tty_driver.h

  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
 14struct tty_struct;
 15struct tty_driver;
 16struct serial_icounter_struct;
 17struct serial_struct;
 18
 19/**
 20 * enum tty_driver_flag -- TTY Driver Flags
 21 *
 22 * These are flags passed to tty_alloc_driver().
 23 *
 24 * @TTY_DRIVER_INSTALLED:
 25 *	Whether this driver was succesfully installed. This is a tty internal
 26 *	flag. Do not touch.
 27 *
 28 * @TTY_DRIVER_RESET_TERMIOS:
 29 *	Requests the tty layer to reset the termios setting when the last
 30 *	process has closed the device. Used for PTYs, in particular.
 31 *
 32 * @TTY_DRIVER_REAL_RAW:
 33 *	Indicates that the driver will guarantee not to set any special
 34 *	character handling flags if this is set for the tty:
 35 *
 36 *	``(IGNBRK || (!BRKINT && !PARMRK)) && (IGNPAR || !INPCK)``
 37 *
 38 *	That is, if there is no reason for the driver to
 39 *	send notifications of parity and break characters up to the line
 40 *	driver, it won't do so.  This allows the line driver to optimize for
 41 *	this case if this flag is set.  (Note that there is also a promise, if
 42 *	the above case is true, not to signal overruns, either.)
 43 *
 44 * @TTY_DRIVER_DYNAMIC_DEV:
 45 *	The individual tty devices need to be registered with a call to
 46 *	tty_register_device() when the device is found in the system and
 47 *	unregistered with a call to tty_unregister_device() so the devices will
 48 *	be show up properly in sysfs.  If not set, all &tty_driver.num entries
 49 *	will be created by the tty core in sysfs when tty_register_driver() is
 50 *	called.  This is to be used by drivers that have tty devices that can
 51 *	appear and disappear while the main tty driver is registered with the
 52 *	tty core.
 53 *
 54 * @TTY_DRIVER_DEVPTS_MEM:
 55 *	Don't use the standard arrays (&tty_driver.ttys and
 56 *	&tty_driver.termios), instead use dynamic memory keyed through the
 57 *	devpts filesystem. This is only applicable to the PTY driver.
 58 *
 59 * @TTY_DRIVER_HARDWARE_BREAK:
 60 *	Hardware handles break signals. Pass the requested timeout to the
 61 *	&tty_operations.break_ctl instead of using a simple on/off interface.
 62 *
 63 * @TTY_DRIVER_DYNAMIC_ALLOC:
 64 *	Do not allocate structures which are needed per line for this driver
 65 *	(&tty_driver.ports) as it would waste memory. The driver will take
 66 *	care. This is only applicable to the PTY driver.
 67 *
 68 * @TTY_DRIVER_UNNUMBERED_NODE:
 69 *	Do not create numbered ``/dev`` nodes. For example, create
 70 *	``/dev/ttyprintk`` and not ``/dev/ttyprintk0``. Applicable only when a
 71 *	driver for a single tty device is being allocated.
 72 */
 73enum tty_driver_flag {
 74	TTY_DRIVER_INSTALLED		= BIT(0),
 75	TTY_DRIVER_RESET_TERMIOS	= BIT(1),
 76	TTY_DRIVER_REAL_RAW		= BIT(2),
 77	TTY_DRIVER_DYNAMIC_DEV		= BIT(3),
 78	TTY_DRIVER_DEVPTS_MEM		= BIT(4),
 79	TTY_DRIVER_HARDWARE_BREAK	= BIT(5),
 80	TTY_DRIVER_DYNAMIC_ALLOC	= BIT(6),
 81	TTY_DRIVER_UNNUMBERED_NODE	= BIT(7),
 82};
 83
 84enum tty_driver_type {
 85	TTY_DRIVER_TYPE_SYSTEM,
 86	TTY_DRIVER_TYPE_CONSOLE,
 87	TTY_DRIVER_TYPE_SERIAL,
 88	TTY_DRIVER_TYPE_PTY,
 89	TTY_DRIVER_TYPE_SCC,
 90	TTY_DRIVER_TYPE_SYSCONS,
 91};
 92
 93enum tty_driver_subtype {
 94	SYSTEM_TYPE_TTY = 1,
 95	SYSTEM_TYPE_CONSOLE,
 96	SYSTEM_TYPE_SYSCONS,
 97	SYSTEM_TYPE_SYSPTMX,
 98
 99	PTY_TYPE_MASTER = 1,
100	PTY_TYPE_SLAVE,
101
102	SERIAL_TYPE_NORMAL = 1,
103};
104
105/**
106 * struct tty_operations -- interface between driver and tty
107 *
108 * @lookup: ``struct tty_struct *()(struct tty_driver *self, struct file *,
109 *				    int idx)``
110 *
111 *	Return the tty device corresponding to @idx, %NULL if there is not
112 *	one currently in use and an %ERR_PTR value on error. Called under
113 *	%tty_mutex (for now!)
