341_CLKRATE / (CH341_CLK_DIV((ps), 1) * 512))
 147
 148 static const speed_t ch341_min_rates[] = {
 149         CH341_MIN_RATE(0),
 150         CH341_MIN_RATE(1),
 151         CH341_MIN_RATE(2),
 152         CH341_MIN_RATE(3),
 153 };
 154
 155 /*
 156  * The device line speed is given by the following equation:
 157  *
 158  *      baudrate = 48000000 / (2^(12 - 3 * ps - fact) * div), where
 159  *
 160  *              0 <= ps <= 3,
 161  *              0 <= fact <= 1,
 162  *              2 <= div <= 256 if fact = 0, or
 163  *              9 <= div <= 256 if fact = 1
 164  */
 165 static int ch341_get_divisor(struct ch341_private *priv)
 166 {
 167         unsigned int fact, div, clk_div;
 168         speed_t speed = priv->baud_rate;
 169         bool force_fact0 = false;
 170         int ps;
 171
 172         /*
 173          * Clamp to supported range, this makes the (ps < 0) and (div < 2)
 174          * sanity checks below redundant.
 175          */
 176         speed = clamp(speed, 46U, 3000000U);
 177
 178         /*
 179          * Start with highest possible base clock (fact = 1) that will give a
 180          * divisor strictly less than 512.
 181          */
 182         fact = 1;
 183         for (ps = 3; ps >= 0; ps--) {
 184                 if (speed > ch341_min_rates[ps])
 185                         break;
 186         }
 187
 188         if (ps < 0)
 189                 return -EINVAL;
 190
 191         /* Determine corresponding divisor, rounding down. */
 192         clk_div = CH341_CLK_DIV(ps, fact);
 193         div = CH341_CLKRATE / (clk_div * speed);
 194
 195         /* Some devices require a lower base clock if ps < 3. */
 196         if (ps < 3 && (priv->quirks & CH341_QUIRK_LIMITED_PRESCALER))
 197                 force_fact0 = true;
 198
 199         /* Halve base clock (fact = 0) if required. */
 200         if (div < 9 || div > 255 || force_fact0) {
 201                 div /= 2;
 202                 clk_div *= 2;
 203                 fact = 0;
 204         }
 205
 206         if (div < 2)
 207                 return -EINVAL;
 208
 209         /*
 210          * Pick next divisor if resulting rate is closer to the requested one,
 211          * scale up to avoid rounding errors on low rates.
 212          */
 213         if (16 * CH341_CLKRATE / (clk_div * div) - 16 * speed >=
 214                         16 * speed - 16 * CH341_CLKRATE / (clk_div * (div + 1)))
 215                 div++;
 216
 217         /*
 218          * Prefer lower base clock (fact = 0) if even divisor.
 219          *
 220          * Note that this makes the receiver more tolerant to errors.
 221          */
 222         if (fact == 1 && div % 2 == 0) {
 223                 div /= 2;
 224                 fact = 0;
 225         }
 226
 227         return (0x100 - div) << 8 | fact << 2 | ps;
 228 }
 229
 230 static int ch341_set_baudrate_lcr(struct usb_device *dev,
 231                                   struct ch341_private *priv, u8 lcr)
 232 {
 233         int val;
 234         int r;
 235
 236         if (!priv->baud_rate)
 237                 return -EINVAL;
 238
 239         val = ch341_get_divisor(priv);
 240         if (val < 0)
 241                 return -EINVAL;
 242
 243         /*
 244          * CH341A buffers data until a full endpoint-size packet (32 bytes)
 245          * has been received unless bit 7 is set.
