EmbeddedPkg: add base DtPlatformDtbLoaderLib implementation

Introduce an implementation of the new DtPlatformDtbLoaderLib library
class that simply retrieves the first raw section of an FV file named
'gDtPlatformDefaultDtbFileGuid'.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

EmbeddedPkg/EmbeddedPkg.dsc

@@ -109,6 +109,9 @@
   HiiLib|MdeModulePkg/Library/UefiHiiLib/UefiHiiLib.inf
   UefiHiiServicesLib|MdeModulePkg/Library/UefiHiiServicesLib/UefiHiiServicesLib.inf
 
+  DxeServicesLib|MdePkg/Library/DxeServicesLib/DxeServicesLib.inf
+  DtPlatformDtbLoaderLib|EmbeddedPkg/Library/DxeDtPlatformDtbLoaderLibDefault/DxeDtPlatformDtbLoaderLibDefault.inf
+
 [LibraryClasses.common.DXE_DRIVER]
   PcdLib|MdePkg/Library/DxePcdLib/DxePcdLib.inf
   ReportStatusCodeLib|IntelFrameworkModulePkg/Library/DxeReportStatusCodeLibFramework/DxeReportStatusCodeLib.inf
@@ -247,6 +250,7 @@
   EmbeddedPkg/Library/TemplateRealTimeClockLib/TemplateRealTimeClockLib.inf
   EmbeddedPkg/Library/LzmaHobCustomDecompressLib/LzmaHobCustomDecompressLib.inf
   EmbeddedPkg/Library/NullDmaLib/NullDmaLib.inf
+  EmbeddedPkg/Library/DxeDtPlatformDtbLoaderLibDefault/DxeDtPlatformDtbLoaderLibDefault.inf
 
   EmbeddedPkg/Ebl/Ebl.inf
 ####  EmbeddedPkg/EblExternCmd/EblExternCmd.inf

EmbeddedPkg/Library/DxeDtPlatformDtbLoaderLibDefault/DxeDtPlatformDtbLoaderLibDefault.c

@@ -0,0 +1,60 @@
+/** @file
+*
+*  Copyright (c) 2017, Linaro, Ltd. 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/BaseLib.h>
+#include <Library/DxeServicesLib.h>
+#include <Library/MemoryAllocationLib.h>
+
+/**
+  Return a pool allocated copy of the DTB image that is appropriate for
+  booting the current platform via DT.
+
+  @param[out]   Dtb                   Pointer to the DTB copy
+  @param[out]   DtbSize               Size of the DTB copy
+
+  @retval       EFI_SUCCESS           Operation completed successfully
+  @retval       EFI_NOT_FOUND         No suitable DTB image could be located
+  @retval       EFI_OUT_OF_RESOURCES  No pool memory available
+
+**/
+EFI_STATUS
+EFIAPI
+DtPlatformLoadDtb (
+  OUT   VOID        **Dtb,
+  OUT   UINTN       *DtbSize
+  )
+{
+  EFI_STATUS      Status;
+  VOID            *OrigDtb;
+  VOID            *CopyDtb;
+  UINTN           OrigDtbSize;
+
+  Status = GetSectionFromAnyFv (&gDtPlatformDefaultDtbFileGuid,
+             EFI_SECTION_RAW, 0, &OrigDtb, &OrigDtbSize);
+  if (EFI_ERROR (Status)) {
+    return EFI_NOT_FOUND;
+  }
+
+  CopyDtb = AllocateCopyPool (OrigDtbSize, OrigDtb);
+  if (CopyDtb == NULL) {
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  *Dtb = CopyDtb;
+  *DtbSize = OrigDtbSize;
+
+  return EFI_SUCCESS;
+}

EmbeddedPkg/Library/DxeDtPlatformDtbLoaderLibDefault/DxeDtPlatformDtbLoaderLibDefault.inf

@@ -0,0 +1,36 @@
+/** @file
+*
+*  Copyright (c) 2017, Linaro, Ltd. 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.
+*
+**/
+
+[Defines]
+  INF_VERSION                    = 0x00010019
+  BASE_NAME                      = DxeDtPlatformDtbLoaderLibDefault
+  FILE_GUID                      = 419a1910-70da-4c99-8696-ba81a57be508
+  MODULE_TYPE                    = DXE_DRIVER
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = DtPlatformDtbLoaderLib|DXE_DRIVER
+
+[Sources]
+  DxeDtPlatformDtbLoaderLibDefault.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  EmbeddedPkg/EmbeddedPkg.dec
+
+[LibraryClasses]
+  BaseLib
+  DxeServicesLib
+  MemoryAllocationLib
+
+[Guids]
+  gDtPlatformDefaultDtbFileGuid