drivers/usb/serial/generic.c

   1 /*
   2  * USB Serial Converter Generic functions
   3  *
   4  * Copyright (C) 2010 - 2013 Johan Hovold (jhovold@gmail.com)
   5  * Copyright (C) 1999 - 2002 Greg Kroah-Hartman (greg@kroah.com)
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License version
   9  *      2 as published by the Free Software Foundation.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/sched/signal.h>
  14 #include <linux/errno.h>
  15 #include <linux/slab.h>
  16 #include <linux/sysrq.h>
  17 #include <linux/tty.h>
  18 #include <linux/tty_flip.h>
  19 #include <linux/module.h>
  20 #include <linux/moduleparam.h>
  21 #include <linux/usb.h>
  22 #include <linux/usb/serial.h>
  23 #include <linux/uaccess.h>
  24 #include <linux/kfifo.h>
  25 #include <linux/serial.h>
  26
  27 #ifdef CONFIG_USB_SERIAL_GENERIC
  28
  29 static __u16 vendor  = 0x05f9;
  30 static __u16 product = 0xffff;
  31
  32 module_param(vendor, ushort, 0);
  33 MODULE_PARM_DESC(vendor, "User specified USB idVendor");
  34
  35 module_param(product, ushort, 0);
  36 MODULE_PARM_DESC(product, "User specified USB idProduct");
  37
  38 static struct usb_device_id generic_device_ids[2]; /* Initially all zeroes. */
  39
  40 static int usb_serial_generic_probe(struct usb_serial *serial,
  41                                         const struct usb_device_id *id)
  42 {
  43         struct device *dev = &serial->interface->dev;
  44
  45         dev_info(dev, "The \"generic\" usb-serial driver is only for testing and one-off prototypes.\n");
  46         dev_info(dev, "Tell linux-usb@vger.kernel.org to add your device to a proper driver.\n");
  47
  48         return 0;
  49 }
  50
  51 static int usb_serial_generic_calc_num_ports(struct usb_serial *serial,
  52                                         struct usb_serial_endpoints *epds)
  53 {
  54         struct device *dev = &serial->interface->dev;
  55         int num_ports;
  56
  57         num_ports = max(epds->num_bulk_in, epds->num_bulk_out);
  58
  59         if (num_ports == 0) {
  60                 dev_err(dev, "device has no bulk endpoints\n");
  61                 return -ENODEV;
  62         }
  63
  64         return num_ports;
  65 }
  66
  67 static struct usb_serial_driver usb_serial_generic_device = {
  68         .driver = {
  69                 .owner =        THIS_MODULE,
  70                 .name =         "generic",
  71         },
  72         .id_table =             generic_device_ids,
  73         .probe =                usb_serial_generic_probe,
  74         .calc_num_ports =       usb_serial_generic_calc_num_ports,
  75         .throttle =             usb_serial_generic_throttle,
  76         .unthrottle =           usb_serial_generic_unthrottle,
  77         .resume =               usb_serial_generic_resume,
  78 };
  79
  80 static struct usb_serial_driver * const serial_drivers[] = {
  81         &usb_serial_generic_device, NULL
  82 };
  83
  84 #endif
  85
  86 int usb_serial_generic_register(void)
  87 {
  88         int retval = 0;
  89
  90 #ifdef CONFIG_USB_SERIAL_GENERIC
  91         generic_device_ids[0].idVendor = vendor;
  92         generic_device_ids[0].idProduct = product;
  93         generic_device_ids[0].match_flags =
  94                 USB_DEVICE_ID_MATCH_VENDOR | USB_DEVICE_ID_MATCH_PRODUCT;
  95
  96         retval = usb_serial_register_drivers(serial_drivers,
  97                         "usbserial_generic", generic_device_ids);
  98 #endif
  99         return retval;
 100 }
 101
 102 void usb_serial_generic_deregister(void)
 103 {
 104 #ifdef CONFIG_USB_SERIAL_GENERIC
 105         usb_serial_deregister_drivers(serial_drivers);
 106 #endif
 107 }
 108
 109 int usb_serial_generic_open(struct tty_struct *tty, struct usb_serial_port *port)
 110 {
 111         int result = 0;
 112         unsigned long flags;
 113
 114         spin_lock_irqsave(&port->lock, flags);
 115         port->throttled = 0;
 116         port->throttle_req = 0;
 117         spin_unlock_irqrestore(&port->lock, flags);
 118
 119         if (port->bulk_in_size)
