linux/drivers/isdn/gigaset/interface.c
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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#include <linux/module.h>
  18
  19/*** our ioctls ***/
  20
  21static 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
  60static 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
  95static 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
 117static int  if_open(struct tty_struct *tty, struct file *filp);
 118static void if_close(struct tty_struct *tty, struct file *filp);
 119static int  if_ioctl(struct tty_struct *tty,
 120                     unsigned int cmd, unsigned long arg);
 121static int  if_write_room(struct tty_struct *tty);
 122static int  if_chars_in_buffer(struct tty_struct *tty);
 123static void if_throttle(struct tty_struct *tty);
 124static void if_unthrottle(struct tty_struct *tty);
 125static void if_set_termios(struct tty_struct *tty, struct ktermios *old);
 126static int  if_tiocmget(struct tty_struct *tty);
 127static int  if_tiocmset(struct tty_struct *tty,
 128                        unsigned int set, unsigned int clear);
 129static int  if_write(struct tty_struct *tty,
 130                     const unsigned char *buf, int count);
 131
 132static 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
 146static 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                module_put(cs->driver->owner);
 162                return -ERESTARTSYS;
 163        }
 164        tty->driver_data = cs;
 165
 166        ++cs->open_count;
 167
 168        if (cs->open_count == 1) {
 169                spin_lock_irqsave(&cs->lock, flags);
 170                cs->tty = tty;
 171                spin_unlock_irqrestore(&cs->lock, flags);
 172                tty->low_latency = 1;
 173        }
 174
 175        mutex_unlock(&cs->mutex);
 176        return 0;
 177}
 178
 179static void if_close(struct tty_struct *tty, struct file *filp)
 180{
 181        struct cardstate *cs;
 182        unsigned long flags;
 183
 184        cs = (struct cardstate *) tty->driver_data;
 185        if (!cs) {
 186                pr_err("%s: no cardstate\n", __func__);
 187                return;
 188        }
 189
 190        gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 191
 192        mutex_lock(&cs->mutex);
 193
 194        if (!cs->connected)
 195                gig_dbg(DEBUG_IF, "not connected");     /* nothing to do */
 196        else 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
 211static int if_ioctl(struct tty_struct *tty,
 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;
 230
 231        if (!cs->connected) {
 232                gig_dbg(DEBUG_IF, "not connected");
 233                retval = -ENODEV;
 234        } else if (!cs->open_count)
 235                dev_warn(cs->dev, "%s: device not opened\n", __func__);
 236        else {
 237                retval = 0;
 238                switch (cmd) {
 239                case GIGASET_REDIR:
 240                        retval = get_user(int_arg, (int __user *) arg);
 241                        if (retval >= 0)
 242                                retval = if_lock(cs, &int_arg);
 243                        if (retval >= 0)
 244                                retval = put_user(int_arg, (int __user *) arg);
 245                        break;
 246                case GIGASET_CONFIG:
 247                        retval = get_user(int_arg, (int __user *) arg);
 248                        if (retval >= 0)
 249                                retval = if_config(cs, &int_arg);
 250                        if (retval >= 0)
 251                                retval = put_user(int_arg, (int __user *) arg);
 252                        break;
 253                case GIGASET_BRKCHARS:
 254                        retval = copy_from_user(&buf,
 255                                        (const unsigned char __user *) arg, 6)
 256                                ? -EFAULT : 0;
 257                        if (retval >= 0) {
 258                                gigaset_dbg_buffer(DEBUG_IF, "GIGASET_BRKCHARS",
 259                                                6, (const unsigned char *) arg);
 260                                retval = cs->ops->brkchars(cs, buf);
 261                        }
 262                        break;
 263                case GIGASET_VERSION:
 264                        retval = copy_from_user(version,
 265                                        (unsigned __user *) arg, sizeof version)
 266                                ? -EFAULT : 0;
 267                        if (retval >= 0)
 268                                retval = if_version(cs, version);
 269                        if (retval >= 0)
 270                                retval = copy_to_user((unsigned __user *) arg,
