xref: /linux-6.15/include/linux/tty.h (revision 6ed7ffdd)
1 #ifndef _LINUX_TTY_H
2 #define _LINUX_TTY_H
3 
4 #include <linux/fs.h>
5 #include <linux/major.h>
6 #include <linux/termios.h>
7 #include <linux/workqueue.h>
8 #include <linux/tty_driver.h>
9 #include <linux/tty_ldisc.h>
10 #include <linux/mutex.h>
11 #include <linux/tty_flags.h>
12 #include <uapi/linux/tty.h>
13 
14 
15 
16 /*
17  * (Note: the *_driver.minor_start values 1, 64, 128, 192 are
18  * hardcoded at present.)
19  */
20 #define NR_UNIX98_PTY_DEFAULT	4096      /* Default maximum for Unix98 ptys */
21 #define NR_UNIX98_PTY_RESERVE	1024	  /* Default reserve for main devpts */
22 #define NR_UNIX98_PTY_MAX	(1 << MINORBITS) /* Absolute limit */
23 
24 /*
25  * This character is the same as _POSIX_VDISABLE: it cannot be used as
26  * a c_cc[] character, but indicates that a particular special character
27  * isn't in use (eg VINTR has no character etc)
28  */
29 #define __DISABLED_CHAR '\0'
30 
31 struct tty_buffer {
32 	struct tty_buffer *next;
33 	char *char_buf_ptr;
34 	unsigned char *flag_buf_ptr;
35 	int used;
36 	int size;
37 	int commit;
38 	int read;
39 	/* Data points here */
40 	unsigned long data[0];
41 };
42 
43 /*
44  * We default to dicing tty buffer allocations to this many characters
45  * in order to avoid multiple page allocations. We know the size of
46  * tty_buffer itself but it must also be taken into account that the
47  * the buffer is 256 byte aligned. See tty_buffer_find for the allocation
48  * logic this must match
49  */
50 
51 #define TTY_BUFFER_PAGE	(((PAGE_SIZE - sizeof(struct tty_buffer)) / 2) & ~0xFF)
52 
53 
54 struct tty_bufhead {
55 	struct work_struct work;
56 	spinlock_t lock;
57 	struct tty_buffer *head;	/* Queue head */
58 	struct tty_buffer *tail;	/* Active buffer */
59 	struct tty_buffer *free;	/* Free queue head */
60 	int memory_used;		/* Buffer space used excluding
61 								free queue */
62 };
63 /*
64  * When a break, frame error, or parity error happens, these codes are
65  * stuffed into the flags buffer.
66  */
67 #define TTY_NORMAL	0
68 #define TTY_BREAK	1
69 #define TTY_FRAME	2
70 #define TTY_PARITY	3
71 #define TTY_OVERRUN	4
72 
73 #define INTR_CHAR(tty) ((tty)->termios.c_cc[VINTR])
74 #define QUIT_CHAR(tty) ((tty)->termios.c_cc[VQUIT])
75 #define ERASE_CHAR(tty) ((tty)->termios.c_cc[VERASE])
76 #define KILL_CHAR(tty) ((tty)->termios.c_cc[VKILL])
77 #define EOF_CHAR(tty) ((tty)->termios.c_cc[VEOF])
78 #define TIME_CHAR(tty) ((tty)->termios.c_cc[VTIME])
79 #define MIN_CHAR(tty) ((tty)->termios.c_cc[VMIN])
80 #define SWTC_CHAR(tty) ((tty)->termios.c_cc[VSWTC])
81 #define START_CHAR(tty) ((tty)->termios.c_cc[VSTART])
82 #define STOP_CHAR(tty) ((tty)->termios.c_cc[VSTOP])
83 #define SUSP_CHAR(tty) ((tty)->termios.c_cc[VSUSP])
84 #define EOL_CHAR(tty) ((tty)->termios.c_cc[VEOL])
85 #define REPRINT_CHAR(tty) ((tty)->termios.c_cc[VREPRINT])
86 #define DISCARD_CHAR(tty) ((tty)->termios.c_cc[VDISCARD])
87 #define WERASE_CHAR(tty) ((tty)->termios.c_cc[VWERASE])
88 #define LNEXT_CHAR(tty)	((tty)->termios.c_cc[VLNEXT])
89 #define EOL2_CHAR(tty) ((tty)->termios.c_cc[VEOL2])
90 
