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| 2 | |
| 3 | * Copyright (C) 2019 Axis Communications AB
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| 4 | *
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| 5 | * Based on ttyprintk.c:
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| 6 | * Copyright (C) 2010 Samo Pogacnik
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| 7 |
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| 8 |
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| 9 | #include <linux/console.h>
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| 10 | #include <linux/module.h>
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| 11 | #include <linux/tty.h>
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| 12 |
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| 13 | static const struct tty_port_operations ttynull_port_ops;
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| 14 | static struct tty_driver *ttynull_driver;
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| 15 | static struct tty_port ttynull_port;
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| 16 |
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| 17 | static int ttynull_open(struct tty_struct *tty, struct file *filp)
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| 18 | {
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| 19 | return tty_port_open(&ttynull_port, tty, filp);
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| 20 | }
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| 21 |
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| 22 | static void ttynull_close(struct tty_struct *tty, struct file *filp)
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| 23 | {
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| 24 | tty_port_close(&ttynull_port, tty, filp);
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| 25 | }
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| 26 |
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| 27 | static void ttynull_hangup(struct tty_struct *tty)
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| 28 | {
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| 29 | tty_port_hangup(&ttynull_port);
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| 30 | }
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| 31 |
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| 32 | static ssize_t ttynull_write(struct tty_struct *tty, const u8 *buf,
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| 33 | size_t count)
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| 34 | {
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| 35 | return count;
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| 36 | }
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| 37 |
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| 38 | static unsigned int ttynull_write_room(struct tty_struct *tty)
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| 39 | {
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| 40 | return 65536;
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| 41 | }
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| 42 |
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| 43 | static const struct tty_operations ttynull_ops = {
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| 44 | .open = ttynull_open,
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| 45 | .close = ttynull_close,
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| 46 | .hangup = ttynull_hangup,
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| 47 | .write = ttynull_write,
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| 48 | .write_room = ttynull_write_room,
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| 49 | };
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| 50 |
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| 51 | static struct tty_driver *ttynull_device(struct console *c, int *index)
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| 52 | {
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| 53 | *index = 0;
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| 54 | return ttynull_driver;
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| 55 | }
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| 56 |
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| 57 | static struct console ttynull_console = {
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| 58 | .name = "ttynull",
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| 59 | .device = ttynull_device,
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| 60 | };
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| 61 |
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| 62 | static int __init ttynull_init(void)
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| 63 | {
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| 64 | struct tty_driver *driver;
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| 65 | int ret;
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| 66 |
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| 67 | driver = tty_alloc_driver(1,
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| 68 | TTY_DRIVER_RESET_TERMIOS |
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| 69 | TTY_DRIVER_REAL_RAW |
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| 70 | TTY_DRIVER_UNNUMBERED_NODE);
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| 71 | if (IS_ERR(driver))
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| 72 | return PTR_ERR(driver);
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| 73 |
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| 74 | tty_port_init(&ttynull_port);
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| 75 | ttynull_port.ops = &ttynull_port_ops;
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| 76 |
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| 77 | driver->driver_name = "ttynull";
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| 78 | driver->name = "ttynull";
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| 79 | driver->type = TTY_DRIVER_TYPE_CONSOLE;
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| 80 | driver->init_termios = tty_std_termios;
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| 81 | driver->init_termios.c_oflag = OPOST | OCRNL | ONOCR | ONLRET;
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| 82 | tty_set_operations(driver, &ttynull_ops);
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| 83 | tty_port_link_device(&ttynull_port, driver, 0);
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| 84 |
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| 85 | ret = tty_register_driver(driver);
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| 86 | if (ret < 0) {
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| 87 | tty_driver_kref_put(driver);
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| 88 | tty_port_destroy(&ttynull_port);
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| 89 | return ret;
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| 90 | }
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| 91 |
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| 92 | ttynull_driver = driver;
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| 93 | register_console(&ttynull_console);
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| 94 |
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| 95 | return 0;
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| 96 | }
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| 97 |
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| 98 | static void __exit ttynull_exit(void)
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| 99 | {
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| 100 | unregister_console(&ttynull_console);
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| 101 | tty_unregister_driver(ttynull_driver);
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| 102 | tty_driver_kref_put(ttynull_driver);
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| 103 | tty_port_destroy(&ttynull_port);
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| 104 | }
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| 105 |
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| 106 | module_init(ttynull_init);
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| 107 | module_exit(ttynull_exit);
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| 108 |
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| 109 | MODULE_LICENSE("GPL v2");
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