bsps: Move shared btimer support to bsps

This patch is a part of the BSP source reorganization.

Update #3285.

bsps/shared/dev/btimer/btimer-cpucounter.c

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2017 embedded brains GmbH.  All rights reserved.
+ *
+ *  embedded brains GmbH
+ *  Dornierstr. 4
+ *  82178 Puchheim
+ *  Germany
+ *  <rtems@embedded-brains.de>
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rtems.org/license/LICENSE.
+ */
+
+#include <rtems/btimer.h>
+#include <rtems/counter.h>
+
+static uint32_t benchmark_timer_base;
+
+void benchmark_timer_initialize(void)
+{
+  benchmark_timer_base = rtems_counter_read();
+}
+
+benchmark_timer_t benchmark_timer_read(void)
+{
+  return rtems_counter_difference(rtems_counter_read(), benchmark_timer_base);
+}
+
+void benchmark_timer_disable_subtracting_average_overhead(
+  bool find_average_overhead
+)
+{
+  (void) find_average_overhead;
+}

bsps/shared/dev/btimer/btimer-stub.c

@@ -0,0 +1,30 @@
+/*
+ *  This file implements a stub benchmark timer that is sufficient to
+ *  satisfy linking the RTEMS Benchmarks.
+ *
+ *  COPYRIGHT (c) 1989-2001.
+ *  On-Line Applications Research Corporation (OAR).
+ */
+
+#include <bsp.h>
+#include <rtems/btimer.h>
+
+bool benchmark_timer_find_average_overhead;
+
+void benchmark_timer_initialize(void)
+{
+}
+
+benchmark_timer_t benchmark_timer_read(void)
+{
+  if (benchmark_timer_find_average_overhead)
+    return 1;
+  return 0;
+}
+
+void benchmark_timer_disable_subtracting_average_overhead(
+  bool find_flag
+)
+{
+  benchmark_timer_find_average_overhead = find_flag;
+}