drivers/isdn/gigaset/interface.c

   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
  49         gig_dbg(DEBUG_CMD, "scheduling IF_LOCK");
  50         gigaset_schedule_event(cs);
  51
  52         wait_event(cs->waitqueue, !cs->waiting);
  53
  54         if (cs->cmd_result >= 0) {
  55                 *arg = cs->cmd_result;
  56                 return 0;
  57         }
  58
  59         return cs->cmd_result;
  60 }
  61
  62 static int if_version(struct cardstate *cs, unsigned arg[4])
  63 {
  64         static const unsigned version[4] = GIG_VERSION;
  65         static const unsigned compat[4] = GIG_COMPAT;
  66         unsigned cmd = arg[0];
  67
  68         gig_dbg(DEBUG_IF, "%u: if_version (%d)", cs->minor_index, cmd);
  69
  70         switch (cmd) {
  71         case GIGVER_DRIVER:
  72                 memcpy(arg, version, sizeof version);
  73                 return 0;
  74         case GIGVER_COMPAT:
  75                 memcpy(arg, compat, sizeof compat);
  76                 return 0;
  77         case GIGVER_FWBASE:
  78                 cs->waiting = 1;
  79                 if (!gigaset_add_event(cs, &cs->at_state, EV_IF_VER,
  80                                        NULL, 0, arg)) {
  81                         cs->waiting = 0;
  82                         return -ENOMEM;
  83                 }
  84
  85                 gig_dbg(DEBUG_CMD, "scheduling IF_VER");
  86                 gigaset_schedule_event(cs);
  87
  88                 wait_event(cs->waitqueue, !cs->waiting);
  89
  90                 if (cs->cmd_result >= 0)
  91                         return 0;
  92
  93                 return cs->cmd_result;
  94         default:
  95                 return -EINVAL;
  96         }
  97 }
  98
  99 static int if_config(struct cardstate *cs, int *arg)
 100 {
 101         gig_dbg(DEBUG_IF, "%u: if_config (%d)", cs->minor_index, *arg);
 102
 103         if (*arg != 1)
 104                 return -EINVAL;
 105
 106         if (cs->mstate != MS_LOCKED)
 107                 return -EBUSY;
 108
 109         if (!cs->connected) {
 110                 pr_err("%s: not connected\n", __func__);
 111                 return -ENODEV;
 112         }
 113
 114         *arg = 0;
 115         return gigaset_enterconfigmode(cs);
 116 }
 117
 118 /*** the terminal driver ***/
 119 /* stolen from usbserial and some other tty drivers */
 120
 121 static int  if_open(struct tty_struct *tty, struct file *filp);
 122 static void if_close(struct tty_struct *tty, struct file *filp);
 123 static int  if_ioctl(struct tty_struct *tty, struct file *file,
 124                      unsigned int cmd, unsigned long arg);
 125 static int  if_write_room(struct tty_struct *tty);
 126 static int  if_chars_in_buffer(struct tty_struct *tty);
 127 static void if_throttle(struct tty_struct *tty);
 128 static void if_unthrottle(struct tty_struct *tty);
 129 static void if_set_termios(struct tty_struct *tty, struct ktermios *old);
 130 static int  if_tiocmget(struct tty_struct *tty, struct file *file);
 131 static int  if_tiocmset(struct tty_struct *tty, struct file *file,
 132                         unsigned int set, unsigned int clear);
 133 static int  if_write(struct tty_struct *tty,
 134                      const unsigned char *buf, int count);
 135
 136 static const struct tty_operations if_ops = {
 137         .open =                 if_open,
 138         .close =                if_close,
 139         .ioctl =                if_ioctl,
 140         .write =                if_write,
 141         .write_room =           if_write_room,
 142         .chars_in_buffer =      if_chars_in_buffer,
 143         .set_termios =          if_set_termios,
 144         .throttle =             if_throttle,
 145         .unthrottle =           if_unthrottle,
 146         .tiocmget =             if_tiocmget,
 147         .tiocmset =             if_tiocmset,
 148 };
 149
 150 static int if_open(struct tty_struct *tty, struct file *filp)
 151 {
 152         struct cardstate *cs;
 153         unsigned long flags;
 154
 155         gig_dbg(DEBUG_IF, "%d+%d: %s()",
 156                 tty->driver->minor_start, tty->index, __func__);
 157
 158         tty->driver_data = NULL;
 159
 160         cs = gigaset_get_cs_by_tty(tty);
 161         if (!cs || !try_module_get(cs->driver->owner))
 162                 return -ENODEV;
 163
 164         if (mutex_lock_interruptible(&cs->mutex))
 165                 return -ERESTARTSYS; // FIXME -EINTR?
