Commit | Line | Data |
---|---|---|
e3b3d0f5 | 1 | // SPDX-License-Identifier: GPL-2.0 |
8a8dabf2 AC |
2 | #include <linux/types.h> |
3 | #include <linux/errno.h> | |
4 | #include <linux/tty.h> | |
5 | #include <linux/module.h> | |
6 | ||
7 | /* | |
8 | * n_null.c - Null line discipline used in the failure path | |
9 | * | |
10 | * Copyright (C) Intel 2017 | |
8a8dabf2 AC |
11 | */ |
12 | ||
13 | static int n_null_open(struct tty_struct *tty) | |
14 | { | |
15 | return 0; | |
16 | } | |
17 | ||
18 | static void n_null_close(struct tty_struct *tty) | |
19 | { | |
20 | } | |
21 | ||
22 | static ssize_t n_null_read(struct tty_struct *tty, struct file *file, | |
3b830a9c LT |
23 | unsigned char *buf, size_t nr, |
24 | void **cookie, unsigned long offset) | |
8a8dabf2 AC |
25 | { |
26 | return -EOPNOTSUPP; | |
27 | } | |
28 | ||
29 | static ssize_t n_null_write(struct tty_struct *tty, struct file *file, | |
30 | const unsigned char *buf, size_t nr) | |
31 | { | |
32 | return -EOPNOTSUPP; | |
33 | } | |
34 | ||
35 | static void n_null_receivebuf(struct tty_struct *tty, | |
0f3dcf3b | 36 | const unsigned char *cp, const char *fp, |
8a8dabf2 AC |
37 | int cnt) |
38 | { | |
39 | } | |
40 | ||
41 | static struct tty_ldisc_ops null_ldisc = { | |
42 | .owner = THIS_MODULE, | |
fbadf70a | 43 | .num = N_NULL, |
8a8dabf2 AC |
44 | .name = "n_null", |
45 | .open = n_null_open, | |
46 | .close = n_null_close, | |
47 | .read = n_null_read, | |
48 | .write = n_null_write, | |
49 | .receive_buf = n_null_receivebuf | |
50 | }; | |
51 | ||
52 | static int __init n_null_init(void) | |
53 | { | |
fbadf70a | 54 | BUG_ON(tty_register_ldisc(&null_ldisc)); |
8a8dabf2 AC |
55 | return 0; |
56 | } | |
57 | ||
58 | static void __exit n_null_exit(void) | |
59 | { | |
f81ee8b8 | 60 | tty_unregister_ldisc(&null_ldisc); |
8a8dabf2 AC |
61 | } |
62 | ||
63 | module_init(n_null_init); | |
64 | module_exit(n_null_exit); | |
65 | ||
66 | MODULE_LICENSE("GPL"); | |
67 | MODULE_AUTHOR("Alan Cox"); | |
68 | MODULE_ALIAS_LDISC(N_NULL); | |
69 | MODULE_DESCRIPTION("Null ldisc driver"); |