[edk2-platforms: PATCH v2 2/2] Platforms/RPi3: Add multiple embedded Device Tree selection

["Pete Batard" <pete@akeo.ie>]

The Raspberry Pi 3 platform currently has 2 different models, each with a
different Device Tree. Rather than embedding a single one, and requiring
users to manually provide the other, this patch ensures that we now embed
both and and serve the relevant one at runtime.

This patch also adds support for the Raspberry Pi 4 in FdtDxe.

Signed-off-by: Pete Batard <pete@akeo.ie>
---
 Platform/RaspberryPi/RPi3/Drivers/FdtDxe/FdtDxe.c   | 56 +++++++++++++++++---
 Platform/RaspberryPi/RPi3/Drivers/FdtDxe/FdtDxe.inf |  5 +-
 Platform/RaspberryPi/RPi3/RPi3.dec                  |  8 ++-
 Platform/RaspberryPi/RPi3/RPi3.fdf                  |  6 ++-
 4 files changed, 66 insertions(+), 9 deletions(-)

diff --git a/Platform/RaspberryPi/RPi3/Drivers/FdtDxe/FdtDxe.c b/Platform/RaspberryPi/RPi3/Drivers/FdtDxe/FdtDxe.c
index da99ef9535c8..45ffe2e394a2 100644
--- a/Platform/RaspberryPi/RPi3/Drivers/FdtDxe/FdtDxe.c
+++ b/Platform/RaspberryPi/RPi3/Drivers/FdtDxe/FdtDxe.c
@@ -366,9 +366,11 @@ FdtDxeInitialize (
   )
 {
   EFI_STATUS Status;
+  EFI_GUID   *FdtGuid;
   VOID       *FdtImage;
   UINTN      FdtSize;
   INT32      Retval;
+  UINT32     BoardRevision;
   BOOLEAN    Internal;
 
   Status = gBS->LocateProtocol (&gRaspberryPiFirmwareProtocolGuid, NULL,
@@ -386,16 +388,58 @@ FdtDxeInitialize (
     DEBUG ((DEBUG_INFO, "Device Tree passed via config.txt (0x%lx bytes)\n", FdtSize));
     Status = EFI_SUCCESS;
   } else {
+    /*
+     * Use one of the embedded FDT's.
+     */
     Internal = TRUE;
     DEBUG ((DEBUG_INFO, "No/Bad Device Tree found at address 0x%p (%a), "
-      "trying internal one...\n", FdtImage, fdt_strerror (Retval)));
-    Status = GetSectionFromAnyFv (&gRaspberryPiFdtFileGuid, EFI_SECTION_RAW, 0,
-               &FdtImage, &FdtSize);
-    if (Status == EFI_SUCCESS) {
-      if (fdt_check_header (FdtImage) != 0) {
-        Status = EFI_INCOMPATIBLE_VERSION;
+      "looking up internal one...\n", FdtImage, fdt_strerror (Retval)));
+    /*
+     * Query the board revision to differentiate between models.
+     */
+    Status = mFwProtocol->GetModelRevision (&BoardRevision);
+    if (EFI_ERROR (Status)) {
+      DEBUG ((DEBUG_ERROR, "Failed to get board type: %r\n", Status));
+      DEBUG ((DEBUG_INFO, "Using default internal Device Tree\n"));
+      FdtGuid = &gRaspberryPiDefaultFdtGuid;
+    } else {
+      // www.raspberrypi.org/documentation/hardware/raspberrypi/revision-codes/README.md
+      switch ((BoardRevision >> 4) & 0xFF) {
+      case 0x08:
+        DEBUG ((DEBUG_INFO, "Using Raspberry Pi 3 Model B internal Device Tree\n"));
+        FdtGuid = &gRaspberryPi3ModelBFdtGuid;
+        break;
+      case 0x0D:
+        DEBUG ((DEBUG_INFO, "Using Raspberry Pi 3 Model B+ internal Device Tree\n"));
+        FdtGuid = &gRaspberryPi3ModelBPlusFdtGuid;
+        break;
+      case 0x11:
+        DEBUG ((DEBUG_INFO, "Using Raspberry Pi 4 Model B internal Device Tree\n"));
+        FdtGuid = &gRaspberryPi4ModelBFdtGuid;
+        break;
+      default:
+        DEBUG ((DEBUG_INFO, "Using default internal Device Tree\n"));
+        FdtGuid = &gRaspberryPiDefaultFdtGuid;
+        break;
       }
     }
+    do {
+      Status = GetSectionFromAnyFv (FdtGuid, EFI_SECTION_RAW, 0, &FdtImage, &FdtSize);
+      if (Status == EFI_SUCCESS) {
+        if (fdt_check_header (FdtImage) != 0) {
+          Status = EFI_INCOMPATIBLE_VERSION;
+        }
+      }
+      // No retry needed if we are successful or are dealing with the default Fdt.
+      if ( (Status == EFI_SUCCESS) ||
+           (CompareGuid (FdtGuid, &gRaspberryPiDefaultFdtGuid)) )
+        break;
+      // Otherwise, try one more time with the default Fdt. An example of this
+      // is if we detected a non-default Fdt, that isn't included in the FDF.
+      DEBUG ((DEBUG_INFO, "Internal Device Tree was not found for this platform, "
+        "falling back to default...\n"));
+      FdtGuid = &gRaspberryPiDefaultFdtGuid;
+    } while (1);
   }
 
   if (EFI_ERROR (Status)) {
diff --git a/Platform/RaspberryPi/RPi3/Drivers/FdtDxe/FdtDxe.inf b/Platform/RaspberryPi/RPi3/Drivers/FdtDxe/FdtDxe.inf
index 5b0b1a09f374..570b05b62564 100644
--- a/Platform/RaspberryPi/RPi3/Drivers/FdtDxe/FdtDxe.inf
+++ b/Platform/RaspberryPi/RPi3/Drivers/FdtDxe/FdtDxe.inf
@@ -35,7 +35,10 @@ [LibraryClasses]
 