114 *
115 *	Optional method. Default behaviour is to use the @self->ttys array.
116 *
117 * @install: ``int ()(struct tty_driver *self, struct tty_struct *tty)``
118 *
119 *	Install a new @tty into the @self's internal tables. Used in
120 *	conjunction with @lookup and @remove methods.
121 *
122 *	Optional method. Default behaviour is to use the @self->ttys array.
123 *
124 * @remove: ``void ()(struct tty_driver *self, struct tty_struct *tty)``
125 *
126 *	Remove a closed @tty from the @self's internal tables. Used in
127 *	conjunction with @lookup and @remove methods.
128 *
129 *	Optional method. Default behaviour is to use the @self->ttys array.
130 *
131 * @open: ``int ()(struct tty_struct *tty, struct file *)``
132 *
133 *	This routine is called when a particular @tty device is opened. This
134 *	routine is mandatory; if this routine is not filled in, the attempted
135 *	open will fail with %ENODEV.
136 *
137 *	Required method. Called with tty lock held. May sleep.
138 *
139 * @close: ``void ()(struct tty_struct *tty, struct file *)``
140 *
141 *	This routine is called when a particular @tty device is closed. At the
142 *	point of return from this call the driver must make no further ldisc
143 *	calls of any kind.
144 *
145 *	Remark: called even if the corresponding @open() failed.
146 *
147 *	Required method. Called with tty lock held. May sleep.
148 *
149 * @shutdown: ``void ()(struct tty_struct *tty)``
150 *
151 *	This routine is called under the tty lock when a particular @tty device
152 *	is closed for the last time. It executes before the @tty resources
153 *	are freed so may execute while another function holds a @tty kref.
154 *
155 * @cleanup: ``void ()(struct tty_struct *tty)``
156 *
157 *	This routine is called asynchronously when a particular @tty device
158 *	is closed for the last time freeing up the resources. This is
159 *	actually the second part of shutdown for routines that might sleep.
160 *
161 * @write: ``ssize_t ()(struct tty_struct *tty, const u8 *buf, size_t count)``
162 *
163 *	This routine is called by the kernel to write a series (@count) of
164 *	characters (@buf) to the @tty device. The characters may come from
165 *	user space or kernel space.  This routine will return the
166 *	number of characters actually accepted for writing.
167 *
168 *	May occur in parallel in special cases. Because this includes panic
169 *	paths drivers generally shouldn't try and do clever locking here.
170 *
171 *	Optional: Required for writable devices. May not sleep.
172 *
173 * @put_char: ``int ()(struct tty_struct *tty, u8 ch)``
174 *
175 *	This routine is called by the kernel to write a single character @ch to
176 *	the @tty device. If the kernel uses this routine, it must call the
177 *	@flush_chars() routine (if defined) when it is done stuffing characters
178 *	into the driver. If there is no room in the queue, the character is
179 *	ignored.
180 *
181 *	Optional: Kernel will use the @write method if not provided. Do not
182 *	call this function directly, call tty_put_char().
183 *
184 * @flush_chars: ``void ()(struct tty_struct *tty)``
185 *
186 *	This routine is called by the kernel after it has written a
187 *	series of characters to the tty device using @put_char().
188 *
189 *	Optional. Do not call this function directly, call
190 *	tty_driver_flush_chars().
191 *
192 * @write_room: ``unsigned int ()(struct tty_struct *tty)``
193 *
194 *	This routine returns the numbers of characters the @tty driver
195 *	will accept for queuing to be written.  This number is subject
196 *	to change as output buffers get emptied, or if the output flow
197 *	control is acted.
198 *
199 *	The ldisc is responsible for being intelligent about multi-threading of
200 *	write_room/write calls
201 *
202 *	Required if @write method is provided else not needed. Do not call this
203 *	function directly, call tty_write_room()
204 *
205 * @chars_in_buffer: ``unsigned int ()(struct tty_struct *tty)``
206 *
207 *	This routine returns the number of characters in the device private
208 *	output queue. Used in tty_wait_until_sent() and for poll()
209 *	implementation.
