// 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 ssize_t ttynull_write(struct tty_struct *tty, const u8 *buf,			     size_t 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");