[nrf528xx] add nrf5AlarmGetRawCounter (#4287)

examples/platforms/nrf528xx/src/alarm.c

@@ -66,6 +66,8 @@
 #define US_PER_S            NRF_802154_US_PER_S
 #define US_PER_OVERFLOW     (512UL * NRF_802154_US_PER_S)  ///< Time that has passed between overflow events. On full RTC speed, it occurs every 512 s.
 
+#define RTC_COUNTER_BITS    24  ///< Number of bits in RTC COUNTER register.
+
 #define MS_PER_S            1000UL
 
 #define MIN_RTC_COMPARE_EVENT_TICKS  2                                                        ///< Minimum number of RTC ticks delay that guarantees that RTC compare event will fire.
@@ -523,6 +525,16 @@ inline uint64_t nrf5AlarmGetCurrentTime(void)
     return GetCurrentTime(kUsTimer);
 }
 
+uint64_t nrf5AlarmGetRawCounter(void)
+{
+    uint32_t offset  = 0;
+    uint32_t counter = 0;
+
+    GetOffsetAndCounter(&offset, &counter);
+
+    return (((uint64_t)offset) << RTC_COUNTER_BITS) | counter;
+}
+
 uint32_t otPlatAlarmMilliGetNow(void)
 {
     return (uint32_t)(nrf5AlarmGetCurrentTime() / US_PER_MS);

examples/platforms/nrf528xx/src/platform-nrf5.h

@@ -89,6 +89,12 @@ void nrf5AlarmProcess(otInstance *aInstance);
  */
 uint64_t nrf5AlarmGetCurrentTime(void);
 
+/**
+ * Function for getting raw counter value in RTC ticks.
+ *
+ */
+uint64_t nrf5AlarmGetRawCounter(void);
+
 /**
  * Initialization of Random Number Generator.
  *