Commit | Line | Data |
---|---|---|
b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
1da177e4 LT |
2 | #ifndef _LINUX_TTY_LDISC_H |
3 | #define _LINUX_TTY_LDISC_H | |
4 | ||
a24bc667 JS |
5 | struct tty_struct; |
6 | ||
1da177e4 LT |
7 | #include <linux/fs.h> |
8 | #include <linux/wait.h> | |
5fd691af | 9 | #include <linux/atomic.h> |
abca9901 JS |
10 | #include <linux/list.h> |
11 | #include <linux/lockdep.h> | |
a24bc667 | 12 | #include <linux/seq_file.h> |
4898e640 PH |
13 | |
14 | /* | |
15 | * the semaphore definition | |
16 | */ | |
17 | struct ld_semaphore { | |
5fd691af | 18 | atomic_long_t count; |
4898e640 PH |
19 | raw_spinlock_t wait_lock; |
20 | unsigned int wait_readers; | |
21 | struct list_head read_wait; | |
22 | struct list_head write_wait; | |
23 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
24 | struct lockdep_map dep_map; | |
25 | #endif | |
26 | }; | |
27 | ||
78941934 | 28 | void __init_ldsem(struct ld_semaphore *sem, const char *name, |
4898e640 PH |
29 | struct lock_class_key *key); |
30 | ||
31 | #define init_ldsem(sem) \ | |
32 | do { \ | |
33 | static struct lock_class_key __key; \ | |
34 | \ | |
35 | __init_ldsem((sem), #sem, &__key); \ | |
36 | } while (0) | |
37 | ||
38 | ||
78941934 JS |
39 | int ldsem_down_read(struct ld_semaphore *sem, long timeout); |
40 | int ldsem_down_read_trylock(struct ld_semaphore *sem); | |
41 | int ldsem_down_write(struct ld_semaphore *sem, long timeout); | |
42 | int ldsem_down_write_trylock(struct ld_semaphore *sem); | |
43 | void ldsem_up_read(struct ld_semaphore *sem); | |
44 | void ldsem_up_write(struct ld_semaphore *sem); | |
4898e640 PH |
45 | |
46 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
78941934 JS |
47 | int ldsem_down_read_nested(struct ld_semaphore *sem, int subclass, |
48 | long timeout); | |
49 | int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass, | |
50 | long timeout); | |
4898e640 PH |
51 | #else |
52 | # define ldsem_down_read_nested(sem, subclass, timeout) \ | |
53 | ldsem_down_read(sem, timeout) | |
54 | # define ldsem_down_write_nested(sem, subclass, timeout) \ | |
55 | ldsem_down_write(sem, timeout) | |
56 | #endif | |
57 | ||
0c6119f9 JS |
58 | /** |
59 | * struct tty_ldisc_ops - ldisc operations | |
60 | * | |
61 | * @name: name of this ldisc rendered in /proc/tty/ldiscs | |
62 | * @num: ``N_*`` number (%N_TTY, %N_HDLC, ...) reserved to this ldisc | |
63 | * | |
40f4268c | 64 | * @open: [TTY] ``int ()(struct tty_struct *tty)`` |
0c6119f9 JS |
65 | * |
66 | * This function is called when the line discipline is associated with the | |
40f4268c JS |
67 | * @tty. No other call into the line discipline for this tty will occur |
68 | * until it completes successfully. It should initialize any state needed | |
69 | * by the ldisc, and set @tty->receive_room to the maximum amount of data | |
70 | * the line discipline is willing to accept from the driver with a single | |
71 | * call to @receive_buf(). Returning an error will prevent the ldisc from | |
72 | * being attached. | |
0c6119f9 | 73 | * |
40f4268c JS |
74 | * Can sleep. |
75 | * | |
76 | * @close: [TTY] ``void ()(struct tty_struct *tty)`` | |
0c6119f9 JS |
77 | * |
78 | * This function is called when the line discipline is being shutdown, | |
79 | * either because the @tty is being closed or because the @tty is being | |
40f4268c JS |
80 | * changed to use a new line discipline. At the point of execution no |
