tty = receive_chars(up, &status, regs);
if ((status.sreg.isr0 & SAB82532_ISR0_CDSC) ||
(status.sreg.isr1 & (SAB82532_ISR1_BRK | SAB82532_ISR1_CSC)))
tty = receive_chars(up, &status, regs);
if ((status.sreg.isr0 & SAB82532_ISR0_CDSC) ||
(status.sreg.isr1 & (SAB82532_ISR1_BRK | SAB82532_ISR1_CSC)))