// 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) { put_tty_driver(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); put_tty_driver(ttynull_driver); tty_port_destroy(&ttynull_port); } module_init(ttynull_init); module_exit(ttynull_exit); MODULE_LICENSE("GPL v2");