210 *
211 *	Optional: if not provided, it is assumed there is no queue on the
212 *	device. Do not call this function directly, call tty_chars_in_buffer().
213 *
214 * @ioctl: ``int ()(struct tty_struct *tty, unsigned int cmd,
215 *		    unsigned long arg)``
216 *
217 *	This routine allows the @tty driver to implement device-specific
218 *	ioctls. If the ioctl number passed in @cmd is not recognized by the
219 *	driver, it should return %ENOIOCTLCMD.
220 *
221 *	Optional.
222 *
223 * @compat_ioctl: ``long ()(struct tty_struct *tty, unsigned int cmd,
224 *			  unsigned long arg)``
225 *
226 *	Implement ioctl processing for 32 bit process on 64 bit system.
227 *
228 *	Optional.
229 *
230 * @set_termios: ``void ()(struct tty_struct *tty, const struct ktermios *old)``
231 *
232 *	This routine allows the @tty driver to be notified when device's
233 *	termios settings have changed. New settings are in @tty->termios.
234 *	Previous settings are passed in the @old argument.
235 *
236 *	The API is defined such that the driver should return the actual modes
237 *	selected. This means that the driver is responsible for modifying any
238 *	bits in @tty->termios it cannot fulfill to indicate the actual modes
239 *	being used.
240 *
241 *	Optional. Called under the @tty->termios_rwsem. May sleep.
242 *
243 * @ldisc_ok: ``int ()(struct tty_struct *tty, int ldisc)``
244 *
245 *	This routine allows the @tty driver to decide if it can deal
246 *	with a particular @ldisc.
247 *
248 *	Optional. Called under the @tty->ldisc_sem and @tty->termios_rwsem.
249 *
250 * @set_ldisc: ``void ()(struct tty_struct *tty)``
251 *
252 *	This routine allows the @tty driver to be notified when the device's
253 *	line discipline is being changed. At the point this is done the
254 *	discipline is not yet usable.
255 *
256 *	Optional. Called under the @tty->ldisc_sem and @tty->termios_rwsem.
257 *
258 * @throttle: ``void ()(struct tty_struct *tty)``
259 *
260 *	This routine notifies the @tty driver that input buffers for the line
261 *	discipline are close to full, and it should somehow signal that no more
262 *	characters should be sent to the @tty.
263 *
264 *	Serialization including with @unthrottle() is the job of the ldisc
265 *	layer.
266 *
267 *	Optional: Always invoke via tty_throttle_safe(). Called under the
268 *	@tty->termios_rwsem.
269 *
270 * @unthrottle: ``void ()(struct tty_struct *tty)``
271 *
272 *	This routine notifies the @tty driver that it should signal that
273 *	characters can now be sent to the @tty without fear of overrunning the
274 *	input buffers of the line disciplines.
275 *
276 *	Optional. Always invoke via tty_unthrottle(). Called under the
277 *	@tty->termios_rwsem.
278 *
279 * @stop: ``void ()(struct tty_struct *tty)``
280 *
281 *	This routine notifies the @tty driver that it should stop outputting
282 *	characters to the tty device.
283 *
284 *	Called with @tty->flow.lock held. Serialized with @start() method.
285 *
286 *	Optional. Always invoke via stop_tty().
287 *
288 * @start: ``void ()(struct tty_struct *tty)``
289 *
290 *	This routine notifies the @tty driver that it resumed sending
291 *	characters to the @tty device.
292 *
293 *	Called with @tty->flow.lock held. Serialized with stop() method.
294 *
295 *	Optional. Always invoke via start_tty().
296 *
297 * @hangup: ``void ()(struct tty_struct *tty)``
298 *
299 *	This routine notifies the @tty driver that it should hang up the @tty
300 *	device.
301 *
302 *	Optional. Called with tty lock held.
303 *
304 * @break_ctl: ``int ()(struct tty_struct *tty, int state)``
305 *
306 *	This optional routine requests the @tty driver to turn on or off BREAK
307 *	status on the RS-232 port. If @state is -1, then the BREAK status
308 *	should be turned on; if @state is 0, then BREAK should be turned off.
309 *
310 *	If this routine is implemented, the high-level tty driver will handle
311 *	the following ioctls: %TCSBRK, %TCSBRKP, %TIOCSBRK, %TIOCCBRK.
