xref: /linux/include/linux/tty_driver.h (revision 36ec807b627b4c0a0a382f0ae48eac7187d14b2b)
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/uaccess.h>
11 #include <linux/termios.h>
12 #include <linux/seq_file.h>
13 
14 struct tty_struct;
15 struct tty_driver;
16 struct serial_icounter_struct;
17 struct serial_struct;
18 
19 /**
20  * struct tty_operations -- interface between driver and tty
21  *
22  * @lookup: ``struct tty_struct *()(struct tty_driver *self, struct file *,
23  *				    int idx)``
24  *
25  *	Return the tty device corresponding to @idx, %NULL if there is not
26  *	one currently in use and an %ERR_PTR value on error. Called under
27  *	%tty_mutex (for now!)
28  *
29  *	Optional method. Default behaviour is to use the @self->ttys array.
30  *
31  * @install: ``int ()(struct tty_driver *self, struct tty_struct *tty)``
32  *
33  *	Install a new @tty into the @self's internal tables. Used in
34  *	conjunction with @lookup and @remove methods.
35  *
36  *	Optional method. Default behaviour is to use the @self->ttys array.
37  *
38  * @remove: ``void ()(struct tty_driver *self, struct tty_struct *tty)``
39  *
40  *	Remove a closed @tty from the @self's internal tables. Used in
41  *	conjunction with @lookup and @remove methods.
42  *
43  *	Optional method. Default behaviour is to use the @self->ttys array.
44  *
45  * @open: ``int ()(struct tty_struct *tty, struct file *)``
46  *
47  *	This routine is called when a particular @tty device is opened. This
48  *	routine is mandatory; if this routine is not filled in, the attempted
49  *	open will fail with %ENODEV.
50  *
51  *	Required method. Called with tty lock held. May sleep.
52  *
53  * @close: ``void ()(struct tty_struct *tty, struct file *)``
54  *
55  *	This routine is called when a particular @tty device is closed. At the
56  *	point of return from this call the driver must make no further ldisc
57  *	calls of any kind.
58  *
59  *	Remark: called even if the corresponding @open() failed.
60  *
61  *	Required method. Called with tty lock held. May sleep.
62  *
63  * @shutdown: ``void ()(struct tty_struct *tty)``
64  *
65  *	This routine is called under the tty lock when a particular @tty device
66  *	is closed for the last time. It executes before the @tty resources
67  *	are freed so may execute while another function holds a @tty kref.
68  *
69  * @cleanup: ``void ()(struct tty_struct *tty)``
70  *
71  *	This routine is called asynchronously when a particular @tty device
72  *	is closed for the last time freeing up the resources. This is
73  *	actually the second part of shutdown for routines that might sleep.
74  *
75  * @write: ``ssize_t ()(struct tty_struct *tty, const u8 *buf, size_t 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, u8 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, const 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  * @ldisc_ok: ``int ()(struct tty_struct *tty, int ldisc)``
158  *
159  *	This routine allows the @tty driver to decide if it can deal
160  *	with a particular @ldisc.
161  *
162  *	Optional. Called under the @tty->ldisc_sem and @tty->termios_rwsem.
163  *
164  * @set_ldisc: ``void ()(struct tty_struct *tty)``
165  *
166  *	This routine allows the @tty driver to be notified when the device's
167  *	line discipline is being changed. At the point this is done the
168  *	discipline is not yet usable.
169  *
170  *	Optional. Called under the @tty->ldisc_sem and @tty->termios_rwsem.
171  *
172  * @throttle: ``void ()(struct tty_struct *tty)``
173  *
174  *	This routine notifies the @tty driver that input buffers for the line
175  *	discipline are close to full, and it should somehow signal that no more
176  *	characters should be sent to the @tty.
177  *
178  *	Serialization including with @unthrottle() is the job of the ldisc
179  *	layer.
180  *
181  *	Optional: Always invoke via tty_throttle_safe(). Called under the
182  *	@tty->termios_rwsem.