91 #define _I_FLAG(tty, f)	((tty)->termios.c_iflag & (f))
92 #define _O_FLAG(tty, f)	((tty)->termios.c_oflag & (f))
93 #define _C_FLAG(tty, f)	((tty)->termios.c_cflag & (f))
94 #define _L_FLAG(tty, f)	((tty)->termios.c_lflag & (f))
95 
96 #define I_IGNBRK(tty)	_I_FLAG((tty), IGNBRK)
97 #define I_BRKINT(tty)	_I_FLAG((tty), BRKINT)
98 #define I_IGNPAR(tty)	_I_FLAG((tty), IGNPAR)
99 #define I_PARMRK(tty)	_I_FLAG((tty), PARMRK)
100 #define I_INPCK(tty)	_I_FLAG((tty), INPCK)
101 #define I_ISTRIP(tty)	_I_FLAG((tty), ISTRIP)
102 #define I_INLCR(tty)	_I_FLAG((tty), INLCR)
103 #define I_IGNCR(tty)	_I_FLAG((tty), IGNCR)
104 #define I_ICRNL(tty)	_I_FLAG((tty), ICRNL)
105 #define I_IUCLC(tty)	_I_FLAG((tty), IUCLC)
106 #define I_IXON(tty)	_I_FLAG((tty), IXON)
107 #define I_IXANY(tty)	_I_FLAG((tty), IXANY)
108 #define I_IXOFF(tty)	_I_FLAG((tty), IXOFF)
109 #define I_IMAXBEL(tty)	_I_FLAG((tty), IMAXBEL)
110 #define I_IUTF8(tty)	_I_FLAG((tty), IUTF8)
111 
112 #define O_OPOST(tty)	_O_FLAG((tty), OPOST)
113 #define O_OLCUC(tty)	_O_FLAG((tty), OLCUC)
114 #define O_ONLCR(tty)	_O_FLAG((tty), ONLCR)
115 #define O_OCRNL(tty)	_O_FLAG((tty), OCRNL)
116 #define O_ONOCR(tty)	_O_FLAG((tty), ONOCR)
117 #define O_ONLRET(tty)	_O_FLAG((tty), ONLRET)
118 #define O_OFILL(tty)	_O_FLAG((tty), OFILL)
119 #define O_OFDEL(tty)	_O_FLAG((tty), OFDEL)
120 #define O_NLDLY(tty)	_O_FLAG((tty), NLDLY)
121 #define O_CRDLY(tty)	_O_FLAG((tty), CRDLY)
122 #define O_TABDLY(tty)	_O_FLAG((tty), TABDLY)
123 #define O_BSDLY(tty)	_O_FLAG((tty), BSDLY)
124 #define O_VTDLY(tty)	_O_FLAG((tty), VTDLY)
125 #define O_FFDLY(tty)	_O_FLAG((tty), FFDLY)
126 
127 #define C_BAUD(tty)	_C_FLAG((tty), CBAUD)
128 #define C_CSIZE(tty)	_C_FLAG((tty), CSIZE)
129 #define C_CSTOPB(tty)	_C_FLAG((tty), CSTOPB)
130 #define C_CREAD(tty)	_C_FLAG((tty), CREAD)
131 #define C_PARENB(tty)	_C_FLAG((tty), PARENB)
132 #define C_PARODD(tty)	_C_FLAG((tty), PARODD)
133 #define C_HUPCL(tty)	_C_FLAG((tty), HUPCL)
134 #define C_CLOCAL(tty)	_C_FLAG((tty), CLOCAL)
135 #define C_CIBAUD(tty)	_C_FLAG((tty), CIBAUD)
136 #define C_CRTSCTS(tty)	_C_FLAG((tty), CRTSCTS)
137 
138 #define L_ISIG(tty)	_L_FLAG((tty), ISIG)
139 #define L_ICANON(tty)	_L_FLAG((tty), ICANON)
140 #define L_XCASE(tty)	_L_FLAG((tty), XCASE)
141 #define L_ECHO(tty)	_L_FLAG((tty), ECHO)
142 #define L_ECHOE(tty)	_L_FLAG((tty), ECHOE)
143 #define L_ECHOK(tty)	_L_FLAG((tty), ECHOK)
144 #define L_ECHONL(tty)	_L_FLAG((tty), ECHONL)
145 #define L_NOFLSH(tty)	_L_FLAG((tty), NOFLSH)
146 #define L_TOSTOP(tty)	_L_FLAG((tty), TOSTOP)
147 #define L_ECHOCTL(tty)	_L_FLAG((tty), ECHOCTL)
148 #define L_ECHOPRT(tty)	_L_FLAG((tty), ECHOPRT)
149 #define L_ECHOKE(tty)	_L_FLAG((tty), ECHOKE)
150 #define L_FLUSHO(tty)	_L_FLAG((tty), FLUSHO)
151 #define L_PENDIN(tty)	_L_FLAG((tty), PENDIN)
152 #define L_IEXTEN(tty)	_L_FLAG((tty), IEXTEN)
153 #define L_EXTPROC(tty)	_L_FLAG((tty), EXTPROC)
154 
155 struct device;
156 struct signal_struct;
157 
158 /*
159  * Port level information. Each device keeps its own port level information
160  * so provide a common structure for those ports wanting to use common support
161  * routines.
162  *
