timer: cortex_m_systick: handle idle timer overflow

The idle timer has its max value and can overflow. We measure time passed since the sys_clock_set_timeout call. Take possibility of the overflow into account. Signed-off-by: Dawid Niedzwiecki <[email protected]>
andak · Nov 27, 2023 · 4104f54 · 4104f54
1 parent 2ae0999
commit 4104f54
Showing 1 changed file with 9 additions and 1 deletion.
diff --git a/drivers/timer/cortex_m_systick.c b/drivers/timer/cortex_m_systick.c
@@ -375,7 +375,15 @@ void sys_clock_idle_exit(void)
 		cycle_post_idle = cycle_count + elapsed();
 
 		/* Calculate has much time has pasted since last measurement for both timers */
-		idle_timer_diff = idle_timer_post - idle_timer_pre_idle;
+		/* Check IDLE timer overflow */
+		if (idle_timer_pre_idle > idle_timer_post) {
+			idle_timer_diff =
+				(counter_get_top_value(idle_timer) - idle_timer_pre_idle) +
+				idle_timer_post + 1;
+
+		} else {
+			idle_timer_diff = idle_timer_post - idle_timer_pre_idle;
+		}
 		idle_timer_us = counter_ticks_to_us(idle_timer, idle_timer_diff);
 
 #ifndef CONFIG_CORTEX_M_SYSTICK_64BIT_CYCLE_COUNTER