2011-05-23 Jennifer Averett <Jennifer.Averett@OARcorp.com>

	* score/Makefile.am, score/include/rtems/score/thread.h,
	score/inline/rtems/score/thread.inl: Add smp support to dispable
	dispatch level accesses.
	* score/src/threaddispatchdisablelevel.c: New file.

1 files changed, 133 insertions, 0 deletions

diff --git a/cpukit/score/src/threaddispatchdisablelevel.c b/cpukit/score/src/threaddispatchdisablelevel.c
new file mode 100644
index 0000000000..f0d1cf7a61
--- /dev/null
+++ b/cpukit/score/src/threaddispatchdisablelevel.c
@@ -0,0 +1,133 @@
+/*
+ *  Thread Dispatch Disable Level Methods
+ *
+ *  COPYRIGHT (c) 1989-2011.
+ *  On-Line Applications Research Corporation (OAR).
+ *
+ *  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.
+ *
+ *  $Id$
+ */
+
+#include <rtems/system.h>
+#include <rtems/score/apiext.h>
+#include <rtems/score/context.h>
+#include <rtems/score/interr.h>
+#include <rtems/score/isr.h>
+#include <rtems/score/object.h>
+#include <rtems/score/priority.h>
+#include <rtems/score/states.h>
+#include <rtems/score/sysstate.h>
+#include <rtems/score/thread.h>
+
+void _Thread_Dispatch_initialization( void )
+{
+  _Thread_Dispatch_disable_level = 0; 
+  _SMP_lock_spinlock_nested_Initialize(&_Thread_Dispatch_disable_level_lock);
+  _Thread_Dispatch_set_disable_level( 1 );
+}
+
+bool _Thread_Dispatch_in_critical_section(void)
+{
+  if (  _Thread_Dispatch_disable_level == 0 )
+   return false;
+
+  return true;
+}
+
+uint32_t _Thread_Dispatch_get_disable_level(void)
+{
+  return _Thread_Dispatch_disable_level;
+}
+
+uint32_t _Thread_Dispatch_increment_disable_level(void)
+{
+  ISR_Level  isr_level;
+  uint32_t   level;
+
+  /*
+   * Note: _SMP_lock_spinlock_nested_Obtain returns
+   *       with ISR's disabled and the isr_level that
+   *       should be restored after a short period.
+   *
+   * Here we obtain the lock and increment the 
+   * Thread dispatch disable level while under the
+   * protection of the isr being off.  After this
+   * point it is safe to re-enable ISRs and allow
+   * the dispatch disable lock to provide protection.
+   */
+
+  isr_level = _SMP_lock_spinlock_nested_Obtain(
+    &_Thread_Dispatch_disable_level_lock
+  );
+  
+  _Thread_Dispatch_disable_level++;
+  level = _Thread_Dispatch_disable_level;
+
+  _ISR_Enable(isr_level); 
+
+  return level;
+}
+
+uint32_t _Thread_Dispatch_decrement_disable_level(void)
+{
+  ISR_Level  isr_level;
+  uint32_t   level;
+
+  /*  First we must disable ISRs in order to protect
+   *  accesses to the dispatch disable level.
+   */
+
+  _ISR_Disable( isr_level );
+
+  _Thread_Dispatch_disable_level--;
+  level = _Thread_Dispatch_disable_level;
+
+
+  /* 
+   * Note: _SMP_lock_spinlock_nested_Obtain returns with
+   *        ISR's disabled and _SMP_lock_spinlock_nested_Release
+   *        is responsable for re-enabling interrupts.
+   */
+  _SMP_lock_spinlock_nested_Release( 
+    &_Thread_Dispatch_disable_level_lock,
+    isr_level
+  ); 
+
+  return level;
+}
+
+
+/*
+ * Note this method is taking a heavy handed approach to 
+ * setting the dispatch level. This may be optimized at a 
+ * later timee, but it must be in such a way that the nesting
+ * level is decremented by the same number as the dispatch level.
+ * This approach is safest until we are sure the nested spinlock
+ * is successfully working with smp isr source code.  
+ */
+
+uint32_t _Thread_Dispatch_set_disable_level(uint32_t value)
+{
+  /*
+   * If we need the dispatch level to go higher 
+   * call increment method the desired number of times.
+   */
+
+  while ( value > _Thread_Dispatch_disable_level ) {
+    _Thread_Dispatch_increment_disable_level();
+  }
+
+  /*
+   * If we need the dispatch level to go lower
+   * call increment method the desired number of times.
+   */
+
+  while ( value < _Thread_Dispatch_disable_level ) {
+    _Thread_Dispatch_decrement_disable_level();
+  }
+
+  return value;
+}