1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_TTY_DRIVER_H
3#define _LINUX_TTY_DRIVER_H
4
5#include <linux/export.h>
6#include <linux/fs.h>
7#include <linux/kref.h>
8#include <linux/list.h>
9#include <linux/cdev.h>
10#include <linux/termios.h>
11#include <linux/seq_file.h>
12
13struct tty_struct;
14struct tty_driver;
15struct serial_icounter_struct;
16struct serial_struct;
17
18/**
19 * struct tty_operations -- interface between driver and tty
20 *
21 * @lookup: ``struct tty_struct *()(struct tty_driver *self, struct file *,
22 * int idx)``
23 *
24 * Return the tty device corresponding to @idx, %NULL if there is not
25 * one currently in use and an %ERR_PTR value on error. Called under
26 * %tty_mutex (for now!)
27 *
28 * Optional method. Default behaviour is to use the @self->ttys array.
29 *
30 * @install: ``int ()(struct tty_driver *self, struct tty_struct *tty)``
31 *
32 * Install a new @tty into the @self's internal tables. Used in
33 * conjunction with @lookup and @remove methods.
34 *
35 * Optional method. Default behaviour is to use the @self->ttys array.
36 *
37 * @remove: ``void ()(struct tty_driver *self, struct tty_struct *tty)``
38 *
39 * Remove a closed @tty from the @self's internal tables. Used in
40 * conjunction with @lookup and @remove methods.
41 *
42 * Optional method. Default behaviour is to use the @self->ttys array.
43 *
44 * @open: ``int ()(struct tty_struct *tty, struct file *)``
45 *
46 * This routine is called when a particular @tty device is opened. This
47 * routine is mandatory; if this routine is not filled in, the attempted
48 * open will fail with %ENODEV.
49 *
50 * Required method. Called with tty lock held. May sleep.
51 *
52 * @close: ``void ()(struct tty_struct *tty, struct file *)``
53 *
54 * This routine is called when a particular @tty device is closed. At the
55 * point of return from this call the driver must make no further ldisc
56 * calls of any kind.
57 *
58 * Remark: called even if the corresponding @open() failed.
59 *
60 * Required method. Called with tty lock held. May sleep.
61 *
62 * @shutdown: ``void ()(struct tty_struct *tty)``
63 *
64 * This routine is called under the tty lock when a particular @tty device
65 * is closed for the last time. It executes before the @tty resources
66 * are freed so may execute while another function holds a @tty kref.
67 *
68 * @cleanup: ``void ()(struct tty_struct *tty)``
69 *
70 * This routine is called asynchronously when a particular @tty device
71 * is closed for the last time freeing up the resources. This is
72 * actually the second part of shutdown for routines that might sleep.
73 *
74 * @write: ``int ()(struct tty_struct *tty, const unsigned char *buf,
75 * int count)``
76 *
77 * This routine is called by the kernel to write a series (@count) of
78 * characters (@buf) to the @tty device. The characters may come from
79 * user space or kernel space. This routine will return the
80 * number of characters actually accepted for writing.
81 *
82 * May occur in parallel in special cases. Because this includes panic
83 * paths drivers generally shouldn't try and do clever locking here.
84 *
85 * Optional: Required for writable devices. May not sleep.
86 *
87 * @put_char: ``int ()(struct tty_struct *tty, unsigned char ch)``
88 *
89 * This routine is called by the kernel to write a single character @ch to
90 * the @tty device. If the kernel uses this routine, it must call the
91 * @flush_chars() routine (if defined) when it is done stuffing characters
92 * into the driver. If there is no room in the queue, the character is
93 * ignored.
94 *
95 * Optional: Kernel will use the @write method if not provided. Do not
96 * call this function directly, call tty_put_char().
97 *
98 * @flush_chars: ``void ()(struct tty_struct *tty)``
99 *
100 * This routine is called by the kernel after it has written a
101 * series of characters to the tty device using @put_char().
102 *
103 * Optional. Do not call this function directly, call
104 * tty_driver_flush_chars().
105 *
106 * @write_room: ``unsigned int ()(struct tty_struct *tty)``
107 *
108 * This routine returns the numbers of characters the @tty driver
109 * will accept for queuing to be written. This number is subject
110 * to change as output buffers get emptied, or if the output flow
111 * control is acted.
