drivers/char/pcmcia/ipwireless/tty.c

   1 /*
   2  * IPWireless 3G PCMCIA Network Driver
   3  *
   4  * Original code
   5  *   by Stephen Blackheath <stephen@blacksapphire.com>,
   6  *      Ben Martel <benm@symmetric.co.nz>
   7  *
   8  * Copyrighted as follows:
   9  *   Copyright (C) 2004 by Symmetric Systems Ltd (NZ)
  10  *
  11  * Various driver changes and rewrites, port to new kernels
  12  *   Copyright (C) 2006-2007 Jiri Kosina
  13  *
  14  * Misc code cleanups and updates
  15  *   Copyright (C) 2007 David Sterba
  16  */
  17
  18 #include <linux/init.h>
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/mutex.h>
  22 #include <linux/ppp_defs.h>
  23 #include <linux/if.h>
  24 #include <linux/if_ppp.h>
  25 #include <linux/sched.h>
  26 #include <linux/serial.h>
  27 #include <linux/slab.h>
  28 #include <linux/tty.h>
  29 #include <linux/tty_driver.h>
  30 #include <linux/tty_flip.h>
  31 #include <linux/uaccess.h>
  32
  33 #include "tty.h"
  34 #include "network.h"
  35 #include "hardware.h"
  36 #include "main.h"
  37
  38 #define IPWIRELESS_PCMCIA_START         (0)
  39 #define IPWIRELESS_PCMCIA_MINORS        (24)
  40 #define IPWIRELESS_PCMCIA_MINOR_RANGE   (8)
  41
  42 #define TTYTYPE_MODEM    (0)
  43 #define TTYTYPE_MONITOR  (1)
  44 #define TTYTYPE_RAS_RAW  (2)
  45
  46 struct ipw_tty {
  47         int index;
  48         struct ipw_hardware *hardware;
  49         unsigned int channel_idx;
  50         unsigned int secondary_channel_idx;
  51         int tty_type;
  52         struct ipw_network *network;
  53         struct tty_struct *linux_tty;
  54         int open_count;
  55         unsigned int control_lines;
  56         struct mutex ipw_tty_mutex;
  57         int tx_bytes_queued;
  58         int closing;
  59 };
  60
  61 static struct ipw_tty *ttys[IPWIRELESS_PCMCIA_MINORS];
  62
  63 static struct tty_driver *ipw_tty_driver;
  64
  65 static char *tty_type_name(int tty_type)
  66 {
  67         static char *channel_names[] = {
  68                 "modem",
  69                 "monitor",
  70                 "RAS-raw"
  71         };
  72
  73         return channel_names[tty_type];
  74 }
  75
  76 static void report_registering(struct ipw_tty *tty)
  77 {
  78         char *iftype = tty_type_name(tty->tty_type);
  79
  80         printk(KERN_INFO IPWIRELESS_PCCARD_NAME
  81                ": registering %s device ttyIPWp%d\n", iftype, tty->index);
  82 }
  83
  84 static void report_deregistering(struct ipw_tty *tty)
  85 {
  86         char *iftype = tty_type_name(tty->tty_type);
  87
  88         printk(KERN_INFO IPWIRELESS_PCCARD_NAME
  89                ": deregistering %s device ttyIPWp%d\n", iftype,
  90                tty->index);
  91 }
  92
  93 static struct ipw_tty *get_tty(int minor)
  94 {
  95         if (minor < ipw_tty_driver->minor_start
  96                         || minor >= ipw_tty_driver->minor_start +
  97                         IPWIRELESS_PCMCIA_MINORS)
  98                 return NULL;
  99         else {
 100                 int minor_offset = minor - ipw_tty_driver->minor_start;
 101
 102                 /*
 103                  * The 'ras_raw' channel is only available when 'loopback' mode
 104                  * is enabled.
 105                  * Number of minor starts with 16 (_RANGE * _RAS_RAW).