 166         tty->driver_data = cs;
 167
 168         ++cs->open_count;
 169
 170         if (cs->open_count == 1) {
 171                 spin_lock_irqsave(&cs->lock, flags);
 172                 cs->tty = tty;
 173                 spin_unlock_irqrestore(&cs->lock, flags);
 174                 tty->low_latency = 1; //FIXME test
 175         }
 176
 177         mutex_unlock(&cs->mutex);
 178         return 0;
 179 }
 180
 181 static void if_close(struct tty_struct *tty, struct file *filp)
 182 {
 183         struct cardstate *cs;
 184         unsigned long flags;
 185
 186         cs = (struct cardstate *) tty->driver_data;
 187         if (!cs) {
 188                 pr_err("%s: no cardstate\n", __func__);
 189                 return;
 190         }
 191
 192         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 193
 194         mutex_lock(&cs->mutex);
 195
 196         if (!cs->connected)
 197                 gig_dbg(DEBUG_IF, "not connected");     /* nothing to do */
 198         else if (!cs->open_count)
 199                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 200         else {
 201                 if (!--cs->open_count) {
 202                         spin_lock_irqsave(&cs->lock, flags);
 203                         cs->tty = NULL;
 204                         spin_unlock_irqrestore(&cs->lock, flags);
 205                 }
 206         }
 207
 208         mutex_unlock(&cs->mutex);
 209
 210         module_put(cs->driver->owner);
 211 }
 212
 213 static int if_ioctl(struct tty_struct *tty, struct file *file,
 214                     unsigned int cmd, unsigned long arg)
 215 {
 216         struct cardstate *cs;
 217         int retval = -ENODEV;
 218         int int_arg;
 219         unsigned char buf[6];
 220         unsigned version[4];
 221
 222         cs = (struct cardstate *) tty->driver_data;
 223         if (!cs) {
 224                 pr_err("%s: no cardstate\n", __func__);
 225                 return -ENODEV;
 226         }
 227
 228         gig_dbg(DEBUG_IF, "%u: %s(0x%x)", cs->minor_index, __func__, cmd);
 229
 230         if (mutex_lock_interruptible(&cs->mutex))
 231                 return -ERESTARTSYS; // FIXME -EINTR?
