smp: Simplify SMP initialization sequence

Delete bsp_smp_wait_for().  Other parts of the system work without
timeout, e.g. the spinlocks.  Using a timeout here does not make the
system more robust.

Delete bsp_smp_cpu_state and replace it with Per_CPU_State.  The
Per_CPU_State follows the Score naming conventions.  Add
_Per_CPU_Change_state() and _Per_CPU_Wait_for_state() functions to
change and observe states.

Use Per_CPU_State in Per_CPU_Control instead of the anonymous integer.

Add _CPU_Processor_event_broadcast() and _CPU_Processor_event_receive()
functions provided by the CPU port.  Use these functions in
_Per_CPU_Change_state() and _Per_CPU_Wait_for_state().

Add prototype for _SMP_Send_message().

Delete RTEMS_BSP_SMP_FIRST_TASK message.  The first context switch is
now performed in rtems_smp_secondary_cpu_initialize().  Issuing the
first context switch in the context of the inter-processor interrupt is
not possible on systems with a modern interrupt controller.  Such an
interrupt controler usually requires a handshake protocol with interrupt
acknowledge and end of interrupt signals.  A direct context switch in an
interrupt handler circumvents the interrupt processing epilogue and may
leave the system in an inconsistent state.

Release lock in rtems_smp_process_interrupt() even if no message was
delivered.  This prevents deadlock of the system.

Simplify and format _SMP_Send_message(),
_SMP_Request_other_cores_to_perform_first_context_switch(),
_SMP_Request_other_cores_to_dispatch() and
_SMP_Request_other_cores_to_shutdown().

1 files changed, 10 insertions, 7 deletions

diff --git a/cpukit/score/include/rtems/score/smp.h b/cpukit/score/include/rtems/score/smp.h
index f4bf72edd9..c7de6d64a9 100644
--- a/cpukit/score/include/rtems/score/smp.h
+++ b/cpukit/score/include/rtems/score/smp.h
@@ -58,13 +58,6 @@ extern "C" {
  */
 #define RTEMS_BSP_SMP_SHUTDOWN                  0x04
 
-/**
- *  This defines the bit which indicates the interprocessor interrupt
- *  has been requested that the receiving CPU needs to perform a context
- *  switch to the first task.
- */
-#define RTEMS_BSP_SMP_FIRST_TASK                0x08
-
 #ifndef ASM
 /**
  *  @brief Number of CPUs in a SMP system.
@@ -75,6 +68,16 @@ extern "C" {
 SCORE_EXTERN uint32_t _SMP_Processor_count;
 
 /**
+ *  @brief Sends a SMP message to a processor.
+ *
+ *  The target processor may be the sending processor.
+ *
+ *  @param[in] cpu The target processor of the message.
+ *  @param[in] message The message.
+ */
+void _SMP_Send_message( int cpu, uint32_t message );
+
+/**
  *  @brief Request of others CPUs.
  *
  *  This method is invoked by RTEMS when it needs to make a request