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(port: &ttynull_port, tty, filp); |
20 | } |
21 | |
22 | static void ttynull_close(struct tty_struct *tty, struct file *filp) |
23 | { |
24 | tty_port_close(port: &ttynull_port, tty, filp); |
25 | } |
26 | |
27 | static void ttynull_hangup(struct tty_struct *tty) |
28 | { |
29 | tty_port_hangup(port: &ttynull_port); |
30 | } |
31 | |
32 | static ssize_t ttynull_write(struct tty_struct *tty, const u8 *buf, |
33 | size_t count) |
34 | { |
35 | return count; |
36 | } |
37 | |
38 | static unsigned int ttynull_write_room(struct tty_struct *tty) |
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(ptr: driver)) |
72 | return PTR_ERR(ptr: driver); |
73 | |
74 | tty_port_init(port: &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, op: &ttynull_ops); |
83 | tty_port_link_device(port: &ttynull_port, driver, index: 0); |
84 | |
85 | ret = tty_register_driver(driver); |
86 | if (ret < 0) { |
87 | tty_driver_kref_put(driver); |
88 | tty_port_destroy(port: &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(driver: ttynull_driver); |
102 | tty_driver_kref_put(driver: ttynull_driver); |
103 | tty_port_destroy(port: &ttynull_port); |
104 | } |
105 | |
106 | module_init(ttynull_init); |
107 | module_exit(ttynull_exit); |
108 | |
109 | MODULE_LICENSE("GPL v2" ); |
110 | |