183  *
184  * @unthrottle: ``void ()(struct tty_struct *tty)``
185  *
186  *	This routine notifies the @tty driver that it should signal that
187  *	characters can now be sent to the @tty without fear of overrunning the
188  *	input buffers of the line disciplines.
189  *
190  *	Optional. Always invoke via tty_unthrottle(). Called under the
191  *	@tty->termios_rwsem.
192  *
193  * @stop: ``void ()(struct tty_struct *tty)``
194  *
195  *	This routine notifies the @tty driver that it should stop outputting
196  *	characters to the tty device.
197  *
198  *	Called with @tty->flow.lock held. Serialized with @start() method.
199  *
200  *	Optional. Always invoke via stop_tty().
201  *
202  * @start: ``void ()(struct tty_struct *tty)``
203  *
204  *	This routine notifies the @tty driver that it resumed sending
205  *	characters to the @tty device.
206  *
207  *	Called with @tty->flow.lock held. Serialized with stop() method.
208  *
209  *	Optional. Always invoke via start_tty().
210  *
211  * @hangup: ``void ()(struct tty_struct *tty)``
212  *
213  *	This routine notifies the @tty driver that it should hang up the @tty
214  *	device.
215  *
216  *	Optional. Called with tty lock held.
217  *
218  * @break_ctl: ``int ()(struct tty_struct *tty, int state)``
219  *
220  *	This optional routine requests the @tty driver to turn on or off BREAK
221  *	status on the RS-232 port. If @state is -1, then the BREAK status
222  *	should be turned on; if @state is 0, then BREAK should be turned off.
223  *
224  *	If this routine is implemented, the high-level tty driver will handle
225  *	the following ioctls: %TCSBRK, %TCSBRKP, %TIOCSBRK, %TIOCCBRK.
226  *
227  *	If the driver sets %TTY_DRIVER_HARDWARE_BREAK in tty_alloc_driver(),
228  *	then the interface will also be called with actual times and the
229  *	hardware is expected to do the delay work itself. 0 and -1 are still
230  *	used for on/off.
231  *
232  *	Optional: Required for %TCSBRK/%BRKP/etc. handling. May sleep.
233  *
234  * @flush_buffer: ``void ()(struct tty_struct *tty)``
235  *
236  *	This routine discards device private output buffer. Invoked on close,
237  *	hangup, to implement %TCOFLUSH ioctl and similar.
238  *
239  *	Optional: if not provided, it is assumed there is no queue on the
240  *	device. Do not call this function directly, call
241  *	tty_driver_flush_buffer().
242  *
243  * @wait_until_sent: ``void ()(struct tty_struct *tty, int timeout)``
244  *
245  *	This routine waits until the device has written out all of the
246  *	characters in its transmitter FIFO. Or until @timeout (in jiffies) is
247  *	reached.
248  *
249  *	Optional: If not provided, the device is assumed to have no FIFO.
250  *	Usually correct to invoke via tty_wait_until_sent(). May sleep.
251  *
252  * @send_xchar: ``void ()(struct tty_struct *tty, u8 ch)``
253  *
254  *	This routine is used to send a high-priority XON/XOFF character (@ch)
255  *	to the @tty device.
256  *
257  *	Optional: If not provided, then the @write method is called under
258  *	the @tty->atomic_write_lock to keep it serialized with the ldisc.
259  *
260  * @tiocmget: ``int ()(struct tty_struct *tty)``
261  *
262  *	This routine is used to obtain the modem status bits from the @tty
263  *	driver.
264  *
265  *	Optional: If not provided, then %ENOTTY is returned from the %TIOCMGET
266  *	ioctl. Do not call this function directly, call tty_tiocmget().
267  *
268  * @tiocmset: ``int ()(struct tty_struct *tty,
269  *		       unsigned int set, unsigned int clear)``
270  *
271  *	This routine is used to set the modem status bits to the @tty driver.
