tty_register_device_attr
return tty_register_device_attr(driver, index, device, NULL, NULL);
EXPORT_SYMBOL_GPL(tty_register_device_attr);
return tty_register_device_attr(driver, index, device, drvdata,
return tty_register_device_attr(driver, index, parent, drvdata,
struct device *tty_register_device_attr(struct tty_driver *driver,