Line data Source code
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 : * int (*get_icount)(struct tty_struct *tty, struct serial_icounter *icount);
228 : *
229 : * Called when the device receives a TIOCGICOUNT ioctl. Passed a kernel
230 : * structure to complete. This method is optional and will only be called
231 : * if provided (otherwise EINVAL will be returned).
232 : */
233 :
234 : #include <linux/export.h>
235 : #include <linux/fs.h>
236 : #include <linux/list.h>
237 : #include <linux/cdev.h>
238 : #include <linux/termios.h>
239 : #include <linux/seq_file.h>
240 :
241 : struct tty_struct;
242 : struct tty_driver;
243 : struct serial_icounter_struct;
244 : struct serial_struct;
245 :
246 : struct tty_operations {
247 : struct tty_struct * (*lookup)(struct tty_driver *driver,
248 : struct file *filp, int idx);
249 : int (*install)(struct tty_driver *driver, struct tty_struct *tty);
250 : void (*remove)(struct tty_driver *driver, struct tty_struct *tty);
251 : int (*open)(struct tty_struct * tty, struct file * filp);
252 : void (*close)(struct tty_struct * tty, struct file * filp);
253 : void (*shutdown)(struct tty_struct *tty);
254 : void (*cleanup)(struct tty_struct *tty);
255 : int (*write)(struct tty_struct * tty,
256 : const unsigned char *buf, int count);
257 : int (*put_char)(struct tty_struct *tty, unsigned char ch);
258 : void (*flush_chars)(struct tty_struct *tty);
259 : int (*write_room)(struct tty_struct *tty);
260 : int (*chars_in_buffer)(struct tty_struct *tty);
261 : int (*ioctl)(struct tty_struct *tty,
262 : unsigned int cmd, unsigned long arg);
263 : long (*compat_ioctl)(struct tty_struct *tty,
264 : unsigned int cmd, unsigned long arg);
265 : void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
266 : void (*throttle)(struct tty_struct * tty);
267 : void (*unthrottle)(struct tty_struct * tty);
268 : void (*stop)(struct tty_struct *tty);
269 : void (*start)(struct tty_struct *tty);
270 : void (*hangup)(struct tty_struct *tty);
271 : int (*break_ctl)(struct tty_struct *tty, int state);
272 : void (*flush_buffer)(struct tty_struct *tty);
273 : void (*set_ldisc)(struct tty_struct *tty);
274 : void (*wait_until_sent)(struct tty_struct *tty, int timeout);
275 : void (*send_xchar)(struct tty_struct *tty, char ch);
276 : int (*tiocmget)(struct tty_struct *tty);
277 : int (*tiocmset)(struct tty_struct *tty,
278 : unsigned int set, unsigned int clear);
279 : int (*resize)(struct tty_struct *tty, struct winsize *ws);
280 : int (*get_icount)(struct tty_struct *tty,
281 : struct serial_icounter_struct *icount);
282 : int (*get_serial)(struct tty_struct *tty, struct serial_struct *p);
283 : int (*set_serial)(struct tty_struct *tty, struct serial_struct *p);
284 : void (*show_fdinfo)(struct tty_struct *tty, struct seq_file *m);
285 : #ifdef CONFIG_CONSOLE_POLL
286 : int (*poll_init)(struct tty_driver *driver, int line, char *options);
287 : int (*poll_get_char)(struct tty_driver *driver, int line);
288 : void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
289 : #endif
290 : int (*proc_show)(struct seq_file *, void *);
291 : } __randomize_layout;
292 :
293 : struct tty_driver {
294 : int magic; /* magic number for this structure */
295 : struct kref kref; /* Reference management */
296 : struct cdev **cdevs;
297 : struct module *owner;
298 : const char *driver_name;
299 : const char *name;
300 : int name_base; /* offset of printed name */
301 : int major; /* major device number */
302 : int minor_start; /* start of minor device number */
303 : unsigned int num; /* number of devices allocated */
304 : short type; /* type of tty driver */
305 : short subtype; /* subtype of tty driver */
306 : struct ktermios init_termios; /* Initial termios */
307 : unsigned long flags; /* tty driver flags */
308 : struct proc_dir_entry *proc_entry; /* /proc fs entry */
309 : struct tty_driver *other; /* only used for the PTY driver */
310 :
311 : /*
312 : * Pointer to the tty data structures
313 : */
314 : struct tty_struct **ttys;
315 : struct tty_port **ports;
316 : struct ktermios **termios;
317 : void *driver_state;
318 :
319 : /*
320 : * Driver methods
321 : */
322 :
323 : const struct tty_operations *ops;
324 : struct list_head tty_drivers;
325 : } __randomize_layout;
326 :
327 : extern struct list_head tty_drivers;
328 :
329 : extern struct tty_driver *__tty_alloc_driver(unsigned int lines,
330 : struct module *owner, unsigned long flags);
331 : extern void put_tty_driver(struct tty_driver *driver);
332 : extern void tty_set_operations(struct tty_driver *driver,
333 : const struct tty_operations *op);
334 : extern struct tty_driver *tty_find_polling_driver(char *name, int *line);
335 :
336 : extern void tty_driver_kref_put(struct tty_driver *driver);
337 :
338 : /* Use TTY_DRIVER_* flags below */
339 : #define tty_alloc_driver(lines, flags) \
340 : __tty_alloc_driver(lines, THIS_MODULE, flags)
341 :
342 : /*
343 : * DEPRECATED Do not use this in new code, use tty_alloc_driver instead.