 246          */
 247         val |= BIT(7);
 248
 249         r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x1312, val);
 250         if (r)
 251                 return r;
 252
 253         r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, lcr);
 254         if (r)
 255                 return r;
 256
 257         return r;
 258 }
 259
 260 static int ch341_set_handshake(struct usb_device *dev, u8 control)
 261 {
 262         return ch341_control_out(dev, CH341_REQ_MODEM_CTRL, ~control, 0);
 263 }
 264
 265 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 266 {
 267         const unsigned int size = 2;
 268         char *buffer;
 269         int r;
 270         unsigned long flags;
 271
 272         buffer = kmalloc(size, GFP_KERNEL);
 273         if (!buffer)
 274                 return -ENOMEM;
 275
 276         r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
 277         if (r < 0)
 278                 goto out;
 279
 280         spin_lock_irqsave(&priv->lock, flags);
 281         priv->msr = (~(*buffer)) & CH341_BITS_MODEM_STAT;
 282         spin_unlock_irqrestore(&priv->lock, flags);
 283
 284 out:    kfree(buffer);
 285         return r;
 286 }
 287
 288 /* -------------------------------------------------------------------------- */
 289
 290 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 291 {
 292         const unsigned int size = 2;
 293         char *buffer;
 294         int r;
 295
 296         buffer = kmalloc(size, GFP_KERNEL);
 297         if (!buffer)
 298                 return -ENOMEM;
 299
 300         /* expect two bytes 0x27 0x00 */
 301         r = ch341_control_in(dev, CH341_REQ_READ_VERSION, 0, 0, buffer, size);
 302         if (r < 0)
 303                 goto out;
 304         dev_dbg(&dev->dev, "Chip version: 0x%02x\n", buffer[0]);
 305
 306         r = ch341_control_out(dev, CH341_REQ_SERIAL_INIT, 0, 0);
 307         if (r < 0)
 308                 goto out;
 309
 310         r = ch341_set_baudrate_lcr(dev, priv, priv->lcr);
 311         if (r < 0)
 312                 goto out;
 313
 314         r = ch341_set_handshake(dev, priv->mcr);
 315
 316 out:    kfree(buffer);
 317         return r;
 318 }
 319
 320 static int ch341_detect_quirks(struct usb_serial_port *port)
 321 {
 322         struct ch341_private *priv = usb_get_serial_port_data(port);
 323         struct usb_device *udev = port->serial->dev;
 324         const unsigned int size = 2;
 325         unsigned long quirks = 0;
 326         char *buffer;
 327         int r;
 328
 329         buffer = kmalloc(size, GFP_KERNEL);
 330         if (!buffer)
 331                 return -ENOMEM;
 332
 333         /*
 334          * A subset of CH34x devices does not support all features. The
 335          * prescaler is limited and there is no support for sending a RS232
 336          * break condition. A read failure when trying to set up the latter is
 337          * used to detect these devices.
 338          */
 339         r = usb_control_msg(udev, usb_rcvctrlpipe(udev, 0), CH341_REQ_READ_REG,
 340                             USB_TYPE_VENDOR | USB_RECIP_DEVICE | USB_DIR_IN,
 341                             CH341_REG_BREAK, 0, buffer, size, DEFAULT_TIMEOUT);
 342         if (r == -EPIPE) {
 343                 dev_dbg(&port->dev, "break control not supported\n");
 344                 quirks = CH341_QUIRK_LIMITED_PRESCALER;
 345                 r = 0;
 346                 goto out;
 347         }
 348
 349         if (r != size) {
 350                 if (r >= 0)
 351                         r = -EIO;
 352                 dev_err(&port->dev, "failed to read break control: %d\n", r);
 353                 goto out;
 354         }
 355
 356         r = 0;
 357 out:
 358         kfree(buffer);
 359
 360         if (quirks) {
 361                 dev_dbg(&port->dev, "enabling quirk flags: 0x%02lx\n", quirks);
 362                 priv->quirks |= quirks;
 363         }
 364
 365         return r;
 366 }
 367
 368 static int ch341_port_probe(struct usb_serial_port *port)
 369 {
 370         struct ch341_private *priv;
 371         int r;
 372
 373         priv = kzalloc(sizeof(struct ch341_private), GFP_KERNEL);
 374         if (!priv)
 375                 return -ENOMEM;
 376
 377         spin_lock_init(&priv->lock);
 378         priv->baud_rate = DEFAULT_BAUD_RATE;
 379         /*
 380          * Some CH340 devices appear unable to change the initial LCR
 381          * settings, so set a sane 8N1 default.