112 *
113 * The ldisc is responsible for being intelligent about multi-threading of
114 * write_room/write calls
115 *
116 * Required if @write method is provided else not needed. Do not call this
117 * function directly, call tty_write_room()
118 *
119 * @chars_in_buffer: ``unsigned int ()(struct tty_struct *tty)``
120 *
121 * This routine returns the number of characters in the device private
122 * output queue. Used in tty_wait_until_sent() and for poll()
123 * implementation.
124 *
125 * Optional: if not provided, it is assumed there is no queue on the
126 * device. Do not call this function directly, call tty_chars_in_buffer().
127 *
128 * @ioctl: ``int ()(struct tty_struct *tty, unsigned int cmd,
129 * unsigned long arg)``
130 *
131 * This routine allows the @tty driver to implement device-specific
132 * ioctls. If the ioctl number passed in @cmd is not recognized by the
133 * driver, it should return %ENOIOCTLCMD.
134 *
135 * Optional.
136 *
137 * @compat_ioctl: ``long ()(struct tty_struct *tty, unsigned int cmd,
138 * unsigned long arg)``
139 *
140 * Implement ioctl processing for 32 bit process on 64 bit system.
141 *
142 * Optional.
143 *
144 * @set_termios: ``void ()(struct tty_struct *tty, struct ktermios *old)``
145 *
146 * This routine allows the @tty driver to be notified when device's
147 * termios settings have changed. New settings are in @tty->termios.
148 * Previous settings are passed in the @old argument.
149 *
150 * The API is defined such that the driver should return the actual modes
151 * selected. This means that the driver is responsible for modifying any
152 * bits in @tty->termios it cannot fulfill to indicate the actual modes
153 * being used.
154 *
155 * Optional. Called under the @tty->termios_rwsem. May sleep.
156 *
157 * @set_ldisc: ``void ()(struct tty_struct *tty)``
158 *
159 * This routine allows the @tty driver to be notified when the device's
160 * line discipline is being changed. At the point this is done the
161 * discipline is not yet usable.
162 *
163 * Optional. Called under the @tty->ldisc_sem and @tty->termios_rwsem.
164 *
165 * @throttle: ``void ()(struct tty_struct *tty)``
166 *
167 * This routine notifies the @tty driver that input buffers for the line
168 * discipline are close to full, and it should somehow signal that no more
169 * characters should be sent to the @tty.
170 *
171 * Serialization including with @unthrottle() is the job of the ldisc
172 * layer.
173 *
174 * Optional: Always invoke via tty_throttle_safe(). Called under the
175 * @tty->termios_rwsem.
176 *
177 * @unthrottle: ``void ()(struct tty_struct *tty)``
178 *
179 * This routine notifies the @tty driver that it should signal that
180 * characters can now be sent to the @tty without fear of overrunning the
181 * input buffers of the line disciplines.
182 *
183 * Optional. Always invoke via tty_unthrottle(). Called under the
184 * @tty->termios_rwsem.
185 *
186 * @stop: ``void ()(struct tty_struct *tty)``
187 *
188 * This routine notifies the @tty driver that it should stop outputting
189 * characters to the tty device.
190 *
191 * Called with @tty->flow.lock held. Serialized with @start() method.
192 *
193 * Optional. Always invoke via stop_tty().
194 *
195 * @start: ``void ()(struct tty_struct *tty)``
196 *
197 * This routine notifies the @tty driver that it resumed sending
198 * characters to the @tty device.
199 *
200 * Called with @tty->flow.lock held. Serialized with stop() method.
201 *
202 * Optional. Always invoke via start_tty().
203 *
204 * @hangup: ``void ()(struct tty_struct *tty)``
205 *
206 * This routine notifies the @tty driver that it should hang up the @tty
207 * device.
208 *
209 * Optional. Called with tty lock held.
210 *
211 * @break_ctl: ``int ()(struct tty_struct *tty, int state)``
212 *
213 * This optional routine requests the @tty driver to turn on or off BREAK
214 * status on the RS-232 port. If @state is -1, then the BREAK status
215 * should be turned on; if @state is 0, then BREAK should be turned off.
216 *
217 * If this routine is implemented, the high-level tty driver will handle
218 * the following ioctls: %TCSBRK, %TCSBRKP, %TIOCSBRK, %TIOCCBRK.
