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