344 : * (And change the return value checks.)
345 : */
346 2 : static inline struct tty_driver *alloc_tty_driver(unsigned int lines)
347 : {
348 2 : struct tty_driver *ret = tty_alloc_driver(lines, 0);
349 2 : if (IS_ERR(ret))
350 0 : return NULL;
351 : return ret;
352 : }
353 :
354 339 : static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
355 : {
356 339 : kref_get(&d->kref);
357 176 : return d;
358 : }
359 :
360 : /* tty driver magic number */
361 : #define TTY_DRIVER_MAGIC 0x5402
362 :
363 : /*
364 : * tty driver flags
365 : *
366 : * TTY_DRIVER_RESET_TERMIOS --- requests the tty layer to reset the
367 : * termios setting when the last process has closed the device.
368 : * Used for PTY's, in particular.
369 : *
370 : * TTY_DRIVER_REAL_RAW --- if set, indicates that the driver will
371 : * guarantee never not to set any special character handling
372 : * flags if ((IGNBRK || (!BRKINT && !PARMRK)) && (IGNPAR ||
373 : * !INPCK)). That is, if there is no reason for the driver to
374 : * send notifications of parity and break characters up to the
375 : * line driver, it won't do so. This allows the line driver to
376 : * optimize for this case if this flag is set. (Note that there
377 : * is also a promise, if the above case is true, not to signal
378 : * overruns, either.)
379 : *
380 : * TTY_DRIVER_DYNAMIC_DEV --- if set, the individual tty devices need
381 : * to be registered with a call to tty_register_device() when the
382 : * device is found in the system and unregistered with a call to
383 : * tty_unregister_device() so the devices will be show up
384 : * properly in sysfs. If not set, driver->num entries will be
385 : * created by the tty core in sysfs when tty_register_driver() is
386 : * called. This is to be used by drivers that have tty devices
387 : * that can appear and disappear while the main tty driver is
388 : * registered with the tty core.
389 : *
390 : * TTY_DRIVER_DEVPTS_MEM -- don't use the standard arrays, instead
391 : * use dynamic memory keyed through the devpts filesystem. This
392 : * is only applicable to the pty driver.
393 : *
394 : * TTY_DRIVER_HARDWARE_BREAK -- hardware handles break signals. Pass
395 : * the requested timeout to the caller instead of using a simple
396 : * on/off interface.
397 : *
398 : * TTY_DRIVER_DYNAMIC_ALLOC -- do not allocate structures which are
399 : * needed per line for this driver as it would waste memory.
400 : * The driver will take care.
401 : *
402 : * TTY_DRIVER_UNNUMBERED_NODE -- do not create numbered /dev nodes. In
403 : * other words create /dev/ttyprintk and not /dev/ttyprintk0.
404 : * Applicable only when a driver for a single tty device is
405 : * being allocated.
406 : */
407 : #define TTY_DRIVER_INSTALLED 0x0001
408 : #define TTY_DRIVER_RESET_TERMIOS 0x0002
409 : #define TTY_DRIVER_REAL_RAW 0x0004
410 : #define TTY_DRIVER_DYNAMIC_DEV 0x0008
411 : #define TTY_DRIVER_DEVPTS_MEM 0x0010
412 : #define TTY_DRIVER_HARDWARE_BREAK 0x0020
413 : #define TTY_DRIVER_DYNAMIC_ALLOC 0x0040
414 : #define TTY_DRIVER_UNNUMBERED_NODE 0x0080
415 :
416 : /* tty driver types */
417 : #define TTY_DRIVER_TYPE_SYSTEM 0x0001
418 : #define TTY_DRIVER_TYPE_CONSOLE 0x0002
419 : #define TTY_DRIVER_TYPE_SERIAL 0x0003
420 : #define TTY_DRIVER_TYPE_PTY 0x0004
421 : #define TTY_DRIVER_TYPE_SCC 0x0005 /* scc driver */
422 : #define TTY_DRIVER_TYPE_SYSCONS 0x0006
423 :
424 : /* system subtypes (magic, used by tty_io.c) */
425 : #define SYSTEM_TYPE_TTY 0x0001
426 : #define SYSTEM_TYPE_CONSOLE 0x0002
427 : #define SYSTEM_TYPE_SYSCONS 0x0003
428 : #define SYSTEM_TYPE_SYSPTMX 0x0004
429 :
430 : /* pty subtypes (magic, used by tty_io.c) */
431 : #define PTY_TYPE_MASTER 0x0001
432 : #define PTY_TYPE_SLAVE 0x0002
433 :
434 : /* serial subtype definitions */
435 : #define SERIAL_TYPE_NORMAL 1
436 :
437 : #endif /* #ifdef _LINUX_TTY_DRIVER_H */
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