 271                                                      version, sizeof version)
 272                                        ? -EFAULT : 0;
 273                        break;
 274                default:
 275                        gig_dbg(DEBUG_IF, "%s: arg not supported - 0x%04x",
 276                                __func__, cmd);
 277                        retval = -ENOIOCTLCMD;
 278                }
 279        }
 280
 281        mutex_unlock(&cs->mutex);
 282
 283        return retval;
 284}
 285
 286static int if_tiocmget(struct tty_struct *tty)
 287{
 288        struct cardstate *cs;
 289        int retval;
 290
 291        cs = (struct cardstate *) tty->driver_data;
 292        if (!cs) {
 293                pr_err("%s: no cardstate\n", __func__);
 294                return -ENODEV;
 295        }
 296
 297        gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 298
 299        if (mutex_lock_interruptible(&cs->mutex))
 300                return -ERESTARTSYS;
 301
 302        retval = cs->control_state & (TIOCM_RTS|TIOCM_DTR);
 303
 304        mutex_unlock(&cs->mutex);
 305
 306        return retval;
 307}
 308
 309static int if_tiocmset(struct tty_struct *tty,
 310                       unsigned int set, unsigned int clear)
 311{
 312        struct cardstate *cs;
 313        int retval;
 314        unsigned mc;
 315
 316        cs = (struct cardstate *) tty->driver_data;
 317        if (!cs) {
 318                pr_err("%s: no cardstate\n", __func__);
 319                return -ENODEV;
 320        }
 321
 322        gig_dbg(DEBUG_IF, "%u: %s(0x%x, 0x%x)",
 323                cs->minor_index, __func__, set, clear);
 324
 325        if (mutex_lock_interruptible(&cs->mutex))
 326                return -ERESTARTSYS;
 327
 328        if (!cs->connected) {
 329                gig_dbg(DEBUG_IF, "not connected");
 330                retval = -ENODEV;
 331        } else {
 332                mc = (cs->control_state | set) & ~clear & (TIOCM_RTS|TIOCM_DTR);
 333                retval = cs->ops->set_modem_ctrl(cs, cs->control_state, mc);
 334                cs->control_state = mc;
 335        }
 336
 337        mutex_unlock(&cs->mutex);
 338
 339        return retval;
 340}
 341
 342static int if_write(struct tty_struct *tty, const unsigned char *buf, int count)
 343{
 344        struct cardstate *cs;
 345        struct cmdbuf_t *cb;
 346        int retval;
 347
 348        cs = (struct cardstate *) tty->driver_data;
 349        if (!cs) {
 350                pr_err("%s: no cardstate\n", __func__);
 351                return -ENODEV;
 352        }
 353
 354        gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 355
 356        if (mutex_lock_interruptible(&cs->mutex))
 357                return -ERESTARTSYS;
 358
 359        if (!cs->connected) {
 360                gig_dbg(DEBUG_IF, "not connected");
 361                retval = -ENODEV;
 362                goto done;
 363        }
 364        if (!cs->open_count) {
 365                dev_warn(cs->dev, "%s: device not opened\n", __func__);
 366                retval = -ENODEV;
 367                goto done;
 368        }
 369        if (cs->mstate != MS_LOCKED) {
 370                dev_warn(cs->dev, "can't write to unlocked device\n");
 371                retval = -EBUSY;
 372                goto done;
 373        }
 374        if (count <= 0) {
 375                /* nothing to do */
 376                retval = 0;
 377                goto done;
 378        }
 379
 380        cb = kmalloc(sizeof(struct cmdbuf_t) + count, GFP_KERNEL);
 381        if (!cb) {
 382                dev_err(cs->dev, "%s: out of memory\n", __func__);
 383                retval = -ENOMEM;
 384                goto done;
 385        }
 386
 387        memcpy(cb->buf, buf, count);
 388        cb->len = count;
 389        cb->offset = 0;
 390        cb->next = NULL;
 391        cb->wake_tasklet = &cs->if_wake_tasklet;
 392        retval = cs->ops->write_cmd(cs, cb);
 393done:
 394        mutex_unlock(&cs->mutex);
 395        return retval;
 396}
 397
 398static int if_write_room(struct tty_struct *tty)
 399{
 400        struct cardstate *cs;
 401        int retval = -ENODEV;
 402
 403        cs = (struct cardstate *) tty->driver_data;
 404        if (!cs) {
 405                pr_err("%s: no cardstate\n", __func__);
 406                return -ENODEV;
 407        }
 408
 409        gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 410
 411        if (mutex_lock_interruptible(&cs->mutex))
 412                return -ERESTARTSYS;
 413
 414        if (!cs->connected) {
 415                gig_dbg(DEBUG_IF, "not connected");
 416                retval = -ENODEV;
 417        } else if (!cs->open_count)
