ArmPlatformPkg: Introduce ArmPlatformGlobalVariableLib

This library hides where the 'XIP' Global Variable are located in the memory.
It is expected the Sec/PrePi modules define the Global Variable area through
the GlobalVariable HOB.

The ArmPlatformGlobalVariableLib library allows access to global variables by
their offsets in this region.




git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12420 6f19259b-4bc3-4df7-8a09-765794883524

ArmPlatformPkg/Library/ArmPlatformGlobalVariableLib/Dxe/DxeArmPlatformGlobalVariableLib.c

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+/** @file
+*
+*  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
+*  which accompanies this distribution.  The full text of the license may be found at
+*  http://opensource.org/licenses/bsd-license.php
+*
+*  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+*  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+*
+**/
+
+#include <PiDxe.h>
+#include <Library/ArmPlatformGlobalVariableLib.h>
+#include <Library/BaseMemoryLib.h>
+#include <Library/DebugLib.h>
+#include <Library/HobLib.h>
+#include <Library/PcdLib.h>
+
+#include <Guid/ArmGlobalVariableHob.h>
+
+UINTN  mGlobalVariableBase = 0;
+
+RETURN_STATUS
+EFIAPI
+ArmPlatformGlobalVariableConstructor (
+  VOID
+  )
+{
+  ARM_HOB_GLOBAL_VARIABLE  *Hob;
+
+  Hob = GetFirstGuidHob (&gArmGlobalVariableGuid);
+  ASSERT (Hob != NULL);
+
+  mGlobalVariableBase = Hob->GlobalVariableBase;
+
+  return EFI_SUCCESS;
+}
+
+VOID
+ArmPlatformGetGlobalVariable (
+  IN  UINTN     VariableOffset,
+  IN  UINTN     VariableSize,
+  OUT VOID*     Variable
+  )
+{
+  if (mGlobalVariableBase == 0) {
+    ArmPlatformGlobalVariableConstructor ();
+  }
+
+  CopyMem (Variable, (VOID*)(mGlobalVariableBase + VariableOffset), VariableSize);
+}
+
+VOID
+ArmPlatformSetGlobalVariable (
+  IN  UINTN     VariableOffset,
+  IN  UINTN     VariableSize,
+  OUT VOID*     Variable
+  )
+{
+  if (mGlobalVariableBase == 0) {
+    ArmPlatformGlobalVariableConstructor ();
+  }
+
+  CopyMem ((VOID*)(mGlobalVariableBase + VariableOffset), Variable, VariableSize);
+}
+