272  *	First, @clear bits should be cleared, then @set bits set.
273  *
274  *	Optional: If not provided, then %ENOTTY is returned from the %TIOCMSET
275  *	ioctl. Do not call this function directly, call tty_tiocmset().
276  *
277  * @resize: ``int ()(struct tty_struct *tty, struct winsize *ws)``
278  *
279  *	Called when a termios request is issued which changes the requested
280  *	terminal geometry to @ws.
281  *
282  *	Optional: the default action is to update the termios structure
283  *	without error. This is usually the correct behaviour. Drivers should
284  *	not force errors here if they are not resizable objects (e.g. a serial
285  *	line). See tty_do_resize() if you need to wrap the standard method
286  *	in your own logic -- the usual case.
287  *
288  * @get_icount: ``int ()(struct tty_struct *tty,
289  *			 struct serial_icounter *icount)``
290  *
291  *	Called when the @tty device receives a %TIOCGICOUNT ioctl. Passed a
292  *	kernel structure @icount to complete.
293  *
294  *	Optional: called only if provided, otherwise %ENOTTY will be returned.
295  *
296  * @get_serial: ``int ()(struct tty_struct *tty, struct serial_struct *p)``
297  *
298  *	Called when the @tty device receives a %TIOCGSERIAL ioctl. Passed a
299  *	kernel structure @p (&struct serial_struct) to complete.
300  *
301  *	Optional: called only if provided, otherwise %ENOTTY will be returned.
302  *	Do not call this function directly, call tty_tiocgserial().
303  *
304  * @set_serial: ``int ()(struct tty_struct *tty, struct serial_struct *p)``
305  *
306  *	Called when the @tty device receives a %TIOCSSERIAL ioctl. Passed a
307  *	kernel structure @p (&struct serial_struct) to set the values from.
308  *
309  *	Optional: called only if provided, otherwise %ENOTTY will be returned.
310  *	Do not call this function directly, call tty_tiocsserial().
311  *
312  * @show_fdinfo: ``void ()(struct tty_struct *tty, struct seq_file *m)``
313  *
314  *	Called when the @tty device file descriptor receives a fdinfo request
315  *	from VFS (to show in /proc/<pid>/fdinfo/). @m should be filled with
316  *	information.
317  *
318  *	Optional: called only if provided, otherwise nothing is written to @m.
319  *	Do not call this function directly, call tty_show_fdinfo().
320  *
321  * @poll_init: ``int ()(struct tty_driver *driver, int line, char *options)``
322  *
323  *	kgdboc support (Documentation/dev-tools/kgdb.rst). This routine is
324  *	called to initialize the HW for later use by calling @poll_get_char or
325  *	@poll_put_char.
326  *
327  *	Optional: called only if provided, otherwise skipped as a non-polling
328  *	driver.
329  *
330  * @poll_get_char: ``int ()(struct tty_driver *driver, int line)``
331  *
332  *	kgdboc support (see @poll_init). @driver should read a character from a
333  *	tty identified by @line and return it.
334  *
335  *	Optional: called only if @poll_init provided.
336  *
337  * @poll_put_char: ``void ()(struct tty_driver *driver, int line, char ch)``
338  *
339  *	kgdboc support (see @poll_init). @driver should write character @ch to
340  *	a tty identified by @line.
341  *
342  *	Optional: called only if @poll_init provided.
343  *
344  * @proc_show: ``int ()(struct seq_file *m, void *driver)``
345  *
346  *	Driver @driver (cast to &struct tty_driver) can show additional info in
347  *	/proc/tty/driver/<driver_name>. It is enough to fill in the information
348  *	into @m.
349  *
350  *	Optional: called only if provided, otherwise no /proc entry created.
351  *
352  * This structure defines the interface between the low-level tty driver and
353  * the tty routines. These routines can be defined. Unless noted otherwise,
354  * they are optional, and can be filled in with a %NULL pointer.