 418                dev_warn(cs->dev, "%s: device not opened\n", __func__);
 419        else if (cs->mstate != MS_LOCKED) {
 420                dev_warn(cs->dev, "can't write to unlocked device\n");
 421                retval = -EBUSY;
 422        } else
 423                retval = cs->ops->write_room(cs);
 424
 425        mutex_unlock(&cs->mutex);
 426
 427        return retval;
 428}
 429
 430static int if_chars_in_buffer(struct tty_struct *tty)
 431{
 432        struct cardstate *cs;
 433        int retval = 0;
 434
 435        cs = (struct cardstate *) tty->driver_data;
 436        if (!cs) {
 437                pr_err("%s: no cardstate\n", __func__);
 438                return 0;
 439        }
 440
 441        gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 442
 443        mutex_lock(&cs->mutex);
 444
 445        if (!cs->connected)
 446                gig_dbg(DEBUG_IF, "not connected");
 447        else if (!cs->open_count)
 448                dev_warn(cs->dev, "%s: device not opened\n", __func__);
 449        else if (cs->mstate != MS_LOCKED)
 450                dev_warn(cs->dev, "can't write to unlocked device\n");
 451        else
 452                retval = cs->ops->chars_in_buffer(cs);
 453
 454        mutex_unlock(&cs->mutex);
 455
 456        return retval;
 457}
 458
 459static void if_throttle(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
 483static void if_unthrottle(struct tty_struct *tty)
 484{
 485        struct cardstate *cs;
 486
 487        cs = (struct cardstate *) tty->driver_data;
 488        if (!cs) {
 489                pr_err("%s: no cardstate\n", __func__);
 490                return;
 491        }
 492
 493        gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 494
 495        mutex_lock(&cs->mutex);
 496
 497        if (!cs->connected)
 498                gig_dbg(DEBUG_IF, "not connected");     /* nothing to do */
 499        else if (!cs->open_count)
 500                dev_warn(cs->dev, "%s: device not opened\n", __func__);
 501        else
 502                gig_dbg(DEBUG_IF, "%s: not implemented\n", __func__);
 503
 504        mutex_unlock(&cs->mutex);
 505}
 506
 507static void if_set_termios(struct tty_struct *tty, struct ktermios *old)
 508{
 509        struct cardstate *cs;
 510        unsigned int iflag;
 511        unsigned int cflag;
 512        unsigned int old_cflag;
 513        unsigned int control_state, new_state;
 514
 515        cs = (struct cardstate *) tty->driver_data;
 516        if (!cs) {
 517                pr_err("%s: no cardstate\n", __func__);
 518                return;
 519        }
 520
 521        gig_dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __func__);
 522
 523        mutex_lock(&cs->mutex);
 524
 525        if (!cs->connected) {
 526                gig_dbg(DEBUG_IF, "not connected");
 527                goto out;
 528        }
 529
 530        if (!cs->open_count) {
 531                dev_warn(cs->dev, "%s: device not opened\n", __func__);
 532                goto out;
 533        }
 534
 535        iflag = tty->termios->c_iflag;
 536        cflag = tty->termios->c_cflag;
 537        old_cflag = old ? old->c_cflag : cflag;
 538        gig_dbg(DEBUG_IF, "%u: iflag %x cflag %x old %x",
 539                cs->minor_index, iflag, cflag, old_cflag);
 540
 541        /* get a local copy of the current port settings */
 542        control_state = cs->control_state;
 543
 544        /*
 545         * Update baud rate.
 546         * Do not attempt to cache old rates and skip settings,
 547         * disconnects screw such tricks up completely.
 548         * Premature optimization is the root of all evil.
 549         */
 550
 551        /* reassert DTR and (maybe) RTS on transition from B0 */
 552        if ((old_cflag & CBAUD) == B0) {
 553                new_state = control_state | TIOCM_DTR;
 554                /* don't set RTS if using hardware flow control */
 555                if (!(old_cflag & CRTSCTS))
 556                        new_state |= TIOCM_RTS;
 557                gig_dbg(DEBUG_IF, "%u: from B0 - set DTR%s",
 558                        cs->minor_index,
 559                        (new_state & TIOCM_RTS) ? " only" : "/RTS");
 560                cs->ops->set_modem_ctrl(cs, control_state, new_state);
 561                control_state = new_state;
 562        }
 563
 564        cs->ops->baud_rate(cs, cflag & CBAUD);
 565
 566        if ((cflag & CBAUD) == B0) {
 567                /* Drop RTS and DTR */
 568                gig_dbg(DEBUG_IF, "%u: to B0 - drop DTR/RTS", cs->minor_index);
 569                new_state = control_state & ~(TIOCM_DTR | TIOCM_RTS);
 570                cs->ops->set_modem_ctrl(cs, control_state, new_state);
 571                control_state = new_state;
 572        }
