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, 46 insertions, 0 deletions

diff --git a/cpukit/rtems/include/rtems/rtems/sem.h b/cpukit/rtems/include/rtems/rtems/sem.h
index 782314d163..2442010113 100644
--- a/cpukit/rtems/include/rtems/rtems/sem.h
+++ b/cpukit/rtems/include/rtems/rtems/sem.h
@@ -38,6 +38,7 @@
 #include <rtems/score/coremutex.h>
 #include <rtems/score/object.h>
 #include <rtems/score/coresem.h>
+#include <rtems/score/mrsp.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -88,6 +89,10 @@ typedef struct {
      *  API Semaphore instance.
      */
     CORE_semaphore_Control semaphore;
+
+#if defined(RTEMS_SMP)
+    MRSP_Control mrsp;
+#endif
   } Core_control;
 }   Semaphore_Control;
 
@@ -208,6 +213,47 @@ rtems_status_code rtems_semaphore_flush(
   rtems_id	   id
 );
 
+/**
+ * @brief Sets the priority value with respect to the specified scheduler of a
+ * semaphore.
+ *
+ * The special priority value @ref RTEMS_CURRENT_PRIORITY can be used to get
+ * the current priority value without changing it.
+ *
+ * The interpretation of the priority value depends on the protocol of the
+ * semaphore object.
+ *
+ * - The Multiprocessor Resource Sharing Protocol needs a ceiling priority per
+ *   scheduler instance.  This operation can be used to specify these priority
+ *   values.
+ * - For the Priority Ceiling Protocol the ceiling priority is used with this
+ *   operation.
+ * - For other protocols this operation is not defined.
+ *
+ * @param[in] semaphore_id Identifier of the semaphore.
+ * @param[in] scheduler_id Identifier of the scheduler.
+ * @param[in] new_priority The new priority value.  Use
+ * @ref RTEMS_CURRENT_PRIORITY to not set a new priority and only get the
+ * current priority.
+ * @param[out] old_priority Reference to store the old priority value.
+ *
+ * @retval RTEMS_SUCCESSFUL Successful operation.
+ * @retval RTEMS_INVALID_ID Invalid semaphore or scheduler identifier.
+ * @retval RTEMS_INVALID_ADDRESS The old priority reference is @c NULL.
+ * @retval RTEMS_INVALID_PRIORITY The new priority value is invalid.
+ * @retval RTEMS_NOT_DEFINED The set priority operation is not defined for the
+ * protocol of this semaphore object.
+ * @retval RTEMS_ILLEGAL_ON_REMOTE_OBJECT Not supported for remote semaphores.
+ *
+ * @see rtems_scheduler_ident() and rtems_task_set_priority().
+ */
+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
+);
+
 /**@}*/
 
 #ifdef __cplusplus