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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
1da177e4 LT |
2 | #ifndef _LINUX_TTY_LDISC_H |
3 | #define _LINUX_TTY_LDISC_H | |
4 | ||
5 | /* | |
6 | * This structure defines the interface between the tty line discipline | |
7 | * implementation 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 | * int (*open)(struct tty_struct *); | |
12 | * | |
6be06e72 PH |
13 | * This function is called when the line discipline is associated |
14 | * with the tty. The line discipline can use this as an | |
15 | * opportunity to initialize any state needed by the ldisc routines. | |
16 | * | |
1da177e4 LT |
17 | * void (*close)(struct tty_struct *); |
18 | * | |
19 | * This function is called when the line discipline is being | |
6be06e72 PH |
20 | * shutdown, either because the tty is being closed or because |
21 | * the tty is being changed to use a new line discipline | |
22 | * | |
1da177e4 LT |
23 | * void (*flush_buffer)(struct tty_struct *tty); |
24 | * | |
6be06e72 PH |
25 | * This function instructs the line discipline to clear its |
26 | * buffers of any input characters it may have queued to be | |
27 | * delivered to the user mode process. | |
28 | * | |
1da177e4 LT |
29 | * ssize_t (*read)(struct tty_struct * tty, struct file * file, |
30 | * unsigned char * buf, size_t nr); | |
31 | * | |
6be06e72 PH |
32 | * This function is called when the user requests to read from |
33 | * the tty. The line discipline will return whatever characters | |
34 | * it has buffered up for the user. If this function is not | |
35 | * defined, the user will receive an EIO error. | |
36 | * | |
1da177e4 | 37 | * ssize_t (*write)(struct tty_struct * tty, struct file * file, |
6be06e72 PH |
38 | * const unsigned char * buf, size_t nr); |
39 | * | |
40 | * This function is called when the user requests to write to the | |
41 | * tty. The line discipline will deliver the characters to the | |
42 | * low-level tty device for transmission, optionally performing | |
43 | * some processing on the characters first. If this function is | |
44 | * not defined, the user will receive an EIO error. | |
45 | * | |
1da177e4 | 46 | * int (*ioctl)(struct tty_struct * tty, struct file * file, |
6be06e72 | 47 | * unsigned int cmd, unsigned long arg); |
1da177e4 LT |
48 | * |
49 | * This function is called when the user requests an ioctl which | |
6be06e72 PH |
50 | * is not handled by the tty layer or the low-level tty driver. |
51 | * It is intended for ioctls which affect line discpline | |
52 | * operation. Note that the search order for ioctls is (1) tty | |
53 | * layer, (2) tty low-level driver, (3) line discpline. So a | |
54 | * low-level driver can "grab" an ioctl request before the line | |
55 | * discpline has a chance to see it. | |
56 | * | |
f0193d3e | 57 | * int (*compat_ioctl)(struct tty_struct * tty, struct file * file, |
6be06e72 | 58 | * unsigned int cmd, unsigned long arg); |
e10cc1df | 59 | * |
6be06e72 | 60 | * Process ioctl calls from 32-bit process on 64-bit system |
e10cc1df | 61 | * |
f0193d3e AV |
62 | * NOTE: only ioctls that are neither "pointer to compatible |
63 | * structure" nor tty-generic. Something private that takes | |
64 | * an integer or a pointer to wordsize-sensitive structure | |
65 | * belongs here, but most of ldiscs will happily leave | |
66 | * it NULL. | |
67 | * | |
edc6afc5 | 68 | * void (*set_termios)(struct tty_struct *tty, struct ktermios * old); |
1da177e4 | 69 | * |
6be06e72 PH |
70 | * This function notifies the line discpline that a change has |
