Revert "TTY: get rid of BTM around devpts_*"
[linux-2.6.git] / 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 #include <asm/system.h>
31
32 #ifdef CONFIG_UNIX98_PTYS
33 static struct tty_driver *ptm_driver;
34 static struct tty_driver *pts_driver;
35 #endif
36
37 static void pty_close(struct tty_struct *tty, struct file *filp)
38 {
39         BUG_ON(!tty);
40         if (tty->driver->subtype == PTY_TYPE_MASTER)
41                 WARN_ON(tty->count > 1);
42         else {
43                 if (tty->count > 2)
44                         return;
45         }
46         wake_up_interruptible(&tty->read_wait);
47         wake_up_interruptible(&tty->write_wait);
48         tty->packet = 0;
49         if (!tty->link)
50                 return;
51         tty->link->packet = 0;
52         set_bit(TTY_OTHER_CLOSED, &tty->link->flags);
53         wake_up_interruptible(&tty->link->read_wait);
54         wake_up_interruptible(&tty->link->write_wait);
55         if (tty->driver->subtype == PTY_TYPE_MASTER) {
56                 set_bit(TTY_OTHER_CLOSED, &tty->flags);
57                 devpts_pty_kill(tty->link);
58                 tty_unlock();
59                 tty_vhangup(tty->link);
60                 tty_lock();
61         }
62 }
63
64 /*
65  * The unthrottle routine is called by the line discipline to signal
66  * that it can receive more characters.  For PTY's, the TTY_THROTTLED
67  * flag is always set, to force the line discipline to always call the
68  * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE
69  * characters in the queue.  This is necessary since each time this
70  * happens, we need to wake up any sleeping processes that could be
71  * (1) trying to send data to the pty, or (2) waiting in wait_until_sent()
72  * for the pty buffer to be drained.
73  */
74 static void pty_unthrottle(struct tty_struct *tty)
75 {
76         tty_wakeup(tty->link);
77         set_bit(TTY_THROTTLED, &tty->flags);
78 }
79
80 /**
81  *      pty_space       -       report space left for writing
82  *      @to: tty we are writing into
83  *
84  *      The tty buffers allow 64K but we sneak a peak and clip at 8K this
85  *      allows a lot of overspill room for echo and other fun messes to
86  *      be handled properly
87  */
88
89 static int pty_space(struct tty_struct *to)
90 {
91         int n = 8192 - to->buf.memory_used;
92         if (n < 0)
93                 return 0;
94         return n;
95 }
96
97 /**
98  *      pty_write               -       write to a pty
99  *      @tty: the tty we write from
100  *      @buf: kernel buffer of data
101  *      @count: bytes to write
102  *
103  *      Our "hardware" write method. Data is coming from the ldisc which
104  *      may be in a non sleeping state. We simply throw this at the other
105  *      end of the link as if we were an IRQ handler receiving stuff for
106  *      the other side of the pty/tty pair.
107  */
108
109 static int pty_write(struct tty_struct *tty, const unsigned char *buf, int c)
110 {
111         struct tty_struct *to = tty->link;
112
113         if (tty->stopped)
114                 return 0;
115
116         if (c > 0) {
117                 /* Stuff the data into the input queue of the other end */
118                 c = tty_insert_flip_string(to, buf, c);
119                 /* And shovel */
120                 if (c) {
121                         tty_flip_buffer_push(to);
122                         tty_wakeup(tty);
123                 }
124         }
125         return c;
126 }
127
128 /**
129  *      pty_write_room  -       write space
130  *      @tty: tty we are writing from
131  *
132  *      Report how many bytes the ldisc can send into the queue for
133  *      the other device.
134  */
135
136 static int pty_write_room(struct tty_struct *tty)
137 {
138         if (tty->stopped)
139                 return 0;
140         return pty_space(tty->link);
141 }
142
143 /**
144  *      pty_chars_in_buffer     -       characters currently in our tx queue
145  *      @tty: our tty
146  *
147  *      Report how much we have in the transmit queue. As everything is
148  *      instantly at the other end this is easy to implement.
