static inline void
uart_insert_char(struct uart_port *port, unsigned int status,
         unsigned int overrun, unsigned int ch, unsigned int flag)
{
    struct tty_struct *tty = port->info->port.tty;

    if ((status & port->ignore_status_mask & ~overrun) == 0)
        tty_insert_flip_char(tty, ch, flag);

    /*
     * Overrun is special.  Since it's reported immediately,
     * it doesn't affect the current character.
     */
    if (status & ~port->ignore_status_mask & overrun)
        tty_insert_flip_char(tty, 0, TTY_OVERRUN);
}