312 *
313 *	If the driver sets %TTY_DRIVER_HARDWARE_BREAK in tty_alloc_driver(),
314 *	then the interface will also be called with actual times and the
315 *	hardware is expected to do the delay work itself. 0 and -1 are still
316 *	used for on/off.
317 *
318 *	Optional: Required for %TCSBRK/%BRKP/etc. handling. May sleep.
319 *
320 * @flush_buffer: ``void ()(struct tty_struct *tty)``
321 *
322 *	This routine discards device private output buffer. Invoked on close,
323 *	hangup, to implement %TCOFLUSH ioctl and similar.
324 *
325 *	Optional: if not provided, it is assumed there is no queue on the
326 *	device. Do not call this function directly, call
327 *	tty_driver_flush_buffer().
328 *
329 * @wait_until_sent: ``void ()(struct tty_struct *tty, int timeout)``
330 *
331 *	This routine waits until the device has written out all of the
332 *	characters in its transmitter FIFO. Or until @timeout (in jiffies) is
333 *	reached.
334 *
335 *	Optional: If not provided, the device is assumed to have no FIFO.
336 *	Usually correct to invoke via tty_wait_until_sent(). May sleep.
337 *
338 * @send_xchar: ``void ()(struct tty_struct *tty, u8 ch)``
339 *
340 *	This routine is used to send a high-priority XON/XOFF character (@ch)
341 *	to the @tty device.
342 *
343 *	Optional: If not provided, then the @write method is called under
344 *	the @tty->atomic_write_lock to keep it serialized with the ldisc.
345 *
346 * @tiocmget: ``int ()(struct tty_struct *tty)``
347 *
348 *	This routine is used to obtain the modem status bits from the @tty
349 *	driver.
350 *
351 *	Optional: If not provided, then %ENOTTY is returned from the %TIOCMGET
352 *	ioctl. Do not call this function directly, call tty_tiocmget().
353 *
354 * @tiocmset: ``int ()(struct tty_struct *tty,
355 *		       unsigned int set, unsigned int clear)``
356 *
357 *	This routine is used to set the modem status bits to the @tty driver.
358 *	First, @clear bits should be cleared, then @set bits set.
359 *
360 *	Optional: If not provided, then %ENOTTY is returned from the %TIOCMSET
361 *	ioctl. Do not call this function directly, call tty_tiocmset().
362 *
363 * @resize: ``int ()(struct tty_struct *tty, struct winsize *ws)``
364 *
365 *	Called when a termios request is issued which changes the requested
366 *	terminal geometry to @ws.
367 *
368 *	Optional: the default action is to update the termios structure
369 *	without error. This is usually the correct behaviour. Drivers should
370 *	not force errors here if they are not resizable objects (e.g. a serial
371 *	line). See tty_do_resize() if you need to wrap the standard method
372 *	in your own logic -- the usual case.
373 *
374 * @get_icount: ``int ()(struct tty_struct *tty,
375 *			 struct serial_icounter *icount)``
376 *
377 *	Called when the @tty device receives a %TIOCGICOUNT ioctl. Passed a
378 *	kernel structure @icount to complete.
379 *
380 *	Optional: called only if provided, otherwise %ENOTTY will be returned.
381 *
382 * @get_serial: ``int ()(struct tty_struct *tty, struct serial_struct *p)``
383 *
384 *	Called when the @tty device receives a %TIOCGSERIAL ioctl. Passed a
385 *	kernel structure @p (&struct serial_struct) to complete.
386 *
387 *	Optional: called only if provided, otherwise %ENOTTY will be returned.
388 *	Do not call this function directly, call tty_tiocgserial().
389 *
390 * @set_serial: ``int ()(struct tty_struct *tty, struct serial_struct *p)``
391 *
392 *	Called when the @tty device receives a %TIOCSSERIAL ioctl. Passed a
393 *	kernel structure @p (&struct serial_struct) to set the values from.
394 *
395 *	Optional: called only if provided, otherwise %ENOTTY will be returned.
396 *	Do not call this function directly, call tty_tiocsserial().
397 *
398 * @show_fdinfo: ``void ()(struct tty_struct *tty, struct seq_file *m)``
399 *
400 *	Called when the @tty device file descriptor receives a fdinfo request
401 *	from VFS (to show in /proc/<pid>/fdinfo/). @m should be filled with
402 *	information.
403 *
404 *	Optional: called only if provided, otherwise nothing is written to @m.
405 *	Do not call this function directly, call tty_show_fdinfo().
