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->open_count)
 197                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 198         else {
 199                 if (!--cs->open_count) {
 200                         spin_lock_irqsave(&cs->lock, flags);
 201                         cs->tty = NULL;
 202                         spin_unlock_irqrestore(&cs->lock, flags);
 203                 }
 204         }
 205
 206         mutex_unlock(&cs->mutex);
 207
 208         module_put(cs->driver->owner);
 209 }
 210
 211 static int if_ioctl(struct tty_struct *tty, struct file *file,
 212                     unsigned int cmd, unsigned long arg)
 213 {
 214         struct cardstate *cs;
 215         int retval = -ENODEV;
 216         int int_arg;
 217         unsigned char buf[6];
 218         unsigned version[4];
 219
 220         cs = (struct cardstate *) tty->driver_data;
 221         if (!cs) {
 222                 pr_err("%s: no cardstate\n", __func__);
 223                 return -ENODEV;
 224         }
 225
 226         gig_dbg(DEBUG_IF, "%u: %s(0x%x)", cs->minor_index, __func__, cmd);
 227
 228         if (mutex_lock_interruptible(&cs->mutex))
 229                 return -ERESTARTSYS; // FIXME -EINTR?
 230
 231         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                         //FIXME test if MS_LOCKED
 252                         if (!cs->connected) {
 253                                 gig_dbg(DEBUG_ANY,
 254                                     "can't communicate with unplugged device");
 255                                 retval = -ENODEV;
 256                                 break;
 257                         }
 258                         retval = copy_from_user(&buf,
 259                                         (const unsigned char __user *) arg, 6)
 260                                 ? -EFAULT : 0;
 261                         if (retval >= 0) {
 262                                 gigaset_dbg_buffer(DEBUG_IF, "GIGASET_BRKCHARS",
 263                                                 6, (const unsigned char *) arg);
 264                                 retval = cs->ops->brkchars(cs, buf);
 265                         }
 266                         break;
 267                 case GIGASET_VERSION:
 268                         retval = copy_from_user(version,
 269                                         (unsigned __user *) arg, sizeof version)
 270                                 ? -EFAULT : 0;
 271                         if (retval >= 0)
 272                                 retval = if_version(cs, version);
 273                         if (retval >= 0)
 274                                 retval = copy_to_user((unsigned __user *) arg,
 275                                                       version, sizeof version)
 276                                         ? -EFAULT : 0;
 277                         break;
 278                 default:
 279                         gig_dbg(DEBUG_ANY, "%s: arg not supported - 0x%04x",
 280                                 __func__, cmd);
 281                         retval = -ENOIOCTLCMD;
 282                 }
 283         }
 284
 285         mutex_unlock(&cs->mutex);
 286
 287         return retval;
 288 }
 289
 290 static int if_tiocmget(struct tty_struct *tty, struct file *file)
 291 {
 292         struct cardstate *cs;
 293         int retval;
 294
 295         cs = (struct cardstate *) tty->driver_data;
 296         if (!cs) {
 297                 pr_err("%s: no cardstate\n", __func__);
 298                 return -ENODEV;
 299         }
 300
 301         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 302
 303         if (mutex_lock_interruptible(&cs->mutex))
 304                 return -ERESTARTSYS; // FIXME -EINTR?
 305
 306         // FIXME read from device?
 307         retval = cs->control_state & (TIOCM_RTS|TIOCM_DTR);
 308
 309         mutex_unlock(&cs->mutex);
 310
 311         return retval;
 312 }
 313
 314 static int if_tiocmset(struct tty_struct *tty, struct file *file,
 315                        unsigned int set, unsigned int clear)
 316 {
 317         struct cardstate *cs;
 318         int retval;
 319         unsigned mc;
 320
 321         cs = (struct cardstate *) tty->driver_data;
 322         if (!cs) {
 323                 pr_err("%s: no cardstate\n", __func__);
 324                 return -ENODEV;
 325         }
 326
 327         gig_dbg(DEBUG_IF, "%u: %s(0x%x, 0x%x)",
 328                 cs->minor_index, __func__, set, clear);
 329
 330         if (mutex_lock_interruptible(&cs->mutex))
 331                 return -ERESTARTSYS; // FIXME -EINTR?
