drivers/tty/pty.c

   1 /*
   2  *  Copyright (C) 1991, 1992  Linus Torvalds
   3  *
   4  *  Added support for a Unix98-style ptmx device.
   5  *    -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998
   6  *
   7  *  When reading this code see also fs/devpts. In particular note that the
   8  *  driver_data field is used by the devpts side as a binding to the devpts
   9  *  inode.
  10  */
  11
  12 #include <linux/module.h>
  13
  14 #include <linux/errno.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/tty.h>
  17 #include <linux/tty_flip.h>
  18 #include <linux/fcntl.h>
  19 #include <linux/sched.h>
  20 #include <linux/string.h>
  21 #include <linux/major.h>
  22 #include <linux/mm.h>
  23 #include <linux/init.h>
  24 #include <linux/device.h>
  25 #include <linux/uaccess.h>
  26 #include <linux/bitops.h>
  27 #include <linux/devpts_fs.h>
  28 #include <linux/slab.h>
  29
  30
  31 #ifdef CONFIG_UNIX98_PTYS
  32 static struct tty_driver *ptm_driver;
  33 static struct tty_driver *pts_driver;
  34 #endif
  35
  36 static void pty_close(struct tty_struct *tty, struct file *filp)
  37 {
  38         BUG_ON(!tty);
  39         if (tty->driver->subtype == PTY_TYPE_MASTER)
  40                 WARN_ON(tty->count > 1);
  41         else {
  42                 if (tty->count > 2)
  43                         return;
  44         }
  45         wake_up_interruptible(&tty->read_wait);
  46         wake_up_interruptible(&tty->write_wait);
  47         tty->packet = 0;
  48         if (!tty->link)
  49                 return;
  50         tty->link->packet = 0;
  51         set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
  52         wake_up_interruptible(&tty->link->read_wait);
  53         wake_up_interruptible(&tty->link->write_wait);
  54         if (tty->driver->subtype == PTY_TYPE_MASTER) {
  55                 set_bit(TTY_OTHER_CLOSED, &tty->flags);
  56 #ifdef CONFIG_UNIX98_PTYS
  57                 if (tty->driver == ptm_driver)
  58                         devpts_pty_kill(tty->link);
  59 #endif
  60                 tty_unlock();
  61                 tty_vhangup(tty->link);
  62                 tty_lock();
  63         }
  64 }
  65
  66 /*
  67  * The unthrottle routine is called by the line discipline to signal
  68  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
  69  * flag is always set, to force the line discipline to always call the
  70  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
  71  * characters in the queue.  This is necessary since each time this
  72  * happens, we need to wake up any sleeping processes that could be
  73  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
  74  * for the pty buffer to be drained.
  75  */
  76 static void pty_unthrottle(struct tty_struct *tty)
  77 {
  78         tty_wakeup(tty->link);
  79         set_bit(TTY_THROTTLED, &tty->flags);
  80 }
  81
  82 /**
  83  *      pty_space       -       report space left for writing
  84  *      @to: tty we are writing into
  85  *
  86  *      The tty buffers allow 64K but we sneak a peak and clip at 8K this
  87  *      allows a lot of overspill room for echo and other fun messes to
  88  *      be handled properly
  89  */
  90
  91 static int pty_space(struct tty_struct *to)
  92 {
  93         int n = 8192 - to->buf.memory_used;
  94         if (n < 0)
  95                 return 0;
  96         return n;
  97 }
  98
  99 /**
 100  *      pty_write               -       write to a pty
 101  *      @tty: the tty we write from
 102  *      @buf: kernel buffer of data
 103  *      @count: bytes to write
 104  *
 105  *      Our "hardware" write method. Data is coming from the ldisc which
 106  *      may be in a non sleeping state. We simply throw this at the other
 107  *      end of the link as if we were an IRQ handler receiving stuff for
 108  *      the other side of the pty/tty pair.
 109  */
 110
 111 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
 112 {
 113         struct tty_struct *to = tty->link;
 114
 115         if (tty->stopped)
 116                 return 0;
 117
 118         if (c > 0) {
 119                 /* Stuff the data into the input queue of the other end */
 120                 c = tty_insert_flip_string(to, buf, c);
 121                 /* And shovel */
 122                 if (c) {
 123                         tty_flip_buffer_push(to);
 124                         tty_wakeup(tty);
 125                 }
 126         }
 127         return c;
 128 }
 129
 130 /**
 131  *      pty_write_room  -       write space
 132  *      @tty: tty we are writing from
 133  *
 134  *      Report how many bytes the ldisc can send into the queue for
 135  *      the other device.
