MTK_UART_IER_CTSI
MTK_UART_IER_RTSI | MTK_UART_IER_CTSI);
mtk8250_enable_intrs(up, MTK_UART_IER_CTSI | MTK_UART_IER_RTSI);
mtk8250_disable_intrs(up, MTK_UART_IER_CTSI|MTK_UART_IER_RTSI);