219 *
220 * If the driver sets %TTY_DRIVER_HARDWARE_BREAK in tty_alloc_driver(),
221 * then the interface will also be called with actual times and the
222 * hardware is expected to do the delay work itself. 0 and -1 are still
223 * used for on/off.
224 *
225 * Optional: Required for %TCSBRK/%BRKP/etc. handling. May sleep.
226 *
227 * @flush_buffer: ``void ()(struct tty_struct *tty)``
228 *
229 * This routine discards device private output buffer. Invoked on close,
230 * hangup, to implement %TCOFLUSH ioctl and similar.
231 *
232 * Optional: if not provided, it is assumed there is no queue on the
233 * device. Do not call this function directly, call
234 * tty_driver_flush_buffer().
235 *
236 * @wait_until_sent: ``void ()(struct tty_struct *tty, int timeout)``
237 *
238 * This routine waits until the device has written out all of the
239 * characters in its transmitter FIFO. Or until @timeout (in jiffies) is
240 * reached.
241 *
242 * Optional: If not provided, the device is assumed to have no FIFO.
243 * Usually correct to invoke via tty_wait_until_sent(). May sleep.
244 *
245 * @send_xchar: ``void ()(struct tty_struct *tty, char ch)``
246 *
247 * This routine is used to send a high-priority XON/XOFF character (@ch)
248 * to the @tty device.
249 *
250 * Optional: If not provided, then the @write method is called under
251 * the @tty->atomic_write_lock to keep it serialized with the ldisc.
252 *
253 * @tiocmget: ``int ()(struct tty_struct *tty)``
254 *
255 * This routine is used to obtain the modem status bits from the @tty
256 * driver.
257 *
258 * Optional: If not provided, then %ENOTTY is returned from the %TIOCMGET
259 * ioctl. Do not call this function directly, call tty_tiocmget().
260 *
261 * @tiocmset: ``int ()(struct tty_struct *tty,
262 * unsigned int set, unsigned int clear)``
263 *
264 * This routine is used to set the modem status bits to the @tty driver.
265 * First, @clear bits should be cleared, then @set bits set.
266 *
267 * Optional: If not provided, then %ENOTTY is returned from the %TIOCMSET
268 * ioctl. Do not call this function directly, call tty_tiocmset().
269 *
270 * @resize: ``int ()(struct tty_struct *tty, struct winsize *ws)``
271 *
272 * Called when a termios request is issued which changes the requested
273 * terminal geometry to @ws.
274 *
275 * Optional: the default action is to update the termios structure
276 * without error. This is usually the correct behaviour. Drivers should
277 * not force errors here if they are not resizable objects (e.g. a serial
278 * line). See tty_do_resize() if you need to wrap the standard method
279 * in your own logic -- the usual case.
280 *
281 * @get_icount: ``int ()(struct tty_struct *tty,
282 * struct serial_icounter *icount)``
283 *
284 * Called when the @tty device receives a %TIOCGICOUNT ioctl. Passed a
285 * kernel structure @icount to complete.
286 *
287 * Optional: called only if provided, otherwise %ENOTTY will be returned.
288 *
289 * @get_serial: ``int ()(struct tty_struct *tty, struct serial_struct *p)``
290 *
291 * Called when the @tty device receives a %TIOCGSERIAL ioctl. Passed a
292 * kernel structure @p (&struct serial_struct) to complete.
293 *
294 * Optional: called only if provided, otherwise %ENOTTY will be returned.
295 * Do not call this function directly, call tty_tiocgserial().
296 *
297 * @set_serial: ``int ()(struct tty_struct *tty, struct serial_struct *p)``
298 *
299 * Called when the @tty device receives a %TIOCSSERIAL ioctl. Passed a
300 * kernel structure @p (&struct serial_struct) to set the values from.
301 *
302 * Optional: called only if provided, otherwise %ENOTTY will be returned.
303 * Do not call this function directly, call tty_tiocsserial().
304 *
305 * @show_fdinfo: ``void ()(struct tty_struct *tty, struct seq_file *m)``
306 *
307 * Called when the @tty device file descriptor receives a fdinfo request
308 * from VFS (to show in /proc/<pid>/fdinfo/). @m should be filled with
309 * information.
310 *
311 * Optional: called only if provided, otherwise nothing is written to @m.