81 | * further users will enter the ldisc code for this tty. | |
82 | * | |
83 | * Can sleep. | |
0c6119f9 | 84 | * |
40f4268c | 85 | * @flush_buffer: [TTY] ``void ()(struct tty_struct *tty)`` |
0c6119f9 JS |
86 | * |
87 | * This function instructs the line discipline to clear its buffers of any | |
88 | * input characters it may have queued to be delivered to the user mode | |
40f4268c | 89 | * process. It may be called at any point between open and close. |
0c6119f9 | 90 | * |
40f4268c | 91 | * @read: [TTY] ``ssize_t ()(struct tty_struct *tty, struct file *file, |
0c6119f9 JS |
92 | * unsigned char *buf, size_t nr)`` |
93 | * | |
94 | * This function is called when the user requests to read from the @tty. | |
95 | * The line discipline will return whatever characters it has buffered up | |
96 | * for the user. If this function is not defined, the user will receive | |
40f4268c JS |
97 | * an %EIO error. Multiple read calls may occur in parallel and the ldisc |
98 | * must deal with serialization issues. | |
99 | * | |
100 | * Can sleep. | |
0c6119f9 | 101 | * |
40f4268c | 102 | * @write: [TTY] ``ssize_t ()(struct tty_struct *tty, struct file *file, |
0c6119f9 JS |
103 | * const unsigned char *buf, size_t nr)`` |
104 | * | |
105 | * This function is called when the user requests to write to the @tty. | |
106 | * The line discipline will deliver the characters to the low-level tty | |
107 | * device for transmission, optionally performing some processing on the | |
108 | * characters first. If this function is not defined, the user will | |
109 | * receive an %EIO error. | |
110 | * | |
40f4268c JS |
111 | * Can sleep. |
112 | * | |
113 | * @ioctl: [TTY] ``int ()(struct tty_struct *tty, unsigned int cmd, | |
0c6119f9 JS |
114 | * unsigned long arg)`` |
115 | * | |
116 | * This function is called when the user requests an ioctl which is not | |
117 | * handled by the tty layer or the low-level tty driver. It is intended | |
118 | * for ioctls which affect line discpline operation. Note that the search | |
119 | * order for ioctls is (1) tty layer, (2) tty low-level driver, (3) line | |
120 | * discpline. So a low-level driver can "grab" an ioctl request before | |
121 | * the line discpline has a chance to see it. | |
122 | * | |
40f4268c | 123 | * @compat_ioctl: [TTY] ``int ()(struct tty_struct *tty, unsigned int cmd, |
0c6119f9 JS |
124 | * unsigned long arg)`` |
125 | * | |
126 | * Process ioctl calls from 32-bit process on 64-bit system. | |
127 | * | |
128 | * Note that only ioctls that are neither "pointer to compatible | |
129 | * structure" nor tty-generic. Something private that takes an integer or | |
130 | * a pointer to wordsize-sensitive structure belongs here, but most of | |
131 | * ldiscs will happily leave it %NULL. | |
132 | * | |
8b7d2d95 | 133 | * @set_termios: [TTY] ``void ()(struct tty_struct *tty, const struct ktermios *old)`` |
0c6119f9 JS |
134 | * |
135 | * This function notifies the line discpline that a change has been made | |
136 | * to the termios structure. | |
137 | * | |
40f4268c | 138 | * @poll: [TTY] ``int ()(struct tty_struct *tty, struct file *file, |
0c6119f9 JS |
139 | * struct poll_table_struct *wait)`` |
140 | * | |
141 | * This function is called when a user attempts to select/poll on a @tty | |
142 | * device. It is solely the responsibility of the line discipline to | |
143 | * handle poll requests. | |
