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3117ff13 VW |
1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * Copyright (C) 2019 Axis Communications AB | |
4 | * | |
5 | * Based on ttyprintk.c: | |
6 | * Copyright (C) 2010 Samo Pogacnik | |
7 | */ | |
8 | ||
9 | #include <linux/console.h> | |
10 | #include <linux/module.h> | |
11 | #include <linux/tty.h> | |
12 | ||
13 | static const struct tty_port_operations ttynull_port_ops; | |
14 | static struct tty_driver *ttynull_driver; | |
15 | static struct tty_port ttynull_port; | |
16 | ||
17 | static int ttynull_open(struct tty_struct *tty, struct file *filp) | |
18 | { | |
19 | return tty_port_open(&ttynull_port, tty, filp); | |
20 | } | |
21 | ||
22 | static void ttynull_close(struct tty_struct *tty, struct file *filp) | |
23 | { | |
24 | tty_port_close(&ttynull_port, tty, filp); | |
25 | } | |
26 | ||
27 | static void ttynull_hangup(struct tty_struct *tty) | |
28 | { | |
29 | tty_port_hangup(&ttynull_port); | |
30 | } | |
31 | ||
32 | static int ttynull_write(struct tty_struct *tty, const unsigned char *buf, | |
33 | int count) | |
34 | { | |
35 | return count; | |
36 | } | |
37 | ||
03b3b1a2 | 38 | static unsigned int ttynull_write_room(struct tty_struct *tty) |
3117ff13 VW |
39 | { |
40 | return 65536; | |
41 | } | |
42 | ||
43 | static const struct tty_operations ttynull_ops = { | |
44 | .open = ttynull_open, | |
45 | .close = ttynull_close, | |
46 | .hangup = ttynull_hangup, | |
47 | .write = ttynull_write, | |
48 | .write_room = ttynull_write_room, | |
49 | }; | |
50 | ||
51 | static struct tty_driver *ttynull_device(struct console *c, int *index) | |
52 | { | |
53 | *index = 0; | |
54 | return ttynull_driver; | |
55 | } | |
56 | ||
57 | static struct console ttynull_console = { | |
58 | .name = "ttynull", | |
59 | .device = ttynull_device, | |
60 | }; | |
61 | ||
62 | static int __init ttynull_init(void) | |
63 | { | |
64 | struct tty_driver *driver; | |
65 | int ret; | |
66 | ||
67 | driver = tty_alloc_driver(1, | |
68 | TTY_DRIVER_RESET_TERMIOS | | |
69 | TTY_DRIVER_REAL_RAW | | |
70 | TTY_DRIVER_UNNUMBERED_NODE); | |
71 | if (IS_ERR(driver)) | |
72 | return PTR_ERR(driver); | |
73 | ||
74 | tty_port_init(&ttynull_port); | |
75 | ttynull_port.ops = &ttynull_port_ops; | |
76 | ||
77 | driver->driver_name = "ttynull"; | |
78 | driver->name = "ttynull"; | |
79 | driver->type = TTY_DRIVER_TYPE_CONSOLE; | |
80 | driver->init_termios = tty_std_termios; | |
81 | driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET; | |
82 | tty_set_operations(driver, &ttynull_ops); | |
83 | tty_port_link_device(&ttynull_port, driver, 0); | |
84 | ||
85 | ret = tty_register_driver(driver); | |
86 | if (ret < 0) { | |
87 | put_tty_driver(driver); | |
88 | tty_port_destroy(&ttynull_port); | |
89 | return ret; | |
90 | } | |
91 | ||
92 | ttynull_driver = driver; | |
93 | register_console(&ttynull_console); | |
94 | ||
95 | return 0; | |
96 | } | |
97 | ||
98 | static void __exit ttynull_exit(void) | |
99 | { | |
100 | unregister_console(&ttynull_console); | |
101 | tty_unregister_driver(ttynull_driver); | |
102 | put_tty_driver(ttynull_driver); | |
103 | tty_port_destroy(&ttynull_port); | |
104 | } | |
105 | ||
106 | module_init(ttynull_init); | |
107 | module_exit(ttynull_exit); | |
108 | ||
109 | MODULE_LICENSE("GPL v2"); |