drivers: timer: arm_arch_timer: assign a initial value to last_cycle

On FVP platform, when parameter 'bp.refcounter.use_real_time' is set
to 1, cntvct_el0 isn't count from 0 and may cause overflow issue in
first timer compare interrupt.

'bp.refcounter.use_real_time' is 0 by default.

Signed-off-by: Huifeng Zhang <[email protected]>

Author: SgrrZhf

drivers/timer/arm_arch_timer.c

@@ -194,7 +194,8 @@ static int sys_clock_driver_init(const struct device *dev)
 	IRQ_CONNECT(ARM_ARCH_TIMER_IRQ, ARM_ARCH_TIMER_PRIO,
 		    arm_arch_timer_compare_isr, NULL, ARM_ARCH_TIMER_FLAGS);
 	arm_arch_timer_init();
-	arm_arch_timer_set_compare(arm_arch_timer_count() + CYC_PER_TICK);
+	last_cycle = arm_arch_timer_count();
+	arm_arch_timer_set_compare(last_cycle + CYC_PER_TICK);
 	arm_arch_timer_enable(true);
 	irq_enable(ARM_ARCH_TIMER_IRQ);
 	arm_arch_timer_set_irq_mask(false);