71 | * been made to the termios structure. | |
72 | * | |
1da177e4 | 73 | * int (*poll)(struct tty_struct * tty, struct file * file, |
6be06e72 | 74 | * poll_table *wait); |
1da177e4 | 75 | * |
6be06e72 PH |
76 | * This function is called when a user attempts to select/poll on a |
77 | * tty device. It is solely the responsibility of the line | |
78 | * discipline to handle poll requests. | |
1da177e4 | 79 | * |
55db4c64 | 80 | * void (*receive_buf)(struct tty_struct *, const unsigned char *cp, |
6be06e72 PH |
81 | * char *fp, int count); |
82 | * | |
83 | * This function is called by the low-level tty driver to send | |
84 | * characters received by the hardware to the line discpline for | |
85 | * processing. <cp> is a pointer to the buffer of input | |
86 | * character received by the device. <fp> is a pointer to a | |
87 | * pointer of flag bytes which indicate whether a character was | |
82f91fe0 PH |
88 | * received with a parity error, etc. <fp> may be NULL to indicate |
89 | * all data received is TTY_NORMAL. | |
6be06e72 | 90 | * |
1da177e4 LT |
91 | * void (*write_wakeup)(struct tty_struct *); |
92 | * | |
6be06e72 PH |
93 | * This function is called by the low-level tty driver to signal |
94 | * that line discpline should try to send more characters to the | |
95 | * low-level driver for transmission. If the line discpline does | |
879eb9c3 HS |
96 | * not have any more data to send, it can just return. If the line |
97 | * discipline does have some data to send, please arise a tasklet | |
98 | * or workqueue to do the real data transfer. Do not send data in | |
99 | * this hook, it may leads to a deadlock. | |
1da177e4 LT |
100 | * |
101 | * int (*hangup)(struct tty_struct *) | |
102 | * | |
103 | * Called on a hangup. Tells the discipline that it should | |
104 | * cease I/O to the tty driver. Can sleep. The driver should | |
105 | * seek to perform this action quickly but should wait until | |
106 | * any pending driver I/O is completed. | |
b3e63afe | 107 | * |
593fb1ae | 108 | * void (*dcd_change)(struct tty_struct *tty, unsigned int status) |
b3e63afe | 109 | * |
593fb1ae GS |
110 | * Tells the discipline that the DCD pin has changed its status. |
111 | * Used exclusively by the N_PPS (Pulse-Per-Second) line discipline. | |
24a89d1c PH |
112 | * |
113 | * int (*receive_buf2)(struct tty_struct *, const unsigned char *cp, | |
114 | * char *fp, int count); | |
115 | * | |
116 | * This function is called by the low-level tty driver to send | |
117 | * characters received by the hardware to the line discpline for | |
118 | * processing. <cp> is a pointer to the buffer of input | |
119 | * character received by the device. <fp> is a pointer to a | |
120 | * pointer of flag bytes which indicate whether a character was | |
82f91fe0 PH |
121 | * received with a parity error, etc. <fp> may be NULL to indicate |
122 | * all data received is TTY_NORMAL. | |
24a89d1c | 123 | * If assigned, prefer this function for automatic flow control. |
1da177e4 LT |
124 | */ |
125 | ||
126 | #include <linux/fs.h> | |
127 | #include <linux/wait.h> | |
5fd691af | 128 | #include <linux/atomic.h> |
4898e640 PH |
129 | |
130 | /* | |
131 | * the semaphore definition | |
132 | */ | |
133 | struct ld_semaphore { | |
5fd691af | 134 | atomic_long_t count; |
4898e640 PH |
135 | raw_spinlock_t wait_lock; |
136 | unsigned int wait_readers; | |
137 | struct list_head read_wait; | |
138 | struct list_head write_wait; | |
139 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
140 | struct lockdep_map dep_map; | |