 120                 result = usb_serial_generic_submit_read_urbs(port, GFP_KERNEL);
 121
 122         return result;
 123 }
 124 EXPORT_SYMBOL_GPL(usb_serial_generic_open);
 125
 126 void usb_serial_generic_close(struct usb_serial_port *port)
 127 {
 128         unsigned long flags;
 129         int i;
 130
 131         if (port->bulk_out_size) {
 132                 for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
 133                         usb_kill_urb(port->write_urbs[i]);
 134
 135                 spin_lock_irqsave(&port->lock, flags);
 136                 kfifo_reset_out(&port->write_fifo);
 137                 spin_unlock_irqrestore(&port->lock, flags);
 138         }
 139         if (port->bulk_in_size) {
 140                 for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i)
 141                         usb_kill_urb(port->read_urbs[i]);
 142         }
 143 }
 144 EXPORT_SYMBOL_GPL(usb_serial_generic_close);
 145
 146 int usb_serial_generic_prepare_write_buffer(struct usb_serial_port *port,
 147                                                 void *dest, size_t size)
 148 {
 149         return kfifo_out_locked(&port->write_fifo, dest, size, &port->lock);
 150 }
 151
 152 /**
 153  * usb_serial_generic_write_start - start writing buffered data
 154  * @port: usb-serial port
 155  * @mem_flags: flags to use for memory allocations
 156  *
 157  * Serialised using USB_SERIAL_WRITE_BUSY flag.
 158  *
 159  * Return: Zero on success or if busy, otherwise a negative errno value.
 160  */
 161 int usb_serial_generic_write_start(struct usb_serial_port *port,
 162                                                         gfp_t mem_flags)
 163 {
 164         struct urb *urb;
 165         int count, result;
 166         unsigned long flags;
 167         int i;
 168
 169         if (test_and_set_bit_lock(USB_SERIAL_WRITE_BUSY, &port->flags))
 170                 return 0;
 171 retry:
 172         spin_lock_irqsave(&port->lock, flags);
 173         if (!port->write_urbs_free || !kfifo_len(&port->write_fifo)) {
 174                 clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags);
 175                 spin_unlock_irqrestore(&port->lock, flags);
 176                 return 0;
 177         }
 178         i = (int)find_first_bit(&port->write_urbs_free,
 179                                                 ARRAY_SIZE(port->write_urbs));
 180         spin_unlock_irqrestore(&port->lock, flags);
 181
 182         urb = port->write_urbs[i];
 183         count = port->serial->type->prepare_write_buffer(port,
 184                                                 urb->transfer_buffer,
 185                                                 port->bulk_out_size);
 186         urb->transfer_buffer_length = count;
 187         usb_serial_debug_data(&port->dev, __func__, count, urb->transfer_buffer);
 188         spin_lock_irqsave(&port->lock, flags);
 189         port->tx_bytes += count;
 190         spin_unlock_irqrestore(&port->lock, flags);
 191
 192         clear_bit(i, &port->write_urbs_free);
 193         result = usb_submit_urb(urb, mem_flags);
 194         if (result) {
 195                 dev_err_console(port, "%s - error submitting urb: %d\n",
 196                                                 __func__, result);
 197                 set_bit(i, &port->write_urbs_free);
 198                 spin_lock_irqsave(&port->lock, flags);
 199                 port->tx_bytes -= count;
 200                 spin_unlock_irqrestore(&port->lock, flags);
 201
 202                 clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags);
 203                 return result;
 204         }
 205
 206         goto retry;     /* try sending off another urb */
 207 }
 208 EXPORT_SYMBOL_GPL(usb_serial_generic_write_start);
 209
 210 /**
 211  * usb_serial_generic_write - generic write function
 212  * @tty: tty for the port
 213  * @port: usb-serial port
 214  * @buf: data to write
 215  * @count: number of bytes to write
 216  *
 217  * Return: The number of characters buffered, which may be anything from
 218  * zero to @count, or a negative errno value.