312 * Do not call this function directly, call tty_show_fdinfo().
313 *
314 * @poll_init: ``int ()(struct tty_driver *driver, int line, char *options)``
315 *
316 * kgdboc support (Documentation/dev-tools/kgdb.rst). This routine is
317 * called to initialize the HW for later use by calling @poll_get_char or
318 * @poll_put_char.
319 *
320 * Optional: called only if provided, otherwise skipped as a non-polling
321 * driver.
322 *
323 * @poll_get_char: ``int ()(struct tty_driver *driver, int line)``
324 *
325 * kgdboc support (see @poll_init). @driver should read a character from a
326 * tty identified by @line and return it.
327 *
328 * Optional: called only if @poll_init provided.
329 *
330 * @poll_put_char: ``void ()(struct tty_driver *driver, int line, char ch)``
331 *
332 * kgdboc support (see @poll_init). @driver should write character @ch to
333 * a tty identified by @line.
334 *
335 * Optional: called only if @poll_init provided.
336 *
337 * @proc_show: ``int ()(struct seq_file *m, void *driver)``
338 *
339 * Driver @driver (cast to &struct tty_driver) can show additional info in
340 * /proc/tty/driver/<driver_name>. It is enough to fill in the information
341 * into @m.
342 *
343 * Optional: called only if provided, otherwise no /proc entry created.
344 *
345 * This structure defines the interface between the low-level tty driver and
346 * the tty routines. These routines can be defined. Unless noted otherwise,
347 * they are optional, and can be filled in with a %NULL pointer.
348 */
349struct tty_operations {
350 struct tty_struct * (*lookup)(struct tty_driver *driver,
351 struct file *filp, int idx);
352 int (*install)(struct tty_driver *driver, struct tty_struct *tty);
353 void (*remove)(struct tty_driver *driver, struct tty_struct *tty);
354 int (*open)(struct tty_struct * tty, struct file * filp);
355 void (*close)(struct tty_struct * tty, struct file * filp);
356 void (*shutdown)(struct tty_struct *tty);
357 void (*cleanup)(struct tty_struct *tty);
358 int (*write)(struct tty_struct * tty,
359 const unsigned char *buf, int count);
360 int (*put_char)(struct tty_struct *tty, unsigned char ch);
361 void (*flush_chars)(struct tty_struct *tty);
362 unsigned int (*write_room)(struct tty_struct *tty);
363 unsigned int (*chars_in_buffer)(struct tty_struct *tty);
364 int (*ioctl)(struct tty_struct *tty,
365 unsigned int cmd, unsigned long arg);
366 long (*compat_ioctl)(struct tty_struct *tty,
367 unsigned int cmd, unsigned long arg);
368 void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
369 void (*throttle)(struct tty_struct * tty);
370 void (*unthrottle)(struct tty_struct * tty);
371 void (*stop)(struct tty_struct *tty);
372 void (*start)(struct tty_struct *tty);
373 void (*hangup)(struct tty_struct *tty);
374 int (*break_ctl)(struct tty_struct *tty, int state);
375 void (*flush_buffer)(struct tty_struct *tty);
376 void (*set_ldisc)(struct tty_struct *tty);
377 void (*wait_until_sent)(struct tty_struct *tty, int timeout);
378 void (*send_xchar)(struct tty_struct *tty, char ch);
379 int (*tiocmget)(struct tty_struct *tty);
380 int (*tiocmset)(struct tty_struct *tty,
381 unsigned int set, unsigned int clear);
382 int (*resize)(struct tty_struct *tty, struct winsize *ws);
383 int (*get_icount)(struct tty_struct *tty,
384 struct serial_icounter_struct *icount);
385 int (*get_serial)(struct tty_struct *tty, struct serial_struct *p);
386 int (*set_serial)(struct tty_struct *tty, struct serial_struct *p);
387 void (*show_fdinfo)(struct tty_struct *tty, struct seq_file *m);
388#ifdef CONFIG_CONSOLE_POLL
389 int (*poll_init)(struct tty_driver *driver, int line, char *options);
390 int (*poll_get_char)(struct tty_driver *driver, int line);
391 void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
392#endif
393 int (*proc_show)(struct seq_file *m, void *driver);
394} __randomize_layout;
395
396/**
397 * struct tty_driver -- driver for TTY devices
398 *
399 * @magic: set to %TTY_DRIVER_MAGIC in __tty_alloc_driver()
400 * @kref: reference counting. Reaching zero frees all the internals and the
401 * driver.
