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   1 /*
   2  * interface to user space for the gigaset driver
   3  *
   4  * Copyright (c) 2004 by Hansjoerg Lipp <hjlipp@web.de>
   5  *
   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 as
   9  *    published by the Free Software Foundation; either version 2 of
  10  *    the License, or (at your option) any later version.
  11  * =====================================================================
  12  */
  13
  14 #include "gigaset.h"
  15 #include <linux/gigaset_dev.h>
  16 #include <linux/tty.h>
  17 #include <linux/tty_flip.h>
  18
  19 /*** our ioctls ***/
  20
  21 static int if_lock(struct cardstate *cs, int *arg)
  22 {
  23         int cmd = *arg;
  24
  25         gig_dbg(DEBUG_IF, "%u: if_lock (%d)", cs->minor_index, cmd);
  26
  27         if (cmd > 1)
  28                 return -EINVAL;
  29
  30         if (cmd < 0) {
  31                 *arg = cs->mstate == MS_LOCKED;
  32                 return 0;
  33         }
  34
  35         if (!cmd && cs->mstate == MS_LOCKED && cs->connected) {
  36                 cs->ops->set_modem_ctrl(cs, 0, TIOCM_DTR|TIOCM_RTS);
  37                 cs->ops->baud_rate(cs, B115200);
  38                 cs->ops->set_line_ctrl(cs, CS8);
  39                 cs->control_state = TIOCM_DTR|TIOCM_RTS;
  40         }
  41
  42         cs->waiting = 1;
  43         if (!gigaset_add_event(cs, &cs->at_state, EV_IF_LOCK,
  44                                NULL, cmd, NULL)) {
  45                 cs->waiting = 0;
  46                 return -ENOMEM;
  47         }
  48         gigaset_schedule_event(cs);
  49
  50         wait_event(cs->waitqueue, !cs->waiting);
  51
  52         if (cs->cmd_result >= 0) {
  53                 *arg = cs->cmd_result;
  54                 return 0;
  55         }
  56
  57         return cs->cmd_result;
  58 }
  59
  60 static int if_version(struct cardstate *cs, unsigned arg[4])
  61 {
  62         static const unsigned version[4] = GIG_VERSION;
  63         static const unsigned compat[4] = GIG_COMPAT;
  64         unsigned cmd = arg[0];
  65
  66         gig_dbg(DEBUG_IF, "%u: if_version (%d)", cs->minor_index, cmd);
  67
  68         switch (cmd) {
  69         case GIGVER_DRIVER:
  70                 memcpy(arg, version, sizeof version);
  71                 return 0;
  72         case GIGVER_COMPAT:
  73                 memcpy(arg, compat, sizeof compat);
  74                 return 0;
  75         case GIGVER_FWBASE:
  76                 cs->waiting = 1;
  77                 if (!gigaset_add_event(cs, &cs->at_state, EV_IF_VER,
  78                                        NULL, 0, arg)) {
  79                         cs->waiting = 0;
  80                         return -ENOMEM;
  81                 }
  82                 gigaset_schedule_event(cs);
  83
  84                 wait_event(cs->waitqueue, !cs->waiting);
  85
  86                 if (cs->cmd_result >= 0)
  87                         return 0;
  88
  89                 return cs->cmd_result;
  90         default:
  91                 return -EINVAL;
  92         }
  93 }
  94
  95 static int if_config(struct cardstate *cs, int *arg)
  96 {
  97         gig_dbg(DEBUG_IF, "%u: if_config (%d)", cs->minor_index, *arg);
  98
  99         if (*arg != 1)
 100                 return -EINVAL;
 101
 102         if (cs->mstate != MS_LOCKED)
 103                 return -EBUSY;
 104
 105         if (!cs->connected) {
 106                 pr_err("%s: not connected\n", __func__);
 107                 return -ENODEV;
 108         }
 109
 110         *arg = 0;
 111         return gigaset_enterconfigmode(cs);
 112 }
 113
 114 /*** the terminal driver ***/
 115 /* stolen from usbserial and some other tty drivers */
 116
 117 static int  if_open(struct tty_struct *tty, struct file *filp);
 118 static void if_close(struct tty_struct *tty, struct file *filp);
 119 static int  if_ioctl(struct tty_struct *tty, struct file *file,
 120                      unsigned int cmd, unsigned long arg);
 121 static int  if_write_room(struct tty_struct *tty);
 122 static int  if_chars_in_buffer(struct tty_struct *tty);
 123 static void if_throttle(struct tty_struct *tty);
 124 static void if_unthrottle(struct tty_struct *tty);
 125 static void if_set_termios(struct tty_struct *tty, struct ktermios *old);