 106                  */
 107                 if (!ipwireless_loopback &&
 108                                 minor_offset >=
 109                                  IPWIRELESS_PCMCIA_MINOR_RANGE * TTYTYPE_RAS_RAW)
 110                         return NULL;
 111
 112                 return ttys[minor_offset];
 113         }
 114 }
 115
 116 static int ipw_open(struct tty_struct *linux_tty, struct file *filp)
 117 {
 118         int minor = linux_tty->index;
 119         struct ipw_tty *tty = get_tty(minor);
 120
 121         if (!tty)
 122                 return -ENODEV;
 123
 124         mutex_lock(&tty->ipw_tty_mutex);
 125
 126         if (tty->closing) {
 127                 mutex_unlock(&tty->ipw_tty_mutex);
 128                 return -ENODEV;
 129         }
 130         if (tty->open_count == 0)
 131                 tty->tx_bytes_queued = 0;
 132
 133         tty->open_count++;
 134
 135         tty->linux_tty = linux_tty;
 136         linux_tty->driver_data = tty;
 137         linux_tty->low_latency = 1;
 138
 139         if (tty->tty_type == TTYTYPE_MODEM)
 140                 ipwireless_ppp_open(tty->network);
 141
 142         mutex_unlock(&tty->ipw_tty_mutex);
 143
 144         return 0;
 145 }
 146
 147 static void do_ipw_close(struct ipw_tty *tty)
 148 {
 149         tty->open_count--;
 150
 151         if (tty->open_count == 0) {
 152                 struct tty_struct *linux_tty = tty->linux_tty;
 153
 154                 if (linux_tty != NULL) {
 155                         tty->linux_tty = NULL;
 156                         linux_tty->driver_data = NULL;
 157
 158                         if (tty->tty_type == TTYTYPE_MODEM)
 159                                 ipwireless_ppp_close(tty->network);
 160                 }
 161         }
 162 }
 163
 164 static void ipw_hangup(struct tty_struct *linux_tty)
 165 {
 166         struct ipw_tty *tty = linux_tty->driver_data;
 167
 168         if (!tty)
 169                 return;
 170
 171         mutex_lock(&tty->ipw_tty_mutex);
 172         if (tty->open_count == 0) {
 173                 mutex_unlock(&tty->ipw_tty_mutex);
 174                 return;
 175         }
 176
 177         do_ipw_close(tty);
 178
 179         mutex_unlock(&tty->ipw_tty_mutex);
 180 }
 181
 182 static void ipw_close(struct tty_struct *linux_tty, struct file *filp)
 183 {
 184         ipw_hangup(linux_tty);
 185 }
 186
 187 /* Take data received from hardware, and send it out the tty */
 188 void ipwireless_tty_received(struct ipw_tty *tty, unsigned char *data,
 189                         unsigned int length)
 190 {
 191         struct tty_struct *linux_tty;
 192         int work = 0;
 193
 194         mutex_lock(&tty->ipw_tty_mutex);
 195         linux_tty = tty->linux_tty;
 196         if (linux_tty == NULL) {
 197                 mutex_unlock(&tty->ipw_tty_mutex);
 198                 return;
 199         }
 200
 201         if (!tty->open_count) {
 202                 mutex_unlock(&tty->ipw_tty_mutex);
 203                 return;
 204         }
 205         mutex_unlock(&tty->ipw_tty_mutex);
 206
 207         work = tty_insert_flip_string(linux_tty, data, length);
 208
 209         if (work != length)
 210                 printk(KERN_DEBUG IPWIRELESS_PCCARD_NAME
 211                                 ": %d chars not inserted to flip buffer!\n",
 212                                 length - work);
 213
 214         /*
 215          * This may sleep if ->low_latency is set
 216          */
 217         if (work)
 218                 tty_flip_buffer_push(linux_tty);
 219 }
 220
 221 static void ipw_write_packet_sent_callback(void *callback_data,
 222                                            unsigned int packet_length)
 223 {
 224         struct ipw_tty *tty = callback_data;
 225
 226         /*
 227          * Packet has been sent, so we subtract the number of bytes from our
 228          * tally of outstanding TX bytes.
