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1 : : /* SPDX-License-Identifier: GPL-2.0 */
2 : : #ifndef _LINUX_TTY_DRIVER_H
3 : : #define _LINUX_TTY_DRIVER_H
4 : :
5 : : /*
6 : : * This structure defines the interface between the low-level tty
7 : : * driver and the tty routines. The following routines can be
8 : : * defined; unless noted otherwise, they are optional, and can be
9 : : * filled in with a null pointer.
10 : : *
11 : : * struct tty_struct * (*lookup)(struct tty_driver *self, struct file *, int idx)
12 : : *
13 : : * Return the tty device corresponding to idx, NULL if there is not
14 : : * one currently in use and an ERR_PTR value on error. Called under
15 : : * tty_mutex (for now!)
16 : : *
17 : : * Optional method. Default behaviour is to use the ttys array
18 : : *
19 : : * int (*install)(struct tty_driver *self, struct tty_struct *tty)
20 : : *
21 : : * Install a new tty into the tty driver internal tables. Used in
22 : : * conjunction with lookup and remove methods.
23 : : *
24 : : * Optional method. Default behaviour is to use the ttys array
25 : : *
26 : : * void (*remove)(struct tty_driver *self, struct tty_struct *tty)
27 : : *
28 : : * Remove a closed tty from the tty driver internal tables. Used in
29 : : * conjunction with lookup and remove methods.
30 : : *
31 : : * Optional method. Default behaviour is to use the ttys array
32 : : *
33 : : * int (*open)(struct tty_struct * tty, struct file * filp);
34 : : *
35 : : * This routine is called when a particular tty device is opened.
36 : : * This routine is mandatory; if this routine is not filled in,
37 : : * the attempted open will fail with ENODEV.
38 : : *
39 : : * Required method. Called with tty lock held.
40 : : *
41 : : * void (*close)(struct tty_struct * tty, struct file * filp);
42 : : *
43 : : * This routine is called when a particular tty device is closed.
44 : : * Note: called even if the corresponding open() failed.
45 : : *
46 : : * Required method. Called with tty lock held.
47 : : *
48 : : * void (*shutdown)(struct tty_struct * tty);
49 : : *
50 : : * This routine is called under the tty lock when a particular tty device
51 : : * is closed for the last time. It executes before the tty resources
52 : : * are freed so may execute while another function holds a tty kref.
53 : : *
54 : : * void (*cleanup)(struct tty_struct * tty);
55 : : *
56 : : * This routine is called asynchronously when a particular tty device
57 : : * is closed for the last time freeing up the resources. This is
58 : : * actually the second part of shutdown for routines that might sleep.
59 : : *
60 : : *
61 : : * int (*write)(struct tty_struct * tty,
62 : : * const unsigned char *buf, int count);
63 : : *
64 : : * This routine is called by the kernel to write a series of
65 : : * characters to the tty device. The characters may come from
66 : : * user space or kernel space. This routine will return the
67 : : * number of characters actually accepted for writing.
68 : : *
69 : : * Optional: Required for writable devices.
70 : : *
71 : : * int (*put_char)(struct tty_struct *tty, unsigned char ch);
72 : : *
73 : : * This routine is called by the kernel to write a single
74 : : * character to the tty device. If the kernel uses this routine,
75 : : * it must call the flush_chars() routine (if defined) when it is
76 : : * done stuffing characters into the driver. If there is no room
77 : : * in the queue, the character is ignored.
78 : : *
79 : : * Optional: Kernel will use the write method if not provided.
80 : : *
81 : : * Note: Do not call this function directly, call tty_put_char
82 : : *
83 : : * void (*flush_chars)(struct tty_struct *tty);
84 : : *
85 : : * This routine is called by the kernel after it has written a
86 : : * series of characters to the tty device using put_char().
87 : : *
88 : : * Optional:
89 : : *
90 : : * Note: Do not call this function directly, call tty_driver_flush_chars
91 : : *
92 : : * int (*write_room)(struct tty_struct *tty);
93 : : *
94 : : * This routine returns the numbers of characters the tty driver
95 : : * will accept for queuing to be written. This number is subject
96 : : * to change as output buffers get emptied, or if the output flow
97 : : * control is acted.
