smp: New SMP lock API

Move the SMP lock implementation to the CPU port.  An optimal SMP lock
implementation is highly architecture dependent.  For example the memory
models may be fundamentally different.

The new SMP lock API has a flaw.  It does not provide the ability to use
a local context for acquire and release pairs.  Such a context is
necessary to implement for example the Mellor-Crummey and Scott (MCS)
locks.  The SMP lock is currently used in _Thread_Disable_dispatch() and
_Thread_Enable_dispatch() and makes them to a giant lock acquire and
release.  Since these functions do not pass state information via a
local context there is currently no use case for such a feature.

3 files changed, 119 insertions, 0 deletions

diff --git a/cpukit/score/cpu/no_cpu/Makefile.am b/cpukit/score/cpu/no_cpu/Makefile.am
index 820579cd42..24517431e7 100644
--- a/cpukit/score/cpu/no_cpu/Makefile.am
+++ b/cpukit/score/cpu/no_cpu/Makefile.am
@@ -8,6 +8,7 @@ include_rtems_score_HEADERS = rtems/score/cpu.h
 include_rtems_score_HEADERS += rtems/score/no_cpu.h
 include_rtems_score_HEADERS += rtems/score/cpu_asm.h
 include_rtems_score_HEADERS += rtems/score/types.h
+include_rtems_score_HEADERS += rtems/score/cpusmplock.h
 
 noinst_LIBRARIES = libscorecpu.a
 libscorecpu_a_SOURCES = cpu.c cpu_asm.c
diff --git a/cpukit/score/cpu/no_cpu/preinstall.am b/cpukit/score/cpu/no_cpu/preinstall.am
index a56caeafd8..a46f8b0bfd 100644
--- a/cpukit/score/cpu/no_cpu/preinstall.am
+++ b/cpukit/score/cpu/no_cpu/preinstall.am
@@ -43,3 +43,7 @@ $(PROJECT_INCLUDE)/rtems/score/types.h: rtems/score/types.h $(PROJECT_INCLUDE)/r
 	$(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/types.h
 PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/types.h
 
+$(PROJECT_INCLUDE)/rtems/score/cpusmplock.h: rtems/score/cpusmplock.h $(PROJECT_INCLUDE)/rtems/score/$(dirstamp)
+	$(INSTALL_DATA) $< $(PROJECT_INCLUDE)/rtems/score/cpusmplock.h
+PREINSTALL_FILES += $(PROJECT_INCLUDE)/rtems/score/cpusmplock.h
+
diff --git a/cpukit/score/cpu/no_cpu/rtems/score/cpusmplock.h b/cpukit/score/cpu/no_cpu/rtems/score/cpusmplock.h
new file mode 100644
index 0000000000..387bbb47c1
--- /dev/null
+++ b/cpukit/score/cpu/no_cpu/rtems/score/cpusmplock.h
@@ -0,0 +1,114 @@
+/**
+ * @file
+ *
+ * @ingroup ScoreSMPLockCPU
+ *
+ * @brief CPU SMP Lock Implementation
+ */
+
+/*
+ * Copyright (c) 2013 embedded brains GmbH
+ *
+ * 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_NO_CPU_SMPLOCK_H
+#define _RTEMS_SCORE_NO_CPU_SMPLOCK_H
+
+#include <rtems/score/cpu.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+/**
+ * @defgroup ScoreSMPLockCPU CPU SMP Locks
+ *
+ * @ingroup ScoreSMPLock
+ *
+ * This example will implement a ticket lock.
+ *
+ * @{
+ */
+
+/**
+ * @brief CPU SMP lock control.
+ */
+typedef struct {
+  unsigned int next_ticket;
+  unsigned int now_serving;
+} CPU_SMP_lock_Control;
+
+/**
+ * @brief CPU SMP lock control initializer for static initialization.
+ */
+#define CPU_SMP_LOCK_INITIALIZER { 0, 0 }
+
+/**
+ * @brief Initializes a CPU SMP lock control.
+ *
+ * @param[out] lock The CPU SMP lock control.
+ */
+static inline void _CPU_SMP_lock_Initialize( CPU_SMP_lock_Control *lock )
+{
+  lock->next_ticket = 0;
+  lock->now_serving = 0;
+}
+
+/**
+ * @brief Acquires a CPU SMP lock.
+ *
+ * @param[in/out] lock The CPU SMP lock control.
+ */
+static inline void _CPU_SMP_lock_Acquire( CPU_SMP_lock_Control *lock )
+{
+  unsigned int my_ticket = _Atomic_Fetch_and_increment( &lock->next_ticket );
+
+  while ( _Atomic_Load_and_acquire( &lock->now_serving ) != my_ticket ) {
+    _Wait_some_time();
+  }
+}
+
+/**
+ * @brief Releases a CPU SMP lock.
+ *
+ * @param[in/out] lock The CPU SMP lock control.
+ */
+static inline void _CPU_SMP_lock_Release( CPU_SMP_lock_Control *lock )
+{
+  _Atomic_Store_and_release( &lock->now_serving, lock->now_serving + 1 );
+}
+
+/**
+ * @brief Disables interrupts and acquires the CPU SMP lock.
+ *
+ * @param[in/out] lock The CPU SMP lock control.
+ * @param[out] isr_cookie The ISR cookie.
+ */
+#define _CPU_SMP_lock_ISR_disable_and_acquire( lock, isr_cookie ) \
+  do { \
+    _CPU_ISR_Disable( isr_cookie ); \
+    _CPU_SMP_lock_Acquire( lock ); \
+  } while (0)
+
+/**
+ * @brief Releases the CPU SMP lock and enables interrupts.
+ *
+ * @param[in/out] lock The CPU SMP lock control.
+ * @param[in] isr_cookie The ISR cookie.
+ */
+#define _CPU_SMP_lock_Release_and_ISR_enable( lock, isr_cookie ) \
+  do { \
+    _CPU_SMP_lock_Release( lock ); \
+    _CPU_ISR_Enable( isr_cookie ); \
+  } while (0)
+
+/**@}*/
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+
+#endif /* _RTEMS_SCORE_NO_CPU_SMPLOCK_H */