 229          */
 230         tty->tx_bytes_queued -= packet_length;
 231 }
 232
 233 static int ipw_write(struct tty_struct *linux_tty,
 234                      const unsigned char *buf, int count)
 235 {
 236         struct ipw_tty *tty = linux_tty->driver_data;
 237         int room, ret;
 238
 239         if (!tty)
 240                 return -ENODEV;
 241
 242         mutex_lock(&tty->ipw_tty_mutex);
 243         if (!tty->open_count) {
 244                 mutex_unlock(&tty->ipw_tty_mutex);
 245                 return -EINVAL;
 246         }
 247
 248         room = IPWIRELESS_TX_QUEUE_SIZE - tty->tx_bytes_queued;
 249         if (room < 0)
 250                 room = 0;
 251         /* Don't allow caller to write any more than we have room for */
 252         if (count > room)
 253                 count = room;
 254
 255         if (count == 0) {
 256                 mutex_unlock(&tty->ipw_tty_mutex);
 257                 return 0;
 258         }
 259
 260         ret = ipwireless_send_packet(tty->hardware, IPW_CHANNEL_RAS,
 261                                buf, count,
 262                                ipw_write_packet_sent_callback, tty);
 263         if (ret == -1) {
 264                 mutex_unlock(&tty->ipw_tty_mutex);
 265                 return 0;
 266         }
 267
 268         tty->tx_bytes_queued += count;
 269         mutex_unlock(&tty->ipw_tty_mutex);
 270
 271         return count;
 272 }
 273
 274 static int ipw_write_room(struct tty_struct *linux_tty)
 275 {
 276         struct ipw_tty *tty = linux_tty->driver_data;
 277         int room;
 278
 279         /* FIXME: Exactly how is the tty object locked here .. */
 280         if (!tty)
 281                 return -ENODEV;
 282
 283         if (!tty->open_count)
 284                 return -EINVAL;
 285
 286         room = IPWIRELESS_TX_QUEUE_SIZE - tty->tx_bytes_queued;
 287         if (room < 0)
 288                 room = 0;
 289
 290         return room;
 291 }
 292
 293 static int ipwireless_get_serial_info(struct ipw_tty *tty,
 294                                       struct serial_struct __user *retinfo)
 295 {
 296         struct serial_struct tmp;
 297
 298         if (!retinfo)
 299                 return (-EFAULT);
 300
 301         memset(&tmp, 0, sizeof(tmp));
 302         tmp.type = PORT_UNKNOWN;
 303         tmp.line = tty->index;
 304         tmp.port = 0;
 305         tmp.irq = 0;
 306         tmp.flags = 0;
 307         tmp.baud_base = 115200;
 308         tmp.close_delay = 0;
 309         tmp.closing_wait = 0;
 310         tmp.custom_divisor = 0;
 311         tmp.hub6 = 0;
 312         if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
 313                 return -EFAULT;
 314
 315         return 0;
 316 }
 317
 318 static int ipw_chars_in_buffer(struct tty_struct *linux_tty)
 319 {
 320         struct ipw_tty *tty = linux_tty->driver_data;
 321
 322         if (!tty)
 323                 return 0;
 324
 325         if (!tty->open_count)
 326                 return 0;
 327
 328         return tty->tx_bytes_queued;
 329 }
 330
 331 static int get_control_lines(struct ipw_tty *tty)
 332 {
 333         unsigned int my = tty->control_lines;
 334         unsigned int out = 0;
 335
 336         if (my & IPW_CONTROL_LINE_RTS)
 337                 out |= TIOCM_RTS;
 338         if (my & IPW_CONTROL_LINE_DTR)
 339                 out |= TIOCM_DTR;
 340         if (my & IPW_CONTROL_LINE_CTS)
 341                 out |= TIOCM_CTS;
 342         if (my & IPW_CONTROL_LINE_DSR)
 343                 out |= TIOCM_DSR;
 344         if (my & IPW_CONTROL_LINE_DCD)
 345                 out |= TIOCM_CD;
 346
 347         return out;
 348 }
 349
 350 static int set_control_lines(struct ipw_tty *tty, unsigned int set,
 351                              unsigned int clear)
 352 {
 353         int ret;
 354
 355         if (set & TIOCM_RTS) {
 356                 ret = ipwireless_set_RTS(tty->hardware, tty->channel_idx, 1);
 357                 if (ret)
 358                         return ret;
 359                 if (tty->secondary_channel_idx != -1) {
 360                         ret = ipwireless_set_RTS(tty->hardware,
 361                                           tty->secondary_channel_idx, 1);
