muorb: abs time on aDSP in sync with Linux side

This adds a call on startup of the muorb on the aDSP side to use an
offset for hrt_absolute_call(). This means that the hrt_absolute_call()
on the appsproc (Linux) side should now match the one on the aDSP
(QURT) side.
The accuracy still needs to be determined.

src/firmware/qurt/px4muorb.idl

@@ -1,6 +1,6 @@
 //=======================================================================
 // Copyright (c) 2016, Mark Charlebois. All rights reserved.
-// 
+//
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
@@ -13,7 +13,7 @@
 //     * Neither the name of The Linux Foundation nor the names of its
 //       contributors may be used to endorse or promote products derived
 //       from this software without specific prior written permission.
-// 
+//
 // THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
 // WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
@@ -30,12 +30,26 @@
 #include "AEEStdDef.idl"
 
 interface px4muorb{
-  
+
    /**
     * interface method to start the uorb service and initialize the muorb
     */
    AEEResult orb_initialize();
 
+   /**
+    * Interface to set an offset to hrt_absolute_time on the DSP.
+    *
+    * @param time_diff_us: time difference of the DSP clock to Linux clock.
+    *   A positive number means the Linux clock is ahead of the DSP one.
+    */
+   AEEResult set_absolute_time_offset( in long time_diff_us );
+
+   /**
+    * Interface to request hrt_absolute_time on the DSP.
+    * @param time_us: pointer to time in us
+    */
+   AEEResult get_absolute_time(rout unsigned long long time_us);
+
    /**
     * Interface to add a subscriber to the identified topic
     * @param topic_name
@@ -130,6 +144,6 @@ interface px4muorb{
      * @return status
      *    0 = success
      *    all others is a failure.
-     **/ 
+     **/
     AEEResult receive_bulk_data( rout sequence<octet> data, rout long bytes_returned, rout long topic_count );
 };