406 *
407 * @poll_init: ``int ()(struct tty_driver *driver, int line, char *options)``
408 *
409 *	kgdboc support (Documentation/process/debugging/kgdb.rst). This routine is
410 *	called to initialize the HW for later use by calling @poll_get_char or
411 *	@poll_put_char.
412 *
413 *	Optional: called only if provided, otherwise skipped as a non-polling
414 *	driver.
415 *
416 * @poll_get_char: ``int ()(struct tty_driver *driver, int line)``
417 *
418 *	kgdboc support (see @poll_init). @driver should read a character from a
419 *	tty identified by @line and return it.
420 *
421 *	Optional: called only if @poll_init provided.
422 *
423 * @poll_put_char: ``void ()(struct tty_driver *driver, int line, char ch)``
424 *
425 *	kgdboc support (see @poll_init). @driver should write character @ch to
426 *	a tty identified by @line.
427 *
428 *	Optional: called only if @poll_init provided.
429 *
430 * @proc_show: ``int ()(struct seq_file *m, void *driver)``
431 *
432 *	Driver @driver (cast to &struct tty_driver) can show additional info in
433 *	/proc/tty/driver/<driver_name>. It is enough to fill in the information
434 *	into @m.
435 *
436 *	Optional: called only if provided, otherwise no /proc entry created.
437 *
438 * This structure defines the interface between the low-level tty driver and
439 * the tty routines. These routines can be defined. Unless noted otherwise,
440 * they are optional, and can be filled in with a %NULL pointer.
441 */
442struct tty_operations {
443	struct tty_struct * (*lookup)(struct tty_driver *driver,
444			struct file *filp, int idx);
445	int  (*install)(struct tty_driver *driver, struct tty_struct *tty);
446	void (*remove)(struct tty_driver *driver, struct tty_struct *tty);
447	int  (*open)(struct tty_struct * tty, struct file * filp);
448	void (*close)(struct tty_struct * tty, struct file * filp);
449	void (*shutdown)(struct tty_struct *tty);
450	void (*cleanup)(struct tty_struct *tty);
451	ssize_t (*write)(struct tty_struct *tty, const u8 *buf, size_t count);
452	int  (*put_char)(struct tty_struct *tty, u8 ch);
453	void (*flush_chars)(struct tty_struct *tty);
454	unsigned int (*write_room)(struct tty_struct *tty);
455	unsigned int (*chars_in_buffer)(struct tty_struct *tty);
456	int  (*ioctl)(struct tty_struct *tty,
457		    unsigned int cmd, unsigned long arg);
458	long (*compat_ioctl)(struct tty_struct *tty,
459			     unsigned int cmd, unsigned long arg);
460	void (*set_termios)(struct tty_struct *tty, const struct ktermios *old);
461	void (*throttle)(struct tty_struct * tty);
462	void (*unthrottle)(struct tty_struct * tty);
463	void (*stop)(struct tty_struct *tty);
464	void (*start)(struct tty_struct *tty);
465	void (*hangup)(struct tty_struct *tty);
466	int (*break_ctl)(struct tty_struct *tty, int state);
467	void (*flush_buffer)(struct tty_struct *tty);
468	int (*ldisc_ok)(struct tty_struct *tty, int ldisc);
469	void (*set_ldisc)(struct tty_struct *tty);
470	void (*wait_until_sent)(struct tty_struct *tty, int timeout);
471	void (*send_xchar)(struct tty_struct *tty, u8 ch);
472	int (*tiocmget)(struct tty_struct *tty);
473	int (*tiocmset)(struct tty_struct *tty,
474			unsigned int set, unsigned int clear);
475	int (*resize)(struct tty_struct *tty, struct winsize *ws);
476	int (*get_icount)(struct tty_struct *tty,
477				struct serial_icounter_struct *icount);
478	int  (*get_serial)(struct tty_struct *tty, struct serial_struct *p);
479	int  (*set_serial)(struct tty_struct *tty, struct serial_struct *p);
480	void (*show_fdinfo)(struct tty_struct *tty, struct seq_file *m);
481#ifdef CONFIG_CONSOLE_POLL
482	int (*poll_init)(struct tty_driver *driver, int line, char *options);
483	int (*poll_get_char)(struct tty_driver *driver, int line);
484	void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
485#endif
486	int (*proc_show)(struct seq_file *m, void *driver);
487} __randomize_layout;
488
489/**
490 * struct tty_driver -- driver for TTY devices
491 *
492 * @kref: reference counting. Reaching zero frees all the internals and the
493 *	  driver.