 136  */
 137
 138 static int pty_write_room(struct tty_struct *tty)
 139 {
 140         if (tty->stopped)
 141                 return 0;
 142         return pty_space(tty->link);
 143 }
 144
 145 /**
 146  *      pty_chars_in_buffer     -       characters currently in our tx queue
 147  *      @tty: our tty
 148  *
 149  *      Report how much we have in the transmit queue. As everything is
 150  *      instantly at the other end this is easy to implement.
 151  */
 152
 153 static int pty_chars_in_buffer(struct tty_struct *tty)
 154 {
 155         return 0;
 156 }
 157
 158 /* Set the lock flag on a pty */
 159 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
 160 {
 161         int val;
 162         if (get_user(val, arg))
 163                 return -EFAULT;
 164         if (val)
 165                 set_bit(TTY_PTY_LOCK, &tty->flags);
 166         else
 167                 clear_bit(TTY_PTY_LOCK, &tty->flags);
 168         return 0;
 169 }
 170
 171 /* Send a signal to the slave */
 172 static int pty_signal(struct tty_struct *tty, int sig)
 173 {
 174         unsigned long flags;
 175         struct pid *pgrp;
 176
 177         if (tty->link) {
 178                 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
 179                 pgrp = get_pid(tty->link->pgrp);
 180                 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
 181
 182                 kill_pgrp(pgrp, sig, 1);
 183                 put_pid(pgrp);
 184         }
 185         return 0;
 186 }
 187
 188 static void pty_flush_buffer(struct tty_struct *tty)
 189 {
 190         struct tty_struct *to = tty->link;
 191         unsigned long flags;
 192
 193         if (!to)
 194                 return;
 195         /* tty_buffer_flush(to); FIXME */
 196         if (to->packet) {
 197                 spin_lock_irqsave(&tty->ctrl_lock, flags);
 198                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
 199                 wake_up_interruptible(&to->read_wait);
 200                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 201         }
 202 }
 203
 204 static int pty_open(struct tty_struct *tty, struct file *filp)
 205 {
 206         int     retval = -ENODEV;
 207
 208         if (!tty || !tty->link)
 209                 goto out;
 210
 211         retval = -EIO;
 212         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
 213                 goto out;
 214         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
 215                 goto out;
 216         if (tty->link->count != 1)
 217                 goto out;
 218
 219         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
 220         set_bit(TTY_THROTTLED, &tty->flags);
 221         retval = 0;
 222 out:
 223         return retval;
 224 }
 225
 226 static void pty_set_termios(struct tty_struct *tty,
 227                                         struct ktermios *old_termios)
 228 {
 229         tty->termios->c_cflag &= ~(CSIZE | PARENB);
 230         tty->termios->c_cflag |= (CS8 | CREAD);
 231 }
 232
 233 /**
 234  *      pty_do_resize           -       resize event
 235  *      @tty: tty being resized
 236  *      @ws: window size being set.
 237  *
 238  *      Update the termios variables and send the necessary signals to
 239  *      peform a terminal resize correctly
 240  */
 241
 242 int pty_resize(struct tty_struct *tty,  struct winsize *ws)
 243 {
 244         struct pid *pgrp, *rpgrp;
 245         unsigned long flags;
 246         struct tty_struct *pty = tty->link;
 247
 248         /* For a PTY we need to lock the tty side */
 249         mutex_lock(&tty->termios_mutex);
 250         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
 251                 goto done;
 252
 253         /* Get the PID values and reference them so we can
 254            avoid holding the tty ctrl lock while sending signals.