 126 static int  if_tiocmget(struct tty_struct *tty, struct file *file);
 127 static int  if_tiocmset(struct tty_struct *tty, struct file *file,
 128                         unsigned int set, unsigned int clear);
 129 static int  if_write(struct tty_struct *tty,
 130                      const unsigned char *buf, int count);
 131
 132 static const struct tty_operations if_ops = {
 133         .open =                 if_open,
 134         .close =                if_close,
 135         .ioctl =                if_ioctl,
 136         .write =                if_write,
 137         .write_room =           if_write_room,
 138         .chars_in_buffer =      if_chars_in_buffer,
 139         .set_termios =          if_set_termios,
 140         .throttle =             if_throttle,
 141         .unthrottle =           if_unthrottle,
 142         .tiocmget =             if_tiocmget,
 143         .tiocmset =             if_tiocmset,
 144 };
 145
 146 static int if_open(struct tty_struct *tty, struct file *filp)
 147 {
 148         struct cardstate *cs;
 149         unsigned long flags;
 150
 151         gig_dbg(DEBUG_IF, "%d+%d: %s()",
 152                 tty->driver->minor_start, tty->index, __func__);
 153
 154         tty->driver_data = NULL;
 155
 156         cs = gigaset_get_cs_by_tty(tty);
 157         if (!cs || !try_module_get(cs->driver->owner))
 158                 return -ENODEV;
 159
 160         if (mutex_lock_interruptible(&cs->mutex))
 161                 return -ERESTARTSYS;
 162         tty->driver_data = cs;
 163
 164         ++cs->open_count;
 165
 166         if (cs->open_count == 1) {
 167                 spin_lock_irqsave(&cs->lock, flags);
 168                 cs->tty = tty;
 169                 spin_unlock_irqrestore(&cs->lock, flags);
 170                 tty->low_latency = 1;
 171         }
 172
 173         mutex_unlock(&cs->mutex);
 174         return 0;
 175 }
 176
 177 static void if_close(struct tty_struct *tty, struct file *filp)
 178 {
 179         struct cardstate *cs;
 180         unsigned long flags;
 181
 182         cs = (struct cardstate *) tty->driver_data;
 183         if (!cs) {
 184                 pr_err("%s: no cardstate\n", __func__);
 185                 return;
 186         }
 187
 188         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 189
 190         mutex_lock(&cs->mutex);
 191
 192         if (!cs->connected)
 193                 gig_dbg(DEBUG_IF, "not connected");     /* nothing to do */
 194         else if (!cs->open_count)
 195                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 196         else {
 197                 if (!--cs->open_count) {
 198                         spin_lock_irqsave(&cs->lock, flags);
 199                         cs->tty = NULL;
 200                         spin_unlock_irqrestore(&cs->lock, flags);
 201                 }
 202         }
 203
 204         mutex_unlock(&cs->mutex);
 205
 206         module_put(cs->driver->owner);
 207 }
 208
 209 static int if_ioctl(struct tty_struct *tty, struct file *file,
 210                     unsigned int cmd, unsigned long arg)
 211 {
 212         struct cardstate *cs;
 213         int retval = -ENODEV;
 214         int int_arg;
 215         unsigned char buf[6];
 216         unsigned version[4];
 217
 218         cs = (struct cardstate *) tty->driver_data;
 219         if (!cs) {
 220                 pr_err("%s: no cardstate\n", __func__);
 221                 return -ENODEV;
 222         }
 223
 224         gig_dbg(DEBUG_IF, "%u: %s(0x%x)", cs->minor_index, __func__, cmd);
 225
 226         if (mutex_lock_interruptible(&cs->mutex))
 227                 return -ERESTARTSYS;
 228
 229         if (!cs->connected) {
 230                 gig_dbg(DEBUG_IF, "not connected");
 231                 retval = -ENODEV;
 232         } else if (!cs->open_count)
 233                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 234         else {
 235                 retval = 0;
 236                 switch (cmd) {
 237                 case GIGASET_REDIR:
 238                         retval = get_user(int_arg, (int __user *) arg);
 239                         if (retval >= 0)
 240                                 retval = if_lock(cs, &int_arg);
 241                         if (retval >= 0)
 242                                 retval = put_user(int_arg, (int __user *) arg);
 243                         break;