149  */
150
151 static int pty_chars_in_buffer(struct tty_struct *tty)
152 {
153         return 0;
154 }
155
156 /* Set the lock flag on a pty */
157 static int pty_set_lock(struct tty_struct *tty, int __user *arg)
158 {
159         int val;
160         if (get_user(val, arg))
161                 return -EFAULT;
162         if (val)
163                 set_bit(TTY_PTY_LOCK, &tty->flags);
164         else
165                 clear_bit(TTY_PTY_LOCK, &tty->flags);
166         return 0;
167 }
168
169 /* Send a signal to the slave */
170 static int pty_signal(struct tty_struct *tty, int sig)
171 {
172         unsigned long flags;
173         struct pid *pgrp;
174
175         if (tty->link) {
176                 spin_lock_irqsave(&tty->link->ctrl_lock, flags);
177                 pgrp = get_pid(tty->link->pgrp);
178                 spin_unlock_irqrestore(&tty->link->ctrl_lock, flags);
179
180                 kill_pgrp(pgrp, sig, 1);
181                 put_pid(pgrp);
182         }
183         return 0;
184 }
185
186 static void pty_flush_buffer(struct tty_struct *tty)
187 {
188         struct tty_struct *to = tty->link;
189         unsigned long flags;
190
191         if (!to)
192                 return;
193         /* tty_buffer_flush(to); FIXME */
194         if (to->packet) {
195                 spin_lock_irqsave(&tty->ctrl_lock, flags);
196                 tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
197                 wake_up_interruptible(&to->read_wait);
198                 spin_unlock_irqrestore(&tty->ctrl_lock, flags);
199         }
200 }
201
202 static int pty_open(struct tty_struct *tty, struct file *filp)
203 {
204         int     retval = -ENODEV;
205
206         if (!tty || !tty->link)
207                 goto out;
208
209         retval = -EIO;
210         if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
211                 goto out;
212         if (test_bit(TTY_PTY_LOCK, &tty->link->flags))
213                 goto out;
214         if (tty->link->count != 1)
215                 goto out;
216
217         clear_bit(TTY_OTHER_CLOSED, &tty->link->flags);
218         set_bit(TTY_THROTTLED, &tty->flags);
219         retval = 0;
220 out:
221         return retval;
222 }
223
224 static void pty_set_termios(struct tty_struct *tty,
225                                         struct ktermios *old_termios)
226 {
227         tty->termios->c_cflag &= ~(CSIZE | PARENB);
228         tty->termios->c_cflag |= (CS8 | CREAD);
229 }
230
231 /**
232  *      pty_do_resize           -       resize event
233  *      @tty: tty being resized
234  *      @ws: window size being set.
235  *
236  *      Update the termios variables and send the necessary signals to
237  *      peform a terminal resize correctly
238  */
239
240 int pty_resize(struct tty_struct *tty,  struct winsize *ws)
241 {
242         struct pid *pgrp, *rpgrp;
243         unsigned long flags;
244         struct tty_struct *pty = tty->link;
245
246         /* For a PTY we need to lock the tty side */
247         mutex_lock(&tty->termios_mutex);
248         if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
249                 goto done;
250
251         /* Get the PID values and reference them so we can
252            avoid holding the tty ctrl lock while sending signals.