98 : : *
99 : : * Required if write method is provided else not needed.
100 : : *
101 : : * Note: Do not call this function directly, call tty_write_room
102 : : *
103 : : * int (*ioctl)(struct tty_struct *tty, unsigned int cmd, unsigned long arg);
104 : : *
105 : : * This routine allows the tty driver to implement
106 : : * device-specific ioctls. If the ioctl number passed in cmd
107 : : * is not recognized by the driver, it should return ENOIOCTLCMD.
108 : : *
109 : : * Optional
110 : : *
111 : : * long (*compat_ioctl)(struct tty_struct *tty,,
112 : : * unsigned int cmd, unsigned long arg);
113 : : *
114 : : * implement ioctl processing for 32 bit process on 64 bit system
115 : : *
116 : : * Optional
117 : : *
118 : : * void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
119 : : *
120 : : * This routine allows the tty driver to be notified when
121 : : * device's termios settings have changed.
122 : : *
123 : : * Optional: Called under the termios lock
124 : : *
125 : : *
126 : : * void (*set_ldisc)(struct tty_struct *tty);
127 : : *
128 : : * This routine allows the tty driver to be notified when the
129 : : * device's termios settings have changed.
130 : : *
131 : : * Optional: Called under BKL (currently)
132 : : *
133 : : * void (*throttle)(struct tty_struct * tty);
134 : : *
135 : : * This routine notifies the tty driver that input buffers for
136 : : * the line discipline are close to full, and it should somehow
137 : : * signal that no more characters should be sent to the tty.
138 : : *
139 : : * Optional: Always invoke via tty_throttle(), called under the
140 : : * termios lock.
141 : : *
142 : : * void (*unthrottle)(struct tty_struct * tty);
143 : : *
144 : : * This routine notifies the tty drivers that it should signals
145 : : * that characters can now be sent to the tty without fear of
146 : : * overrunning the input buffers of the line disciplines.
147 : : *
148 : : * Optional: Always invoke via tty_unthrottle(), called under the
149 : : * termios lock.
150 : : *
151 : : * void (*stop)(struct tty_struct *tty);
152 : : *
153 : : * This routine notifies the tty driver that it should stop
154 : : * outputting characters to the tty device.
155 : : *
156 : : * Called with ->flow_lock held. Serialized with start() method.
157 : : *
158 : : * Optional:
159 : : *
160 : : * Note: Call stop_tty not this method.
161 : : *
162 : : * void (*start)(struct tty_struct *tty);
163 : : *
164 : : * This routine notifies the tty driver that it resume sending
165 : : * characters to the tty device.
166 : : *
167 : : * Called with ->flow_lock held. Serialized with stop() method.
168 : : *
169 : : * Optional:
170 : : *
171 : : * Note: Call start_tty not this method.
172 : : *
173 : : * void (*hangup)(struct tty_struct *tty);
174 : : *
175 : : * This routine notifies the tty driver that it should hang up the
176 : : * tty device.
177 : : *
178 : : * Optional:
179 : : *
180 : : * Called with tty lock held.
181 : : *
182 : : * int (*break_ctl)(struct tty_struct *tty, int state);
183 : : *
184 : : * This optional routine requests the tty driver to turn on or
185 : : * off BREAK status on the RS-232 port. If state is -1,
186 : : * then the BREAK status should be turned on; if state is 0, then
187 : : * BREAK should be turned off.
188 : : *
189 : : * If this routine is implemented, the high-level tty driver will
190 : : * handle the following ioctls: TCSBRK, TCSBRKP, TIOCSBRK,
191 : : * TIOCCBRK.
192 : : *
193 : : * If the driver sets TTY_DRIVER_HARDWARE_BREAK then the interface
194 : : * will also be called with actual times and the hardware is expected
195 : : * to do the delay work itself. 0 and -1 are still used for on/off.
196 : : *
197 : : * Optional: Required for TCSBRK/BRKP/etc handling.
198 : : *
199 : : * void (*wait_until_sent)(struct tty_struct *tty, int timeout);
200 : : *
201 : : * This routine waits until the device has written out all of the
202 : : * characters in its transmitter FIFO.