 244                 case GIGASET_CONFIG:
 245                         retval = get_user(int_arg, (int __user *) arg);
 246                         if (retval >= 0)
 247                                 retval = if_config(cs, &int_arg);
 248                         if (retval >= 0)
 249                                 retval = put_user(int_arg, (int __user *) arg);
 250                         break;
 251                 case GIGASET_BRKCHARS:
 252                         retval = copy_from_user(&buf,
 253                                         (const unsigned char __user *) arg, 6)
 254                                 ? -EFAULT : 0;
 255                         if (retval >= 0) {
 256                                 gigaset_dbg_buffer(DEBUG_IF, "GIGASET_BRKCHARS",
 257                                                 6, (const unsigned char *) arg);
 258                                 retval = cs->ops->brkchars(cs, buf);
 259                         }
 260                         break;
 261                 case GIGASET_VERSION:
 262                         retval = copy_from_user(version,
 263                                         (unsigned __user *) arg, sizeof version)
 264                                 ? -EFAULT : 0;
 265                         if (retval >= 0)
 266                                 retval = if_version(cs, version);
 267                         if (retval >= 0)
 268                                 retval = copy_to_user((unsigned __user *) arg,
 269                                                       version, sizeof version)
 270                                         ? -EFAULT : 0;
 271                         break;
 272                 default:
 273                         gig_dbg(DEBUG_IF, "%s: arg not supported - 0x%04x",
 274                                 __func__, cmd);
 275                         retval = -ENOIOCTLCMD;
 276                 }
 277         }
 278
 279         mutex_unlock(&cs->mutex);
 280
 281         return retval;
 282 }
 283
 284 static int if_tiocmget(struct tty_struct *tty, struct file *file)
 285 {
 286         struct cardstate *cs;
 287         int retval;
 288
 289         cs = (struct cardstate *) tty->driver_data;
 290         if (!cs) {
 291                 pr_err("%s: no cardstate\n", __func__);
 292                 return -ENODEV;
 293         }
 294
 295         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 296
 297         if (mutex_lock_interruptible(&cs->mutex))
 298                 return -ERESTARTSYS;
 299
 300         retval = cs->control_state & (TIOCM_RTS|TIOCM_DTR);
 301
 302         mutex_unlock(&cs->mutex);
 303
 304         return retval;
 305 }
 306
 307 static int if_tiocmset(struct tty_struct *tty, struct file *file,
 308                        unsigned int set, unsigned int clear)
 309 {
 310         struct cardstate *cs;
 311         int retval;
 312         unsigned mc;
 313
 314         cs = (struct cardstate *) tty->driver_data;
 315         if (!cs) {
 316                 pr_err("%s: no cardstate\n", __func__);
 317                 return -ENODEV;
 318         }
 319
 320         gig_dbg(DEBUG_IF, "%u: %s(0x%x, 0x%x)",
 321                 cs->minor_index, __func__, set, clear);
 322
 323         if (mutex_lock_interruptible(&cs->mutex))
 324                 return -ERESTARTSYS;
 325
 326         if (!cs->connected) {
 327                 gig_dbg(DEBUG_IF, "not connected");
 328                 retval = -ENODEV;
 329         } else {
 330                 mc = (cs->control_state | set) & ~clear & (TIOCM_RTS|TIOCM_DTR);
 331                 retval = cs->ops->set_modem_ctrl(cs, cs->control_state, mc);
 332                 cs->control_state = mc;
 333         }
 334
 335         mutex_unlock(&cs->mutex);
 336
 337         return retval;
 338 }
 339
 340 static int if_write(struct tty_struct *tty, const unsigned char *buf, int count)
 341 {
 342         struct cardstate *cs;
 343         int retval = -ENODEV;
 344
 345         cs = (struct cardstate *) tty->driver_data;
 346         if (!cs) {
 347                 pr_err("%s: no cardstate\n", __func__);
 348                 return -ENODEV;
 349         }
 350
 351         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 352
 353         if (mutex_lock_interruptible(&cs->mutex))
 354                 return -ERESTARTSYS;
 355
 356         if (!cs->connected) {