494 * @cdevs: allocated/registered character /dev devices
495 * @owner: modules owning this driver. Used drivers cannot be rmmod'ed.
496 *	   Automatically set by tty_alloc_driver().
497 * @driver_name: name of the driver used in /proc/tty
498 * @name: used for constructing /dev node name
499 * @name_base: used as a number base for constructing /dev node name
500 * @major: major /dev device number (zero for autoassignment)
501 * @minor_start: the first minor /dev device number
502 * @num: number of devices allocated
503 * @type: type of tty driver (enum tty_driver_type)
504 * @subtype: subtype of tty driver (enum tty_driver_subtype)
505 * @init_termios: termios to set to each tty initially (e.g. %tty_std_termios)
506 * @flags: tty driver flags (%TTY_DRIVER_)
507 * @proc_entry: proc fs entry, used internally
508 * @other: driver of the linked tty; only used for the PTY driver
509 * @ttys: array of active &struct tty_struct, set by tty_standard_install()
510 * @ports: array of &struct tty_port; can be set during initialization by
511 *	   tty_port_link_device() and similar
512 * @termios: storage for termios at each TTY close for the next open
513 * @driver_state: pointer to driver's arbitrary data
514 * @ops: driver hooks for TTYs. Set them using tty_set_operations(). Use &struct
515 *	 tty_port helpers in them as much as possible.
516 * @tty_drivers: used internally to link tty_drivers together
517 *
518 * The usual handling of &struct tty_driver is to allocate it by
519 * tty_alloc_driver(), set up all the necessary members, and register it by
520 * tty_register_driver(). At last, the driver is torn down by calling
521 * tty_unregister_driver() followed by tty_driver_kref_put().
522 *
523 * The fields required to be set before calling tty_register_driver() include
524 * @driver_name, @name, @type, @subtype, @init_termios, and @ops.
525 */
526struct tty_driver {
527	struct kref kref;
528	struct cdev **cdevs;
529	struct module	*owner;
530	const char	*driver_name;
531	const char	*name;
532	int	name_base;
533	int	major;
534	int	minor_start;
535	unsigned int	num;
536	enum tty_driver_type type;
537	enum tty_driver_subtype subtype;
538	struct ktermios init_termios;
539	unsigned long	flags;
540	struct proc_dir_entry *proc_entry;
541	struct tty_driver *other;
542
543	/*
544	 * Pointer to the tty data structures
545	 */
546	struct tty_struct **ttys;
547	struct tty_port **ports;
548	struct ktermios **termios;
549	void *driver_state;
550
551	/*
552	 * Driver methods
553	 */
554
555	const struct tty_operations *ops;
556	struct list_head tty_drivers;
557} __randomize_layout;
558
559extern struct list_head tty_drivers;
560
561struct tty_driver *__tty_alloc_driver(unsigned int lines, struct module *owner,
562		unsigned long flags);
563struct tty_driver *tty_find_polling_driver(char *name, int *line);
564
565void tty_driver_kref_put(struct tty_driver *driver);
566
567/**
568 * tty_alloc_driver - allocate tty driver
569 * @lines: count of lines this driver can handle at most
570 * @flags: some of enum tty_driver_flag, will be set in driver->flags
571 *
572 * Returns: struct tty_driver or a PTR-encoded error (use IS_ERR() and friends).
573 */
574#define tty_alloc_driver(lines, flags) \
575		__tty_alloc_driver(lines, THIS_MODULE, flags)
576
577static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
578{
579	kref_get(&d->kref);
580	return d;
581}
582
583static inline void tty_set_operations(struct tty_driver *driver,
584		const struct tty_operations *op)
585{
586	driver->ops = op;
587}
588
589int tty_register_driver(struct tty_driver *driver);
590void tty_unregister_driver(struct tty_driver *driver);
591struct device *tty_register_device(struct tty_driver *driver, unsigned index,
592		struct device *dev);
593struct device *tty_register_device_attr(struct tty_driver *driver,
594		unsigned index, struct device *device, void *drvdata,
595		const struct attribute_group **attr_grp);
596void tty_unregister_device(struct tty_driver *driver, unsigned index);
597
598#ifdef CONFIG_PROC_FS
599void proc_tty_register_driver(struct tty_driver *);
600void proc_tty_unregister_driver(struct tty_driver *);
601#else
602static inline void proc_tty_register_driver(struct tty_driver *d) {}
603static inline void proc_tty_unregister_driver(struct tty_driver *d) {}
604#endif
605
606#endif /* #ifdef _LINUX_TTY_DRIVER_H */