score: Remove _CPU_Counter_difference()

All CPU ports used the same _CPU_Counter_difference() implementation.  Remove
this CPU port interface and mandate a monotonically increasing CPU counter.

Close #3456.

3 files changed, 7 insertions, 10 deletions

diff --git a/cpukit/include/rtems/counter.h b/cpukit/include/rtems/counter.h
index ad6d5517a3..61a0677bd3 100644
--- a/cpukit/include/rtems/counter.h
+++ b/cpukit/include/rtems/counter.h
@@ -99,20 +99,20 @@ static inline rtems_counter_ticks rtems_counter_read( void )
  * @brief Returns the difference between the second and first CPU counter
  * value.
  *
- * This operation may be carried out as a modulo operation depending on the
- * range of the CPU counter device.
+ * This function is provided for backward compatibility.
+ * You may use "second - first" directly in the code.
  *
  * @param[in] second The second CPU counter value.
  * @param[in] first The first CPU counter value.
  *
- * @return Returns second minus first modulo counter period.
+ * @return Returns second minus first.
  */
 static inline rtems_counter_ticks rtems_counter_difference(
   rtems_counter_ticks second,
   rtems_counter_ticks first
 )
 {
-  return _CPU_Counter_difference( second, first );
+  return second - first;
 }
 
 /**
diff --git a/cpukit/include/rtems/score/profiling.h b/cpukit/include/rtems/score/profiling.h
index 90e470a775..90d441b0d0 100644
--- a/cpukit/include/rtems/score/profiling.h
+++ b/cpukit/include/rtems/score/profiling.h
@@ -129,10 +129,7 @@ static inline void _Profiling_Thread_dispatch_enable(
   if ( new_thread_dispatch_disable_level == 0 ) {
     Per_CPU_Stats *stats = &cpu->Stats;
     CPU_Counter_ticks now = _CPU_Counter_read();
-    CPU_Counter_ticks delta = _CPU_Counter_difference(
-      now,
-      stats->thread_dispatch_disabled_instant
-    );
+    CPU_Counter_ticks delta = now - stats->thread_dispatch_disabled_instant;
 
     stats->total_thread_dispatch_disabled_time += delta;
 
diff --git a/cpukit/include/rtems/score/smplockstats.h b/cpukit/include/rtems/score/smplockstats.h
index 102fb6eac5..cebfb80bd6 100644
--- a/cpukit/include/rtems/score/smplockstats.h
+++ b/cpukit/include/rtems/score/smplockstats.h
@@ -235,7 +235,7 @@ static inline void _SMP_lock_Stats_acquire_end(
 
   second = _CPU_Counter_read();
   stats_context->acquire_instant = second;
-  delta = _CPU_Counter_difference( second, acquire_context->first );
+  delta = second - acquire_context->first;
 
   ++stats->usage_count;
 
@@ -270,7 +270,7 @@ static inline void _SMP_lock_Stats_release_update(
   stats = stats_context->stats;
   first = stats_context->acquire_instant;
   second = _CPU_Counter_read();
-  delta = _CPU_Counter_difference( second, first );
+  delta = second - first;
 
   stats->total_section_time += delta;