[PATCH 1/6] EmbeddedPkg/DtPlatformDxe: allow multiple entries in DTB FV file

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

To allow some dynamic behavior in selecting the DTB to expose to the
OS, allow the DTB FV file to contain multiple sections, and indirect
the choice of section via a fixed/dynamic PCD, which defaults to 0.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 EmbeddedPkg/Drivers/DtPlatformDxe/DtPlatformDxe.c   | 5 ++++-
 EmbeddedPkg/Drivers/DtPlatformDxe/DtPlatformDxe.inf | 4 ++++
 EmbeddedPkg/EmbeddedPkg.dec                         | 3 +++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/EmbeddedPkg/Drivers/DtPlatformDxe/DtPlatformDxe.c b/EmbeddedPkg/Drivers/DtPlatformDxe/DtPlatformDxe.c
index 5778633b4985..72f9f5721cda 100644
--- a/EmbeddedPkg/Drivers/DtPlatformDxe/DtPlatformDxe.c
+++ b/EmbeddedPkg/Drivers/DtPlatformDxe/DtPlatformDxe.c
@@ -17,6 +17,7 @@
 #include <Library/DevicePathLib.h>
 #include <Library/DxeServicesLib.h>
 #include <Library/HiiLib.h>
+#include <Library/PcdLib.h>
 #include <Library/MemoryAllocationLib.h>
 #include <Library/UefiBootServicesTableLib.h>
 #include <Library/UefiDriverEntryPoint.h>
@@ -121,7 +122,9 @@ DtPlatformDxeEntryPoint (
   //
   Dtb = NULL;
   Status = GetSectionFromAnyFv (&gDtPlatformDefaultDtbFileGuid,
-             EFI_SECTION_RAW, 0, &Dtb, &DtbSize);
+             EFI_SECTION_RAW,
+             PcdGet8 (PcdDtPlatformDefaultDtbSectionIndex),
+             &Dtb, &DtbSize);
   if (EFI_ERROR (Status)) {
     DEBUG ((DEBUG_WARN, "%a: no DTB blob found, defaulting to ACPI\n",
       __FUNCTION__));
diff --git a/EmbeddedPkg/Drivers/DtPlatformDxe/DtPlatformDxe.inf b/EmbeddedPkg/Drivers/DtPlatformDxe/DtPlatformDxe.inf
index b73877a6086b..c16202790ed9 100644
--- a/EmbeddedPkg/Drivers/DtPlatformDxe/DtPlatformDxe.inf
+++ b/EmbeddedPkg/Drivers/DtPlatformDxe/DtPlatformDxe.inf
@@ -43,6 +43,7 @@ [LibraryClasses]
   DxeServicesLib
   HiiLib
   MemoryAllocationLib
+  PcdLib
   UefiBootServicesTableLib
   UefiDriverEntryPoint
   UefiRuntimeServicesTableLib
@@ -56,3 +57,6 @@ [Guids]
 [Depex]
   gEfiVariableArchProtocolGuid        AND
   gEfiVariableWriteArchProtocolGuid
+
+[Pcd]
+  gEmbeddedTokenSpaceGuid.PcdDtPlatformDefaultDtbSectionIndex
diff --git a/EmbeddedPkg/EmbeddedPkg.dec b/EmbeddedPkg/EmbeddedPkg.dec
index 871fc5ff4016..f1b7af347861 100644
--- a/EmbeddedPkg/EmbeddedPkg.dec
+++ b/EmbeddedPkg/EmbeddedPkg.dec
@@ -198,3 +198,6 @@ [PcdsFixedAtBuild.X64]
 
 [PcdsFixedAtBuild.common, PcdsDynamic.common]
   gEmbeddedTokenSpaceGuid.PcdFdtDevicePaths|L""|VOID*|0x00000055
+
+  # the section containing the default DTB for the current platform
+  gEmbeddedTokenSpaceGuid.PcdDtPlatformDefaultDtbSectionIndex|0|UINT8|0x00000057
-- 
2.9.3