144 | * | |
40f4268c | 145 | * @hangup: [TTY] ``void ()(struct tty_struct *tty)`` |
0c6119f9 JS |
146 | * |
147 | * Called on a hangup. Tells the discipline that it should cease I/O to | |
40f4268c JS |
148 | * the tty driver. The driver should seek to perform this action quickly |
149 | * but should wait until any pending driver I/O is completed. No further | |
150 | * calls into the ldisc code will occur. | |
151 | * | |
152 | * Can sleep. | |
0c6119f9 | 153 | * |
40f4268c JS |
154 | * @receive_buf: [DRV] ``void ()(struct tty_struct *tty, |
155 | * const unsigned char *cp, const char *fp, int count)`` | |
0c6119f9 JS |
156 | * |
157 | * This function is called by the low-level tty driver to send characters | |
158 | * received by the hardware to the line discpline for processing. @cp is | |
159 | * a pointer to the buffer of input character received by the device. @fp | |
160 | * is a pointer to an array of flag bytes which indicate whether a | |
161 | * character was received with a parity error, etc. @fp may be %NULL to | |
162 | * indicate all data received is %TTY_NORMAL. | |
163 | * | |
40f4268c | 164 | * @write_wakeup: [DRV] ``void ()(struct tty_struct *tty)`` |
0c6119f9 JS |
165 | * |
166 | * This function is called by the low-level tty driver to signal that line | |
167 | * discpline should try to send more characters to the low-level driver | |
168 | * for transmission. If the line discpline does not have any more data to | |
169 | * send, it can just return. If the line discipline does have some data to | |
170 | * send, please arise a tasklet or workqueue to do the real data transfer. | |
171 | * Do not send data in this hook, it may lead to a deadlock. | |
172 | * | |
0388a152 | 173 | * @dcd_change: [DRV] ``void ()(struct tty_struct *tty, bool active)`` |
0c6119f9 JS |
174 | * |
175 | * Tells the discipline that the DCD pin has changed its status. Used | |
176 | * exclusively by the %N_PPS (Pulse-Per-Second) line discipline. | |
177 | * | |
40f4268c JS |
178 | * @receive_buf2: [DRV] ``int ()(struct tty_struct *tty, |
179 | * const unsigned char *cp, const char *fp, int count)`` | |
0c6119f9 JS |
180 | * |
181 | * This function is called by the low-level tty driver to send characters | |
182 | * received by the hardware to the line discpline for processing. @cp is a | |
183 | * pointer to the buffer of input character received by the device. @fp | |
184 | * is a pointer to an array of flag bytes which indicate whether a | |
185 | * character was received with a parity error, etc. @fp may be %NULL to | |
186 | * indicate all data received is %TTY_NORMAL. If assigned, prefer this | |
187 | * function for automatic flow control. | |
188 | * | |
6bb6fa69 | 189 | * @lookahead_buf: [DRV] ``void ()(struct tty_struct *tty, |
ab24a01b | 190 | * const unsigned char *cp, const char *fp, int count)`` |
6bb6fa69 IJ |
191 | * |
192 | * This function is called by the low-level tty driver for characters | |
193 | * not eaten by ->receive_buf() or ->receive_buf2(). It is useful for | |
194 | * processing high-priority characters such as software flow-control | |
195 | * characters that could otherwise get stuck into the intermediate | |
196 | * buffer until tty has room to receive them. Ldisc must be able to | |
197 | * handle later a ->receive_buf() or ->receive_buf2() call for the | |
198 | * same characters (e.g. by skipping the actions for high-priority | |
