/* Initialize system timer driver. 
Enable the hw timer, setting its tick period, and setup its interrupt  */
static int sys_clock_driver_init(void)
/* Initialize system timer driver. 
Enable the hw timer, setting its tick period, and setup its interrupt  */
static int sys_clock_driver_init(void)
{
	tick_period = 1000000ul / CONFIG_SYS_CLOCK_TICKS_PER_SEC;
	last_tick_time = hwm_get_time();
	hwtimer_enable(tick_period);
	IRQ_CONNECT(TIMER_TICK_IRQ, 1, np_timer_isr, 0, 0);
	irq_enable(TIMER_TICK_IRQ);
	return 0;
}