 [Guids]
   gFdtTableGuid
-  gRaspberryPiFdtFileGuid
+  gRaspberryPi3ModelBFdtGuid
+  gRaspberryPi3ModelBPlusFdtGuid
+  gRaspberryPi4ModelBFdtGuid
+  gRaspberryPiDefaultFdtGuid
 
 [Protocols]
   gRaspberryPiFirmwareProtocolGuid              ## CONSUMES
diff --git a/Platform/RaspberryPi/RPi3/RPi3.dec b/Platform/RaspberryPi/RPi3/RPi3.dec
index 22de439fde8f..d2a813417648 100644
--- a/Platform/RaspberryPi/RPi3/RPi3.dec
+++ b/Platform/RaspberryPi/RPi3/RPi3.dec
@@ -24,9 +24,15 @@ [Protocols]
 
 [Guids]
   gRaspberryPiTokenSpaceGuid = {0xCD7CC258, 0x31DB, 0x11E6, {0x9F, 0xD3, 0x63, 0xB0, 0xB8, 0xEE, 0xD6, 0xB5}}
-  gRaspberryPiFdtFileGuid = {0xDF5DA223, 0x1D27, 0x47C3, { 0x8D, 0x1B, 0x9A, 0x41, 0xB5, 0x5A, 0x18, 0xBC}}
   gRaspberryPiEventResetGuid = {0xCD7CC258, 0x31DB, 0x11E6, {0x9F, 0xD3, 0x63, 0xB4, 0xB4, 0xE4, 0xD4, 0xB4}}
   gConfigDxeFormSetGuid = {0xCD7CC258, 0x31DB, 0x22E6, {0x9F, 0x22, 0x63, 0xB0, 0xB8, 0xEE, 0xD6, 0xB5}}
+  # GUIDs used by FdtDxe to serve a Device Tree at runtime. Not all of these need to apply
+  # to the current platform or match an actual FDF binary, but they need to be defined.
+  gRaspberryPi3ModelBFdtGuid = { 0xDF5DA223, 0x1D27, 0x47C3, { 0x8D, 0x1B, 0x9A, 0x41, 0xB5, 0x5A, 0x18, 0xBC } }
+  gRaspberryPi3ModelBPlusFdtGuid = { 0x3D523012, 0x73FE, 0x40E5, { 0x89, 0x2E, 0x1A, 0x4D, 0xF6, 0x0F, 0x3C, 0x0C } }
+  gRaspberryPi4ModelBFdtGuid = { 0x80AB6833, 0xCAE4, 0x4CEE, { 0xB5, 0x9D, 0xEB, 0x20, 0x39, 0xB0, 0x55, 0x51 } }
+  # Default Fdt to serve if the hardware model can't be detected. Should match one of the above.
+  gRaspberryPiDefaultFdtGuid = {0xDF5DA223, 0x1D27, 0x47C3, { 0x8D, 0x1B, 0x9A, 0x41, 0xB5, 0x5A, 0x18, 0xBC}}
 
 [PcdsFixedAtBuild.common]
   gRaspberryPiTokenSpaceGuid.PcdFdtBaseAddress|0x10000|UINT32|0x00000001
diff --git a/Platform/RaspberryPi/RPi3/RPi3.fdf b/Platform/RaspberryPi/RPi3/RPi3.fdf
index c62d649834c7..17c0094ac1cf 100644
--- a/Platform/RaspberryPi/RPi3/RPi3.fdf
+++ b/Platform/RaspberryPi/RPi3/RPi3.fdf
@@ -300,11 +300,15 @@ [FV.FvMain]
   INF Platform/RaspberryPi/$(PLATFORM_NAME)/Drivers/LogoDxe/LogoDxe.inf
 
   #
-  # FDT (GUID matches gRaspberryPiFdtFileGuid in FdtDxe)
+  # Device Tree support (used by FdtDxe)
+  # GUIDs should match gRaspberryPi#####FdtGuid's from the .dec
   #
   FILE FREEFORM = DF5DA223-1D27-47C3-8D1B-9A41B55A18BC {
     SECTION RAW = Platform/RaspberryPi/$(PLATFORM_NAME)/DeviceTree/bcm2710-rpi-3-b.dtb
   }
+  FILE FREEFORM = 3D523012-73FE-40E5-892E-1A4DF60F3C0C {
+    SECTION RAW = Platform/RaspberryPi/$(PLATFORM_NAME)/DeviceTree/bcm2710-rpi-3-b-plus.dtb
+  }
 
 [FV.FVMAIN_COMPACT]
 FvAlignment        = 16
-- 
2.21.0.windows.1