 232
 233         if (!cs->connected) {
 234                 gig_dbg(DEBUG_IF, "not connected");
 235                 retval = -ENODEV;
 236         } else if (!cs->open_count)
 237                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 238         else {
 239                 retval = 0;
 240                 switch (cmd) {
 241                 case GIGASET_REDIR:
 242                         retval = get_user(int_arg, (int __user *) arg);
 243                         if (retval >= 0)
 244                                 retval = if_lock(cs, &int_arg);
 245                         if (retval >= 0)
 246                                 retval = put_user(int_arg, (int __user *) arg);
 247                         break;
 248                 case GIGASET_CONFIG:
 249                         retval = get_user(int_arg, (int __user *) arg);
 250                         if (retval >= 0)
 251                                 retval = if_config(cs, &int_arg);
 252                         if (retval >= 0)
 253                                 retval = put_user(int_arg, (int __user *) arg);
 254                         break;
 255                 case GIGASET_BRKCHARS:
 256                         retval = copy_from_user(&buf,
 257                                         (const unsigned char __user *) arg, 6)
 258                                 ? -EFAULT : 0;
 259                         if (retval >= 0) {
 260                                 gigaset_dbg_buffer(DEBUG_IF, "GIGASET_BRKCHARS",
 261                                                 6, (const unsigned char *) arg);
 262                                 retval = cs->ops->brkchars(cs, buf);
 263                         }
 264                         break;
 265                 case GIGASET_VERSION:
 266                         retval = copy_from_user(version,
 267                                         (unsigned __user *) arg, sizeof version)
 268                                 ? -EFAULT : 0;
 269                         if (retval >= 0)
 270                                 retval = if_version(cs, version);
 271                         if (retval >= 0)
 272                                 retval = copy_to_user((unsigned __user *) arg,
 273                                                       version, sizeof version)
 274                                         ? -EFAULT : 0;
 275                         break;
 276                 default:
 277                         gig_dbg(DEBUG_ANY, "%s: arg not supported - 0x%04x",
 278                                 __func__, cmd);
 279                         retval = -ENOIOCTLCMD;
 280                 }
 281         }
 282
 283         mutex_unlock(&cs->mutex);
 284
 285         return retval;
 286 }
 287
 288 static int if_tiocmget(struct tty_struct *tty, struct file *file)
 289 {
 290         struct cardstate *cs;
 291         int retval;
 292
 293         cs = (struct cardstate *) tty->driver_data;
 294         if (!cs) {
 295                 pr_err("%s: no cardstate\n", __func__);
 296                 return -ENODEV;
 297         }
 298
 299         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 300
 301         if (mutex_lock_interruptible(&cs->mutex))
 302                 return -ERESTARTSYS; // FIXME -EINTR?
 303
 304         // FIXME read from device?
 305         retval = cs->control_state & (TIOCM_RTS|TIOCM_DTR);
 306
 307         mutex_unlock(&cs->mutex);
 308
 309         return retval;
 310 }
 311
 312 static int if_tiocmset(struct tty_struct *tty, struct file *file,
 313                        unsigned int set, unsigned int clear)
 314 {
 315         struct cardstate *cs;
 316         int retval;
 317         unsigned mc;
 318
 319         cs = (struct cardstate *) tty->driver_data;
 320         if (!cs) {
 321                 pr_err("%s: no cardstate\n", __func__);
 322                 return -ENODEV;
 323         }
 324
 325         gig_dbg(DEBUG_IF, "%u: %s(0x%x, 0x%x)",
 326                 cs->minor_index, __func__, set, clear);
 327
 328         if (mutex_lock_interruptible(&cs->mutex))
 329                 return -ERESTARTSYS; // FIXME -EINTR?
 330
 331         if (!cs->connected) {
 332                 gig_dbg(DEBUG_IF, "not connected");
 333                 retval = -ENODEV;
 334         } else {
 335                 mc = (cs->control_state | set) & ~clear & (TIOCM_RTS|TIOCM_DTR);
 336                 retval = cs->ops->set_modem_ctrl(cs, cs->control_state, mc);
 337                 cs->control_state = mc;
 338         }
 339
 340         mutex_unlock(&cs->mutex);
 341
 342         return retval;
 343 }
 344
 345 static int if_write(struct tty_struct *tty, const unsigned char *buf, int count)
 346 {
 347         struct cardstate *cs;
 348         int retval = -ENODEV;
 349
 350         cs = (struct cardstate *) tty->driver_data;
 351         if (!cs) {
 352                 pr_err("%s: no cardstate\n", __func__);
 353                 return -ENODEV;
 354         }
 355
 356         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 357
 358         if (mutex_lock_interruptible(&cs->mutex))
 359                 return -ERESTARTSYS; // FIXME -EINTR?