163  * The tty port has a different lifetime to the tty so must be kept apart.
164  * In addition be careful as tty -> port mappings are valid for the life
165  * of the tty object but in many cases port -> tty mappings are valid only
166  * until a hangup so don't use the wrong path.
167  */
168 
169 struct tty_port;
170 
171 struct tty_port_operations {
172 	/* Return 1 if the carrier is raised */
173 	int (*carrier_raised)(struct tty_port *port);
174 	/* Control the DTR line */
175 	void (*dtr_rts)(struct tty_port *port, int raise);
176 	/* Called when the last close completes or a hangup finishes
177 	   IFF the port was initialized. Do not use to free resources. Called
178 	   under the port mutex to serialize against activate/shutdowns */
179 	void (*shutdown)(struct tty_port *port);
180 	void (*drop)(struct tty_port *port);
181 	/* Called under the port mutex from tty_port_open, serialized using
182 	   the port mutex */
183         /* FIXME: long term getting the tty argument *out* of this would be
184            good for consoles */
185 	int (*activate)(struct tty_port *port, struct tty_struct *tty);
186 	/* Called on the final put of a port */
187 	void (*destruct)(struct tty_port *port);
188 };
189 
190 struct tty_port {
191 	struct tty_bufhead	buf;		/* Locked internally */
192 	struct tty_struct	*tty;		/* Back pointer */
193 	struct tty_struct	*itty;		/* internal back ptr */
194 	const struct tty_port_operations *ops;	/* Port operations */
195 	spinlock_t		lock;		/* Lock protecting tty field */
196 	int			blocked_open;	/* Waiting to open */
197 	int			count;		/* Usage count */
198 	wait_queue_head_t	open_wait;	/* Open waiters */
199 	wait_queue_head_t	close_wait;	/* Close waiters */
200 	wait_queue_head_t	delta_msr_wait;	/* Modem status change */
201 	unsigned long		flags;		/* TTY flags ASY_*/
202 	unsigned long		iflags;		/* TTYP_ internal flags */
203 #define TTYP_FLUSHING			1  /* Flushing to ldisc in progress */
204 #define TTYP_FLUSHPENDING		2  /* Queued buffer flush pending */
205 	unsigned char		console:1,	/* port is a console */
206 				low_latency:1;	/* direct buffer flush */
207 	struct mutex		mutex;		/* Locking */
208 	struct mutex		buf_mutex;	/* Buffer alloc lock */
209 	unsigned char		*xmit_buf;	/* Optional buffer */
210 	unsigned int		close_delay;	/* Close port delay */
211 	unsigned int		closing_wait;	/* Delay for output */
212 	int			drain_delay;	/* Set to zero if no pure time
213 						   based drain is needed else
214 						   set to size of fifo */
215 	struct kref		kref;		/* Ref counter */
216 };
217 
218 /*
219  * Where all of the state associated with a tty is kept while the tty
220  * is open.  Since the termios state should be kept even if the tty
221  * has been closed --- for things like the baud rate, etc --- it is
222  * not stored here, but rather a pointer to the real state is stored
223  * here.  Possible the winsize structure should have the same
224  * treatment, but (1) the default 80x24 is usually right and (2) it's
225  * most often used by a windowing system, which will set the correct
226  * size each time the window is created or resized anyway.