141 | #endif | |
142 | }; | |
143 | ||
144 | extern void __init_ldsem(struct ld_semaphore *sem, const char *name, | |
145 | struct lock_class_key *key); | |
146 | ||
147 | #define init_ldsem(sem) \ | |
148 | do { \ | |
149 | static struct lock_class_key __key; \ | |
150 | \ | |
151 | __init_ldsem((sem), #sem, &__key); \ | |
152 | } while (0) | |
153 | ||
154 | ||
155 | extern int ldsem_down_read(struct ld_semaphore *sem, long timeout); | |
156 | extern int ldsem_down_read_trylock(struct ld_semaphore *sem); | |
157 | extern int ldsem_down_write(struct ld_semaphore *sem, long timeout); | |
158 | extern int ldsem_down_write_trylock(struct ld_semaphore *sem); | |
159 | extern void ldsem_up_read(struct ld_semaphore *sem); | |
160 | extern void ldsem_up_write(struct ld_semaphore *sem); | |
161 | ||
162 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
163 | extern int ldsem_down_read_nested(struct ld_semaphore *sem, int subclass, | |
164 | long timeout); | |
165 | extern int ldsem_down_write_nested(struct ld_semaphore *sem, int subclass, | |
166 | long timeout); | |
167 | #else | |
168 | # define ldsem_down_read_nested(sem, subclass, timeout) \ | |
169 | ldsem_down_read(sem, timeout) | |
170 | # define ldsem_down_write_nested(sem, subclass, timeout) \ | |
171 | ldsem_down_write(sem, timeout) | |
172 | #endif | |
173 | ||
174 | ||
a352def2 | 175 | struct tty_ldisc_ops { |
1da177e4 LT |
176 | int magic; |
177 | char *name; | |
178 | int num; | |
179 | int flags; | |
6be06e72 | 180 | |
1da177e4 LT |
181 | /* |
182 | * The following routines are called from above. | |
183 | */ | |
184 | int (*open)(struct tty_struct *); | |
185 | void (*close)(struct tty_struct *); | |
186 | void (*flush_buffer)(struct tty_struct *tty); | |
6be06e72 PH |
187 | ssize_t (*read)(struct tty_struct *tty, struct file *file, |
188 | unsigned char __user *buf, size_t nr); | |
189 | ssize_t (*write)(struct tty_struct *tty, struct file *file, | |
190 | const unsigned char *buf, size_t nr); | |
191 | int (*ioctl)(struct tty_struct *tty, struct file *file, | |
1da177e4 | 192 | unsigned int cmd, unsigned long arg); |
f0193d3e | 193 | int (*compat_ioctl)(struct tty_struct *tty, struct file *file, |
e10cc1df | 194 | unsigned int cmd, unsigned long arg); |
6be06e72 | 195 | void (*set_termios)(struct tty_struct *tty, struct ktermios *old); |
a3f8683b | 196 | __poll_t (*poll)(struct tty_struct *, struct file *, |
1da177e4 LT |
197 | struct poll_table_struct *); |
198 | int (*hangup)(struct tty_struct *tty); | |
6be06e72 | 199 | |
1da177e4 LT |
200 | /* |
201 | * The following routines are called from below. | |
202 | */ | |
55db4c64 LT |
203 | void (*receive_buf)(struct tty_struct *, const unsigned char *cp, |
204 | char *fp, int count); | |
1da177e4 | 205 | void (*write_wakeup)(struct tty_struct *); |
593fb1ae | 206 | void (*dcd_change)(struct tty_struct *, unsigned int); |
24a89d1c PH |
207 | int (*receive_buf2)(struct tty_struct *, const unsigned char *cp, |
208 | char *fp, int count); | |
1da177e4 LT |
209 | |
210 | struct module *owner; | |
6be06e72 | 211 | |
1da177e4 LT |
212 | int refcount; |
213 | }; | |
214 | ||
a352def2 AC |
215 | struct tty_ldisc { |
216 | struct tty_ldisc_ops *ops; | |
36697529 | 217 | struct tty_struct *tty; |
a352def2 AC |
218 | }; |
219 | ||
1da177e4 LT |
220 | #define TTY_LDISC_MAGIC 0x5403 |
221 | ||
222 | #define LDISC_FLAG_DEFINED 0x00000001 | |
223 | ||
224 | #define MODULE_ALIAS_LDISC(ldisc) \ | |
225 | MODULE_ALIAS("tty-ldisc-" __stringify(ldisc)) | |
226 | ||
227 | #endif /* _LINUX_TTY_LDISC_H */ |