 360
 361         if (!cs->connected) {
 362                 gig_dbg(DEBUG_IF, "not connected");
 363                 retval = -ENODEV;
 364         } else if (!cs->open_count)
 365                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 366         else if (cs->mstate != MS_LOCKED) {
 367                 dev_warn(cs->dev, "can't write to unlocked device\n");
 368                 retval = -EBUSY;
 369         } else {
 370                 retval = cs->ops->write_cmd(cs, buf, count,
 371                                             &cs->if_wake_tasklet);
 372         }
 373
 374         mutex_unlock(&cs->mutex);
 375
 376         return retval;
 377 }
 378
 379 static int if_write_room(struct tty_struct *tty)
 380 {
 381         struct cardstate *cs;
 382         int retval = -ENODEV;
 383
 384         cs = (struct cardstate *) tty->driver_data;
 385         if (!cs) {
 386                 pr_err("%s: no cardstate\n", __func__);
 387                 return -ENODEV;
 388         }
 389
 390         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 391
 392         if (mutex_lock_interruptible(&cs->mutex))
 393                 return -ERESTARTSYS; // FIXME -EINTR?
 394
 395         if (!cs->connected) {
 396                 gig_dbg(DEBUG_IF, "not connected");
 397                 retval = -ENODEV;
 398         } else if (!cs->open_count)
 399                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 400         else if (cs->mstate != MS_LOCKED) {
 401                 dev_warn(cs->dev, "can't write to unlocked device\n");
 402                 retval = -EBUSY;
 403         } else
 404                 retval = cs->ops->write_room(cs);
 405
 406         mutex_unlock(&cs->mutex);
 407
 408         return retval;
 409 }
 410
 411 static int if_chars_in_buffer(struct tty_struct *tty)
 412 {
 413         struct cardstate *cs;
 414         int retval = 0;
 415
 416         cs = (struct cardstate *) tty->driver_data;
 417         if (!cs) {
 418                 pr_err("%s: no cardstate\n", __func__);
 419                 return 0;
 420         }
 421
 422         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 423
 424         mutex_lock(&cs->mutex);
 425
 426         if (!cs->connected)
 427                 gig_dbg(DEBUG_IF, "not connected");
 428         else if (!cs->open_count)
 429                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 430         else if (cs->mstate != MS_LOCKED)
 431                 dev_warn(cs->dev, "can't write to unlocked device\n");
 432         else
 433                 retval = cs->ops->chars_in_buffer(cs);
 434
 435         mutex_unlock(&cs->mutex);
 436
 437         return retval;
 438 }
 439
 440 static void if_throttle(struct tty_struct *tty)
 441 {
 442         struct cardstate *cs;
 443
 444         cs = (struct cardstate *) tty->driver_data;
 445         if (!cs) {
 446                 pr_err("%s: no cardstate\n", __func__);
 447                 return;
 448         }
 449
 450         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 451
 452         mutex_lock(&cs->mutex);
 453
 454         if (!cs->connected)
 455                 gig_dbg(DEBUG_IF, "not connected");     /* nothing to do */
 456         else if (!cs->open_count)
 457                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 458         else {
 459                 //FIXME
 460         }
 461
 462         mutex_unlock(&cs->mutex);
 463 }
 464
 465 static void if_unthrottle(struct tty_struct *tty)
 466 {
 467         struct cardstate *cs;
 468
 469         cs = (struct cardstate *) tty->driver_data;
 470         if (!cs) {
 471                 pr_err("%s: no cardstate\n", __func__);
 472                 return;
 473         }
 474
 475         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 476
 477         mutex_lock(&cs->mutex);
 478
 479         if (!cs->connected)
 480                 gig_dbg(DEBUG_IF, "not connected");     /* nothing to do */
 481         else if (!cs->open_count)
 482                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 483         else {
 484                 //FIXME
 485         }
 486
 487         mutex_unlock(&cs->mutex);
 488 }
 489
 490 static void if_set_termios(struct tty_struct *tty, struct ktermios *old)
 491 {
 492         struct cardstate *cs;
 493         unsigned int iflag;
 494         unsigned int cflag;
 495         unsigned int old_cflag;
 496         unsigned int control_state, new_state;
 497
 498         cs = (struct cardstate *) tty->driver_data;
 499         if (!cs) {
 500                 pr_err("%s: no cardstate\n", __func__);
 501                 return;
 502         }
 503
 504         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 505
 506         mutex_lock(&cs->mutex);
 507
 508         if (!cs->connected) {
 509                 gig_dbg(DEBUG_IF, "not connected");
 510                 goto out;
 511         }
 512
 513         if (!cs->open_count) {
 514                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 515                 goto out;
 516         }
 517
 518         // stolen from mct_u232.c
 519         iflag = tty->termios->c_iflag;
 520         cflag = tty->termios->c_cflag;
 521         old_cflag = old ? old->c_cflag : cflag; //FIXME?