 255            We need to lock these individually however. */
 256
 257         spin_lock_irqsave(&tty->ctrl_lock, flags);
 258         pgrp = get_pid(tty->pgrp);
 259         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
 260
 261         spin_lock_irqsave(&pty->ctrl_lock, flags);
 262         rpgrp = get_pid(pty->pgrp);
 263         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
 264
 265         if (pgrp)
 266                 kill_pgrp(pgrp, SIGWINCH, 1);
 267         if (rpgrp != pgrp && rpgrp)
 268                 kill_pgrp(rpgrp, SIGWINCH, 1);
 269
 270         put_pid(pgrp);
 271         put_pid(rpgrp);
 272
 273         tty->winsize = *ws;
 274         pty->winsize = *ws;     /* Never used so will go away soon */
 275 done:
 276         mutex_unlock(&tty->termios_mutex);
 277         return 0;
 278 }
 279
 280 /* Traditional BSD devices */
 281 #ifdef CONFIG_LEGACY_PTYS
 282
 283 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
 284 {
 285         struct tty_struct *o_tty;
 286         int idx = tty->index;
 287         int retval;
 288
 289         o_tty = alloc_tty_struct();
 290         if (!o_tty)
 291                 return -ENOMEM;
 292         if (!try_module_get(driver->other->owner)) {
 293                 /* This cannot in fact currently happen */
 294                 retval = -ENOMEM;
 295                 goto err_free_tty;
 296         }
 297         initialize_tty_struct(o_tty, driver->other, idx);
 298
 299         /* We always use new tty termios data so we can do this
 300            the easy way .. */
 301         retval = tty_init_termios(tty);
 302         if (retval)
 303                 goto err_deinit_tty;
 304
 305         retval = tty_init_termios(o_tty);
 306         if (retval)
 307                 goto err_free_termios;
 308
 309         /*
 310          * Everything allocated ... set up the o_tty structure.
 311          */
 312         driver->other->ttys[idx] = o_tty;
 313         tty_driver_kref_get(driver->other);
 314         if (driver->subtype == PTY_TYPE_MASTER)
 315                 o_tty->count++;
 316         /* Establish the links in both directions */
 317         tty->link   = o_tty;
 318         o_tty->link = tty;
 319
 320         tty_driver_kref_get(driver);
 321         tty->count++;
 322         driver->ttys[idx] = tty;
 323         return 0;
 324 err_free_termios:
 325         tty_free_termios(tty);
 326 err_deinit_tty:
 327         deinitialize_tty_struct(o_tty);
 328         module_put(o_tty->driver->owner);
 329 err_free_tty:
 330         free_tty_struct(o_tty);
 331         return retval;
 332 }
 333
 334 static int pty_bsd_ioctl(struct tty_struct *tty,
 335                          unsigned int cmd, unsigned long arg)
 336 {
 337         switch (cmd) {
 338         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 339                 return pty_set_lock(tty, (int __user *) arg);
 340         case TIOCSIG:    /* Send signal to other side of pty */
 341                 return pty_signal(tty, (int) arg);
 342         }
 343         return -ENOIOCTLCMD;
 344 }
 345
 346 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
 347 module_param(legacy_count, int, 0);
 348
 349 /*
 350  * The master side of a pty can do TIOCSPTLCK and thus
 351  * has pty_bsd_ioctl.
 352  */
 353 static const struct tty_operations master_pty_ops_bsd = {
 354         .install = pty_install,
 355         .open = pty_open,
 356         .close = pty_close,
 357         .write = pty_write,
 358         .write_room = pty_write_room,
 359         .flush_buffer = pty_flush_buffer,
 360         .chars_in_buffer = pty_chars_in_buffer,
 361         .unthrottle = pty_unthrottle,
 362         .set_termios = pty_set_termios,
 363         .ioctl = pty_bsd_ioctl,
 364         .resize = pty_resize
 365 };
 366
 367 static const struct tty_operations slave_pty_ops_bsd = {
 368         .install = pty_install,
 369         .open = pty_open,
 370         .close = pty_close,
 371         .write = pty_write,
 372         .write_room = pty_write_room,
 373         .flush_buffer = pty_flush_buffer,
 374         .chars_in_buffer = pty_chars_in_buffer,