 573
 574        /*
 575         * Update line control register (LCR)
 576         */
 577
 578        cs->ops->set_line_ctrl(cs, cflag);
 579
 580        /* save off the modified port settings */
 581        cs->control_state = control_state;
 582
 583out:
 584        mutex_unlock(&cs->mutex);
 585}
 586
 587
 588/* wakeup tasklet for the write operation */
 589static void if_wake(unsigned long data)
 590{
 591        struct cardstate *cs = (struct cardstate *) data;
 592
 593        if (cs->tty)
 594                tty_wakeup(cs->tty);
 595}
 596
 597/*** interface to common ***/
 598
 599void gigaset_if_init(struct cardstate *cs)
 600{
 601        struct gigaset_driver *drv;
 602
 603        drv = cs->driver;
 604        if (!drv->have_tty)
 605                return;
 606
 607        tasklet_init(&cs->if_wake_tasklet, if_wake, (unsigned long) cs);
 608
 609        mutex_lock(&cs->mutex);
 610        cs->tty_dev = tty_register_device(drv->tty, cs->minor_index, NULL);
 611
 612        if (!IS_ERR(cs->tty_dev))
 613                dev_set_drvdata(cs->tty_dev, cs);
 614        else {
 615                pr_warning("could not register device to the tty subsystem\n");
 616                cs->tty_dev = NULL;
 617        }
 618        mutex_unlock(&cs->mutex);
 619}
 620
 621void gigaset_if_free(struct cardstate *cs)
 622{
 623        struct gigaset_driver *drv;
 624
 625        drv = cs->driver;
 626        if (!drv->have_tty)
 627                return;
 628
 629        tasklet_disable(&cs->if_wake_tasklet);
 630        tasklet_kill(&cs->if_wake_tasklet);
 631        cs->tty_dev = NULL;
 632        tty_unregister_device(drv->tty, cs->minor_index);
 633}
 634
 635/**
 636 * gigaset_if_receive() - pass a received block of data to the tty device
 637 * @cs:         device descriptor structure.
 638 * @buffer:     received data.
 639 * @len:        number of bytes received.
 640 *
 641 * Called by asyncdata/isocdata if a block of data received from the
 642 * device must be sent to userspace through the ttyG* device.
 643 */
 644void gigaset_if_receive(struct cardstate *cs,
 645                        unsigned char *buffer, size_t len)
 646{
 647        unsigned long flags;
 648        struct tty_struct *tty;
 649
 650        spin_lock_irqsave(&cs->lock, flags);
 651        tty = cs->tty;
 652        if (tty == NULL)
 653                gig_dbg(DEBUG_IF, "receive on closed device");
 654        else {
 655                tty_insert_flip_string(tty, buffer, len);
 656                tty_flip_buffer_push(tty);
 657        }
 658        spin_unlock_irqrestore(&cs->lock, flags);
 659}
 660EXPORT_SYMBOL_GPL(gigaset_if_receive);
 661
 662/* gigaset_if_initdriver
 663 * Initialize tty interface.
 664 * parameters:
 665 *      drv             Driver
 666 *      procname        Name of the driver (e.g. for /proc/tty/drivers)
 667 *      devname         Name of the device files (prefix without minor number)
 668 */
 669void gigaset_if_initdriver(struct gigaset_driver *drv, const char *procname,
 670                           const char *devname)
 671{
 672        unsigned minors = drv->minors;
 673        int ret;
 674        struct tty_driver *tty;
 675
 676        drv->have_tty = 0;
 677
 678        drv->tty = tty = alloc_tty_driver(minors);
 679        if (tty == NULL)
 680                goto enomem;
 681
 682        tty->magic =            TTY_DRIVER_MAGIC,
 683        tty->type =             TTY_DRIVER_TYPE_SERIAL,
 684        tty->subtype =          SERIAL_TYPE_NORMAL,
 685        tty->flags =            TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
 686
 687        tty->driver_name =      procname;
 688        tty->name =             devname;
 689        tty->minor_start =      drv->minor;
 690        tty->num =              drv->minors;
 691
 692        tty->owner =            THIS_MODULE;
 693
 694        tty->init_termios          = tty_std_termios;
 695        tty->init_termios.c_cflag  = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
 696        tty_set_operations(tty, &if_ops);
 697
 698        ret = tty_register_driver(tty);
 699        if (ret < 0) {
 700                pr_err("error %d registering tty driver\n", ret);
 701                goto error;
 702        }
 703        gig_dbg(DEBUG_IF, "tty driver initialized");
 704        drv->have_tty = 1;
 705        return;
 706
 707enomem:
 708        pr_err("out of memory\n");
 709error:
 710        if (drv->tty)
 711                put_tty_driver(drv->tty);
 712}
 713
 714void gigaset_if_freedriver(struct gigaset_driver *drv)
 715{
 716        if (!drv->have_tty)
 717                return;
 718
 719        drv->have_tty = 0;
 720        tty_unregister_driver(drv->tty);
 721        put_tty_driver(drv->tty);
 722}
 723