 332
 333         if (!cs->connected) {
 334                 gig_dbg(DEBUG_ANY, "can't communicate with unplugged device");
 335                 retval = -ENODEV;
 336         } else {
 337                 mc = (cs->control_state | set) & ~clear & (TIOCM_RTS|TIOCM_DTR);
 338                 retval = cs->ops->set_modem_ctrl(cs, cs->control_state, mc);
 339                 cs->control_state = mc;
 340         }
 341
 342         mutex_unlock(&cs->mutex);
 343
 344         return retval;
 345 }
 346
 347 static int if_write(struct tty_struct *tty, const unsigned char *buf, int count)
 348 {
 349         struct cardstate *cs;
 350         int retval = -ENODEV;
 351
 352         cs = (struct cardstate *) tty->driver_data;
 353         if (!cs) {
 354                 pr_err("%s: no cardstate\n", __func__);
 355                 return -ENODEV;
 356         }
 357
 358         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 359
 360         if (mutex_lock_interruptible(&cs->mutex))
 361                 return -ERESTARTSYS; // FIXME -EINTR?
 362
 363         if (!cs->open_count)
 364                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 365         else if (cs->mstate != MS_LOCKED) {
 366                 dev_warn(cs->dev, "can't write to unlocked device\n");
 367                 retval = -EBUSY;
 368         } else if (!cs->connected) {
 369                 gig_dbg(DEBUG_ANY, "can't write to unplugged device");
 370                 retval = -EBUSY; //FIXME
 371         } else {
 372                 retval = cs->ops->write_cmd(cs, buf, count,
 373                                             &cs->if_wake_tasklet);
 374         }
 375
 376         mutex_unlock(&cs->mutex);
 377
 378         return retval;
 379 }
 380
 381 static int if_write_room(struct tty_struct *tty)
 382 {
 383         struct cardstate *cs;
 384         int retval = -ENODEV;
 385
 386         cs = (struct cardstate *) tty->driver_data;
 387         if (!cs) {
 388                 pr_err("%s: no cardstate\n", __func__);
 389                 return -ENODEV;
 390         }
 391
 392         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 393
 394         if (mutex_lock_interruptible(&cs->mutex))
 395                 return -ERESTARTSYS; // FIXME -EINTR?
 396
 397         if (!cs->open_count)
 398                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 399         else if (cs->mstate != MS_LOCKED) {
 400                 dev_warn(cs->dev, "can't write to unlocked device\n");
 401                 retval = -EBUSY;
 402         } else if (!cs->connected) {
 403                 gig_dbg(DEBUG_ANY, "can't write to unplugged device");
 404                 retval = -EBUSY; //FIXME
 405         } else
 406                 retval = cs->ops->write_room(cs);
 407
 408         mutex_unlock(&cs->mutex);
 409
 410         return retval;
 411 }
 412
 413 static int if_chars_in_buffer(struct tty_struct *tty)
 414 {
 415         struct cardstate *cs;
 416         int retval = -ENODEV;
 417
 418         cs = (struct cardstate *) tty->driver_data;
 419         if (!cs) {
 420                 pr_err("%s: no cardstate\n", __func__);
 421                 return -ENODEV;
 422         }
 423
 424         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 425
 426         if (mutex_lock_interruptible(&cs->mutex))
 427                 return -ERESTARTSYS; // FIXME -EINTR?