203 : : *
204 : : * Optional: If not provided the device is assumed to have no FIFO
205 : : *
206 : : * Note: Usually correct to call tty_wait_until_sent
207 : : *
208 : : * void (*send_xchar)(struct tty_struct *tty, char ch);
209 : : *
210 : : * This routine is used to send a high-priority XON/XOFF
211 : : * character to the device.
212 : : *
213 : : * Optional: If not provided then the write method is called under
214 : : * the atomic write lock to keep it serialized with the ldisc.
215 : : *
216 : : * int (*resize)(struct tty_struct *tty, struct winsize *ws)
217 : : *
218 : : * Called when a termios request is issued which changes the
219 : : * requested terminal geometry.
220 : : *
221 : : * Optional: the default action is to update the termios structure
222 : : * without error. This is usually the correct behaviour. Drivers should
223 : : * not force errors here if they are not resizable objects (eg a serial
224 : : * line). See tty_do_resize() if you need to wrap the standard method
225 : : * in your own logic - the usual case.
226 : : *
227 : : * void (*set_termiox)(struct tty_struct *tty, struct termiox *new);
228 : : *
229 : : * Called when the device receives a termiox based ioctl. Passes down
230 : : * the requested data from user space. This method will not be invoked
231 : : * unless the tty also has a valid tty->termiox pointer.
232 : : *
233 : : * Optional: Called under the termios lock
234 : : *
235 : : * int (*get_icount)(struct tty_struct *tty, struct serial_icounter *icount);
236 : : *
237 : : * Called when the device receives a TIOCGICOUNT ioctl. Passed a kernel
238 : : * structure to complete. This method is optional and will only be called
239 : : * if provided (otherwise EINVAL will be returned).
240 : : */
241 : :
242 : : #include <linux/export.h>
243 : : #include <linux/fs.h>
244 : : #include <linux/list.h>
245 : : #include <linux/cdev.h>
246 : : #include <linux/termios.h>
247 : : #include <linux/seq_file.h>
248 : :
249 : : struct tty_struct;
250 : : struct tty_driver;
251 : : struct serial_icounter_struct;
252 : : struct serial_struct;
253 : :
254 : : struct tty_operations {
255 : : struct tty_struct * (*lookup)(struct tty_driver *driver,
256 : : struct file *filp, int idx);
257 : : int (*install)(struct tty_driver *driver, struct tty_struct *tty);
258 : : void (*remove)(struct tty_driver *driver, struct tty_struct *tty);
259 : : int (*open)(struct tty_struct * tty, struct file * filp);
260 : : void (*close)(struct tty_struct * tty, struct file * filp);
261 : : void (*shutdown)(struct tty_struct *tty);
262 : : void (*cleanup)(struct tty_struct *tty);
263 : : int (*write)(struct tty_struct * tty,
264 : : const unsigned char *buf, int count);
265 : : int (*put_char)(struct tty_struct *tty, unsigned char ch);
266 : : void (*flush_chars)(struct tty_struct *tty);
267 : : int (*write_room)(struct tty_struct *tty);
268 : : int (*chars_in_buffer)(struct tty_struct *tty);
269 : : int (*ioctl)(struct tty_struct *tty,
270 : : unsigned int cmd, unsigned long arg);
271 : : long (*compat_ioctl)(struct tty_struct *tty,
272 : : unsigned int cmd, unsigned long arg);
273 : : void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
274 : : void (*throttle)(struct tty_struct * tty);
275 : : void (*unthrottle)(struct tty_struct * tty);
276 : : void (*stop)(struct tty_struct *tty);
277 : : void (*start)(struct tty_struct *tty);
278 : : void (*hangup)(struct tty_struct *tty);
279 : : int (*break_ctl)(struct tty_struct *tty, int state);
280 : : void (*flush_buffer)(struct tty_struct *tty);
281 : : void (*set_ldisc)(struct tty_struct *tty);
282 : : void (*wait_until_sent)(struct tty_struct *tty, int timeout);