 219  */
 220 int usb_serial_generic_write(struct tty_struct *tty,
 221         struct usb_serial_port *port, const unsigned char *buf, int count)
 222 {
 223         int result;
 224
 225         if (!port->bulk_out_size)
 226                 return -ENODEV;
 227
 228         if (!count)
 229                 return 0;
 230
 231         count = kfifo_in_locked(&port->write_fifo, buf, count, &port->lock);
 232         result = usb_serial_generic_write_start(port, GFP_ATOMIC);
 233         if (result)
 234                 return result;
 235
 236         return count;
 237 }
 238 EXPORT_SYMBOL_GPL(usb_serial_generic_write);
 239
 240 int usb_serial_generic_write_room(struct tty_struct *tty)
 241 {
 242         struct usb_serial_port *port = tty->driver_data;
 243         unsigned long flags;
 244         int room;
 245
 246         if (!port->bulk_out_size)
 247                 return 0;
 248
 249         spin_lock_irqsave(&port->lock, flags);
 250         room = kfifo_avail(&port->write_fifo);
 251         spin_unlock_irqrestore(&port->lock, flags);
 252
 253         dev_dbg(&port->dev, "%s - returns %d\n", __func__, room);
 254         return room;
 255 }
 256
 257 int usb_serial_generic_chars_in_buffer(struct tty_struct *tty)
 258 {
 259         struct usb_serial_port *port = tty->driver_data;
 260         unsigned long flags;
 261         int chars;
 262
 263         if (!port->bulk_out_size)
 264                 return 0;
 265
 266         spin_lock_irqsave(&port->lock, flags);
 267         chars = kfifo_len(&port->write_fifo) + port->tx_bytes;
 268         spin_unlock_irqrestore(&port->lock, flags);
 269
 270         dev_dbg(&port->dev, "%s - returns %d\n", __func__, chars);
 271         return chars;
 272 }
 273 EXPORT_SYMBOL_GPL(usb_serial_generic_chars_in_buffer);
 274
 275 void usb_serial_generic_wait_until_sent(struct tty_struct *tty, long timeout)
 276 {
 277         struct usb_serial_port *port = tty->driver_data;
 278         unsigned int bps;
 279         unsigned long period;
 280         unsigned long expire;
 281
 282         bps = tty_get_baud_rate(tty);
 283         if (!bps)
 284                 bps = 9600;     /* B0 */
 285         /*
 286          * Use a poll-period of roughly the time it takes to send one
 287          * character or at least one jiffy.
 288          */
 289         period = max_t(unsigned long, (10 * HZ / bps), 1);
 290         if (timeout)
 291                 period = min_t(unsigned long, period, timeout);
 292
 293         dev_dbg(&port->dev, "%s - timeout = %u ms, period = %u ms\n",
 294                                         __func__, jiffies_to_msecs(timeout),
 295                                         jiffies_to_msecs(period));
 296         expire = jiffies + timeout;
 297         while (!port->serial->type->tx_empty(port)) {
 298                 schedule_timeout_interruptible(period);
 299                 if (signal_pending(current))
 300                         break;
 301                 if (timeout && time_after(jiffies, expire))
 302                         break;
 303         }
 304 }
 305 EXPORT_SYMBOL_GPL(usb_serial_generic_wait_until_sent);
 306
 307 static int usb_serial_generic_submit_read_urb(struct usb_serial_port *port,
 308                                                 int index, gfp_t mem_flags)
 309 {
 310         int res;
 311
 312         if (!test_and_clear_bit(index, &port->read_urbs_free))
 313                 return 0;
 314
 315         dev_dbg(&port->dev, "%s - urb %d\n", __func__, index);
 316
 317         res = usb_submit_urb(port->read_urbs[index], mem_flags);
 318         if (res) {
 319                 if (res != -EPERM && res != -ENODEV) {
 320                         dev_err(&port->dev,
 321                                         "%s - usb_submit_urb failed: %d\n",
 322                                         __func__, res);
 323                 }
 324                 set_bit(index, &port->read_urbs_free);
 325                 return res;
 326         }
 327
 328         return 0;
 329 }
 330
 331 int usb_serial_generic_submit_read_urbs(struct usb_serial_port *port,
 332                                         gfp_t mem_flags)
 333 {
 334         int res;
 335         int i;
 336
 337         for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i) {
 338                 res = usb_serial_generic_submit_read_urb(port, i, mem_flags);
 339                 if (res)
 340                         goto err;
 341         }
 342
 343         return 0;
 344 err:
 345         for (; i >= 0; --i)
 346                 usb_kill_urb(port->read_urbs[i]);
 347
 348         return res;
 349 }
 350 EXPORT_SYMBOL_GPL(usb_serial_generic_submit_read_urbs);
 351
 352 void usb_serial_generic_process_read_urb(struct urb *urb)
 353 {
 354         struct usb_serial_port *port = urb->context;
 355         char *ch = (char *)urb->transfer_buffer;
 356         int i;
 357
 358         if (!urb->actual_length)
 359                 return;
 360         /*
 361          * The per character mucking around with sysrq path it too slow for
 362          * stuff like 3G modems, so shortcircuit it in the 99.9999999% of
 363          * cases where the USB serial is not a console anyway.
