OCW2_EOI
if ((val & OCW2_EOI) != 0) {
atpic_write(sc, ATPIC_SLAVE, 0, OCW2_EOI);
atpic_write(sc, ATPIC_MASTER, 0, OCW2_EOI);
outb(atpics[MASTER].at_ioaddr, OCW2_EOI);
outb(atpics[SLAVE].at_ioaddr, OCW2_EOI);
outb(atpics[MASTER].at_ioaddr, OCW2_EOI);