 362                         if (ret)
 363                                 return ret;
 364                 }
 365         }
 366         if (set & TIOCM_DTR) {
 367                 ret = ipwireless_set_DTR(tty->hardware, tty->channel_idx, 1);
 368                 if (ret)
 369                         return ret;
 370                 if (tty->secondary_channel_idx != -1) {
 371                         ret = ipwireless_set_DTR(tty->hardware,
 372                                           tty->secondary_channel_idx, 1);
 373                         if (ret)
 374                                 return ret;
 375                 }
 376         }
 377         if (clear & TIOCM_RTS) {
 378                 ret = ipwireless_set_RTS(tty->hardware, tty->channel_idx, 0);
 379                 if (tty->secondary_channel_idx != -1) {
 380                         ret = ipwireless_set_RTS(tty->hardware,
 381                                           tty->secondary_channel_idx, 0);
 382                         if (ret)
 383                                 return ret;
 384                 }
 385         }
 386         if (clear & TIOCM_DTR) {
 387                 ret = ipwireless_set_DTR(tty->hardware, tty->channel_idx, 0);
 388                 if (tty->secondary_channel_idx != -1) {
 389                         ret = ipwireless_set_DTR(tty->hardware,
 390                                           tty->secondary_channel_idx, 0);
 391                         if (ret)
 392                                 return ret;
 393                 }
 394         }
 395         return 0;
 396 }
 397
 398 static int ipw_tiocmget(struct tty_struct *linux_tty, struct file *file)
 399 {
 400         struct ipw_tty *tty = linux_tty->driver_data;
 401         /* FIXME: Exactly how is the tty object locked here .. */
 402
 403         if (!tty)
 404                 return -ENODEV;
 405
 406         if (!tty->open_count)
 407                 return -EINVAL;
 408
 409         return get_control_lines(tty);
 410 }
 411
 412 static int
 413 ipw_tiocmset(struct tty_struct *linux_tty, struct file *file,
 414              unsigned int set, unsigned int clear)
 415 {
 416         struct ipw_tty *tty = linux_tty->driver_data;
 417         /* FIXME: Exactly how is the tty object locked here .. */
 418
 419         if (!tty)
 420                 return -ENODEV;
 421
 422         if (!tty->open_count)
 423                 return -EINVAL;
 424
 425         return set_control_lines(tty, set, clear);
 426 }
 427
 428 static int ipw_ioctl(struct tty_struct *linux_tty, struct file *file,
 429                      unsigned int cmd, unsigned long arg)
 430 {
 431         struct ipw_tty *tty = linux_tty->driver_data;
 432
 433         if (!tty)
 434                 return -ENODEV;
 435
 436         if (!tty->open_count)
 437                 return -EINVAL;
 438
 439         /* FIXME: Exactly how is the tty object locked here .. */
 440
 441         switch (cmd) {
 442         case TIOCGSERIAL:
 443                 return ipwireless_get_serial_info(tty, (void __user *) arg);
 444
 445         case TIOCSSERIAL:
 446                 return 0;       /* Keeps the PCMCIA scripts happy. */
 447         }
 448
 449         if (tty->tty_type == TTYTYPE_MODEM) {
 450                 switch (cmd) {
 451                 case PPPIOCGCHAN:
 452                         {
 453                                 int chan = ipwireless_ppp_channel_index(
 454                                                         tty->network);
 455
 456                                 if (chan < 0)
 457                                         return -ENODEV;
 458                                 if (put_user(chan, (int __user *) arg))
 459                                         return -EFAULT;
 460                         }
 461                         return 0;
 462
 463                 case PPPIOCGUNIT:
 464                         {
 465                                 int unit = ipwireless_ppp_unit_number(
 466                                                 tty->network);
 467
 468                                 if (unit < 0)
 469                                         return -ENODEV;
