Make reading the global ms tick atomic in order to prevent glitches

stm-firmware/include/reflow-controller/systick.h

@@ -45,7 +45,7 @@ extern volatile uint32_t wait_tick_ms;
  * @brief Systemclock in milliseconds.
  *
  * This value must not be reset during the whole runtime.
- *
+ * @warning In order to use this, you must assure that the read access is atomic.
  */
 extern volatile uint64_t global_tick_ms;
 

stm-firmware/systick.c

@@ -43,7 +43,13 @@ void systick_wait_ms(uint32_t ms)
 
 uint64_t systick_get_global_tick()
 {
-	return global_tick_ms;
+	uint64_t temp;
+
+	__disable_irq();
+	temp = global_tick_ms;
+	__enable_irq();
+
+	return temp;
 }
 
 bool __attribute__((optimize("O3"))) systick_ticks_have_passed(uint64_t start_timestamp, uint64_t ticks)