UART_RSA_MSR
mode = serial_in(up, UART_RSA_MSR);
serial_out(up, UART_RSA_MSR, mode | UART_RSA_MSR_FIFO);
mode = serial_in(up, UART_RSA_MSR);
mode = serial_in(up, UART_RSA_MSR);
serial_out(up, UART_RSA_MSR, mode & ~UART_RSA_MSR_FIFO);
mode = serial_in(up, UART_RSA_MSR);
mode = serial_in(up, UART_RSA_MSR);
serial_out(up, UART_RSA_MSR, mode | UART_RSA_MSR_FIFO);
mode = serial_in(up, UART_RSA_MSR);
mode = serial_in(up, UART_RSA_MSR);
serial_out(up, UART_RSA_MSR, mode & ~UART_RSA_MSR_FIFO);
mode = serial_in(up, UART_RSA_MSR);