score: Multiprocessor Resource Sharing Protocol

Add basic support for the Multiprocessor Resource Sharing Protocol
(MrsP).

The Multiprocessor Resource Sharing Protocol (MrsP) is defined in A.
Burns and A.J.  Wellings, A Schedulability Compatible Multiprocessor
Resource Sharing Protocol - MrsP, Proceedings of the 25th Euromicro
Conference on Real-Time Systems (ECRTS 2013), July 2013.  It is a
generalization of the Priority Ceiling Protocol to SMP systems.  Each
MrsP semaphore uses a ceiling priority per scheduler instance.  These
ceiling priorities can be specified with rtems_semaphore_set_priority().
A task obtaining or owning a MrsP semaphore will execute with the
ceiling priority for its scheduler instance as specified by the MrsP
semaphore object.  Tasks waiting to get ownership of a MrsP semaphore
will not relinquish the processor voluntarily.  In case the owner of a
MrsP semaphore gets preempted it can ask all tasks waiting for this
semaphore to help out and temporarily borrow the right to execute on one
of their assigned processors.

The help out feature is not implemented with this patch.

1 files changed, 116 insertions, 0 deletions

diff --git a/cpukit/rtems/src/semsetpriority.c b/cpukit/rtems/src/semsetpriority.c
new file mode 100644
index 0000000000..b5dd1db101
--- /dev/null
+++ b/cpukit/rtems/src/semsetpriority.c
@@ -0,0 +1,116 @@
+/*
+ * 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.org/license/LICENSE.
+ */
+
+#if HAVE_CONFIG_H
+  #include "config.h"
+#endif
+
+#include <rtems/rtems/semimpl.h>
+#include <rtems/rtems/attrimpl.h>
+#include <rtems/rtems/tasksimpl.h>
+#include <rtems/score/schedulerimpl.h>
+
+static rtems_status_code _Semaphore_Set_priority(
+  Semaphore_Control   *the_semaphore,
+  rtems_id             scheduler_id,
+  rtems_task_priority  new_priority,
+  rtems_task_priority *old_priority_p
+)
+{
+  rtems_status_code   sc;
+  rtems_attribute     attribute_set = the_semaphore->attribute_set;
+  rtems_task_priority old_priority;
+
+  new_priority = _RTEMS_tasks_Priority_to_Core( new_priority );
+
+#if defined(RTEMS_SMP)
+  if ( _Attributes_Is_multiprocessor_resource_sharing( attribute_set ) ) {
+    MRSP_Control *mrsp = &the_semaphore->Core_control.mrsp;
+    uint32_t scheduler_index = _Scheduler_Get_index_by_id( scheduler_id );
+
+    old_priority = _MRSP_Get_ceiling_priority( mrsp, scheduler_index );
+
+    if ( new_priority != RTEMS_CURRENT_PRIORITY ) {
+      _MRSP_Set_ceiling_priority( mrsp, scheduler_index, new_priority );
+    }
+
+    sc = RTEMS_SUCCESSFUL;
+  } else
+#endif
+  if ( _Attributes_Is_priority_ceiling( attribute_set ) ) {
+    CORE_mutex_Control *mutex = &the_semaphore->Core_control.mutex;
+
+    old_priority = mutex->Attributes.priority_ceiling;
+
+    if ( new_priority != RTEMS_CURRENT_PRIORITY ) {
+      mutex->Attributes.priority_ceiling = new_priority;
+    }
+
+    sc = RTEMS_SUCCESSFUL;
+  } else {
+    old_priority = 0;
+
+    sc = RTEMS_NOT_DEFINED;
+  }
+
+  *old_priority_p = _RTEMS_tasks_Priority_from_Core( old_priority );
+
+  _Objects_Put( &the_semaphore->Object );
+
+  return sc;
+}
+
+rtems_status_code rtems_semaphore_set_priority(
+  rtems_id             semaphore_id,
+  rtems_id             scheduler_id,
+  rtems_task_priority  new_priority,
+  rtems_task_priority *old_priority
+)
+{
+  Semaphore_Control *the_semaphore;
+  Objects_Locations  location;
+
+  if ( new_priority != RTEMS_CURRENT_PRIORITY &&
+       !_RTEMS_tasks_Priority_is_valid( new_priority ) ) {
+    return RTEMS_INVALID_PRIORITY;
+  }
+
+  if ( old_priority == NULL ) {
+    return RTEMS_INVALID_ADDRESS;
+  }
+
+  if ( !_Scheduler_Is_id_valid( scheduler_id ) ) {
+    return RTEMS_INVALID_ID;
+  }
+
+  the_semaphore = _Semaphore_Get( semaphore_id, &location );
+  switch ( location ) {
+    case OBJECTS_LOCAL:
+      return _Semaphore_Set_priority(
+        the_semaphore,
+        scheduler_id,
+        new_priority,
+        old_priority
+      );
+#if defined(RTEMS_MULTIPROCESSING)
+    case OBJECTS_REMOTE:
+      _Thread_Dispatch();
+      return RTEMS_ILLEGAL_ON_REMOTE_OBJECT;
+#endif
+    case OBJECTS_ERROR:
+      break;
+  }
+
+  return RTEMS_INVALID_ID;
+}