355  */
356 struct tty_operations {
357 	struct tty_struct * (*lookup)(struct tty_driver *driver,
358 			struct file *filp, int idx);
359 	int  (*install)(struct tty_driver *driver, struct tty_struct *tty);
360 	void (*remove)(struct tty_driver *driver, struct tty_struct *tty);
361 	int  (*open)(struct tty_struct * tty, struct file * filp);
362 	void (*close)(struct tty_struct * tty, struct file * filp);
363 	void (*shutdown)(struct tty_struct *tty);
364 	void (*cleanup)(struct tty_struct *tty);
365 	ssize_t (*write)(struct tty_struct *tty, const u8 *buf, size_t count);
366 	int  (*put_char)(struct tty_struct *tty, u8 ch);
367 	void (*flush_chars)(struct tty_struct *tty);
368 	unsigned int (*write_room)(struct tty_struct *tty);
369 	unsigned int (*chars_in_buffer)(struct tty_struct *tty);
370 	int  (*ioctl)(struct tty_struct *tty,
371 		    unsigned int cmd, unsigned long arg);
372 	long (*compat_ioctl)(struct tty_struct *tty,
373 			     unsigned int cmd, unsigned long arg);
374 	void (*set_termios)(struct tty_struct *tty, const struct ktermios *old);
375 	void (*throttle)(struct tty_struct * tty);
376 	void (*unthrottle)(struct tty_struct * tty);
377 	void (*stop)(struct tty_struct *tty);
378 	void (*start)(struct tty_struct *tty);
379 	void (*hangup)(struct tty_struct *tty);
380 	int (*break_ctl)(struct tty_struct *tty, int state);
381 	void (*flush_buffer)(struct tty_struct *tty);
382 	int (*ldisc_ok)(struct tty_struct *tty, int ldisc);
383 	void (*set_ldisc)(struct tty_struct *tty);
384 	void (*wait_until_sent)(struct tty_struct *tty, int timeout);
385 	void (*send_xchar)(struct tty_struct *tty, u8 ch);
386 	int (*tiocmget)(struct tty_struct *tty);
387 	int (*tiocmset)(struct tty_struct *tty,
388 			unsigned int set, unsigned int clear);
389 	int (*resize)(struct tty_struct *tty, struct winsize *ws);
390 	int (*get_icount)(struct tty_struct *tty,
391 				struct serial_icounter_struct *icount);
392 	int  (*get_serial)(struct tty_struct *tty, struct serial_struct *p);
393 	int  (*set_serial)(struct tty_struct *tty, struct serial_struct *p);
394 	void (*show_fdinfo)(struct tty_struct *tty, struct seq_file *m);
395 #ifdef CONFIG_CONSOLE_POLL
396 	int (*poll_init)(struct tty_driver *driver, int line, char *options);
397 	int (*poll_get_char)(struct tty_driver *driver, int line);
398 	void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
399 #endif
400 	int (*proc_show)(struct seq_file *m, void *driver);
401 } __randomize_layout;
402 
403 /**
404  * struct tty_driver -- driver for TTY devices
405  *
406  * @kref: reference counting. Reaching zero frees all the internals and the
407  *	  driver.
408  * @cdevs: allocated/registered character /dev devices
409  * @owner: modules owning this driver. Used drivers cannot be rmmod'ed.
410  *	   Automatically set by tty_alloc_driver().
