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 * unsigned 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_safe(), 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 ENOTTY will be returned).
232 */
233
234 #include <linux/export.h>
235 #include <linux/fs.h>
236 #include <linux/kref.h>
237 #include <linux/list.h>
238 #include <linux/cdev.h>
239 #include <linux/termios.h>
240 #include <linux/seq_file.h>
241
242 struct tty_struct;
243 struct tty_driver;
244 struct serial_icounter_struct;
245 struct serial_struct;
246
247 struct tty_operations {
248 struct tty_struct * (*lookup)(struct tty_driver *driver,
249 struct file *filp, int idx);
250 int (*install)(struct tty_driver *driver, struct tty_struct *tty);
251 void (*remove)(struct tty_driver *driver, struct tty_struct *tty);
252 int (*open)(struct tty_struct * tty, struct file * filp);
253 void (*close)(struct tty_struct * tty, struct file * filp);
254 void (*shutdown)(struct tty_struct *tty);
255 void (*cleanup)(struct tty_struct *tty);
256 int (*write)(struct tty_struct * tty,
257 const unsigned char *buf, int count);
258 int (*put_char)(struct tty_struct *tty, unsigned char ch);
259 void (*flush_chars)(struct tty_struct *tty);
260 unsigned int (*write_room)(struct tty_struct *tty);
261 unsigned int (*chars_in_buffer)(struct tty_struct *tty);
262 int (*ioctl)(struct tty_struct *tty,
263 unsigned int cmd, unsigned long arg);
264 long (*compat_ioctl)(struct tty_struct *tty,
265 unsigned int cmd, unsigned long arg);
266 void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
267 void (*throttle)(struct tty_struct * tty);
268 void (*unthrottle)(struct tty_struct * tty);
269 void (*stop)(struct tty_struct *tty);
270 void (*start)(struct tty_struct *tty);
271 void (*hangup)(struct tty_struct *tty);
272 int (*break_ctl)(struct tty_struct *tty, int state);
273 void (*flush_buffer)(struct tty_struct *tty);
274 void (*set_ldisc)(struct tty_struct *tty);
275 void (*wait_until_sent)(struct tty_struct *tty, int timeout);
276 void (*send_xchar)(struct tty_struct *tty, char ch);
277 int (*tiocmget)(struct tty_struct *tty);
278 int (*tiocmset)(struct tty_struct *tty,
279 unsigned int set, unsigned int clear);
280 int (*resize)(struct tty_struct *tty, struct winsize *ws);
281 int (*get_icount)(struct tty_struct *tty,
282 struct serial_icounter_struct *icount);
283 int (*get_serial)(struct tty_struct *tty, struct serial_struct *p);
284 int (*set_serial)(struct tty_struct *tty, struct serial_struct *p);
285 void (*show_fdinfo)(struct tty_struct *tty, struct seq_file *m);
286 #ifdef CONFIG_CONSOLE_POLL
287 int (*poll_init)(struct tty_driver *driver, int line, char *options);
288 int (*poll_get_char)(struct tty_driver *driver, int line);
289 void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
290 #endif
291 int (*proc_show)(struct seq_file *, void *);
292 } __randomize_layout;
293
294 struct tty_driver {
295 int magic; /* magic number for this structure */
296 struct kref kref; /* Reference management */
297 struct cdev **cdevs;
298 struct module *owner;
299 const char *driver_name;
300 const char *name;
301 int name_base; /* offset of printed name */
302 int major; /* major device number */
303 int minor_start; /* start of minor device number */
304 unsigned int num; /* number of devices allocated */
305 short type; /* type of tty driver */
306 short subtype; /* subtype of tty driver */
307 struct ktermios init_termios; /* Initial termios */
308 unsigned long flags; /* tty driver flags */
309 struct proc_dir_entry *proc_entry; /* /proc fs entry */
310 struct tty_driver *other; /* only used for the PTY driver */
311
312 /*
313 * Pointer to the tty data structures
314 */
315 struct tty_struct **ttys;
316 struct tty_port **ports;
317 struct ktermios **termios;
318 void *driver_state;
319
320 /*
321 * Driver methods
322 */
323
324 const struct tty_operations *ops;
325 struct list_head tty_drivers;
326 } __randomize_layout;
327
328 extern struct list_head tty_drivers;
329
330 extern struct tty_driver *__tty_alloc_driver(unsigned int lines,
331 struct module *owner, unsigned long flags);
332 extern struct tty_driver *tty_find_polling_driver(char *name, int *line);
333
334 extern void tty_driver_kref_put(struct tty_driver *driver);
335
336 /* Use TTY_DRIVER_* flags below */
337 #define tty_alloc_driver(lines, flags) \
338 __tty_alloc_driver(lines, THIS_MODULE, flags)
339
tty_driver_kref_get(struct tty_driver * d)340 static inline struct tty_driver *tty_driver_kref_get(struct tty_driver *d)
341 {
342 kref_get(&d->kref);
343 return d;
344 }
345
tty_set_operations(struct tty_driver * driver,const struct tty_operations * op)346 static inline void tty_set_operations(struct tty_driver *driver,
347 const struct tty_operations *op)
348 {
349 driver->ops = op;
350 }
351
352 /* tty driver magic number */
353 #define TTY_DRIVER_MAGIC 0x5402
354
355 /*
356 * tty driver flags
357 *
358 * TTY_DRIVER_RESET_TERMIOS --- requests the tty layer to reset the
359 * termios setting when the last process has closed the device.
