GNU Linux-libre 5.13.14-gnu1
[releases.git] / drivers / tty / ttynull.c
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
38 static 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(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");