 364          */
 365         if (!port->port.console || !port->sysrq) {
 366                 tty_insert_flip_string(&port->port, ch, urb->actual_length);
 367         } else {
 368                 for (i = 0; i < urb->actual_length; i++, ch++) {
 369                         if (!usb_serial_handle_sysrq_char(port, *ch))
 370                                 tty_insert_flip_char(&port->port, *ch, TTY_NORMAL);
 371                 }
 372         }
 373         tty_flip_buffer_push(&port->port);
 374 }
 375 EXPORT_SYMBOL_GPL(usb_serial_generic_process_read_urb);
 376
 377 void usb_serial_generic_read_bulk_callback(struct urb *urb)
 378 {
 379         struct usb_serial_port *port = urb->context;
 380         unsigned char *data = urb->transfer_buffer;
 381         unsigned long flags;
 382         bool stopped = false;
 383         int status = urb->status;
 384         int i;
 385
 386         for (i = 0; i < ARRAY_SIZE(port->read_urbs); ++i) {
 387                 if (urb == port->read_urbs[i])
 388                         break;
 389         }
 390
 391         dev_dbg(&port->dev, "%s - urb %d, len %d\n", __func__, i,
 392                                                         urb->actual_length);
 393         switch (status) {
 394         case 0:
 395                 usb_serial_debug_data(&port->dev, __func__, urb->actual_length,
 396                                                         data);
 397                 port->serial->type->process_read_urb(urb);
 398                 break;
 399         case -ENOENT:
 400         case -ECONNRESET:
 401         case -ESHUTDOWN:
 402                 dev_dbg(&port->dev, "%s - urb stopped: %d\n",
 403                                                         __func__, status);
 404                 stopped = true;
 405                 break;
 406         case -EPIPE:
 407                 dev_err(&port->dev, "%s - urb stopped: %d\n",
 408                                                         __func__, status);
 409                 stopped = true;
 410                 break;
 411         default:
 412                 dev_dbg(&port->dev, "%s - nonzero urb status: %d\n",
 413                                                         __func__, status);
 414                 break;
 415         }
 416
 417         /*
 418          * Make sure URB processing is done before marking as free to avoid
 419          * racing with unthrottle() on another CPU. Matches the barriers
 420          * implied by the test_and_clear_bit() in
 421          * usb_serial_generic_submit_read_urb().
 422          */
 423         smp_mb__before_atomic();
 424         set_bit(i, &port->read_urbs_free);
 425         /*
 426          * Make sure URB is marked as free before checking the throttled flag
 427          * to avoid racing with unthrottle() on another CPU. Matches the
 428          * smp_mb() in unthrottle().