402 * @cdevs: allocated/registered character /dev devices
403 * @owner: modules owning this driver. Used drivers cannot be rmmod'ed.
404 * Automatically set by tty_alloc_driver().
405 * @driver_name: name of the driver used in /proc/tty
406 * @name: used for constructing /dev node name
407 * @name_base: used as a number base for constructing /dev node name
408 * @major: major /dev device number (zero for autoassignment)
409 * @minor_start: the first minor /dev device number
410 * @num: number of devices allocated
411 * @type: type of tty driver (%TTY_DRIVER_TYPE_)
412 * @subtype: subtype of tty driver (%SYSTEM_TYPE_, %PTY_TYPE_, %SERIAL_TYPE_)
413 * @init_termios: termios to set to each tty initially (e.g. %tty_std_termios)
414 * @flags: tty driver flags (%TTY_DRIVER_)
415 * @proc_entry: proc fs entry, used internally
416 * @other: driver of the linked tty; only used for the PTY driver
417 * @ttys: array of active &struct tty_struct, set by tty_standard_install()
418 * @ports: array of &struct tty_port; can be set during initialization by
419 * tty_port_link_device() and similar
420 * @termios: storage for termios at each TTY close for the next open
421 * @driver_state: pointer to driver's arbitrary data
422 * @ops: driver hooks for TTYs. Set them using tty_set_operations(). Use &struct
423 * tty_port helpers in them as much as possible.
424 * @tty_drivers: used internally to link tty_drivers together
425 *
426 * The usual handling of &struct tty_driver is to allocate it by
427 * tty_alloc_driver(), set up all the necessary members, and register it by
428 * tty_register_driver(). At last, the driver is torn down by calling
429 * tty_unregister_driver() followed by tty_driver_kref_put().
430 *
431 * The fields required to be set before calling tty_register_driver() include
432 * @driver_name, @name, @type, @subtype, @init_termios, and @ops.
433 */
434struct tty_driver {
435 int magic;
436 struct kref kref;
437 struct cdev **cdevs;
438 struct module *owner;
439 const char *driver_name;
440 const char *name;
441 int name_base;
442 int major;
443 int minor_start;
444 unsigned int num;
445 short type;
446 short subtype;
447 struct ktermios init_termios;
448 unsigned long flags;
449 struct proc_dir_entry *proc_entry;
450 struct tty_driver *other;
451
452 /*
453 * Pointer to the tty data structures
454 */
455 struct tty_struct **ttys;
456 struct tty_port **ports;
457 struct ktermios **termios;
458 void *driver_state;
459
460 /*
461 * Driver methods
462 */
463
464 const struct tty_operations *ops;
465 struct list_head tty_drivers;
466} __randomize_layout;
467
468extern struct list_head tty_drivers;
469
470struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
471 unsigned long flags);
472struct tty_driver *tty_find_polling_driver(char *name, int *line);
473
474void tty_driver_kref_put(struct tty_driver *driver);
475
476/* Use TTY_DRIVER_* flags below */
477#define tty_alloc_driver(lines, flags) \
478 __tty_alloc_driver(lines, THIS_MODULE, flags)
479
480static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
481{
482 kref_get(&d->kref);
483 return d;
484}
485
486static inline void tty_set_operations(struct tty_driver *driver,
487 const struct tty_operations *op)
488{
489 driver->ops = op;
490}
491
492/* tty driver magic number */
493#define TTY_DRIVER_MAGIC 0x5402
494
495/**
496 * DOC: TTY Driver Flags
497 *
498 * TTY_DRIVER_RESET_TERMIOS
499 * Requests the tty layer to reset the termios setting when the last
500 * process has closed the device. Used for PTYs, in particular.
501 *
502 * TTY_DRIVER_REAL_RAW
503 * Indicates that the driver will guarantee not to set any special
504 * character handling flags if this is set for the tty:
505 *
506 * ``(IGNBRK || (!BRKINT && !PARMRK)) && (IGNPAR || !INPCK)``
507 *
508 * That is, if there is no reason for the driver to
509 * send notifications of parity and break characters up to the line
510 * driver, it won't do so. This allows the line driver to optimize for
511 * this case if this flag is set. (Note that there is also a promise, if
512 * the above case is true, not to signal overruns, either.)