411  * @driver_name: name of the driver used in /proc/tty
412  * @name: used for constructing /dev node name
413  * @name_base: used as a number base for constructing /dev node name
414  * @major: major /dev device number (zero for autoassignment)
415  * @minor_start: the first minor /dev device number
416  * @num: number of devices allocated
417  * @type: type of tty driver (%TTY_DRIVER_TYPE_)
418  * @subtype: subtype of tty driver (%SYSTEM_TYPE_, %PTY_TYPE_, %SERIAL_TYPE_)
419  * @init_termios: termios to set to each tty initially (e.g. %tty_std_termios)
420  * @flags: tty driver flags (%TTY_DRIVER_)
421  * @proc_entry: proc fs entry, used internally
422  * @other: driver of the linked tty; only used for the PTY driver
423  * @ttys: array of active &struct tty_struct, set by tty_standard_install()
424  * @ports: array of &struct tty_port; can be set during initialization by
425  *	   tty_port_link_device() and similar
426  * @termios: storage for termios at each TTY close for the next open
427  * @driver_state: pointer to driver's arbitrary data
428  * @ops: driver hooks for TTYs. Set them using tty_set_operations(). Use &struct
429  *	 tty_port helpers in them as much as possible.
430  * @tty_drivers: used internally to link tty_drivers together
431  *
432  * The usual handling of &struct tty_driver is to allocate it by
433  * tty_alloc_driver(), set up all the necessary members, and register it by
434  * tty_register_driver(). At last, the driver is torn down by calling
435  * tty_unregister_driver() followed by tty_driver_kref_put().
436  *
437  * The fields required to be set before calling tty_register_driver() include
438  * @driver_name, @name, @type, @subtype, @init_termios, and @ops.
439  */
440 struct tty_driver {
441 	struct kref kref;
442 	struct cdev **cdevs;
443 	struct module	*owner;
444 	const char	*driver_name;
445 	const char	*name;
446 	int	name_base;
447 	int	major;
448 	int	minor_start;
449 	unsigned int	num;
450 	short	type;
451 	short	subtype;
452 	struct ktermios init_termios;
453 	unsigned long	flags;
454 	struct proc_dir_entry *proc_entry;
455 	struct tty_driver *other;
456 
457 	/*
458 	 * Pointer to the tty data structures
459 	 */
460 	struct tty_struct **ttys;
461 	struct tty_port **ports;
462 	struct ktermios **termios;
463 	void *driver_state;
464 
465 	/*
466 	 * Driver methods
467 	 */
468 
469 	const struct tty_operations *ops;
470 	struct list_head tty_drivers;
471 } __randomize_layout;
472 
473 extern struct list_head tty_drivers;
474 
475 struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
476 		unsigned long flags);
477 struct tty_driver *tty_find_polling_driver(char *name, int *line);
478 
479 void tty_driver_kref_put(struct tty_driver *driver);
480 
481 /* Use TTY_DRIVER_* flags below */
482 #define tty_alloc_driver(lines, flags) \
483 		__tty_alloc_driver(lines, THIS_MODULE, flags)
484 
485 static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
486 {
487 	kref_get(&d->kref);
488 	return d;
489 }
490 
491 static inline void tty_set_operations(struct tty_driver *driver,
492 		const struct tty_operations *op)
493 {
494 	driver->ops = op;
495 }
496 
497 /**
498  * DOC: TTY Driver Flags
499  *
500  * TTY_DRIVER_RESET_TERMIOS
501  *	Requests the tty layer to reset the termios setting when the last
502  *	process has closed the device. Used for PTYs, in particular.
503  *
504  * TTY_DRIVER_REAL_RAW
505  *	Indicates that the driver will guarantee not to set any special
506  *	character handling flags if this is set for the tty:
507  *
508  *	``(IGNBRK || (!BRKINT && !PARMRK)) && (IGNPAR || !INPCK)``
509  *
510  *	That is, if there is no reason for the driver to
511  *	send notifications of parity and break characters up to the line
512  *	driver, it won't do so.  This allows the line driver to optimize for
513  *	this case if this flag is set.  (Note that there is also a promise, if
514  *	the above case is true, not to signal overruns, either.)
515  *
516  * TTY_DRIVER_DYNAMIC_DEV
517  *	The individual tty devices need to be registered with a call to
518  *	tty_register_device() when the device is found in the system and
519  *	unregistered with a call to tty_unregister_device() so the devices will
520  *	be show up properly in sysfs.  If not set, all &tty_driver.num entries
521  *	will be created by the tty core in sysfs when tty_register_driver() is
522  *	called.  This is to be used by drivers that have tty devices that can
523  *	appear and disappear while the main tty driver is registered with the
524  *	tty core.