 375         .unthrottle = pty_unthrottle,
 376         .set_termios = pty_set_termios,
 377         .resize = pty_resize
 378 };
 379
 380 static void __init legacy_pty_init(void)
 381 {
 382         struct tty_driver *pty_driver, *pty_slave_driver;
 383
 384         if (legacy_count <= 0)
 385                 return;
 386
 387         pty_driver = alloc_tty_driver(legacy_count);
 388         if (!pty_driver)
 389                 panic("Couldn't allocate pty driver");
 390
 391         pty_slave_driver = alloc_tty_driver(legacy_count);
 392         if (!pty_slave_driver)
 393                 panic("Couldn't allocate pty slave driver");
 394
 395         pty_driver->driver_name = "pty_master";
 396         pty_driver->name = "pty";
 397         pty_driver->major = PTY_MASTER_MAJOR;
 398         pty_driver->minor_start = 0;
 399         pty_driver->type = TTY_DRIVER_TYPE_PTY;
 400         pty_driver->subtype = PTY_TYPE_MASTER;
 401         pty_driver->init_termios = tty_std_termios;
 402         pty_driver->init_termios.c_iflag = 0;
 403         pty_driver->init_termios.c_oflag = 0;
 404         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 405         pty_driver->init_termios.c_lflag = 0;
 406         pty_driver->init_termios.c_ispeed = 38400;
 407         pty_driver->init_termios.c_ospeed = 38400;
 408         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
 409         pty_driver->other = pty_slave_driver;
 410         tty_set_operations(pty_driver, &master_pty_ops_bsd);
 411
 412         pty_slave_driver->driver_name = "pty_slave";
 413         pty_slave_driver->name = "ttyp";
 414         pty_slave_driver->major = PTY_SLAVE_MAJOR;
 415         pty_slave_driver->minor_start = 0;
 416         pty_slave_driver->type = TTY_DRIVER_TYPE_PTY;
 417         pty_slave_driver->subtype = PTY_TYPE_SLAVE;
 418         pty_slave_driver->init_termios = tty_std_termios;
 419         pty_slave_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 420         pty_slave_driver->init_termios.c_ispeed = 38400;
 421         pty_slave_driver->init_termios.c_ospeed = 38400;
 422         pty_slave_driver->flags = TTY_DRIVER_RESET_TERMIOS |
 423                                         TTY_DRIVER_REAL_RAW;
 424         pty_slave_driver->other = pty_driver;
 425         tty_set_operations(pty_slave_driver, &slave_pty_ops_bsd);
 426
 427         if (tty_register_driver(pty_driver))
 428                 panic("Couldn't register pty driver");
 429         if (tty_register_driver(pty_slave_driver))
 430                 panic("Couldn't register pty slave driver");
 431 }
 432 #else
 433 static inline void legacy_pty_init(void) { }
 434 #endif
 435
 436 /* Unix98 devices */
 437 #ifdef CONFIG_UNIX98_PTYS
 438
 439 static struct cdev ptmx_cdev;
 440
 441 static int pty_unix98_ioctl(struct tty_struct *tty,
 442                             unsigned int cmd, unsigned long arg)
 443 {
 444         switch (cmd) {
 445         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
 446                 return pty_set_lock(tty, (int __user *)arg);
 447         case TIOCGPTN: /* Get PT Number */
 448                 return put_user(tty->index, (unsigned int __user *)arg);
 449         case TIOCSIG:    /* Send signal to other side of pty */
 450                 return pty_signal(tty, (int) arg);
 451         }
 452
 453         return -ENOIOCTLCMD;
 454 }
 455
 456 /**
 457  *      ptm_unix98_lookup       -       find a pty master
 458  *      @driver: ptm driver
 459  *      @idx: tty index
 460  *
 461  *      Look up a pty master device. Called under the tty_mutex for now.
 462  *      This provides our locking.
 463  */
 464
 465 static struct tty_struct *ptm_unix98_lookup(struct tty_driver *driver,
 466                 struct inode *ptm_inode, int idx)
 467 {
 468         /* Master must be open via /dev/ptmx */
 469         return ERR_PTR(-EIO);
 470 }
 471
 472 /**
 473  *      pts_unix98_lookup       -       find a pty slave
 474  *      @driver: pts driver
 475  *      @idx: tty index
 476  *
 477  *      Look up a pty master device. Called under the tty_mutex for now.
 478  *      This provides our locking.