253            We need to lock these individually however. */
254
255         spin_lock_irqsave(&tty->ctrl_lock, flags);
256         pgrp = get_pid(tty->pgrp);
257         spin_unlock_irqrestore(&tty->ctrl_lock, flags);
258
259         spin_lock_irqsave(&pty->ctrl_lock, flags);
260         rpgrp = get_pid(pty->pgrp);
261         spin_unlock_irqrestore(&pty->ctrl_lock, flags);
262
263         if (pgrp)
264                 kill_pgrp(pgrp, SIGWINCH, 1);
265         if (rpgrp != pgrp && rpgrp)
266                 kill_pgrp(rpgrp, SIGWINCH, 1);
267
268         put_pid(pgrp);
269         put_pid(rpgrp);
270
271         tty->winsize = *ws;
272         pty->winsize = *ws;     /* Never used so will go away soon */
273 done:
274         mutex_unlock(&tty->termios_mutex);
275         return 0;
276 }
277
278 /* Traditional BSD devices */
279 #ifdef CONFIG_LEGACY_PTYS
280
281 static int pty_install(struct tty_driver *driver, struct tty_struct *tty)
282 {
283         struct tty_struct *o_tty;
284         int idx = tty->index;
285         int retval;
286
287         o_tty = alloc_tty_struct();
288         if (!o_tty)
289                 return -ENOMEM;
290         if (!try_module_get(driver->other->owner)) {
291                 /* This cannot in fact currently happen */
292                 retval = -ENOMEM;
293                 goto err_free_tty;
294         }
295         initialize_tty_struct(o_tty, driver->other, idx);
296
297         /* We always use new tty termios data so we can do this
298            the easy way .. */
299         retval = tty_init_termios(tty);
300         if (retval)
301                 goto err_deinit_tty;
302
303         retval = tty_init_termios(o_tty);
304         if (retval)
305                 goto err_free_termios;
306
307         /*
308          * Everything allocated ... set up the o_tty structure.
309          */
310         driver->other->ttys[idx] = o_tty;
311         tty_driver_kref_get(driver->other);
312         if (driver->subtype == PTY_TYPE_MASTER)
313                 o_tty->count++;
314         /* Establish the links in both directions */
315         tty->link   = o_tty;
316         o_tty->link = tty;
317
318         tty_driver_kref_get(driver);
319         tty->count++;
320         driver->ttys[idx] = tty;
321         return 0;
322 err_free_termios:
323         tty_free_termios(tty);
324 err_deinit_tty:
325         deinitialize_tty_struct(o_tty);
326         module_put(o_tty->driver->owner);
327 err_free_tty:
328         free_tty_struct(o_tty);
329         return retval;
330 }
331
332 static int pty_bsd_ioctl(struct tty_struct *tty,
333                          unsigned int cmd, unsigned long arg)
334 {
335         switch (cmd) {
336         case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */
337                 return pty_set_lock(tty, (int __user *) arg);
338         case TIOCSIG:    /* Send signal to other side of pty */
339                 return pty_signal(tty, (int) arg);
340         }
341         return -ENOIOCTLCMD;
342 }
343
344 static int legacy_count = CONFIG_LEGACY_PTY_COUNT;
345 module_param(legacy_count, int, 0);
346
347 /*
348  * The master side of a pty can do TIOCSPTLCK and thus
349  * has pty_bsd_ioctl.
350  */
351 static const struct tty_operations master_pty_ops_bsd = {
352         .install = pty_install,
353         .open = pty_open,
354         .close = pty_close,
355         .write = pty_write,
356         .write_room = pty_write_room,
357         .flush_buffer = pty_flush_buffer,
358         .chars_in_buffer = pty_chars_in_buffer,
359         .unthrottle = pty_unthrottle,
360         .set_termios = pty_set_termios,
361         .ioctl = pty_bsd_ioctl,
362         .resize = pty_resize
363 };
364
365 static const struct tty_operations slave_pty_ops_bsd = {
366         .install = pty_install,
367         .open = pty_open,
368         .close = pty_close,
369         .write = pty_write,
370         .write_room = pty_write_room,
371         .flush_buffer = pty_flush_buffer,
372         .chars_in_buffer = pty_chars_in_buffer,
373         .unthrottle = pty_unthrottle,
374         .set_termios = pty_set_termios,
375         .resize = pty_resize
376 };
377
378 static void __init legacy_pty_init(void)
