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