 357                 gig_dbg(DEBUG_IF, "not connected");
 358                 retval = -ENODEV;
 359         } else if (!cs->open_count)
 360                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 361         else if (cs->mstate != MS_LOCKED) {
 362                 dev_warn(cs->dev, "can't write to unlocked device\n");
 363                 retval = -EBUSY;
 364         } else {
 365                 retval = cs->ops->write_cmd(cs, buf, count,
 366                                             &cs->if_wake_tasklet);
 367         }
 368
 369         mutex_unlock(&cs->mutex);
 370
 371         return retval;
 372 }
 373
 374 static int if_write_room(struct tty_struct *tty)
 375 {
 376         struct cardstate *cs;
 377         int retval = -ENODEV;
 378
 379         cs = (struct cardstate *) tty->driver_data;
 380         if (!cs) {
 381                 pr_err("%s: no cardstate\n", __func__);
 382                 return -ENODEV;
 383         }
 384
 385         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 386
 387         if (mutex_lock_interruptible(&cs->mutex))
 388                 return -ERESTARTSYS;
 389
 390         if (!cs->connected) {
 391                 gig_dbg(DEBUG_IF, "not connected");
 392                 retval = -ENODEV;
 393         } else if (!cs->open_count)
 394                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 395         else if (cs->mstate != MS_LOCKED) {
 396                 dev_warn(cs->dev, "can't write to unlocked device\n");
 397                 retval = -EBUSY;
 398         } else
 399                 retval = cs->ops->write_room(cs);
 400
 401         mutex_unlock(&cs->mutex);
 402
 403         return retval;
 404 }
 405
 406 static int if_chars_in_buffer(struct tty_struct *tty)
 407 {
 408         struct cardstate *cs;
 409         int retval = 0;
 410
 411         cs = (struct cardstate *) tty->driver_data;
 412         if (!cs) {
 413                 pr_err("%s: no cardstate\n", __func__);
 414                 return 0;
 415         }
 416
 417         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 418
 419         mutex_lock(&cs->mutex);
 420
 421         if (!cs->connected)
 422                 gig_dbg(DEBUG_IF, "not connected");
 423         else if (!cs->open_count)
 424                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 425         else if (cs->mstate != MS_LOCKED)
 426                 dev_warn(cs->dev, "can't write to unlocked device\n");
 427         else
 428                 retval = cs->ops->chars_in_buffer(cs);
 429
 430         mutex_unlock(&cs->mutex);
 431
 432         return retval;
 433 }
 434
 435 static void if_throttle(struct tty_struct *tty)
 436 {
 437         struct cardstate *cs;
 438
 439         cs = (struct cardstate *) tty->driver_data;
 440         if (!cs) {
 441                 pr_err("%s: no cardstate\n", __func__);
 442                 return;
 443         }
 444
 445         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 446
 447         mutex_lock(&cs->mutex);
 448
 449         if (!cs->connected)
 450                 gig_dbg(DEBUG_IF, "not connected");     /* nothing to do */
 451         else if (!cs->open_count)
 452                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 453         else
 454                 gig_dbg(DEBUG_IF, "%s: not implemented\n", __func__);
 455
 456         mutex_unlock(&cs->mutex);
 457 }
 458
 459 static void if_unthrottle(struct tty_struct *tty)
 460 {
 461         struct cardstate *cs;
 462
 463         cs = (struct cardstate *) tty->driver_data;
 464         if (!cs) {
 465                 pr_err("%s: no cardstate\n", __func__);
 466                 return;
 467         }
 468
 469         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 470
 471         mutex_lock(&cs->mutex);
 472
 473         if (!cs->connected)
 474                 gig_dbg(DEBUG_IF, "not connected");     /* nothing to do */
 475         else if (!cs->open_count)
 476                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 477         else
 478                 gig_dbg(DEBUG_IF, "%s: not implemented\n", __func__);
 479
 480         mutex_unlock(&cs->mutex);
 481 }
 482
 483 static void if_set_termios(struct tty_struct *tty, struct ktermios *old)
 484 {
 485         struct cardstate *cs;
 486         unsigned int iflag;