379 {
380         struct tty_driver *pty_driver, *pty_slave_driver;
381
382         if (legacy_count <= 0)
383                 return;
384
385         pty_driver = alloc_tty_driver(legacy_count);
386         if (!pty_driver)
387                 panic("Couldn't allocate pty driver");
388
389         pty_slave_driver = alloc_tty_driver(legacy_count);
390         if (!pty_slave_driver)
391                 panic("Couldn't allocate pty slave driver");
392
393         pty_driver->owner = THIS_MODULE;
394         pty_driver->driver_name = "pty_master";
395         pty_driver->name = "pty";
396         pty_driver->major = PTY_MASTER_MAJOR;
397         pty_driver->minor_start = 0;
398         pty_driver->type = TTY_DRIVER_TYPE_PTY;
399         pty_driver->subtype = PTY_TYPE_MASTER;
400         pty_driver->init_termios = tty_std_termios;
401         pty_driver->init_termios.c_iflag = 0;
402         pty_driver->init_termios.c_oflag = 0;
403         pty_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
404         pty_driver->init_termios.c_lflag = 0;
405         pty_driver->init_termios.c_ispeed = 38400;
406         pty_driver->init_termios.c_ospeed = 38400;
407         pty_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW;
408         pty_driver->other = pty_slave_driver;
409         tty_set_operations(pty_driver, &master_pty_ops_bsd);
410
411         pty_slave_driver->owner = THIS_MODULE;
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->owner = THIS_MODULE;
672         ptm_driver->driver_name = "pty_master";
673         ptm_driver->name = "ptm";
674         ptm_driver->major = UNIX98_PTY_MASTER_MAJOR;
675         ptm_driver->minor_start = 0;
676         ptm_driver->type = TTY_DRIVER_TYPE_PTY;
677         ptm_driver->subtype = PTY_TYPE_MASTER;
678         ptm_driver->init_termios = tty_std_termios;
679         ptm_driver->init_termios.c_iflag = 0;
680         ptm_driver->init_termios.c_oflag = 0;
681         ptm_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
682         ptm_driver->init_termios.c_lflag = 0;
683         ptm_driver->init_termios.c_ispeed = 38400;
684         ptm_driver->init_termios.c_ospeed = 38400;
685         ptm_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
686                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
687         ptm_driver->other = pts_driver;
688         tty_set_operations(ptm_driver, &ptm_unix98_ops);
689
690         pts_driver->owner = THIS_MODULE;
691         pts_driver->driver_name = "pty_slave";
692         pts_driver->name = "pts";
693         pts_driver->major = UNIX98_PTY_SLAVE_MAJOR;
694         pts_driver->minor_start = 0;
695         pts_driver->type = TTY_DRIVER_TYPE_PTY;
696         pts_driver->subtype = PTY_TYPE_SLAVE;
697         pts_driver->init_termios = tty_std_termios;
698         pts_driver->init_termios.c_cflag = B38400 | CS8 | CREAD;
699         pts_driver->init_termios.c_ispeed = 38400;
700         pts_driver->init_termios.c_ospeed = 38400;
701         pts_driver->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
702                 TTY_DRIVER_DYNAMIC_DEV | TTY_DRIVER_DEVPTS_MEM;
703         pts_driver->other = ptm_driver;
704         tty_set_operations(pts_driver, &pty_unix98_ops);
705
706         if (tty_register_driver(ptm_driver))
707                 panic("Couldn't register Unix98 ptm driver");
708         if (tty_register_driver(pts_driver))
709                 panic("Couldn't register Unix98 pts driver");
710
711         /* Now create the /dev/ptmx special device */
712         tty_default_fops(&ptmx_fops);
713         ptmx_fops.open = ptmx_open;
714
715         cdev_init(&ptmx_cdev, &ptmx_fops);
716         if (cdev_add(&ptmx_cdev, MKDEV(TTYAUX_MAJOR, 2), 1) ||
717             register_chrdev_region(MKDEV(TTYAUX_MAJOR, 2), 1, "/dev/ptmx") < 0)
718                 panic("Couldn't register /dev/ptmx driver\n");
719         device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 2), NULL, "ptmx");
720 }
721
722 #else
723 static inline void unix98_pty_init(void) { }
724 #endif
725
726 static int __init pty_init(void)
727 {
728         legacy_pty_init();
729         unix98_pty_init();
730         return 0;
731 }
732 module_init(pty_init);