 382          */
 383         priv->lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
 384
 385         r = ch341_configure(port->serial->dev, priv);
 386         if (r < 0)
 387                 goto error;
 388
 389         usb_set_serial_port_data(port, priv);
 390
 391         r = ch341_detect_quirks(port);
 392         if (r < 0)
 393                 goto error;
 394
 395         return 0;
 396
 397 error:  kfree(priv);
 398         return r;
 399 }
 400
 401 static int ch341_port_remove(struct usb_serial_port *port)
 402 {
 403         struct ch341_private *priv;
 404
 405         priv = usb_get_serial_port_data(port);
 406         kfree(priv);
 407
 408         return 0;
 409 }
 410
 411 static int ch341_carrier_raised(struct usb_serial_port *port)
 412 {
 413         struct ch341_private *priv = usb_get_serial_port_data(port);
 414         if (priv->msr & CH341_BIT_DCD)
 415                 return 1;
 416         return 0;
 417 }
 418
 419 static void ch341_dtr_rts(struct usb_serial_port *port, int on)
 420 {
 421         struct ch341_private *priv = usb_get_serial_port_data(port);
 422         unsigned long flags;
 423
 424         /* drop DTR and RTS */
 425         spin_lock_irqsave(&priv->lock, flags);
 426         if (on)
 427                 priv->mcr |= CH341_BIT_RTS | CH341_BIT_DTR;
 428         else
 429                 priv->mcr &= ~(CH341_BIT_RTS | CH341_BIT_DTR);
 430         spin_unlock_irqrestore(&priv->lock, flags);
 431         ch341_set_handshake(port->serial->dev, priv->mcr);
 432 }
 433
 434 static void ch341_close(struct usb_serial_port *port)
 435 {
 436         usb_serial_generic_close(port);
 437         usb_kill_urb(port->interrupt_in_urb);
 438 }
 439
 440
 441 /* open this device, set default parameters */
 442 static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
 443 {
 444         struct ch341_private *priv = usb_get_serial_port_data(port);
 445         int r;
 446
 447         if (tty)
 448                 ch341_set_termios(tty, port, NULL);
 449
 450         dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
 451         r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 452         if (r) {
 453                 dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n",
 454                         __func__, r);
 455                 return r;
 456         }
 457
 458         r = ch341_get_status(port->serial->dev, priv);
 459         if (r < 0) {
 460                 dev_err(&port->dev, "failed to read modem status: %d\n", r);
 461                 goto err_kill_interrupt_urb;
 462         }
 463
 464         r = usb_serial_generic_open(tty, port);
 465         if (r)
 466                 goto err_kill_interrupt_urb;
 467
 468         return 0;
 469
 470 err_kill_interrupt_urb:
 471         usb_kill_urb(port->interrupt_in_urb);
 472
 473         return r;
 474 }
 475
 476 /* Old_termios contains the original termios settings and
 477  * tty->termios contains the new setting to be used.
 478  */
 479 static void ch341_set_termios(struct tty_struct *tty,
 480                 struct usb_serial_port *port, struct ktermios *old_termios)
 481 {
 482         struct ch341_private *priv = usb_get_serial_port_data(port);
 483         unsigned baud_rate;
 484         unsigned long flags;
 485         u8 lcr;
 486         int r;
 487
 488         /* redundant changes may cause the chip to lose bytes */
 489         if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
 490                 return;
 491
 492         baud_rate = tty_get_baud_rate(tty);
 493
 494         lcr = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
 495
 496         switch (C_CSIZE(tty)) {
 497         case CS5:
 498                 lcr |= CH341_LCR_CS5;
 499                 break;
 500         case CS6:
 501                 lcr |= CH341_LCR_CS6;
 502                 break;
 503         case CS7:
 504                 lcr |= CH341_LCR_CS7;
 505                 break;
 506         case CS8:
 507                 lcr |= CH341_LCR_CS8;
 508                 break;
 509         }
 510
 511         if (C_PARENB(tty)) {
 512                 lcr |= CH341_LCR_ENABLE_PAR;
 513                 if (C_PARODD(tty) == 0)
 514                         lcr |= CH341_LCR_PAR_EVEN;
 515                 if (C_CMSPAR(tty))
 516                         lcr |= CH341_LCR_MARK_SPACE;
 517         }
 518
 519         if (C_CSTOPB(tty))
 520                 lcr |= CH341_LCR_STOP_BITS_2;
 521
 522         if (baud_rate) {
 523                 priv->baud_rate = baud_rate;
 524
 525                 r = ch341_set_baudrate_lcr(port->serial->dev, priv, lcr);
 526                 if (r < 0 && old_termios) {
 527                         priv->baud_rate = tty_termios_baud_rate(old_termios);
