score: Add CPU counter support

Add a CPU counter interface to allow access to a free-running counter.
It is useful to measure short time intervals.  This can be used for
example to enable profiling of critical low-level functions.

Add two busy wait functions rtems_counter_delay_ticks() and
rtems_counter_delay_nanoseconds() implemented via the CPU counter.

testsuites/sptests/Makefile.am

@@ -30,6 +30,7 @@ SUBDIRS = \
     spsimplesched03 spnsext01 spedfsched01 spedfsched02 spedfsched03 \
     spcbssched01 spcbssched02 spcbssched03 spqreslib sptimespec01 \
     spregion_err01 sppartition_err01
+SUBDIRS += spcpucounter01
 if HAS_CPLUSPLUS
 SUBDIRS += sptls02
 endif

testsuites/sptests/configure.ac

@@ -36,6 +36,7 @@ AM_CONDITIONAL(HAS_CPUSET,test x"${ac_cv_header_sys_cpuset_h}" = x"yes")
 
 # Explicitly list all Makefiles here
 AC_CONFIG_FILES([Makefile
+spcpucounter01/Makefile
 sptls02/Makefile
 sptls01/Makefile
 spintrcritical20/Makefile

testsuites/sptests/spcpucounter01/Makefile.am

@@ -0,0 +1,19 @@
+rtems_tests_PROGRAMS = spcpucounter01
+spcpucounter01_SOURCES = init.c
+
+dist_rtems_tests_DATA = spcpucounter01.scn spcpucounter01.doc
+
+include $(RTEMS_ROOT)/make/custom/@RTEMS_BSP@.cfg
+include $(top_srcdir)/../automake/compile.am
+include $(top_srcdir)/../automake/leaf.am
+
+AM_CPPFLAGS += -I$(top_srcdir)/../support/include
+
+LINK_OBJS = $(spcpucounter01_OBJECTS)
+LINK_LIBS = $(spcpucounter01_LDLIBS)
+
+spcpucounter01$(EXEEXT): $(spcpucounter01_OBJECTS) $(spcpucounter01_DEPENDENCIES)
+	@rm -f spcpucounter01$(EXEEXT)
+	$(make-exe)
+
+include $(top_srcdir)/../automake/local.am

testsuites/sptests/spcpucounter01/init.c

@@ -0,0 +1,112 @@
+/*
+ * Copyright (c) 2014 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.com/license/LICENSE.
+ */
+
+#ifdef HAVE_CONFIG_H
+  #include "config.h"
+#endif
+
+#include <stdio.h>
+#include <inttypes.h>
+
+#include <rtems.h>
+#include <rtems/counter.h>
+
+#define TESTS_USE_PRINTF
+#include "tmacros.h"
+
+#define NS_PER_TICK 1000000
+
+static rtems_interval sync_with_clock_tick(void)
+{
+  rtems_interval start = rtems_clock_get_ticks_since_boot();
+  rtems_interval current;
+
+  do {
+    current = rtems_clock_get_ticks_since_boot();
+  } while (current == start);
+
+  return current;
+}
+
+static void test_converter(void)
+{
+  CPU_Counter_ticks frequency = rtems_counter_nanoseconds_to_ticks(1000000000);
+  uint64_t ns = rtems_counter_ticks_to_nanoseconds(frequency);
+
+  printf("CPU counter frequency: %" PRIu32 "Hz\n", frequency);
+  printf("nanoseconds for frequency count ticks: %" PRIu64 "\n", ns);
+
+  rtems_test_assert(ns == 1000000000);
+}
+
+static void test_delay_nanoseconds(void)
+{
+  rtems_counter_ticks start;
+  rtems_counter_ticks end;
+  rtems_counter_ticks delta;
+  double ns_per_tick = NS_PER_TICK;
+  double ns_delta;
+  rtems_interval tick;
+  int n = 10;
+  int i;
+
+  printf("test delay nanoseconds (%i times)\n", n);
+
+  for (i = 0; i < n; ++i) {
+    tick = sync_with_clock_tick();
+
+    start = rtems_counter_read();
+    rtems_counter_delay_nanoseconds(NS_PER_TICK);
+    end = rtems_counter_read();
+
+    rtems_test_assert(tick < rtems_clock_get_ticks_since_boot());
+
+    delta = rtems_counter_difference(end, start);
+    ns_delta = rtems_counter_ticks_to_nanoseconds(delta);
+
+    rtems_test_assert(ns_delta >= ns_per_tick);
+
+    printf(
+      "busy wait relative to clock tick: %f\n",
+      (ns_delta - ns_per_tick) / ns_per_tick
+    );
+  }
+}
+
+static void Init(rtems_task_argument arg)
+{
+  puts("\n\n*** TEST SPCPUCOUNTER 1 ***");
+
+  test_converter();
+  test_delay_nanoseconds();
+
+  puts("*** END OF TEST SPCPUCOUNTER 1 ***");
+
+  rtems_test_exit(0);
+}
+
+#define CONFIGURE_APPLICATION_NEEDS_CLOCK_DRIVER
+#define CONFIGURE_APPLICATION_NEEDS_CONSOLE_DRIVER
+
+#define CONFIGURE_MICROSECONDS_PER_TICK (NS_PER_TICK / 1000)
+
+#define CONFIGURE_MAXIMUM_TASKS 1
+
+#define CONFIGURE_INIT_TASK_ATTRIBUTES RTEMS_FLOATING_POINT
+
+#define CONFIGURE_RTEMS_INIT_TASKS_TABLE
+
+#define CONFIGURE_INIT
+
+#include <rtems/confdefs.h>

testsuites/sptests/spcpucounter01/spcpucounter01.doc

@@ -0,0 +1,16 @@
+This file describes the directives and concepts tested by this test set.
+
+test set name: spcpucounter01
+
+directives:
+
+  - rtems_counter_read()
+  - rtems_counter_difference()
+  - rtems_counter_ticks_to_nanoseconds()
+  - rtems_counter_nanoseconds_to_ticks()
+
+concepts:
+
+  - Ensure that the CPU counter converter functions produce consistent values.
+  - Ensure that the busy wait functions are consistent with the clock tick
+    durations.

testsuites/sptests/spcpucounter01/spcpucounter01.scn

@@ -0,0 +1,15 @@
+*** TEST SPCPUCOUNTER 1 ***
+CPU counter frequency: 25000000Hz
+nanoseconds for frequency count ticks: 1000000000
+test delay nanoseconds (10 times)
+busy wait relative to clock tick: 0.001320
+busy wait relative to clock tick: 0.001640
+busy wait relative to clock tick: 0.001320
+busy wait relative to clock tick: 0.001160
+busy wait relative to clock tick: 0.001280
+busy wait relative to clock tick: 0.001240
+busy wait relative to clock tick: 0.001280
+busy wait relative to clock tick: 0.001280
+busy wait relative to clock tick: 0.001320
+busy wait relative to clock tick: 0.001280
+*** END OF TEST SPCPUCOUNTER 1 ***