513 *
514 * TTY_DRIVER_DYNAMIC_DEV
515 * The individual tty devices need to be registered with a call to
516 * tty_register_device() when the device is found in the system and
517 * unregistered with a call to tty_unregister_device() so the devices will
518 * be show up properly in sysfs. If not set, all &tty_driver.num entries
519 * will be created by the tty core in sysfs when tty_register_driver() is
520 * called. This is to be used by drivers that have tty devices that can
521 * appear and disappear while the main tty driver is registered with the
522 * tty core.
523 *
524 * TTY_DRIVER_DEVPTS_MEM
525 * Don't use the standard arrays (&tty_driver.ttys and
526 * &tty_driver.termios), instead use dynamic memory keyed through the
527 * devpts filesystem. This is only applicable to the PTY driver.
528 *
529 * TTY_DRIVER_HARDWARE_BREAK
530 * Hardware handles break signals. Pass the requested timeout to the
531 * &tty_operations.break_ctl instead of using a simple on/off interface.
532 *
533 * TTY_DRIVER_DYNAMIC_ALLOC
534 * Do not allocate structures which are needed per line for this driver
535 * (&tty_driver.ports) as it would waste memory. The driver will take
536 * care. This is only applicable to the PTY driver.
537 *
538 * TTY_DRIVER_UNNUMBERED_NODE
539 * Do not create numbered ``/dev`` nodes. For example, create
540 * ``/dev/ttyprintk`` and not ``/dev/ttyprintk0``. Applicable only when a
541 * driver for a single tty device is being allocated.
542 */
543#define TTY_DRIVER_INSTALLED 0x0001
544#define TTY_DRIVER_RESET_TERMIOS 0x0002
545#define TTY_DRIVER_REAL_RAW 0x0004
546#define TTY_DRIVER_DYNAMIC_DEV 0x0008
547#define TTY_DRIVER_DEVPTS_MEM 0x0010
548#define TTY_DRIVER_HARDWARE_BREAK 0x0020
549#define TTY_DRIVER_DYNAMIC_ALLOC 0x0040
550#define TTY_DRIVER_UNNUMBERED_NODE 0x0080
551
552/* tty driver types */
553#define TTY_DRIVER_TYPE_SYSTEM 0x0001
554#define TTY_DRIVER_TYPE_CONSOLE 0x0002
555#define TTY_DRIVER_TYPE_SERIAL 0x0003
556#define TTY_DRIVER_TYPE_PTY 0x0004
557#define TTY_DRIVER_TYPE_SCC 0x0005 /* scc driver */
558#define TTY_DRIVER_TYPE_SYSCONS 0x0006
559
560/* system subtypes (magic, used by tty_io.c) */
561#define SYSTEM_TYPE_TTY 0x0001
562#define SYSTEM_TYPE_CONSOLE 0x0002
563#define SYSTEM_TYPE_SYSCONS 0x0003
564#define SYSTEM_TYPE_SYSPTMX 0x0004
565
566/* pty subtypes (magic, used by tty_io.c) */
567#define PTY_TYPE_MASTER 0x0001
568#define PTY_TYPE_SLAVE 0x0002
569
570/* serial subtype definitions */
571#define SERIAL_TYPE_NORMAL 1
572
573int tty_register_driver(struct tty_driver *driver);
574void tty_unregister_driver(struct tty_driver *driver);
575struct device *tty_register_device(struct tty_driver *driver, unsigned index,
576 struct device *dev);
577struct device *tty_register_device_attr(struct tty_driver *driver,
578 unsigned index, struct device *device, void *drvdata,
579 const struct attribute_group **attr_grp);
580void tty_unregister_device(struct tty_driver *driver, unsigned index);
581
582#ifdef CONFIG_PROC_FS
583void proc_tty_register_driver(struct tty_driver *);
584void proc_tty_unregister_driver(struct tty_driver *);
585#else
586static inline void proc_tty_register_driver(struct tty_driver *d) {}
587static inline void proc_tty_unregister_driver(struct tty_driver *d) {}
588#endif
589
590#endif /* #ifdef _LINUX_TTY_DRIVER_H */
591

source code of linux/include/linux/tty_driver.h