525  *
526  * TTY_DRIVER_DEVPTS_MEM
527  *	Don't use the standard arrays (&tty_driver.ttys and
528  *	&tty_driver.termios), instead use dynamic memory keyed through the
529  *	devpts filesystem. This is only applicable to the PTY driver.
530  *
531  * TTY_DRIVER_HARDWARE_BREAK
532  *	Hardware handles break signals. Pass the requested timeout to the
533  *	&tty_operations.break_ctl instead of using a simple on/off interface.
534  *
535  * TTY_DRIVER_DYNAMIC_ALLOC
536  *	Do not allocate structures which are needed per line for this driver
537  *	(&tty_driver.ports) as it would waste memory. The driver will take
538  *	care. This is only applicable to the PTY driver.
539  *
540  * TTY_DRIVER_UNNUMBERED_NODE
541  *	Do not create numbered ``/dev`` nodes. For example, create
542  *	``/dev/ttyprintk`` and not ``/dev/ttyprintk0``. Applicable only when a
543  *	driver for a single tty device is being allocated.
544  */
545 #define TTY_DRIVER_INSTALLED		0x0001
546 #define TTY_DRIVER_RESET_TERMIOS	0x0002
547 #define TTY_DRIVER_REAL_RAW		0x0004
548 #define TTY_DRIVER_DYNAMIC_DEV		0x0008
549 #define TTY_DRIVER_DEVPTS_MEM		0x0010
550 #define TTY_DRIVER_HARDWARE_BREAK	0x0020
551 #define TTY_DRIVER_DYNAMIC_ALLOC	0x0040
552 #define TTY_DRIVER_UNNUMBERED_NODE	0x0080
553 
554 /* tty driver types */
555 #define TTY_DRIVER_TYPE_SYSTEM		0x0001
556 #define TTY_DRIVER_TYPE_CONSOLE		0x0002
557 #define TTY_DRIVER_TYPE_SERIAL		0x0003
558 #define TTY_DRIVER_TYPE_PTY		0x0004
559 #define TTY_DRIVER_TYPE_SCC		0x0005	/* scc driver */
560 #define TTY_DRIVER_TYPE_SYSCONS		0x0006
561 
562 /* system subtypes (magic, used by tty_io.c) */
563 #define SYSTEM_TYPE_TTY			0x0001
564 #define SYSTEM_TYPE_CONSOLE		0x0002
565 #define SYSTEM_TYPE_SYSCONS		0x0003
566 #define SYSTEM_TYPE_SYSPTMX		0x0004
567 
568 /* pty subtypes (magic, used by tty_io.c) */
569 #define PTY_TYPE_MASTER			0x0001
570 #define PTY_TYPE_SLAVE			0x0002
571 
572 /* serial subtype definitions */
573 #define SERIAL_TYPE_NORMAL	1
574 
575 int tty_register_driver(struct tty_driver *driver);
576 void tty_unregister_driver(struct tty_driver *driver);
577 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
578 		struct device *dev);
579 struct device *tty_register_device_attr(struct tty_driver *driver,
580 		unsigned index, struct device *device, void *drvdata,
581 		const struct attribute_group **attr_grp);
582 void tty_unregister_device(struct tty_driver *driver, unsigned index);
583 
584 #ifdef CONFIG_PROC_FS
585 void proc_tty_register_driver(struct tty_driver *);
586 void proc_tty_unregister_driver(struct tty_driver *);
587 #else
588 static inline void proc_tty_register_driver(struct tty_driver *d) {}
589 static inline void proc_tty_unregister_driver(struct tty_driver *d) {}
590 #endif
591 
592 #endif /* #ifdef _LINUX_TTY_DRIVER_H */
593