 428
 429         if (!cs->open_count)
 430                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 431         else if (cs->mstate != MS_LOCKED) {
 432                 dev_warn(cs->dev, "can't write to unlocked device\n");
 433                 retval = -EBUSY;
 434         } else if (!cs->connected) {
 435                 gig_dbg(DEBUG_ANY, "can't write to unplugged device");
 436                 retval = -EBUSY; //FIXME
 437         } else
 438                 retval = cs->ops->chars_in_buffer(cs);
 439
 440         mutex_unlock(&cs->mutex);
 441
 442         return retval;
 443 }
 444
 445 static void if_throttle(struct tty_struct *tty)
 446 {
 447         struct cardstate *cs;
 448
 449         cs = (struct cardstate *) tty->driver_data;
 450         if (!cs) {
 451                 pr_err("%s: no cardstate\n", __func__);
 452                 return;
 453         }
 454
 455         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 456
 457         mutex_lock(&cs->mutex);
 458
 459         if (!cs->open_count)
 460                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 461         else {
 462                 //FIXME
 463         }
 464
 465         mutex_unlock(&cs->mutex);
 466 }
 467
 468 static void if_unthrottle(struct tty_struct *tty)
 469 {
 470         struct cardstate *cs;
 471
 472         cs = (struct cardstate *) tty->driver_data;
 473         if (!cs) {
 474                 pr_err("%s: no cardstate\n", __func__);
 475                 return;
 476         }
 477
 478         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 479
 480         mutex_lock(&cs->mutex);
 481
 482         if (!cs->open_count)
 483                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 484         else {
 485                 //FIXME
 486         }
 487
 488         mutex_unlock(&cs->mutex);
 489 }
 490
 491 static void if_set_termios(struct tty_struct *tty, struct ktermios *old)
 492 {
 493         struct cardstate *cs;
 494         unsigned int iflag;
 495         unsigned int cflag;
 496         unsigned int old_cflag;
 497         unsigned int control_state, new_state;
 498
 499         cs = (struct cardstate *) tty->driver_data;
 500         if (!cs) {
 501                 pr_err("%s: no cardstate\n", __func__);
 502                 return;
 503         }
 504
 505         gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 506
 507         mutex_lock(&cs->mutex);
 508
 509         if (!cs->open_count) {
 510                 dev_warn(cs->dev, "%s: device not opened\n", __func__);
 511                 goto out;
 512         }
 513
 514         if (!cs->connected) {
 515                 gig_dbg(DEBUG_ANY, "can't communicate with unplugged device");
 516                 goto out;
 517         }
 518
 519         // stolen from mct_u232.c
 520         iflag = tty->termios->c_iflag;
 521         cflag = tty->termios->c_cflag;
 522         old_cflag = old ? old->c_cflag : cflag; //FIXME?
 523         gig_dbg(DEBUG_IF, "%u: iflag %x cflag %x old %x",
 524                 cs->minor_index, iflag, cflag, old_cflag);
 525
 526         /* get a local copy of the current port settings */
 527         control_state = cs->control_state;
 528
 529         /*
 530          * Update baud rate.
 531          * Do not attempt to cache old rates and skip settings,
 532          * disconnects screw such tricks up completely.
 533          * Premature optimization is the root of all evil.
 534          */
 535
 536         /* reassert DTR and (maybe) RTS on transition from B0 */
 537         if ((old_cflag & CBAUD) == B0) {
 538                 new_state = control_state | TIOCM_DTR;
 539                 /* don't set RTS if using hardware flow control */
 540                 if (!(old_cflag & CRTSCTS))
 541                         new_state |= TIOCM_RTS;
 542                 gig_dbg(DEBUG_IF, "%u: from B0 - set DTR%s",
 543                         cs->minor_index,
 544                         (new_state & TIOCM_RTS) ? " only" : "/RTS");
 545                 cs->ops->set_modem_ctrl(cs, control_state, new_state);
 546                 control_state = new_state;
 547         }
 548
 549         cs->ops->baud_rate(cs, cflag & CBAUD);
 550
 551         if ((cflag & CBAUD) == B0) {
 552                 /* Drop RTS and DTR */
 553                 gig_dbg(DEBUG_IF, "%u: to B0 - drop DTR/RTS", cs->minor_index);
 554                 new_state = control_state & ~(TIOCM_DTR | TIOCM_RTS);
 555                 cs->ops->set_modem_ctrl(cs, control_state, new_state);
 556                 control_state = new_state;
 557         }
 558