227  * 						- TYT, 9/14/92
228  */
229 
230 struct tty_operations;
231 
232 struct tty_struct {
233 	int	magic;
234 	struct kref kref;
235 	struct device *dev;
236 	struct tty_driver *driver;
237 	const struct tty_operations *ops;
238 	int index;
239 
240 	/* Protects ldisc changes: Lock tty not pty */
241 	struct mutex ldisc_mutex;
242 	struct tty_ldisc *ldisc;
243 
244 	struct mutex atomic_write_lock;
245 	struct mutex legacy_mutex;
246 	struct mutex termios_mutex;
247 	spinlock_t ctrl_lock;
248 	/* Termios values are protected by the termios mutex */
249 	struct ktermios termios, termios_locked;
250 	struct termiox *termiox;	/* May be NULL for unsupported */
251 	char name[64];
252 	struct pid *pgrp;		/* Protected by ctrl lock */
253 	struct pid *session;
254 	unsigned long flags;
255 	int count;
256 	struct winsize winsize;		/* termios mutex */
257 	unsigned char stopped:1, hw_stopped:1, flow_stopped:1, packet:1;
258 	unsigned char warned:1;
259 	unsigned char ctrl_status;	/* ctrl_lock */
260 	unsigned int receive_room;	/* Bytes free for queue */
261 
262 	struct tty_struct *link;
263 	struct fasync_struct *fasync;
264 	int alt_speed;		/* For magic substitution of 38400 bps */
265 	wait_queue_head_t write_wait;
266 	wait_queue_head_t read_wait;
267 	struct work_struct hangup_work;
268 	void *disc_data;
269 	void *driver_data;
270 	struct list_head tty_files;
271 
272 #define N_TTY_BUF_SIZE 4096
273 
274 	unsigned char closing:1;
275 	unsigned short minimum_to_wake;
276 	unsigned char *write_buf;
277 	int write_cnt;
278 	/* If the tty has a pending do_SAK, queue it here - akpm */
279 	struct work_struct SAK_work;
280 	struct tty_port *port;
281 };
282 
283 /* Each of a tty's open files has private_data pointing to tty_file_private */
284 struct tty_file_private {
285 	struct tty_struct *tty;
286 	struct file *file;
287 	struct list_head list;
288 };
289 
290 /* tty magic number */
291 #define TTY_MAGIC		0x5401
292 
293 /*
294  * These bits are used in the flags field of the tty structure.
295  *
296  * So that interrupts won't be able to mess up the queues,
297  * copy_to_cooked must be atomic with respect to itself, as must
298  * tty->write.  Thus, you must use the inline functions set_bit() and
299  * clear_bit() to make things atomic.