 522         gig_dbg(DEBUG_IF, "%u: iflag %x cflag %x old %x",
 523                 cs->minor_index, iflag, cflag, old_cflag);
 524
 525         /* get a local copy of the current port settings */
 526         control_state = cs->control_state;
 527
 528         /*
 529          * Update baud rate.
 530          * Do not attempt to cache old rates and skip settings,
 531          * disconnects screw such tricks up completely.
 532          * Premature optimization is the root of all evil.
 533          */
 534
 535         /* reassert DTR and (maybe) RTS on transition from B0 */
 536         if ((old_cflag & CBAUD) == B0) {
 537                 new_state = control_state | TIOCM_DTR;
 538                 /* don't set RTS if using hardware flow control */
 539                 if (!(old_cflag & CRTSCTS))
 540                         new_state |= TIOCM_RTS;
 541                 gig_dbg(DEBUG_IF, "%u: from B0 - set DTR%s",
 542                         cs->minor_index,
 543                         (new_state & TIOCM_RTS) ? " only" : "/RTS");
 544                 cs->ops->set_modem_ctrl(cs, control_state, new_state);
 545                 control_state = new_state;
 546         }
 547
 548         cs->ops->baud_rate(cs, cflag & CBAUD);
 549
 550         if ((cflag & CBAUD) == B0) {
 551                 /* Drop RTS and DTR */
 552                 gig_dbg(DEBUG_IF, "%u: to B0 - drop DTR/RTS", cs->minor_index);
 553                 new_state = control_state & ~(TIOCM_DTR | TIOCM_RTS);
 554                 cs->ops->set_modem_ctrl(cs, control_state, new_state);
 555                 control_state = new_state;
 556         }
 557
 558         /*
 559          * Update line control register (LCR)
 560          */
 561
 562         cs->ops->set_line_ctrl(cs, cflag);
 563
 564         /* save off the modified port settings */
 565         cs->control_state = control_state;
 566
 567 out:
 568         mutex_unlock(&cs->mutex);
 569 }
 570
 571
 572 /* wakeup tasklet for the write operation */
 573 static void if_wake(unsigned long data)
 574 {
 575         struct cardstate *cs = (struct cardstate *) data;
 576
 577         if (cs->tty)
 578                 tty_wakeup(cs->tty);
 579 }
 580
 581 /*** interface to common ***/
 582
 583 void gigaset_if_init(struct cardstate *cs)
 584 {
 585         struct gigaset_driver *drv;
 586
 587         drv = cs->driver;
 588         if (!drv->have_tty)
 589                 return;
 590
 591         tasklet_init(&cs->if_wake_tasklet, &if_wake, (unsigned long) cs);
 592
 593         mutex_lock(&cs->mutex);
 594         cs->tty_dev = tty_register_device(drv->tty, cs->minor_index, NULL);
 595
 596         if (!IS_ERR(cs->tty_dev))
 597                 dev_set_drvdata(cs->tty_dev, cs);
 598         else {
 599                 pr_warning("could not register device to the tty subsystem\n");
 600                 cs->tty_dev = NULL;
 601         }
 602         mutex_unlock(&cs->mutex);
 603 }
 604
 605 void gigaset_if_free(struct cardstate *cs)
 606 {
 607         struct gigaset_driver *drv;
 608
 609         drv = cs->driver;
 610         if (!drv->have_tty)