 559         /*
 560          * Update line control register (LCR)
 561          */
 562
 563         cs->ops->set_line_ctrl(cs, cflag);
 564
 565         /* save off the modified port settings */
 566         cs->control_state = control_state;
 567
 568 out:
 569         mutex_unlock(&cs->mutex);
 570 }
 571
 572
 573 /* wakeup tasklet for the write operation */
 574 static void if_wake(unsigned long data)
 575 {
 576         struct cardstate *cs = (struct cardstate *) data;
 577
 578         if (cs->tty)
 579                 tty_wakeup(cs->tty);
 580 }
 581
 582 /*** interface to common ***/
 583
 584 void gigaset_if_init(struct cardstate *cs)
 585 {
 586         struct gigaset_driver *drv;
 587
 588         drv = cs->driver;
 589         if (!drv->have_tty)
 590                 return;
 591
 592         tasklet_init(&cs->if_wake_tasklet, &if_wake, (unsigned long) cs);
 593
 594         mutex_lock(&cs->mutex);
 595         cs->tty_dev = tty_register_device(drv->tty, cs->minor_index, NULL);
 596
 597         if (!IS_ERR(cs->tty_dev))
 598                 dev_set_drvdata(cs->tty_dev, cs);
 599         else {
 600                 dev_warn(cs->dev,
 601                          "could not register device to the tty subsystem\n");
 602                 cs->tty_dev = NULL;
 603         }
 604         mutex_unlock(&cs->mutex);
 605 }
 606
 607 void gigaset_if_free(struct cardstate *cs)
 608 {
 609         struct gigaset_driver *drv;
 610
 611         drv = cs->driver;
 612         if (!drv->have_tty)
 613                 return;
 614
 615         tasklet_disable(&cs->if_wake_tasklet);
 616         tasklet_kill(&cs->if_wake_tasklet);
 617         cs->tty_dev = NULL;
 618         tty_unregister_device(drv->tty, cs->minor_index);
 619 }
 620
 621 void gigaset_if_receive(struct cardstate *cs,
 622                         unsigned char *buffer, size_t len)
 623 {
 624         unsigned long flags;
 625         struct tty_struct *tty;
 626
 627         spin_lock_irqsave(&cs->lock, flags);
 628         if ((tty = cs->tty) == NULL)
 629                 gig_dbg(DEBUG_ANY, "receive on closed device");
 630         else {
 631                 tty_buffer_request_room(tty, len);
 632                 tty_insert_flip_string(tty, buffer, len);
 633                 tty_flip_buffer_push(tty);
 634         }
 635         spin_unlock_irqrestore(&cs->lock, flags);
 636 }
 637 EXPORT_SYMBOL_GPL(gigaset_if_receive);
 638
 639 /* gigaset_if_initdriver
 640  * Initialize tty interface.
 641  * parameters:
 642  *      drv             Driver
 643  *      procname        Name of the driver (e.g. for /proc/tty/drivers)
 644  *      devname         Name of the device files (prefix without minor number)
 645  */
 646 void gigaset_if_initdriver(struct gigaset_driver *drv, const char *procname,
 647                            const char *devname)
 648 {
 649         unsigned minors = drv->minors;
 650         int ret;
 651         struct tty_driver *tty;
 652
 653         drv->have_tty = 0;
 654
 655         if ((drv->tty = alloc_tty_driver(minors)) == NULL)
 656                 goto enomem;
 657         tty = drv->tty;
 658
 659         tty->magic =            TTY_DRIVER_MAGIC,
 660         tty->major =            GIG_MAJOR,
 661         tty->type =             TTY_DRIVER_TYPE_SERIAL,
 662         tty->subtype =          SERIAL_TYPE_NORMAL,
 663         tty->flags =            TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
 664
 665         tty->driver_name =      procname;
 666         tty->name =             devname;
 667         tty->minor_start =      drv->minor;
 668         tty->num =              drv->minors;
 669
 670         tty->owner =            THIS_MODULE;
 671
 672         tty->init_termios          = tty_std_termios; //FIXME
 673         tty->init_termios.c_cflag  = B9600 | CS8 | CREAD | HUPCL | CLOCAL; //FIXME
 674         tty_set_operations(tty, &if_ops);
 675
 676         ret = tty_register_driver(tty);
 677         if (ret < 0) {
 678                 pr_err("error %d registering tty driver\n", ret);
 679                 goto error;
 680         }
 681         gig_dbg(DEBUG_IF, "tty driver initialized");
 682         drv->have_tty = 1;
 683         return;
 684
 685 enomem:
 686         pr_err("out of memory\n");
 687 error:
 688         if (drv->tty)
 689                 put_tty_driver(drv->tty);
 690 }
 691
 692 void gigaset_if_freedriver(struct gigaset_driver *drv)
 693 {
 694         if (!drv->have_tty)
 695                 return;
 696
 697         drv->have_tty = 0;
 698         tty_unregister_driver(drv->tty);
 699         put_tty_driver(drv->tty);
 700 }