300  */
301 #define TTY_THROTTLED 		0	/* Call unthrottle() at threshold min */
302 #define TTY_IO_ERROR 		1	/* Cause an I/O error (may be no ldisc too) */
303 #define TTY_OTHER_CLOSED 	2	/* Other side (if any) has closed */
304 #define TTY_EXCLUSIVE 		3	/* Exclusive open mode */
305 #define TTY_DEBUG 		4	/* Debugging */
306 #define TTY_DO_WRITE_WAKEUP 	5	/* Call write_wakeup after queuing new */
307 #define TTY_PUSH 		6	/* n_tty private */
308 #define TTY_CLOSING 		7	/* ->close() in progress */
309 #define TTY_LDISC 		9	/* Line discipline attached */
310 #define TTY_LDISC_CHANGING 	10	/* Line discipline changing */
311 #define TTY_LDISC_OPEN	 	11	/* Line discipline is open */
312 #define TTY_HW_COOK_OUT 	14	/* Hardware can do output cooking */
313 #define TTY_HW_COOK_IN 		15	/* Hardware can do input cooking */
314 #define TTY_PTY_LOCK 		16	/* pty private */
315 #define TTY_NO_WRITE_SPLIT 	17	/* Preserve write boundaries to driver */
316 #define TTY_HUPPED 		18	/* Post driver->hangup() */
317 #define TTY_HUPPING 		21	/* ->hangup() in progress */
318 
319 #define TTY_WRITE_FLUSH(tty) tty_write_flush((tty))
320 
321 #ifdef CONFIG_TTY
322 extern void console_init(void);
323 extern void tty_kref_put(struct tty_struct *tty);
324 extern struct pid *tty_get_pgrp(struct tty_struct *tty);
325 extern void tty_vhangup_self(void);
326 extern void disassociate_ctty(int priv);
327 extern dev_t tty_devnum(struct tty_struct *tty);
328 extern void proc_clear_tty(struct task_struct *p);
329 extern struct tty_struct *get_current_tty(void);
330 /* tty_io.c */
331 extern int __init tty_init(void);
332 #else
333 static inline void console_init(void)
334 { }
335 static inline void tty_kref_put(struct tty_struct *tty)
336 { }
337 static inline struct pid *tty_get_pgrp(struct tty_struct *tty)
338 { return NULL; }
339 static inline void tty_vhangup_self(void)
340 { }
341 static inline void disassociate_ctty(int priv)
342 { }
343 static inline dev_t tty_devnum(struct tty_struct *tty)
344 { return 0; }
345 static inline void proc_clear_tty(struct task_struct *p)
346 { }
347 static inline struct tty_struct *get_current_tty(void)
348 { return NULL; }
349 /* tty_io.c */
350 static inline int __init tty_init(void)
351 { return 0; }
352 #endif
353 
354 extern void tty_write_flush(struct tty_struct *);
355 
356 extern struct ktermios tty_std_termios;
357 
358 extern int vcs_init(void);
359 
360 extern struct class *tty_class;
361 
362 /**
363  *	tty_kref_get		-	get a tty reference
364  *	@tty: tty device
365  *
366  *	Return a new reference to a tty object. The caller must hold
367  *	sufficient locks/counts to ensure that their existing reference cannot
368  *	go away
369  */
370 
371 static inline struct tty_struct *tty_kref_get(struct tty_struct *tty)
372 {
373 	if (tty)
374 		kref_get(&tty->kref);
375 	return tty;
376 }
377 
378 extern int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
379 			      const char *routine);
380 extern char *tty_name(struct tty_struct *tty, char *buf);
381 extern void tty_wait_until_sent(struct tty_struct *tty, long timeout);
382 extern int tty_check_change(struct tty_struct *tty);
383 extern void stop_tty(struct tty_struct *tty);
384 extern void start_tty(struct tty_struct *tty);
385 extern int tty_register_driver(struct tty_driver *driver);
386 extern int tty_unregister_driver(struct tty_driver *driver);
387 extern struct device *tty_register_device(struct tty_driver *driver,
388 					  unsigned index, struct device *dev);
389 extern struct device *tty_register_device_attr(struct tty_driver *driver,
390 				unsigned index, struct device *device,
391 				void *drvdata,
392 				const struct attribute_group **attr_grp);
393 extern void tty_unregister_device(struct tty_driver *driver, unsigned index);