 487         unsigned int cflag;
 488         unsigned int old_cflag;
 489         unsigned int control_state, new_state;
 490
 491         cs = (struct cardstate *) tty->driver_data;
 492         if (!cs) {
 493                 pr_err("%s: no cardstate\n", __func__);
 494                 return;
 495         }
 496
 497         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 498
 499         mutex_lock(&cs->mutex);
 500
 501         if (!cs->connected) {
 502                 gig_dbg(DEBUG_IF, "not connected");
 503                 goto out;
 504         }
 505
 506         if (!cs->open_count) {
 507                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 508                 goto out;
 509         }
 510
 511         iflag = tty->termios->c_iflag;
 512         cflag = tty->termios->c_cflag;
 513         old_cflag = old ? old->c_cflag : cflag;
 514         gig_dbg(DEBUG_IF, "%u: iflag %x cflag %x old %x",
 515                 cs->minor_index, iflag, cflag, old_cflag);
 516
 517         /* get a local copy of the current port settings */
 518         control_state = cs->control_state;
 519
 520         /*
 521          * Update baud rate.
 522          * Do not attempt to cache old rates and skip settings,
 523          * disconnects screw such tricks up completely.
 524          * Premature optimization is the root of all evil.
 525          */
 526
 527         /* reassert DTR and (maybe) RTS on transition from B0 */
 528         if ((old_cflag & CBAUD) == B0) {
 529                 new_state = control_state | TIOCM_DTR;
 530                 /* don't set RTS if using hardware flow control */
 531                 if (!(old_cflag & CRTSCTS))
 532                         new_state |= TIOCM_RTS;
 533                 gig_dbg(DEBUG_IF, "%u: from B0 - set DTR%s",
 534                         cs->minor_index,
 535                         (new_state & TIOCM_RTS) ? " only" : "/RTS");
 536                 cs->ops->set_modem_ctrl(cs, control_state, new_state);
 537                 control_state = new_state;
 538         }
 539
 540         cs->ops->baud_rate(cs, cflag & CBAUD);
 541
 542         if ((cflag & CBAUD) == B0) {
 543                 /* Drop RTS and DTR */
 544                 gig_dbg(DEBUG_IF, "%u: to B0 - drop DTR/RTS", cs->minor_index);
 545                 new_state = control_state & ~(TIOCM_DTR | TIOCM_RTS);
 546                 cs->ops->set_modem_ctrl(cs, control_state, new_state);
 547                 control_state = new_state;
 548         }
 549
 550         /*
 551          * Update line control register (LCR)
 552          */
 553
 554         cs->ops->set_line_ctrl(cs, cflag);
 555
 556         /* save off the modified port settings */
 557         cs->control_state = control_state;
 558
 559 out:
 560         mutex_unlock(&cs->mutex);
 561 }
 562
 563
 564 /* wakeup tasklet for the write operation */
 565 static void if_wake(unsigned long data)
 566 {
 567         struct cardstate *cs = (struct cardstate *) data;
 568
 569         if (cs->tty)
 570                 tty_wakeup(cs->tty);
 571 }
 572
 573 /*** interface to common ***/
 574
 575 void gigaset_if_init(struct cardstate *cs)
 576 {
 577         struct gigaset_driver *drv;
 578
 579         drv = cs->driver;
 580         if (!drv->have_tty)
 581                 return;
 582
 583         tasklet_init(&cs->if_wake_tasklet, if_wake, (unsigned long) cs);
 584
 585         mutex_lock(&cs->mutex);
 586         cs->tty_dev = tty_register_device(drv->tty, cs->minor_index, NULL);
 587
 588         if (!IS_ERR(cs->tty_dev))
 589                 dev_set_drvdata(cs->tty_dev, cs);
 590         else {
 591                 pr_warning("could not register device to the tty subsystem\n");
 592                 cs->tty_dev = NULL;
 593         }
 594         mutex_unlock(&cs->mutex);
 595 }
 596
 597 void gigaset_if_free(struct cardstate *cs)
 598 {
 599         struct gigaset_driver *drv;
 600
 601         drv = cs->driver;
 602         if (!drv->have_tty)
 603                 return;
 604
 605         tasklet_disable(&cs->if_wake_tasklet);
 606         tasklet_kill(&cs->if_wake_tasklet);
 607         cs->tty_dev = NULL;
 608         tty_unregister_device(drv->tty, cs->minor_index);
 609 }
 610
 611 /**
 612  * gigaset_if_receive() - pass a received block of data to the tty device
 613  * @cs:         device descriptor structure.