 479  */
 480
 481 static struct tty_struct *pts_unix98_lookup(struct tty_driver *driver,
 482                 struct inode *pts_inode, int idx)
 483 {
 484         struct tty_struct *tty = devpts_get_tty(pts_inode, idx);
 485         /* Master must be open before slave */
 486         if (!tty)
 487                 return ERR_PTR(-EIO);
 488         return tty;
 489 }
 490
 491 static void pty_unix98_shutdown(struct tty_struct *tty)
 492 {
 493         tty_driver_remove_tty(tty->driver, tty);
 494         /* We have our own method as we don't use the tty index */
 495         kfree(tty->termios);
 496 }
 497
 498 /* We have no need to install and remove our tty objects as devpts does all
 499    the work for us */
 500
 501 static int pty_unix98_install(struct tty_driver *driver, struct tty_struct *tty)
 502 {
 503         struct tty_struct *o_tty;
 504         int idx = tty->index;
 505
 506         o_tty = alloc_tty_struct();
 507         if (!o_tty)
 508                 return -ENOMEM;
 509         if (!try_module_get(driver->other->owner)) {
 510                 /* This cannot in fact currently happen */
 511                 goto err_free_tty;
 512         }
 513         initialize_tty_struct(o_tty, driver->other, idx);
 514
 515         tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 516         if (tty->termios == NULL)
 517                 goto err_free_mem;
 518         *tty->termios = driver->init_termios;
 519         tty->termios_locked = tty->termios + 1;
 520
 521         o_tty->termios = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
 522         if (o_tty->termios == NULL)
 523                 goto err_free_mem;
 524         *o_tty->termios = driver->other->init_termios;
 525         o_tty->termios_locked = o_tty->termios + 1;
 526
 527         tty_driver_kref_get(driver->other);
 528         if (driver->subtype == PTY_TYPE_MASTER)
 529                 o_tty->count++;
 530         /* Establish the links in both directions */
 531         tty->link   = o_tty;
 532         o_tty->link = tty;
 533         /*
 534          * All structures have been allocated, so now we install them.
 535          * Failures after this point use release_tty to clean up, so
 536          * there's no need to null out the local pointers.
 537          */
 538         tty_driver_kref_get(driver);
 539         tty->count++;
 540         return 0;
 541 err_free_mem:
 542         deinitialize_tty_struct(o_tty);
 543         kfree(o_tty->termios);
 544         kfree(tty->termios);
 545         module_put(o_tty->driver->owner);
 546 err_free_tty:
 547         free_tty_struct(o_tty);
 548         return -ENOMEM;
 549 }
 550
 551 static void ptm_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 552 {
 553 }
 554
 555 static void pts_unix98_remove(struct tty_driver *driver, struct tty_struct *tty)
 556 {
 557 }
 558
 559 static const struct tty_operations ptm_unix98_ops = {
 560         .lookup = ptm_unix98_lookup,
 561         .install = pty_unix98_install,
 562         .remove = ptm_unix98_remove,
 563         .open = pty_open,
 564         .close = pty_close,
 565         .write = pty_write,
 566         .write_room = pty_write_room,
 567         .flush_buffer = pty_flush_buffer,
 568         .chars_in_buffer = pty_chars_in_buffer,
 569         .unthrottle = pty_unthrottle,
 570         .set_termios = pty_set_termios,
 571         .ioctl = pty_unix98_ioctl,
 572         .shutdown = pty_unix98_shutdown,
 573         .resize = pty_resize
 574 };
 575
 576 static const struct tty_operations pty_unix98_ops = {
 577         .lookup = pts_unix98_lookup,
 578         .install = pty_unix98_install,
 579         .remove = pts_unix98_remove,
 580         .open = pty_open,
 581         .close = pty_close,
 582         .write = pty_write,
 583         .write_room = pty_write_room,
 584         .flush_buffer = pty_flush_buffer,
 585         .chars_in_buffer = pty_chars_in_buffer,
 586         .unthrottle = pty_unthrottle,
 587         .set_termios = pty_set_termios,
 588         .shutdown = pty_unix98_shutdown
 589 };
 590
 591 /**
 592  *      ptmx_open               -       open a unix 98 pty master
 593  *      @inode: inode of device file
 594  *      @filp: file pointer to tty
 595  *
 596  *      Allocate a unix98 pty master device from the ptmx driver.
 597  *
 598  *      Locking: tty_mutex protects the init_dev work. tty->count should
 599  *              protect the rest.