 611                 return;
 612
 613         tasklet_disable(&cs->if_wake_tasklet);
 614         tasklet_kill(&cs->if_wake_tasklet);
 615         cs->tty_dev = NULL;
 616         tty_unregister_device(drv->tty, cs->minor_index);
 617 }
 618
 619 void gigaset_if_receive(struct cardstate *cs,
 620                         unsigned char *buffer, size_t len)
 621 {
 622         unsigned long flags;
 623         struct tty_struct *tty;
 624
 625         spin_lock_irqsave(&cs->lock, flags);
 626         if ((tty = cs->tty) == NULL)
 627                 gig_dbg(DEBUG_ANY, "receive on closed device");
 628         else {
 629                 tty_buffer_request_room(tty, len);
 630                 tty_insert_flip_string(tty, buffer, len);
 631                 tty_flip_buffer_push(tty);
 632         }
 633         spin_unlock_irqrestore(&cs->lock, flags);
 634 }
 635 EXPORT_SYMBOL_GPL(gigaset_if_receive);
 636
 637 /* gigaset_if_initdriver
 638  * Initialize tty interface.
 639  * parameters:
 640  *      drv             Driver
 641  *      procname        Name of the driver (e.g. for /proc/tty/drivers)
 642  *      devname         Name of the device files (prefix without minor number)
 643  */
 644 void gigaset_if_initdriver(struct gigaset_driver *drv, const char *procname,
 645                            const char *devname)
 646 {
 647         unsigned minors = drv->minors;
 648         int ret;
 649         struct tty_driver *tty;
 650
 651         drv->have_tty = 0;
 652
 653         if ((drv->tty = alloc_tty_driver(minors)) == NULL)
 654                 goto enomem;
 655         tty = drv->tty;
 656
 657         tty->magic =            TTY_DRIVER_MAGIC,
 658         tty->major =            GIG_MAJOR,
 659         tty->type =             TTY_DRIVER_TYPE_SERIAL,
 660         tty->subtype =          SERIAL_TYPE_NORMAL,
 661         tty->flags =            TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
 662
 663         tty->driver_name =      procname;
 664         tty->name =             devname;
 665         tty->minor_start =      drv->minor;
 666         tty->num =              drv->minors;
 667
 668         tty->owner =            THIS_MODULE;
 669
 670         tty->init_termios          = tty_std_termios; //FIXME
 671         tty->init_termios.c_cflag  = B9600 | CS8 | CREAD | HUPCL | CLOCAL; //FIXME
 672         tty_set_operations(tty, &if_ops);
 673
 674         ret = tty_register_driver(tty);
 675         if (ret < 0) {
 676                 pr_err("error %d registering tty driver\n", ret);
 677                 goto error;
 678         }
 679         gig_dbg(DEBUG_IF, "tty driver initialized");
 680         drv->have_tty = 1;
 681         return;
 682
 683 enomem:
 684         pr_err("out of memory\n");
 685 error:
 686         if (drv->tty)
 687                 put_tty_driver(drv->tty);
 688 }
 689
 690 void gigaset_if_freedriver(struct gigaset_driver *drv)
 691 {
 692         if (!drv->have_tty)
 693                 return;
 694
 695         drv->have_tty = 0;
 696         tty_unregister_driver(drv->tty);
 697         put_tty_driver(drv->tty);
 698 }