 429          */
 430         smp_mb__after_atomic();
 431
 432         if (stopped)
 433                 return;
 434
 435         /* Throttle the device if requested by tty */
 436         spin_lock_irqsave(&port->lock, flags);
 437         port->throttled = port->throttle_req;
 438         if (!port->throttled) {
 439                 spin_unlock_irqrestore(&port->lock, flags);
 440                 usb_serial_generic_submit_read_urb(port, i, GFP_ATOMIC);
 441         } else {
 442                 spin_unlock_irqrestore(&port->lock, flags);
 443         }
 444 }
 445 EXPORT_SYMBOL_GPL(usb_serial_generic_read_bulk_callback);
 446
 447 void usb_serial_generic_write_bulk_callback(struct urb *urb)
 448 {
 449         unsigned long flags;
 450         struct usb_serial_port *port = urb->context;
 451         int status = urb->status;
 452         int i;
 453
 454         for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i) {
 455                 if (port->write_urbs[i] == urb)
 456                         break;
 457         }
 458         spin_lock_irqsave(&port->lock, flags);
 459         port->tx_bytes -= urb->transfer_buffer_length;
 460         set_bit(i, &port->write_urbs_free);
 461         spin_unlock_irqrestore(&port->lock, flags);
 462
 463         switch (status) {
 464         case 0:
 465                 break;
 466         case -ENOENT:
 467         case -ECONNRESET:
 468         case -ESHUTDOWN:
 469                 dev_dbg(&port->dev, "%s - urb stopped: %d\n",
 470                                                         __func__, status);
 471                 return;
 472         case -EPIPE:
 473                 dev_err_console(port, "%s - urb stopped: %d\n",
 474                                                         __func__, status);
 475                 return;
 476         default:
 477                 dev_err_console(port, "%s - nonzero urb status: %d\n",
 478                                                         __func__, status);
 479                 goto resubmit;
 480         }
 481
 482 resubmit:
 483         usb_serial_generic_write_start(port, GFP_ATOMIC);
 484         usb_serial_port_softint(port);
 485 }
 486 EXPORT_SYMBOL_GPL(usb_serial_generic_write_bulk_callback);
 487
 488 void usb_serial_generic_throttle(struct tty_struct *tty)
 489 {
 490         struct usb_serial_port *port = tty->driver_data;
 491         unsigned long flags;
 492
 493         spin_lock_irqsave(&port->lock, flags);
 494         port->throttle_req = 1;
 495         spin_unlock_irqrestore(&port->lock, flags);
 496 }
 497 EXPORT_SYMBOL_GPL(usb_serial_generic_throttle);
 498
 499 void usb_serial_generic_unthrottle(struct tty_struct *tty)
 500 {
 501         struct usb_serial_port *port = tty->driver_data;
 502         int was_throttled;
 503
 504         spin_lock_irq(&port->lock);
 505         was_throttled = port->throttled;
 506         port->throttled = port->throttle_req = 0;
 507         spin_unlock_irq(&port->lock);
 508
 509         /*
 510          * Matches the smp_mb__after_atomic() in
 511          * usb_serial_generic_read_bulk_callback().
 512          */
 513         smp_mb();
 514
 515         if (was_throttled)
 516                 usb_serial_generic_submit_read_urbs(port, GFP_KERNEL);
 517 }
 518 EXPORT_SYMBOL_GPL(usb_serial_generic_unthrottle);
 519
 520 static bool usb_serial_generic_msr_changed(struct tty_struct *tty,
 521                                 unsigned long arg, struct async_icount *cprev)
 522 {
 523         struct usb_serial_port *port = tty->driver_data;
 524         struct async_icount cnow;
 525         unsigned long flags;
 526         bool ret;
 527
 528         /*
 529          * Use tty-port initialised flag to detect all hangups including the
 530          * one generated at USB-device disconnect.
 531          */
 532         if (!tty_port_initialized(&port->port))
 533                 return true;
 534
 535         spin_lock_irqsave(&port->lock, flags);
 536         cnow = port->icount;                            /* atomic copy*/
 537         spin_unlock_irqrestore(&port->lock, flags);
 538
 539         ret =   ((arg & TIOCM_RNG) && (cnow.rng != cprev->rng)) ||
 540                 ((arg & TIOCM_DSR) && (cnow.dsr != cprev->dsr)) ||
 541                 ((arg & TIOCM_CD)  && (cnow.dcd != cprev->dcd)) ||
 542                 ((arg & TIOCM_CTS) && (cnow.cts != cprev->cts));
 543
 544         *cprev = cnow;
 545
 546         return ret;
 547 }
 548
 549 int usb_serial_generic_tiocmiwait(struct tty_struct *tty, unsigned long arg)
 550 {
 551         struct usb_serial_port *port = tty->driver_data;
 552         struct async_icount cnow;
 553         unsigned long flags;