 600  *              allocated_ptys_lock handles the list of free pty numbers
 601  */
 602
 603 static int ptmx_open(struct inode *inode, struct file *filp)
 604 {
 605         struct tty_struct *tty;
 606         int retval;
 607         int index;
 608
 609         nonseekable_open(inode, filp);
 610
 611         retval = tty_alloc_file(filp);
 612         if (retval)
 613                 return retval;
 614
 615         /* find a device that is not in use. */
 616         tty_lock();
 617         index = devpts_new_index(inode);
 618         tty_unlock();
 619         if (index < 0) {
 620                 retval = index;
 621                 goto err_file;
 622         }
 623
 624         mutex_lock(&tty_mutex);
 625         tty_lock();
 626         tty = tty_init_dev(ptm_driver, index);
 627         mutex_unlock(&tty_mutex);
 628
 629         if (IS_ERR(tty)) {
 630                 retval = PTR_ERR(tty);
 631                 goto out;
 632         }
 633
 634         set_bit(TTY_PTY_LOCK, &tty->flags); /* LOCK THE SLAVE */
 635
 636         tty_add_file(tty, filp);
 637
 638         retval = devpts_pty_new(inode, tty->link);
 639         if (retval)
 640                 goto err_release;
 641
 642         retval = ptm_driver->ops->open(tty, filp);
 643         if (retval)
 644                 goto err_release;
 645
 646         tty_unlock();
 647         return 0;
 648 err_release:
 649         tty_unlock();
 650         tty_release(inode, filp);
 651         return retval;
 652 out:
 653         devpts_kill_index(inode, index);
 654         tty_unlock();
 655 err_file:
 656         tty_free_file(filp);
 657         return retval;
 658 }
 659
 660 static struct file_operations ptmx_fops;
 661
 662 static void __init unix98_pty_init(void)
 663 {
 664         ptm_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 665         if (!ptm_driver)
 666                 panic("Couldn't allocate Unix98 ptm driver");
 667         pts_driver = alloc_tty_driver(NR_UNIX98_PTY_MAX);
 668         if (!pts_driver)
 669                 panic("Couldn't allocate Unix98 pts driver");
 670
 671         ptm_driver->driver_name = "pty_master";
 672         ptm_driver->name = "ptm";
 673         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
 674         ptm_driver->minor_start = 0;
 675         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
 676         ptm_driver->subtype = PTY_TYPE_MASTER;
 677         ptm_driver->init_termios = tty_std_termios;
 678         ptm_driver->init_termios.c_iflag = 0;
 679         ptm_driver->init_termios.c_oflag = 0;
 680         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 681         ptm_driver->init_termios.c_lflag = 0;
 682         ptm_driver->init_termios.c_ispeed = 38400;
 683         ptm_driver->init_termios.c_ospeed = 38400;
 684         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 685                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 686         ptm_driver->other = pts_driver;
 687         tty_set_operations(ptm_driver, &ptm_unix98_ops);
 688
 689         pts_driver->driver_name = "pty_slave";
 690         pts_driver->name = "pts";
 691         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
 692         pts_driver->minor_start = 0;
 693         pts_driver->type = TTY_DRIVER_TYPE_PTY;
 694         pts_driver->subtype = PTY_TYPE_SLAVE;
 695         pts_driver->init_termios = tty_std_termios;
 696         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
 697         pts_driver->init_termios.c_ispeed = 38400;
 698         pts_driver->init_termios.c_ospeed = 38400;
 699         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 700                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
 701         pts_driver->other = ptm_driver;
 702         tty_set_operations(pts_driver, &pty_unix98_ops);
 703
 704         if (tty_register_driver(ptm_driver))
 705                 panic("Couldn't register Unix98 ptm driver");
 706         if (tty_register_driver(pts_driver))
 707                 panic("Couldn't register Unix98 pts driver");
 708
 709         /* Now create the /dev/ptmx special device */
 710         tty_default_fops(&ptmx_fops);
 711         ptmx_fops.open = ptmx_open;
 712
 713         cdev_init(&ptmx_cdev, &ptmx_fops);
 714         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
 715             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
 716                 panic("Couldn't register /dev/ptmx driver\n");
 717         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
 718 }
 719
 720 #else
 721 static inline void unix98_pty_init(void) { }
 722 #endif
 723
 724 static int __init pty_init(void)
 725 {
 726         legacy_pty_init();
 727         unix98_pty_init();
 728         return 0;
 729 }
 730 module_init(pty_init);