394 extern int tty_read_raw_data(struct tty_struct *tty, unsigned char *bufp,
395 			     int buflen);
396 extern void tty_write_message(struct tty_struct *tty, char *msg);
397 extern int tty_put_char(struct tty_struct *tty, unsigned char c);
398 extern int tty_chars_in_buffer(struct tty_struct *tty);
399 extern int tty_write_room(struct tty_struct *tty);
400 extern void tty_driver_flush_buffer(struct tty_struct *tty);
401 extern void tty_throttle(struct tty_struct *tty);
402 extern void tty_unthrottle(struct tty_struct *tty);
403 extern int tty_do_resize(struct tty_struct *tty, struct winsize *ws);
404 extern void tty_driver_remove_tty(struct tty_driver *driver,
405 				  struct tty_struct *tty);
406 extern void tty_free_termios(struct tty_struct *tty);
407 extern int is_current_pgrp_orphaned(void);
408 extern int is_ignored(int sig);
409 extern int tty_signal(int sig, struct tty_struct *tty);
410 extern void tty_hangup(struct tty_struct *tty);
411 extern void tty_vhangup(struct tty_struct *tty);
412 extern void tty_vhangup_locked(struct tty_struct *tty);
413 extern void tty_unhangup(struct file *filp);
414 extern int tty_hung_up_p(struct file *filp);
415 extern void do_SAK(struct tty_struct *tty);
416 extern void __do_SAK(struct tty_struct *tty);
417 extern void no_tty(void);
418 extern void tty_flush_to_ldisc(struct tty_struct *tty);
419 extern void tty_buffer_free_all(struct tty_port *port);
420 extern void tty_buffer_flush(struct tty_struct *tty);
421 extern void tty_buffer_init(struct tty_port *port);
422 extern speed_t tty_get_baud_rate(struct tty_struct *tty);
423 extern speed_t tty_termios_baud_rate(struct ktermios *termios);
424 extern speed_t tty_termios_input_baud_rate(struct ktermios *termios);
425 extern void tty_termios_encode_baud_rate(struct ktermios *termios,
426 						speed_t ibaud, speed_t obaud);
427 extern void tty_encode_baud_rate(struct tty_struct *tty,
428 						speed_t ibaud, speed_t obaud);
429 extern void tty_termios_copy_hw(struct ktermios *new, struct ktermios *old);
430 extern int tty_termios_hw_change(struct ktermios *a, struct ktermios *b);
431 extern int tty_set_termios(struct tty_struct *tty, struct ktermios *kt);
432 
433 extern struct tty_ldisc *tty_ldisc_ref(struct tty_struct *);
434 extern void tty_ldisc_deref(struct tty_ldisc *);
435 extern struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *);
436 extern void tty_ldisc_hangup(struct tty_struct *tty);
437 extern const struct file_operations tty_ldiscs_proc_fops;
438 
439 extern void tty_wakeup(struct tty_struct *tty);
440 extern void tty_ldisc_flush(struct tty_struct *tty);
441 
442 extern long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
443 extern int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
444 			unsigned int cmd, unsigned long arg);
445 extern int tty_perform_flush(struct tty_struct *tty, unsigned long arg);
446 extern void tty_default_fops(struct file_operations *fops);
447 extern struct tty_struct *alloc_tty_struct(void);
448 extern int tty_alloc_file(struct file *file);
449 extern void tty_add_file(struct tty_struct *tty, struct file *file);
450 extern void tty_free_file(struct file *file);
451 extern void free_tty_struct(struct tty_struct *tty);
452 extern void initialize_tty_struct(struct tty_struct *tty,
453 		struct tty_driver *driver, int idx);
454 extern void deinitialize_tty_struct(struct tty_struct *tty);
455 extern struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx);
456 extern int tty_release(struct inode *inode, struct file *filp);
457 extern int tty_init_termios(struct tty_struct *tty);
458 extern int tty_standard_install(struct tty_driver *driver,
459 		struct tty_struct *tty);
460 
461 extern struct tty_struct *tty_pair_get_tty(struct tty_struct *tty);
