From 323940278e0c94d18b3824764236162e2b0dcfcf Mon Sep 17 00:00:00 2001
From: jljusten <jljusten@6f19259b-4bc3-4df7-8a09-765794883524>
Date: Thu, 16 Jun 2011 23:28:16 +0000
Subject: [PATCH] UefiCpuPkg/CpuDxe: Put CPU to sleep during Idle events

When the MdeModulePkg gCoreEventIdleGuid event is signaled,
CpuSleep is called.  This will cause the CPU to sleep until
the next interrupt occurs.

Signed-off-by: jljusten
Reviewed-by: mdkinney
Reviewed-by: rsun3

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@11842 6f19259b-4bc3-4df7-8a09-765794883524
---
 UefiCpuPkg/CpuDxe/CpuDxe.c   | 33 +++++++++++++++++++++++++++++++++
 UefiCpuPkg/CpuDxe/CpuDxe.h   |  3 ++-
 UefiCpuPkg/CpuDxe/CpuDxe.inf |  6 +++++-
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/UefiCpuPkg/CpuDxe/CpuDxe.c b/UefiCpuPkg/CpuDxe/CpuDxe.c
index 04d76a5ceb..ad4599dab9 100644
--- a/UefiCpuPkg/CpuDxe/CpuDxe.c
+++ b/UefiCpuPkg/CpuDxe/CpuDxe.c
@@ -1154,6 +1154,25 @@ InitInterruptDescriptorTable (
 }
 
 
+/**
+  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 ();
+}
+
+
 /**
   Initialize the state information for the CPU Architectural Protocol.
 
@@ -1173,6 +1192,7 @@ InitializeCpu (
   )
 {
   EFI_STATUS  Status;
+  EFI_EVENT   IdleLoopEvent;
 
   //
   // Make sure interrupts are disabled
@@ -1204,6 +1224,19 @@ InitializeCpu (
   //
   RefreshGcdMemoryAttributes ();
 
+  //
+  // Setup a callback for idle events
+  //
+  Status = gBS->CreateEventEx (
+                  EVT_NOTIFY_SIGNAL,
+                  TPL_NOTIFY,
+                  IdleLoopEventCallback,
+                  NULL,
+                  &gIdleLoopEventGuid,
+                  &IdleLoopEvent
+                  );
+  ASSERT_EFI_ERROR (Status);
+
   return Status;
 }
 
diff --git a/UefiCpuPkg/CpuDxe/CpuDxe.h b/UefiCpuPkg/CpuDxe/CpuDxe.h
index d42f82e0bd..e36cf1c82c 100644
--- a/UefiCpuPkg/CpuDxe/CpuDxe.h
+++ b/UefiCpuPkg/CpuDxe/CpuDxe.h
@@ -1,7 +1,7 @@
 /** @file
   CPU DXE Module.
 
-  Copyright (c) 2008 - 2010, Intel Corporation. All rights reserved.<BR>
+  Copyright (c) 2008 - 2011, Intel Corporation. All rights reserved.<BR>
   This program and the accompanying materials
   are licensed and made available under the terms and conditions of the BSD License
   which accompanies this distribution.  The full text of the license may be found at
@@ -28,6 +28,7 @@
 #include <Library/MemoryAllocationLib.h>
 #include <Library/DebugLib.h>
 #include <Library/MtrrLib.h>
+#include <Guid/IdleLoopEvent.h>
 
 //
 //
diff --git a/UefiCpuPkg/CpuDxe/CpuDxe.inf b/UefiCpuPkg/CpuDxe/CpuDxe.inf
index 7790d3505d..0c70b3276d 100644
--- a/UefiCpuPkg/CpuDxe/CpuDxe.inf
+++ b/UefiCpuPkg/CpuDxe/CpuDxe.inf
@@ -2,7 +2,7 @@
 #
 #    Component description file for simple CPU driver
 #
-#  Copyright (c) 2008 - 2010, Intel Corporation. All rights reserved.<BR>
+#  Copyright (c) 2008 - 2011, Intel Corporation. All rights reserved.<BR>
 #  This program and the accompanying materials
 #  are licensed and made available under the terms and conditions of the BSD License
 #  which accompanies this distribution.  The full text of the license may be found at
@@ -24,6 +24,7 @@
 
 [Packages]
   MdePkg/MdePkg.dec
+  MdeModulePkg/MdeModulePkg.dec
   UefiCpuPkg/UefiCpuPkg.dec
 
 [LibraryClasses]
@@ -59,6 +60,9 @@
 [Protocols]
   gEfiCpuArchProtocolGuid
 
+[Guids]
+  gIdleLoopEventGuid                            ## CONSUMES ## GUID
+
 [Depex]
   TRUE