TTY: simserial, use tty_port_close_start

{

	struct serial_state *info = tty->driver_data;

	struct tty_port *port = &info->port;

	unsigned long flags;

	if (!info)

		return;

	local_irq_save(flags);

	if (tty_hung_up_p(filp)) {

#ifdef SIMSERIAL_DEBUG

		printk("rs_close: hung_up\n");

#endif

		local_irq_restore(flags);

	if (tty_port_close_start(port, tty, filp) == 0)

		return;

	}

#ifdef SIMSERIAL_DEBUG

	printk("rs_close ttys%d, count = %d\n", info->line, port->count);

#endif

	if ((tty->count == 1) && (port->count != 1)) {

		/*

		 * Uh, oh.  tty->count is 1, which means that the tty

		 * structure will be freed.  port->count should always

		 * be one in these conditions.  If it's greater than

		 * one, we've got real problems, since it means the

		 * serial port won't be shutdown.

		 */

		printk(KERN_ERR "rs_close: bad serial port count; tty->count is 1, "

		       "port->count is %d\n", port->count);

		port->count = 1;

	}

	if (--port->count < 0) {

		printk(KERN_ERR "rs_close: bad serial port count for ttys%d: %d\n",

		       tty->index, port->count);

		port->count = 0;

	}

	if (port->count) {

		local_irq_restore(flags);

		return;

	}

	port->flags |= ASYNC_CLOSING;

	local_irq_restore(flags);

	/*

	 * Now we wait for the transmit buffer to clear; and we notify

	 */

	shutdown(tty, info);

	rs_flush_buffer(tty);

	tty_ldisc_flush(tty);

	port->tty = NULL;

	tty_port_close_end(port, tty);