462 extern struct tty_struct *tty_pair_get_pty(struct tty_struct *tty);
463 
464 extern struct mutex tty_mutex;
465 extern spinlock_t tty_files_lock;
466 
467 extern void tty_write_unlock(struct tty_struct *tty);
468 extern int tty_write_lock(struct tty_struct *tty, int ndelay);
469 #define tty_is_writelocked(tty)  (mutex_is_locked(&tty->atomic_write_lock))
470 
471 extern void tty_port_init(struct tty_port *port);
472 extern void tty_port_link_device(struct tty_port *port,
473 		struct tty_driver *driver, unsigned index);
474 extern struct device *tty_port_register_device(struct tty_port *port,
475 		struct tty_driver *driver, unsigned index,
476 		struct device *device);
477 extern struct device *tty_port_register_device_attr(struct tty_port *port,
478 		struct tty_driver *driver, unsigned index,
479 		struct device *device, void *drvdata,
480 		const struct attribute_group **attr_grp);
481 extern int tty_port_alloc_xmit_buf(struct tty_port *port);
482 extern void tty_port_free_xmit_buf(struct tty_port *port);
483 extern void tty_port_destroy(struct tty_port *port);
484 extern void tty_port_put(struct tty_port *port);
485 
486 static inline struct tty_port *tty_port_get(struct tty_port *port)
487 {
488 	if (port)
489 		kref_get(&port->kref);
490 	return port;
491 }
492 
493 /* If the cts flow control is enabled, return true. */
494 static inline bool tty_port_cts_enabled(struct tty_port *port)
495 {
496 	return port->flags & ASYNC_CTS_FLOW;
497 }
498 
499 extern struct tty_struct *tty_port_tty_get(struct tty_port *port);
500 extern void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty);
501 extern int tty_port_carrier_raised(struct tty_port *port);
502 extern void tty_port_raise_dtr_rts(struct tty_port *port);
503 extern void tty_port_lower_dtr_rts(struct tty_port *port);
504 extern void tty_port_hangup(struct tty_port *port);
505 extern int tty_port_block_til_ready(struct tty_port *port,
506 				struct tty_struct *tty, struct file *filp);
507 extern int tty_port_close_start(struct tty_port *port,
508 				struct tty_struct *tty, struct file *filp);
509 extern void tty_port_close_end(struct tty_port *port, struct tty_struct *tty);
510 extern void tty_port_close(struct tty_port *port,
511 				struct tty_struct *tty, struct file *filp);
512 extern int tty_port_install(struct tty_port *port, struct tty_driver *driver,
513 				struct tty_struct *tty);
514 extern int tty_port_open(struct tty_port *port,
515 				struct tty_struct *tty, struct file *filp);
516 static inline int tty_port_users(struct tty_port *port)
517 {
518 	return port->count + port->blocked_open;
519 }
520 
521 extern int tty_register_ldisc(int disc, struct tty_ldisc_ops *new_ldisc);
522 extern int tty_unregister_ldisc(int disc);
523 extern int tty_set_ldisc(struct tty_struct *tty, int ldisc);
524 extern int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty);
525 extern void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty);
526 extern void tty_ldisc_init(struct tty_struct *tty);
527 extern void tty_ldisc_deinit(struct tty_struct *tty);
528 extern void tty_ldisc_begin(void);
529 /* This last one is just for the tty layer internals and shouldn't be used elsewhere */
530 extern void tty_ldisc_enable(struct tty_struct *tty);
531 
532 
533 /* n_tty.c */
534 extern struct tty_ldisc_ops tty_ldisc_N_TTY;
535 extern void n_tty_inherit_ops(struct tty_ldisc_ops *ops);
536 
537 /* tty_audit.c */
538 #ifdef CONFIG_AUDIT
539 extern void tty_audit_add_data(struct tty_struct *tty, unsigned char *data,
540 			       size_t size, unsigned icanon);
541 extern void tty_audit_exit(void);
542 extern void tty_audit_fork(struct signal_struct *sig);
543 extern void tty_audit_tiocsti(struct tty_struct *tty, char ch);
544 extern void tty_audit_push(struct tty_struct *tty);