 614  * @buffer:     received data.
 615  * @len:        number of bytes received.
 616  *
 617  * Called by asyncdata/isocdata if a block of data received from the
 618  * device must be sent to userspace through the ttyG* device.
 619  */
 620 void gigaset_if_receive(struct cardstate *cs,
 621                         unsigned char *buffer, size_t len)
 622 {
 623         unsigned long flags;
 624         struct tty_struct *tty;
 625
 626         spin_lock_irqsave(&cs->lock, flags);
 627         tty = cs->tty;
 628         if (tty == NULL)
 629                 gig_dbg(DEBUG_IF, "receive on closed device");
 630         else {
 631                 tty_insert_flip_string(tty, buffer, len);
 632                 tty_flip_buffer_push(tty);
 633         }
 634         spin_unlock_irqrestore(&cs->lock, flags);
 635 }
 636 EXPORT_SYMBOL_GPL(gigaset_if_receive);
 637
 638 /* gigaset_if_initdriver
 639  * Initialize tty interface.
 640  * parameters:
 641  *      drv             Driver
 642  *      procname        Name of the driver (e.g. for /proc/tty/drivers)
 643  *      devname         Name of the device files (prefix without minor number)
 644  */
 645 void gigaset_if_initdriver(struct gigaset_driver *drv, const char *procname,
 646                            const char *devname)
 647 {
 648         unsigned minors = drv->minors;
 649         int ret;
 650         struct tty_driver *tty;
 651
 652         drv->have_tty = 0;
 653
 654         drv->tty = tty = alloc_tty_driver(minors);
 655         if (tty == NULL)
 656                 goto enomem;
 657
 658         tty->magic =            TTY_DRIVER_MAGIC,
 659         tty->major =            GIG_MAJOR,
 660         tty->type =             TTY_DRIVER_TYPE_SERIAL,
 661         tty->subtype =          SERIAL_TYPE_NORMAL,
 662         tty->flags =            TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
 663
 664         tty->driver_name =      procname;
 665         tty->name =             devname;
 666         tty->minor_start =      drv->minor;
 667         tty->num =              drv->minors;
 668
 669         tty->owner =            THIS_MODULE;
 670
 671         tty->init_termios          = tty_std_termios;
 672         tty->init_termios.c_cflag  = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
 673         tty_set_operations(tty, &if_ops);
 674
 675         ret = tty_register_driver(tty);
 676         if (ret < 0) {
 677                 pr_err("error %d registering tty driver\n", ret);
 678                 goto error;
 679         }
 680         gig_dbg(DEBUG_IF, "tty driver initialized");
 681         drv->have_tty = 1;
 682         return;
 683
 684 enomem:
 685         pr_err("out of memory\n");
 686 error:
 687         if (drv->tty)
 688                 put_tty_driver(drv->tty);
 689 }
 690
 691 void gigaset_if_freedriver(struct gigaset_driver *drv)
 692 {
 693         if (!drv->have_tty)
 694                 return;
 695
 696         drv->have_tty = 0;
 697         tty_unregister_driver(drv->tty);
 698         put_tty_driver(drv->tty);
 699 }