 470                                 if (put_user(unit, (int __user *) arg))
 471                                         return -EFAULT;
 472                         }
 473                         return 0;
 474
 475                 case FIONREAD:
 476                         {
 477                                 int val = 0;
 478
 479                                 if (put_user(val, (int __user *) arg))
 480                                         return -EFAULT;
 481                         }
 482                         return 0;
 483                 case TCFLSH:
 484                         return tty_perform_flush(linux_tty, arg);
 485                 }
 486         }
 487         return tty_mode_ioctl(linux_tty, file, cmd , arg);
 488 }
 489
 490 static int add_tty(dev_node_t *nodesp, int j,
 491                     struct ipw_hardware *hardware,
 492                     struct ipw_network *network, int channel_idx,
 493                     int secondary_channel_idx, int tty_type)
 494 {
 495         ttys[j] = kzalloc(sizeof(struct ipw_tty), GFP_KERNEL);
 496         if (!ttys[j])
 497                 return -ENOMEM;
 498         ttys[j]->index = j;
 499         ttys[j]->hardware = hardware;
 500         ttys[j]->channel_idx = channel_idx;
 501         ttys[j]->secondary_channel_idx = secondary_channel_idx;
 502         ttys[j]->network = network;
 503         ttys[j]->tty_type = tty_type;
 504         mutex_init(&ttys[j]->ipw_tty_mutex);
 505
 506         tty_register_device(ipw_tty_driver, j, NULL);
 507         ipwireless_associate_network_tty(network, channel_idx, ttys[j]);
 508
 509         if (secondary_channel_idx != -1)
 510                 ipwireless_associate_network_tty(network,
 511                                                  secondary_channel_idx,
 512                                                  ttys[j]);
 513         if (nodesp != NULL) {
 514                 sprintf(nodesp->dev_name, "ttyIPWp%d", j);
 515                 nodesp->major = ipw_tty_driver->major;
 516                 nodesp->minor = j + ipw_tty_driver->minor_start;
 517         }
 518         if (get_tty(j + ipw_tty_driver->minor_start) == ttys[j])
 519                 report_registering(ttys[j]);
 520         return 0;
 521 }
 522
 523 struct ipw_tty *ipwireless_tty_create(struct ipw_hardware *hardware,
 524                                       struct ipw_network *network,
 525                                       dev_node_t *nodes)
 526 {
 527         int i, j;
 528
 529         for (i = 0; i < IPWIRELESS_PCMCIA_MINOR_RANGE; i++) {
 530                 int allfree = 1;
 531
 532                 for (j = i; j < IPWIRELESS_PCMCIA_MINORS;
 533                                 j += IPWIRELESS_PCMCIA_MINOR_RANGE)
 534                         if (ttys[j] != NULL) {
 535                                 allfree = 0;
 536                                 break;
 537                         }
 538
 539                 if (allfree) {
 540                         j = i;
 541
 542                         if (add_tty(&nodes[0], j, hardware, network,
 543                                         IPW_CHANNEL_DIALLER, IPW_CHANNEL_RAS,
 544                                         TTYTYPE_MODEM))
 545                                 return NULL;
 546
 547                         j += IPWIRELESS_PCMCIA_MINOR_RANGE;
 548                         if (add_tty(&nodes[1], j, hardware, network,
 549                                         IPW_CHANNEL_DIALLER, -1,
 550                                         TTYTYPE_MONITOR))
 551                                 return NULL;
 552
 553                         j += IPWIRELESS_PCMCIA_MINOR_RANGE;
 554                         if (add_tty(NULL, j, hardware, network,
 555                                         IPW_CHANNEL_RAS, -1,
 556                                         TTYTYPE_RAS_RAW))
 557                                 return NULL;
 558
 559                         nodes[0].next = &nodes[1];
 560                         nodes[1].next = NULL;
 561
 562                         return ttys[i];
 563                 }
 564         }
 565         return NULL;
 566 }
 567
 568 /*
 569  * Must be called before ipwireless_network_free().