283 : : void (*send_xchar)(struct tty_struct *tty, char ch);
284 : : int (*tiocmget)(struct tty_struct *tty);
285 : : int (*tiocmset)(struct tty_struct *tty,
286 : : unsigned int set, unsigned int clear);
287 : : int (*resize)(struct tty_struct *tty, struct winsize *ws);
288 : : int (*set_termiox)(struct tty_struct *tty, struct termiox *tnew);
289 : : int (*get_icount)(struct tty_struct *tty,
290 : : struct serial_icounter_struct *icount);
291 : : int (*get_serial)(struct tty_struct *tty, struct serial_struct *p);
292 : : int (*set_serial)(struct tty_struct *tty, struct serial_struct *p);
293 : : void (*show_fdinfo)(struct tty_struct *tty, struct seq_file *m);
294 : : #ifdef CONFIG_CONSOLE_POLL
295 : : int (*poll_init)(struct tty_driver *driver, int line, char *options);
296 : : int (*poll_get_char)(struct tty_driver *driver, int line);
297 : : void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
298 : : #endif
299 : : int (*proc_show)(struct seq_file *, void *);
300 : : } __randomize_layout;
301 : :
302 : : struct tty_driver {
303 : : int magic; /* magic number for this structure */
304 : : struct kref kref; /* Reference management */
305 : : struct cdev **cdevs;
306 : : struct module *owner;
307 : : const char *driver_name;
308 : : const char *name;
309 : : int name_base; /* offset of printed name */
310 : : int major; /* major device number */
311 : : int minor_start; /* start of minor device number */
312 : : unsigned int num; /* number of devices allocated */
313 : : short type; /* type of tty driver */
314 : : short subtype; /* subtype of tty driver */
315 : : struct ktermios init_termios; /* Initial termios */
316 : : unsigned long flags; /* tty driver flags */
317 : : struct proc_dir_entry *proc_entry; /* /proc fs entry */
318 : : struct tty_driver *other; /* only used for the PTY driver */
319 : :
320 : : /*
321 : : * Pointer to the tty data structures
322 : : */
323 : : struct tty_struct **ttys;
324 : : struct tty_port **ports;
325 : : struct ktermios **termios;
326 : : void *driver_state;
327 : :
328 : : /*
329 : : * Driver methods
330 : : */
331 : :
332 : : const struct tty_operations *ops;
333 : : struct list_head tty_drivers;
334 : : } __randomize_layout;
335 : :
336 : : extern struct list_head tty_drivers;
337 : :
338 : : extern struct tty_driver *__tty_alloc_driver(unsigned int lines,
339 : : struct module *owner, unsigned long flags);
340 : : extern void put_tty_driver(struct tty_driver *driver);
341 : : extern void tty_set_operations(struct tty_driver *driver,
342 : : const struct tty_operations *op);
343 : : extern struct tty_driver *tty_find_polling_driver(char *name, int *line);
344 : :
345 : : extern void tty_driver_kref_put(struct tty_driver *driver);
346 : :
347 : : /* Use TTY_DRIVER_* flags below */
348 : : #define tty_alloc_driver(lines, flags) \
349 : : __tty_alloc_driver(lines, THIS_MODULE, flags)
350 : :
351 : : /*
352 : : * DEPRECATED Do not use this in new code, use tty_alloc_driver instead.
353 : : * (And change the return value checks.)
354 : : */
355 : : static inline struct tty_driver *alloc_tty_driver(unsigned int lines)
356 : : {
357 : 808 : struct tty_driver *ret = tty_alloc_driver(lines, 0);
358 [ + - ]: 808 : if (IS_ERR(ret))
359 : : return NULL;
360 : : return ret;
361 : : }
362 : :
363 : : static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
364 : : {
365 : : kref_get(&d->kref);
366 : : return d;
367 : : }
368 : :
369 : : /* tty driver magic number */
370 : : #define TTY_DRIVER_MAGIC 0x5402
371 : :
372 : : /*
373 : : * tty driver flags
374 : : *
375 : : * TTY_DRIVER_RESET_TERMIOS --- requests the tty layer to reset the
376 : : * termios setting when the last process has closed the device.
