AP_HAL_Linux: tidy set/get of hw RTC

libraries/AP_HAL_Linux/Util.cpp

@@ -62,12 +62,23 @@ void Util::commandline_arguments(uint8_t &argc, char * const *&argv)
     argv = saved_argv;
 }
 
+uint64_t Util::get_hw_rtc() const
+{
+    struct timespec ts;
+    clock_gettime(CLOCK_REALTIME, &ts);
+    const uint64_t seconds = ts.tv_sec;
+    const uint64_t nanoseconds = ts.tv_nsec;
+    return (seconds * 1000000ULL + nanoseconds/1000ULL);
+}
+
 void Util::set_hw_rtc(uint64_t time_utc_usec)
 {
+// don't reset the HW clock time on people's laptops.
 #if CONFIG_HAL_BOARD_SUBTYPE != HAL_BOARD_SUBTYPE_LINUX_NONE
-    // call superclass method to set time.  We've guarded this so we
-    // don't reset the HW clock time on people's laptops.
-    AP_HAL::Util::set_hw_rtc(time_utc_usec);
+    timespec ts;
+    ts.tv_sec = time_utc_usec/1000000ULL;
+    ts.tv_nsec = (time_utc_usec % 1000000ULL) * 1000ULL;
+    clock_settime(CLOCK_REALTIME, &ts);
 #endif
 }
 
@@ -342,4 +353,4 @@ bool Util::parse_cpu_set(const char *str, cpu_set_t *cpu_set) const
     } while (*endptr != '\0');
 
     return true;
-}
+}

libraries/AP_HAL_Linux/Util.h

@@ -37,9 +37,11 @@ public:
     void commandline_arguments(uint8_t &argc, char * const *&argv) override;
 
     /*
-      set system clock in UTC microseconds
+      get/set system clock in UTC microseconds
      */
     void set_hw_rtc(uint64_t time_utc_usec) override;
+    uint64_t get_hw_rtc() const override;
+
     const char *get_custom_log_directory() const override final { return custom_log_directory; }
     const char *get_custom_terrain_directory() const override final { return custom_terrain_directory; }
     const char *get_custom_storage_directory() const override final { return custom_storage_directory; }