CDNS_UART_FIFO
c = (unsigned char) readl(port->membase + CDNS_UART_FIFO);
writel(c, port->membase + CDNS_UART_FIFO);
writel(ch, port->membase + CDNS_UART_FIFO);
readl(port->membase + CDNS_UART_FIFO);
data = readl(port->membase + CDNS_UART_FIFO);
writel(ch, port->membase + CDNS_UART_FIFO);