 528                         tty_termios_copy_hw(&tty->termios, old_termios);
 529                 } else if (r == 0) {
 530                         priv->lcr = lcr;
 531                 }
 532         }
 533
 534         spin_lock_irqsave(&priv->lock, flags);
 535         if (C_BAUD(tty) == B0)
 536                 priv->mcr &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
 537         else if (old_termios && (old_termios->c_cflag & CBAUD) == B0)
 538                 priv->mcr |= (CH341_BIT_DTR | CH341_BIT_RTS);
 539         spin_unlock_irqrestore(&priv->lock, flags);
 540
 541         ch341_set_handshake(port->serial->dev, priv->mcr);
 542 }
 543
 544 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 545 {
 546         const uint16_t ch341_break_reg =
 547                         ((uint16_t) CH341_REG_LCR << 8) | CH341_REG_BREAK;
 548         struct usb_serial_port *port = tty->driver_data;
 549         int r;
 550         uint16_t reg_contents;
 551         uint8_t *break_reg;
 552
 553         break_reg = kmalloc(2, GFP_KERNEL);
 554         if (!break_reg)
 555                 return;
 556
 557         r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
 558                         ch341_break_reg, 0, break_reg, 2);
 559         if (r < 0) {
 560                 dev_err(&port->dev, "%s - USB control read error (%d)\n",
 561                                 __func__, r);
 562                 goto out;
 563         }
 564         dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
 565                 __func__, break_reg[0], break_reg[1]);
 566         if (break_state != 0) {
 567                 dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
 568                 break_reg[0] &= ~CH341_NBREAK_BITS;
 569                 break_reg[1] &= ~CH341_LCR_ENABLE_TX;
 570         } else {
 571                 dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
 572                 break_reg[0] |= CH341_NBREAK_BITS;
 573                 break_reg[1] |= CH341_LCR_ENABLE_TX;
 574         }
 575         dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
 576                 __func__, break_reg[0], break_reg[1]);
 577         reg_contents = get_unaligned_le16(break_reg);
 578         r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
 579                         ch341_break_reg, reg_contents);
 580         if (r < 0)
 581                 dev_err(&port->dev, "%s - USB control write error (%d)\n",
 582                                 __func__, r);
 583 out:
 584         kfree(break_reg);
 585 }
 586
 587 static int ch341_tiocmset(struct tty_struct *tty,
 588                           unsigned int set, unsigned int clear)
 589 {
 590         struct usb_serial_port *port = tty->driver_data;
 591         struct ch341_private *priv = usb_get_serial_port_data(port);
 592         unsigned long flags;
 593         u8 control;
 594
 595         spin_lock_irqsave(&priv->lock, flags);
 596         if (set & TIOCM_RTS)
 597                 priv->mcr |= CH341_BIT_RTS;
 598         if (set & TIOCM_DTR)
 599                 priv->mcr |= CH341_BIT_DTR;
 600         if (clear & TIOCM_RTS)
 601                 priv->mcr &= ~CH341_BIT_RTS;
 602         if (clear & TIOCM_DTR)
 603                 priv->mcr &= ~CH341_BIT_DTR;
 604         control = priv->mcr;
 605         spin_unlock_irqrestore(&priv->lock, flags);
 606
 607         return ch341_set_handshake(port->serial->dev, control);
 608 }
 609
 610 static void ch341_update_status(struct usb_serial_port *port,
 611                                         unsigned char *data, size_t len)
 612 {
 613         struct ch341_private *priv = usb_get_serial_port_data(port);
 614         struct tty_struct *tty;
 615         unsigned long flags;
 616         u8 status;
 617         u8 delta;
 618
 619         if (len < 4)
 620                 return;
 621
 622         status = ~data[2] & CH341_BITS_MODEM_STAT;
 623
 624         spin_lock_irqsave(&priv->lock, flags);
 625         delta = status ^ priv->msr;
 626         priv->msr = status;
 627         spin_unlock_irqrestore(&priv->lock, flags);
 628
 629         if (data[1] & CH341_MULT_STAT)
 630                 dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
 631
 632         if (!delta)
 633                 return;
 634
 635         if (delta & CH341_BIT_CTS)
 636                 port->icount.cts++;
 637         if (delta & CH341_BIT_DSR)
 638                 port->icount.dsr++;
 639         if (delta & CH341_BIT_RI)
 640                 port->icount.rng++;
 641         if (delta & CH341_BIT_DCD) {
 642                 port->icount.dcd++;
 643                 tty = tty_port_tty_get(&port->port);
 644                 if (tty) {
 645                         usb_serial_handle_dcd_change(port, tty,
 646                                                 status & CH341_BIT_DCD);