199 | * characters already handled by ->lookahead_buf()). | |
200 | * | |
0c6119f9 JS |
201 | * @owner: module containting this ldisc (for reference counting) |
202 | * | |
203 | * This structure defines the interface between the tty line discipline | |
204 | * implementation and the tty routines. The above routines can be defined. | |
205 | * Unless noted otherwise, they are optional, and can be filled in with a %NULL | |
206 | * pointer. | |
40f4268c JS |
207 | * |
208 | * Hooks marked [TTY] are invoked from the TTY core, the [DRV] ones from the | |
209 | * tty_driver side. | |
0c6119f9 | 210 | */ |
a352def2 | 211 | struct tty_ldisc_ops { |
1da177e4 LT |
212 | char *name; |
213 | int num; | |
6be06e72 | 214 | |
1da177e4 LT |
215 | /* |
216 | * The following routines are called from above. | |
217 | */ | |
0c6119f9 JS |
218 | int (*open)(struct tty_struct *tty); |
219 | void (*close)(struct tty_struct *tty); | |
1da177e4 | 220 | void (*flush_buffer)(struct tty_struct *tty); |
6be06e72 | 221 | ssize_t (*read)(struct tty_struct *tty, struct file *file, |
3b830a9c LT |
222 | unsigned char *buf, size_t nr, |
223 | void **cookie, unsigned long offset); | |
6be06e72 PH |
224 | ssize_t (*write)(struct tty_struct *tty, struct file *file, |
225 | const unsigned char *buf, size_t nr); | |
d78328bc JS |
226 | int (*ioctl)(struct tty_struct *tty, unsigned int cmd, |
227 | unsigned long arg); | |
228 | int (*compat_ioctl)(struct tty_struct *tty, unsigned int cmd, | |
229 | unsigned long arg); | |
8b7d2d95 | 230 | void (*set_termios)(struct tty_struct *tty, const struct ktermios *old); |
0c6119f9 JS |
231 | __poll_t (*poll)(struct tty_struct *tty, struct file *file, |
232 | struct poll_table_struct *wait); | |
28f194da | 233 | void (*hangup)(struct tty_struct *tty); |
6be06e72 | 234 | |
1da177e4 LT |
235 | /* |
236 | * The following routines are called from below. | |
237 | */ | |
0c6119f9 | 238 | void (*receive_buf)(struct tty_struct *tty, const unsigned char *cp, |
0f3dcf3b | 239 | const char *fp, int count); |
0c6119f9 | 240 | void (*write_wakeup)(struct tty_struct *tty); |
0388a152 | 241 | void (*dcd_change)(struct tty_struct *tty, bool active); |
0c6119f9 | 242 | int (*receive_buf2)(struct tty_struct *tty, const unsigned char *cp, |
0f3dcf3b | 243 | const char *fp, int count); |
6bb6fa69 IJ |
244 | void (*lookahead_buf)(struct tty_struct *tty, const unsigned char *cp, |
245 | const unsigned char *fp, unsigned int count); | |
1da177e4 LT |
246 | |
247 | struct module *owner; | |
1da177e4 LT |
248 | }; |
249 | ||
a352def2 AC |
250 | struct tty_ldisc { |
251 | struct tty_ldisc_ops *ops; | |
36697529 | 252 | struct tty_struct *tty; |
a352def2 AC |
253 | }; |
254 | ||
1da177e4 LT |
255 | #define MODULE_ALIAS_LDISC(ldisc) \ |
256 | MODULE_ALIAS("tty-ldisc-" __stringify(ldisc)) | |
257 | ||
a24bc667 JS |
258 | extern const struct seq_operations tty_ldiscs_seq_ops; |
259 | ||
260 | struct tty_ldisc *tty_ldisc_ref(struct tty_struct *); | |
261 | void tty_ldisc_deref(struct tty_ldisc *); | |
262 | struct tty_ldisc *tty_ldisc_ref_wait(struct tty_struct *); | |
263 | ||
264 | void tty_ldisc_flush(struct tty_struct *tty); | |
265 | ||
266 | int tty_register_ldisc(struct tty_ldisc_ops *new_ldisc); | |
267 | void tty_unregister_ldisc(struct tty_ldisc_ops *ldisc); | |
268 | int tty_set_ldisc(struct tty_struct *tty, int disc); | |
269 | ||
1da177e4 | 270 | #endif /* _LINUX_TTY_LDISC_H */ |