score: Add SMP barrier

4 files changed, 181 insertions, 0 deletions

diff --git a/cpukit/score/Makefile.am b/cpukit/score/Makefile.am
index 267e8b2556..482e78de12 100644
--- a/cpukit/score/Makefile.am
+++ b/cpukit/score/Makefile.am
@@ -59,6 +59,7 @@ include_rtems_score_HEADERS += include/rtems/score/schedulersimpleimpl.h
 include_rtems_score_HEADERS += include/rtems/score/schedulersmp.h
 include_rtems_score_HEADERS += include/rtems/score/schedulersmpimpl.h
 include_rtems_score_HEADERS += include/rtems/score/smp.h
+include_rtems_score_HEADERS += include/rtems/score/smpbarrier.h
 include_rtems_score_HEADERS += include/rtems/score/smplock.h
 include_rtems_score_HEADERS += include/rtems/score/stack.h
 include_rtems_score_HEADERS += include/rtems/score/stackimpl.h
@@ -276,6 +277,7 @@ libscore_a_SOURCES += src/thread.c src/threadchangepriority.c \
     src/threadblockingoperationcancel.c
 
 if HAS_SMP
+libscore_a_SOURCES += src/smpbarrierwait.c
 libscore_a_SOURCES += src/threaddispatchdisablelevel.c
 endif
 
diff --git a/cpukit/score/include/rtems/score/smpbarrier.h b/cpukit/score/include/rtems/score/smpbarrier.h
new file mode 100644
index 0000000000..549887d0ae
--- /dev/null
+++ b/cpukit/score/include/rtems/score/smpbarrier.h
@@ -0,0 +1,127 @@
+/**
+ * @file
+ *
+ * @ingroup ScoreSMPBarrier
+ *
+ * @brief SMP Barrier API
+ */
+
+/*
+ * Copyright (c) 2013-2014 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.
+ */
+
+#ifndef _RTEMS_SCORE_SMPBARRIER_H
+#define _RTEMS_SCORE_SMPBARRIER_H
+
+#include <rtems/score/cpuopts.h>
+
+#if defined( RTEMS_SMP )
+
+#include <rtems/score/atomic.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+/**
+ * @defgroup ScoreSMPBarrier SMP Barriers
+ *
+ * @ingroup Score
+ *
+ * @brief The SMP barrier provides barrier synchronization for SMP systems at
+ * the lowest level.
+ *
+ * The SMP barrier is implemented as a sense barrier, see also Herlihy and
+ * Shavit, "The Art of Multiprocessor Programming", 17.3 Sense-Reversing
+ * Barrier.
+ *
+ * @{
+ */
+
+/**
+ * @brief SMP barrier control.
+ */
+typedef struct {
+  Atomic_Uint value;
+  Atomic_Uint sense;
+} SMP_barrier_Control;
+
+/**
+ * @brief SMP barrier per-thread state.
+ *
+ * Each user of the barrier must provide this per-thread state.
+ */
+typedef struct {
+  unsigned int sense;
+} SMP_barrier_State;
+
+/**
+ * @brief SMP barrier control initializer for static initialization.
+ */
+#define SMP_BARRIER_CONTROL_INITIALIZER \
+  { ATOMIC_INITIALIZER_UINT( 0U ), ATOMIC_INITIALIZER_UINT( 0U ) }
+
+/**
+ * @brief SMP barrier per-thread state initializer for static initialization.
+ */
+#define SMP_BARRIER_STATE_INITIALIZER { 0U }
+
+/**
+ * @brief Initializes a SMP barrier control.
+ *
+ * Concurrent initialization leads to unpredictable results.
+ *
+ * @param[out] control The SMP barrier control.
+ */
+static inline void _SMP_barrier_Control_initialize(
+  SMP_barrier_Control *control
+)
+{
+  _Atomic_Init_uint( &control->value, 0U );
+  _Atomic_Init_uint( &control->sense, 0U );
+}
+
+/**
+ * @brief Initializes a SMP barrier per-thread state.
+ *
+ * @param[out] state The SMP barrier control.
+ */
+static inline void _SMP_barrier_State_initialize(
+  SMP_barrier_State *state
+)
+{
+  state->sense = 0U;
+}
+
+/**
+ * @brief Waits on the SMP barrier until count threads rendezvoused.
+ *
+ * @param[in, out] control The SMP barrier control.
+ * @param[in, out] state The SMP barrier per-thread state.
+ * @param[in] count The thread count bound to rendezvous.
+ */
+void _SMP_barrier_Wait(
+  SMP_barrier_Control *control,
+  SMP_barrier_State *state,
+  unsigned int count
+);
+
+/**@}*/
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+#endif /* defined( RTEMS_SMP ) */
+
+#endif /* _RTEMS_SCORE_SMPBARRIER_H */
diff --git a/cpukit/score/preinstall.am b/cpukit/score/preinstall.am
index a3c9685dc5..ceefbe7e6e 100644
--- a/cpukit/score/preinstall.am
+++ b/cpukit/score/preinstall.am
@@ -219,6 +219,10 @@ $(PROJECT_INCLUDE)/rtems/score/smp.h: include/rtems/score/smp.h $(PROJECT_INCLUD
 	$(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/smp.h
 PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/smp.h
 
+$(PROJECT_INCLUDE)/rtems/score/smpbarrier.h: include/rtems/score/smpbarrier.h $(PROJECT_INCLUDE)/rtems/score/$(dirstamp)
+	$(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/smpbarrier.h
+PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/smpbarrier.h
+
 $(PROJECT_INCLUDE)/rtems/score/smplock.h: include/rtems/score/smplock.h $(PROJECT_INCLUDE)/rtems/score/$(dirstamp)
 	$(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/smplock.h
 PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/smplock.h
diff --git a/cpukit/score/src/smpbarrierwait.c b/cpukit/score/src/smpbarrierwait.c
new file mode 100644
index 0000000000..0a3cedba00
--- /dev/null
+++ b/cpukit/score/src/smpbarrierwait.c
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2013-2014 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.
+ */
+
+#if HAVE_CONFIG_H
+  #include "config.h"
+#endif
+
+#include <rtems/score/smpbarrier.h>
+
+void _SMP_barrier_Wait(
+  SMP_barrier_Control *control,
+  SMP_barrier_State *state,
+  unsigned int count
+)
+{
+  unsigned int sense = ~state->sense;
+  unsigned int previous_value;
+
+  state->sense = sense;
+
+  previous_value = _Atomic_Fetch_add_uint(
+    &control->value,
+    1U,
+    ATOMIC_ORDER_RELAXED
+  );
+
+  if ( previous_value + 1U == count ) {
+    _Atomic_Store_uint( &control->value, 0U, ATOMIC_ORDER_RELAXED );
+    _Atomic_Store_uint( &control->sense, sense, ATOMIC_ORDER_RELEASE );
+  } else {
+    while (
+      _Atomic_Load_uint( &control->sense, ATOMIC_ORDER_ACQUIRE ) != sense
+    ) {
+      /* Wait */
+    }
+  }
+}