 554         int ret;
 555
 556         spin_lock_irqsave(&port->lock, flags);
 557         cnow = port->icount;                            /* atomic copy */
 558         spin_unlock_irqrestore(&port->lock, flags);
 559
 560         ret = wait_event_interruptible(port->port.delta_msr_wait,
 561                         usb_serial_generic_msr_changed(tty, arg, &cnow));
 562         if (!ret && !tty_port_initialized(&port->port))
 563                 ret = -EIO;
 564
 565         return ret;
 566 }
 567 EXPORT_SYMBOL_GPL(usb_serial_generic_tiocmiwait);
 568
 569 int usb_serial_generic_get_icount(struct tty_struct *tty,
 570                                         struct serial_icounter_struct *icount)
 571 {
 572         struct usb_serial_port *port = tty->driver_data;
 573         struct async_icount cnow;
 574         unsigned long flags;
 575
 576         spin_lock_irqsave(&port->lock, flags);
 577         cnow = port->icount;                            /* atomic copy */
 578         spin_unlock_irqrestore(&port->lock, flags);
 579
 580         icount->cts = cnow.cts;
 581         icount->dsr = cnow.dsr;
 582         icount->rng = cnow.rng;
 583         icount->dcd = cnow.dcd;
 584         icount->tx = cnow.tx;
 585         icount->rx = cnow.rx;
 586         icount->frame = cnow.frame;
 587         icount->parity = cnow.parity;
 588         icount->overrun = cnow.overrun;
 589         icount->brk = cnow.brk;
 590         icount->buf_overrun = cnow.buf_overrun;
 591
 592         return 0;
 593 }
 594 EXPORT_SYMBOL_GPL(usb_serial_generic_get_icount);
 595
 596 #ifdef CONFIG_MAGIC_SYSRQ
 597 int usb_serial_handle_sysrq_char(struct usb_serial_port *port, unsigned int ch)
 598 {
 599         if (port->sysrq && port->port.console) {
 600                 if (ch && time_before(jiffies, port->sysrq)) {
 601                         handle_sysrq(ch);
 602                         port->sysrq = 0;
 603                         return 1;
 604                 }
 605                 port->sysrq = 0;
 606         }
 607         return 0;
 608 }
 609 #else
 610 int usb_serial_handle_sysrq_char(struct usb_serial_port *port, unsigned int ch)
 611 {
 612         return 0;
 613 }
 614 #endif
 615 EXPORT_SYMBOL_GPL(usb_serial_handle_sysrq_char);
 616
 617 int usb_serial_handle_break(struct usb_serial_port *port)
 618 {
 619         if (!port->sysrq) {
 620                 port->sysrq = jiffies + HZ*5;
 621                 return 1;
 622         }
 623         port->sysrq = 0;
 624         return 0;
 625 }
 626 EXPORT_SYMBOL_GPL(usb_serial_handle_break);
 627
 628 /**
 629  * usb_serial_handle_dcd_change - handle a change of carrier detect state
 630  * @port: usb-serial port
 631  * @tty: tty for the port
 632  * @status: new carrier detect status, nonzero if active
 633  */
 634 void usb_serial_handle_dcd_change(struct usb_serial_port *usb_port,
 635                                 struct tty_struct *tty, unsigned int status)
 636 {
 637         struct tty_port *port = &usb_port->port;
 638
 639         dev_dbg(&usb_port->dev, "%s - status %d\n", __func__, status);
 640
 641         if (tty) {
 642                 struct tty_ldisc *ld = tty_ldisc_ref(tty);
 643
 644                 if (ld) {
 645                         if (ld->ops->dcd_change)
 646                                 ld->ops->dcd_change(tty, status);
 647                         tty_ldisc_deref(ld);
 648                 }
 649         }
 650
 651         if (status)
 652                 wake_up_interruptible(&port->open_wait);
 653         else if (tty && !C_CLOCAL(tty))
 654                 tty_hangup(tty);
 655 }
 656 EXPORT_SYMBOL_GPL(usb_serial_handle_dcd_change);
 657
 658 int usb_serial_generic_resume(struct usb_serial *serial)
 659 {
 660         struct usb_serial_port *port;
 661         int i, c = 0, r;
 662
 663         for (i = 0; i < serial->num_ports; i++) {
 664                 port = serial->port[i];
 665                 if (!tty_port_initialized(&port->port))
 666                         continue;
 667
 668                 if (port->bulk_in_size) {
 669                         r = usb_serial_generic_submit_read_urbs(port,
 670                                                                 GFP_NOIO);
 671                         if (r < 0)
 672                                 c++;
 673                 }
 674
 675                 if (port->bulk_out_size) {
 676                         r = usb_serial_generic_write_start(port, GFP_NOIO);
 677                         if (r < 0)
 678                                 c++;
 679                 }
 680         }
 681
 682         return c ? -EIO : 0;
 683 }
 684 EXPORT_SYMBOL_GPL(usb_serial_generic_resume);