377 : : * Used for PTY's, in particular.
378 : : *
379 : : * TTY_DRIVER_REAL_RAW --- if set, indicates that the driver will
380 : : * guarantee never not to set any special character handling
381 : : * flags if ((IGNBRK || (!BRKINT && !PARMRK)) && (IGNPAR ||
382 : : * !INPCK)). That is, if there is no reason for the driver to
383 : : * send notifications of parity and break characters up to the
384 : : * line driver, it won't do so. This allows the line driver to
385 : : * optimize for this case if this flag is set. (Note that there
386 : : * is also a promise, if the above case is true, not to signal
387 : : * overruns, either.)
388 : : *
389 : : * TTY_DRIVER_DYNAMIC_DEV --- if set, the individual tty devices need
390 : : * to be registered with a call to tty_register_device() when the
391 : : * device is found in the system and unregistered with a call to
392 : : * tty_unregister_device() so the devices will be show up
393 : : * properly in sysfs. If not set, driver->num entries will be
394 : : * created by the tty core in sysfs when tty_register_driver() is
395 : : * called. This is to be used by drivers that have tty devices
396 : : * that can appear and disappear while the main tty driver is
397 : : * registered with the tty core.
398 : : *
399 : : * TTY_DRIVER_DEVPTS_MEM -- don't use the standard arrays, instead
400 : : * use dynamic memory keyed through the devpts filesystem. This
401 : : * is only applicable to the pty driver.
402 : : *
403 : : * TTY_DRIVER_HARDWARE_BREAK -- hardware handles break signals. Pass
404 : : * the requested timeout to the caller instead of using a simple
405 : : * on/off interface.
406 : : *
407 : : * TTY_DRIVER_DYNAMIC_ALLOC -- do not allocate structures which are
408 : : * needed per line for this driver as it would waste memory.
409 : : * The driver will take care.
410 : : *
411 : : * TTY_DRIVER_UNNUMBERED_NODE -- do not create numbered /dev nodes. In
412 : : * other words create /dev/ttyprintk and not /dev/ttyprintk0.
413 : : * Applicable only when a driver for a single tty device is
414 : : * being allocated.
415 : : */
416 : : #define TTY_DRIVER_INSTALLED 0x0001
417 : : #define TTY_DRIVER_RESET_TERMIOS 0x0002
418 : : #define TTY_DRIVER_REAL_RAW 0x0004
419 : : #define TTY_DRIVER_DYNAMIC_DEV 0x0008
420 : : #define TTY_DRIVER_DEVPTS_MEM 0x0010
421 : : #define TTY_DRIVER_HARDWARE_BREAK 0x0020
422 : : #define TTY_DRIVER_DYNAMIC_ALLOC 0x0040
423 : : #define TTY_DRIVER_UNNUMBERED_NODE 0x0080
424 : :
425 : : /* tty driver types */
426 : : #define TTY_DRIVER_TYPE_SYSTEM 0x0001
427 : : #define TTY_DRIVER_TYPE_CONSOLE 0x0002
428 : : #define TTY_DRIVER_TYPE_SERIAL 0x0003
429 : : #define TTY_DRIVER_TYPE_PTY 0x0004
430 : : #define TTY_DRIVER_TYPE_SCC 0x0005 /* scc driver */
431 : : #define TTY_DRIVER_TYPE_SYSCONS 0x0006
432 : :
433 : : /* system subtypes (magic, used by tty_io.c) */
434 : : #define SYSTEM_TYPE_TTY 0x0001
435 : : #define SYSTEM_TYPE_CONSOLE 0x0002
436 : : #define SYSTEM_TYPE_SYSCONS 0x0003
437 : : #define SYSTEM_TYPE_SYSPTMX 0x0004
438 : :
439 : : /* pty subtypes (magic, used by tty_io.c) */
440 : : #define PTY_TYPE_MASTER 0x0001
441 : : #define PTY_TYPE_SLAVE 0x0002
442 : :
443 : : /* serial subtype definitions */
444 : : #define SERIAL_TYPE_NORMAL 1
445 : :
446 : : #endif /* #ifdef _LINUX_TTY_DRIVER_H */
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