ArmPkg/CpuDxe: Register a callback for the gIdleLoopEventGuid event

This gIdleLoopEventGuid event signals the Cpu that it should go into
the idle state waiting for any events.
CpuSleep() is used in this implementation to make the Cpu wait for
the next interrupt (WFI instruction).



git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11863 6f19259b-4bc3-4df7-8a09-765794883524

ArmPkg/Drivers/CpuDxe/CpuDxe.c

@@ -1,6 +1,7 @@
 /** @file
 
   Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
+  Copyright (c) 2011, ARM Limited. All rights reserved.
   
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
@@ -14,6 +15,8 @@
 
 #include "CpuDxe.h"
 
+#include <Guid/IdleLoopEvent.h>
+
 BOOLEAN mInterruptState   = FALSE;
 
 
@@ -194,6 +197,23 @@ CpuGetTimerValue (
   return EFI_UNSUPPORTED;
 }
 
+/**
+  Callback function for idle events.
+ 
+  @param  Event                 Event whose notification function is being invoked.
+  @param  Context               The pointer to the notification function's context,
+                                which is implementation-dependent.
+
+**/
+VOID
+EFIAPI
+IdleLoopEventCallback (
+  IN EFI_EVENT                Event,
+  IN VOID                     *Context
+  )
+{
+  CpuSleep ();
+}
 
 //
 // Globals used to initialize the protocol
@@ -219,10 +239,10 @@ CpuDxeInitialize (
   )
 {
   EFI_STATUS  Status;
+  EFI_EVENT    IdleLoopEvent;
 
   InitializeExceptions (&mCpu);  
   
-  
   Status = gBS->InstallMultipleProtocolInterfaces (
                 &mCpuHandle, 
                 &gEfiCpuArchProtocolGuid,           &mCpu, 
@@ -237,6 +257,18 @@ CpuDxeInitialize (
   //
   SyncCacheConfig (&mCpu);
   
+  //
+  // Setup a callback for idle events
+  //
+  Status = gBS->CreateEventEx (
+                  EVT_NOTIFY_SIGNAL,
+                  TPL_NOTIFY,
+                  IdleLoopEventCallback,
+                  NULL,
+                  &gIdleLoopEventGuid,
+                  &IdleLoopEvent
+                  );
+  ASSERT_EFI_ERROR (Status);
+
   return Status;
 }
-