 570  */
 571 void ipwireless_tty_free(struct ipw_tty *tty)
 572 {
 573         int j;
 574         struct ipw_network *network = ttys[tty->index]->network;
 575
 576         for (j = tty->index; j < IPWIRELESS_PCMCIA_MINORS;
 577                         j += IPWIRELESS_PCMCIA_MINOR_RANGE) {
 578                 struct ipw_tty *ttyj = ttys[j];
 579
 580                 if (ttyj) {
 581                         mutex_lock(&ttyj->ipw_tty_mutex);
 582                         if (get_tty(j + ipw_tty_driver->minor_start) == ttyj)
 583                                 report_deregistering(ttyj);
 584                         ttyj->closing = 1;
 585                         if (ttyj->linux_tty != NULL) {
 586                                 mutex_unlock(&ttyj->ipw_tty_mutex);
 587                                 tty_hangup(ttyj->linux_tty);
 588                                 /* Wait till the tty_hangup has completed */
 589                                 flush_scheduled_work();
 590                                 /* FIXME: Exactly how is the tty object locked here
 591                                    against a parallel ioctl etc */
 592                                 mutex_lock(&ttyj->ipw_tty_mutex);
 593                         }
 594                         while (ttyj->open_count)
 595                                 do_ipw_close(ttyj);
 596                         ipwireless_disassociate_network_ttys(network,
 597                                                              ttyj->channel_idx);
 598                         tty_unregister_device(ipw_tty_driver, j);
 599                         ttys[j] = NULL;
 600                         mutex_unlock(&ttyj->ipw_tty_mutex);
 601                         kfree(ttyj);
 602                 }
 603         }
 604 }
 605
 606 static struct tty_operations tty_ops = {
 607         .open = ipw_open,
 608         .close = ipw_close,
 609         .hangup = ipw_hangup,
 610         .write = ipw_write,
 611         .write_room = ipw_write_room,
 612         .ioctl = ipw_ioctl,
 613         .chars_in_buffer = ipw_chars_in_buffer,
 614         .tiocmget = ipw_tiocmget,
 615         .tiocmset = ipw_tiocmset,
 616 };
 617
 618 int ipwireless_tty_init(void)
 619 {
 620         int result;
 621
 622         ipw_tty_driver = alloc_tty_driver(IPWIRELESS_PCMCIA_MINORS);
 623         if (!ipw_tty_driver)
 624                 return -ENOMEM;
 625
 626         ipw_tty_driver->owner = THIS_MODULE;
 627         ipw_tty_driver->driver_name = IPWIRELESS_PCCARD_NAME;
 628         ipw_tty_driver->name = "ttyIPWp";
 629         ipw_tty_driver->major = 0;
 630         ipw_tty_driver->minor_start = IPWIRELESS_PCMCIA_START;
 631         ipw_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
 632         ipw_tty_driver->subtype = SERIAL_TYPE_NORMAL;
 633         ipw_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
 634         ipw_tty_driver->init_termios = tty_std_termios;
 635         ipw_tty_driver->init_termios.c_cflag =
 636             B9600 | CS8 | CREAD | HUPCL | CLOCAL;
 637         ipw_tty_driver->init_termios.c_ispeed = 9600;
 638         ipw_tty_driver->init_termios.c_ospeed = 9600;
 639         tty_set_operations(ipw_tty_driver, &tty_ops);
 640         result = tty_register_driver(ipw_tty_driver);
 641         if (result) {
 642                 printk(KERN_ERR IPWIRELESS_PCCARD_NAME
 643                        ": failed to register tty driver\n");
 644                 put_tty_driver(ipw_tty_driver);
 645                 return result;
 646         }
 647
 648         return 0;
 649 }
 650
 651 void ipwireless_tty_release(void)
 652 {
 653         int ret;
 654
 655         ret = tty_unregister_driver(ipw_tty_driver);
 656         put_tty_driver(ipw_tty_driver);
 657         if (ret != 0)
 658                 printk(KERN_ERR IPWIRELESS_PCCARD_NAME
 659                         ": tty_unregister_driver failed with code %d\n", ret);
 660 }
 661
 662 int ipwireless_tty_is_modem(struct ipw_tty *tty)
 663 {
 664         return tty->tty_type == TTYTYPE_MODEM;
 665 }
 666
 667 void
 668 ipwireless_tty_notify_control_line_change(struct ipw_tty *tty,
 669                                           unsigned int channel_idx,
 670                                           unsigned int control_lines,
 671                                           unsigned int changed_mask)
 672 {
 673         unsigned int old_control_lines = tty->control_lines;
 674
 675         tty->control_lines = (tty->control_lines & ~changed_mask)
 676                 | (control_lines & changed_mask);
 677
 678         /*
 679          * If DCD is de-asserted, we close the tty so pppd can tell that we
 680          * have gone offline.
 681          */
 682         if ((old_control_lines & IPW_CONTROL_LINE_DCD)
 683                         && !(tty->control_lines & IPW_CONTROL_LINE_DCD)
 684                         && tty->linux_tty) {
 685                 tty_hangup(tty->linux_tty);
 686         }
 687 }
 688