TIMER_MODE
outb(TIMER_MODE, TIMER_SEL2 | (mode & 0x3f));
outb(TIMER_MODE, TIMER_SEL2 | TIMER_SQWAVE | TIMER_16BIT);
outb(TIMER_MODE, i8254_walltimer_sel | TIMER_LATCH);
outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH); /* count-down timer */
outb(TIMER_MODE, TIMER_SEL0 | TIMER_SWSTROBE | TIMER_16BIT);
outb(TIMER_MODE, TIMER_SEL0 | TIMER_SWSTROBE | TIMER_16BIT);
outb(TIMER_MODE, TIMER_SEL0 | TIMER_SWSTROBE | TIMER_16BIT);
outb(TIMER_MODE, i8254_walltimer_sel | TIMER_RATEGEN | TIMER_16BIT);