360 * Used for PTY's, in particular.
361 *
362 * TTY_DRIVER_REAL_RAW --- if set, indicates that the driver will
363 * guarantee never not to set any special character handling
364 * flags if ((IGNBRK || (!BRKINT && !PARMRK)) && (IGNPAR ||
365 * !INPCK)). That is, if there is no reason for the driver to
366 * send notifications of parity and break characters up to the
367 * line driver, it won't do so. This allows the line driver to
368 * optimize for this case if this flag is set. (Note that there
369 * is also a promise, if the above case is true, not to signal
370 * overruns, either.)
371 *
372 * TTY_DRIVER_DYNAMIC_DEV --- if set, the individual tty devices need
373 * to be registered with a call to tty_register_device() when the
374 * device is found in the system and unregistered with a call to
375 * tty_unregister_device() so the devices will be show up
376 * properly in sysfs. If not set, driver->num entries will be
377 * created by the tty core in sysfs when tty_register_driver() is
378 * called. This is to be used by drivers that have tty devices
379 * that can appear and disappear while the main tty driver is
380 * registered with the tty core.
381 *
382 * TTY_DRIVER_DEVPTS_MEM -- don't use the standard arrays, instead
383 * use dynamic memory keyed through the devpts filesystem. This
384 * is only applicable to the pty driver.
385 *
386 * TTY_DRIVER_HARDWARE_BREAK -- hardware handles break signals. Pass
387 * the requested timeout to the caller instead of using a simple
388 * on/off interface.
389 *
390 * TTY_DRIVER_DYNAMIC_ALLOC -- do not allocate structures which are
391 * needed per line for this driver as it would waste memory.
392 * The driver will take care.
393 *
394 * TTY_DRIVER_UNNUMBERED_NODE -- do not create numbered /dev nodes. In
395 * other words create /dev/ttyprintk and not /dev/ttyprintk0.
396 * Applicable only when a driver for a single tty device is
397 * being allocated.
398 */
399 #define TTY_DRIVER_INSTALLED 0x0001
400 #define TTY_DRIVER_RESET_TERMIOS 0x0002
401 #define TTY_DRIVER_REAL_RAW 0x0004
402 #define TTY_DRIVER_DYNAMIC_DEV 0x0008
403 #define TTY_DRIVER_DEVPTS_MEM 0x0010
404 #define TTY_DRIVER_HARDWARE_BREAK 0x0020
405 #define TTY_DRIVER_DYNAMIC_ALLOC 0x0040
406 #define TTY_DRIVER_UNNUMBERED_NODE 0x0080
407
408 /* tty driver types */
409 #define TTY_DRIVER_TYPE_SYSTEM 0x0001
410 #define TTY_DRIVER_TYPE_CONSOLE 0x0002
411 #define TTY_DRIVER_TYPE_SERIAL 0x0003
412 #define TTY_DRIVER_TYPE_PTY 0x0004
413 #define TTY_DRIVER_TYPE_SCC 0x0005 /* scc driver */
414 #define TTY_DRIVER_TYPE_SYSCONS 0x0006
415
416 /* system subtypes (magic, used by tty_io.c) */
417 #define SYSTEM_TYPE_TTY 0x0001
418 #define SYSTEM_TYPE_CONSOLE 0x0002
419 #define SYSTEM_TYPE_SYSCONS 0x0003
420 #define SYSTEM_TYPE_SYSPTMX 0x0004
421
422 /* pty subtypes (magic, used by tty_io.c) */
423 #define PTY_TYPE_MASTER 0x0001
424 #define PTY_TYPE_SLAVE 0x0002
425
426 /* serial subtype definitions */
427 #define SERIAL_TYPE_NORMAL 1
428
429 int tty_register_driver(struct tty_driver *driver);
430 void tty_unregister_driver(struct tty_driver *driver);
431 struct device *tty_register_device(struct tty_driver *driver, unsigned index,
432 struct device *dev);
433 struct device *tty_register_device_attr(struct tty_driver *driver,
434 unsigned index, struct device *device, void *drvdata,
435 const struct attribute_group **attr_grp);
436 void tty_unregister_device(struct tty_driver *driver, unsigned index);
437
438 #ifdef CONFIG_PROC_FS
439 void proc_tty_register_driver(struct tty_driver *);
440 void proc_tty_unregister_driver(struct tty_driver *);
441 #else
proc_tty_register_driver(struct tty_driver * d)442 static inline void proc_tty_register_driver(struct tty_driver *d) {}
proc_tty_unregister_driver(struct tty_driver * d)443 static inline void proc_tty_unregister_driver(struct tty_driver *d) {}
444 #endif
445
446 #endif /* #ifdef _LINUX_TTY_DRIVER_H */
447