545 extern int tty_audit_push_task(struct task_struct *tsk,
546 			       kuid_t loginuid, u32 sessionid);
547 #else
548 static inline void tty_audit_add_data(struct tty_struct *tty,
549 		unsigned char *data, size_t size, unsigned icanon)
550 {
551 }
552 static inline void tty_audit_tiocsti(struct tty_struct *tty, char ch)
553 {
554 }
555 static inline void tty_audit_exit(void)
556 {
557 }
558 static inline void tty_audit_fork(struct signal_struct *sig)
559 {
560 }
561 static inline void tty_audit_push(struct tty_struct *tty)
562 {
563 }
564 static inline int tty_audit_push_task(struct task_struct *tsk,
565 				      kuid_t loginuid, u32 sessionid)
566 {
567 	return 0;
568 }
569 #endif
570 
571 /* tty_ioctl.c */
572 extern int n_tty_ioctl_helper(struct tty_struct *tty, struct file *file,
573 		       unsigned int cmd, unsigned long arg);
574 extern long n_tty_compat_ioctl_helper(struct tty_struct *tty, struct file *file,
575 		       unsigned int cmd, unsigned long arg);
576 
577 /* serial.c */
578 
579 extern void serial_console_init(void);
580 
581 /* pcxx.c */
582 
583 extern int pcxe_open(struct tty_struct *tty, struct file *filp);
584 
585 /* vt.c */
586 
587 extern int vt_ioctl(struct tty_struct *tty,
588 		    unsigned int cmd, unsigned long arg);
589 
590 extern long vt_compat_ioctl(struct tty_struct *tty,
591 		     unsigned int cmd, unsigned long arg);
592 
593 /* tty_mutex.c */
594 /* functions for preparation of BKL removal */
595 extern void __lockfunc tty_lock(struct tty_struct *tty);
596 extern void __lockfunc tty_unlock(struct tty_struct *tty);
597 extern void __lockfunc tty_lock_pair(struct tty_struct *tty,
598 				struct tty_struct *tty2);
599 extern void __lockfunc tty_unlock_pair(struct tty_struct *tty,
600 				struct tty_struct *tty2);
601 
602 /*
603  * this shall be called only from where BTM is held (like close)
604  *
605  * We need this to ensure nobody waits for us to finish while we are waiting.
606  * Without this we were encountering system stalls.
607  *
608  * This should be indeed removed with BTM removal later.
609  *
610  * Locking: BTM required. Nobody is allowed to hold port->mutex.
611  */
612 static inline void tty_wait_until_sent_from_close(struct tty_struct *tty,
613 		long timeout)
614 {
615 	tty_unlock(tty); /* tty->ops->close holds the BTM, drop it while waiting */
616 	tty_wait_until_sent(tty, timeout);
617 	tty_lock(tty);
618 }
619 
620 /*
621  * wait_event_interruptible_tty -- wait for a condition with the tty lock held
622  *
623  * The condition we are waiting for might take a long time to
624  * become true, or might depend on another thread taking the
625  * BTM. In either case, we need to drop the BTM to guarantee
626  * forward progress. This is a leftover from the conversion
627  * from the BKL and should eventually get removed as the BTM
628  * falls out of use.
629  *
630  * Do not use in new code.
631  */
632 #define wait_event_interruptible_tty(tty, wq, condition)		\
633 ({									\
634 	int __ret = 0;							\
635 	if (!(condition)) {						\
636 		__wait_event_interruptible_tty(tty, wq, condition, __ret);	\
637 	}								\
638 	__ret;								\
639 })
640 
641 #define __wait_event_interruptible_tty(tty, wq, condition, ret)		\
642 do {									\
643 	DEFINE_WAIT(__wait);						\
644 									\
645 	for (;;) {							\
646 		prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);	\
647 		if (condition)						\
648 			break;						\
649 		if (!signal_pending(current)) {				\
650 			tty_unlock(tty);					\
651 			schedule();					\
652 			tty_lock(tty);					\
653 			continue;					\
654 		}							\
655 		ret = -ERESTARTSYS;					\
656 		break;							\
657 	}								\
658 	finish_wait(&wq, &__wait);					\
659 } while (0)
660 
661 
662 #endif
663