extern spinlock_t i8253_lock;
void setup_pit_timer(void){	extern spinlock_t i8253_lock;	unsigned long flags;	spin_lock_irqsave(&i8253_lock, flags);	outb_p(0x34,PIT_MODE);		/* binary, mode 2, LSB/MSB, ch 0 */	udelay(10);	outb_p(LATCH & 0xff , PIT_CH0);	/* LSB */	udelay(10);	outb(LATCH >> 8 , PIT_CH0);	/* MSB */	spin_unlock_irqrestore(&i8253_lock, flags);}