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