 647                         tty_kref_put(tty);
 648                 }
 649         }
 650
 651         wake_up_interruptible(&port->port.delta_msr_wait);
 652 }
 653
 654 static void ch341_read_int_callback(struct urb *urb)
 655 {
 656         struct usb_serial_port *port = urb->context;
 657         unsigned char *data = urb->transfer_buffer;
 658         unsigned int len = urb->actual_length;
 659         int status;
 660
 661         switch (urb->status) {
 662         case 0:
 663                 /* success */
 664                 break;
 665         case -ECONNRESET:
 666         case -ENOENT:
 667         case -ESHUTDOWN:
 668                 /* this urb is terminated, clean up */
 669                 dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
 670                         __func__, urb->status);
 671                 return;
 672         default:
 673                 dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
 674                         __func__, urb->status);
 675                 goto exit;
 676         }
 677
 678         usb_serial_debug_data(&port->dev, __func__, len, data);
 679         ch341_update_status(port, data, len);
 680 exit:
 681         status = usb_submit_urb(urb, GFP_ATOMIC);
 682         if (status) {
 683                 dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
 684                         __func__, status);
 685         }
 686 }
 687
 688 static int ch341_tiocmget(struct tty_struct *tty)
 689 {
 690         struct usb_serial_port *port = tty->driver_data;
 691         struct ch341_private *priv = usb_get_serial_port_data(port);
 692         unsigned long flags;
 693         u8 mcr;
 694         u8 status;
 695         unsigned int result;
 696
 697         spin_lock_irqsave(&priv->lock, flags);
 698         mcr = priv->mcr;
 699         status = priv->msr;
 700         spin_unlock_irqrestore(&priv->lock, flags);
 701
 702         result = ((mcr & CH341_BIT_DTR)         ? TIOCM_DTR : 0)
 703                   | ((mcr & CH341_BIT_RTS)      ? TIOCM_RTS : 0)
 704                   | ((status & CH341_BIT_CTS)   ? TIOCM_CTS : 0)
 705                   | ((status & CH341_BIT_DSR)   ? TIOCM_DSR : 0)
 706                   | ((status & CH341_BIT_RI)    ? TIOCM_RI  : 0)
 707                   | ((status & CH341_BIT_DCD)   ? TIOCM_CD  : 0);
 708
 709         dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
 710
 711         return result;
 712 }
 713
 714 static int ch341_reset_resume(struct usb_serial *serial)
 715 {
 716         struct usb_serial_port *port = serial->port[0];
 717         struct ch341_private *priv;
 718         int ret;
 719
 720         priv = usb_get_serial_port_data(port);
 721         if (!priv)
 722                 return 0;
 723
 724         /* reconfigure ch341 serial port after bus-reset */
 725         ch341_configure(serial->dev, priv);
 726
 727         if (tty_port_initialized(&port->port)) {
 728                 ret = usb_submit_urb(port->interrupt_in_urb, GFP_NOIO);
 729                 if (ret) {
 730                         dev_err(&port->dev, "failed to submit interrupt urb: %d\n",
 731                                 ret);
 732                         return ret;
 733                 }
 734
 735                 ret = ch341_get_status(port->serial->dev, priv);
 736                 if (ret < 0) {
 737                         dev_err(&port->dev, "failed to read modem status: %d\n",
 738                                 ret);
 739                 }
 740         }
 741
 742         return usb_serial_generic_resume(serial);
 743 }
 744
 745 static struct usb_serial_driver ch341_device = {
 746         .driver = {
 747                 .owner  = THIS_MODULE,
 748                 .name   = "ch341-uart",
 749         },
 750         .id_table          = id_table,
 751         .num_ports         = 1,
 752         .open              = ch341_open,
 753         .dtr_rts           = ch341_dtr_rts,
 754         .carrier_raised    = ch341_carrier_raised,
 755         .close             = ch341_close,
 756         .set_termios       = ch341_set_termios,
 757         .break_ctl         = ch341_break_ctl,
 758         .tiocmget          = ch341_tiocmget,
 759         .tiocmset          = ch341_tiocmset,
 760         .tiocmiwait        = usb_serial_generic_tiocmiwait,
 761         .read_int_callback = ch341_read_int_callback,
 762         .port_probe        = ch341_port_probe,
 763         .port_remove       = ch341_port_remove,
 764         .reset_resume      = ch341_reset_resume,
 765 };
 766
 767 static struct usb_serial_driver * const serial_drivers[] = {
 768         &ch341_device, NULL
 769 };
 770
 771 module_usb_serial_driver(serial_drivers, id_table);
 772
 773 MODULE_LICENSE("GPL v2");