[edk2-devel][PATCH 4/5] Platform/RPi: Make Device Tree provision a runtime (BIOS setup) choice

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

With this and the previous commit, ACPI_BASIC_MODE_ENABLE becomes
superfluous so remove it.

New option defaults to enabled on Pi 3, disabled on Pi 4.

Signed-off-by: Pete Batard <pete@akeo.ie>
---
 Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c      |  8 ++++++++
 Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf    |  1 +
 Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.uni |  5 +++++
 Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.vfr | 21 ++++++++++++++++++++
 Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.c            |  5 +++++
 Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.inf          |  3 +++
 Platform/RaspberryPi/RPi3/RPi3.dsc                      |  5 +++++
 Platform/RaspberryPi/RPi4/RPi4.dsc                      | 10 +++++-----
 Platform/RaspberryPi/RPi4/RPi4.fdf                      |  2 --
 Platform/RaspberryPi/RPi4/Readme.md                     | 15 ++++++--------
 Platform/RaspberryPi/RaspberryPi.dec                    |  4 +---
 11 files changed, 60 insertions(+), 19 deletions(-)

diff --git a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c
index 451a419a5358..31a62094e33e 100644
--- a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c
+++ b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.c
@@ -151,6 +151,14 @@ SetupVariables (
     PcdSet32 (PcdRamLimitTo3GB, 0);
   }
 
+  Size = sizeof (UINT32);
+  Status = gRT->GetVariable (L"OptDeviceTree",
+                  &gConfigDxeFormSetGuid,
+                  NULL, &Size, &Var32);
+  if (EFI_ERROR (Status)) {
+    PcdSet32 (PcdOptDeviceTree, PcdGet32 (PcdOptDeviceTree));
+  }
+
   Size = sizeof (UINT32);
   Status = gRT->GetVariable (L"SdIsArasan",
                   &gConfigDxeFormSetGuid,
diff --git a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf
index 407aac89c7b3..736d49df562b 100644
--- a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf
+++ b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf
@@ -72,6 +72,7 @@ [Pcd]
   gRaspberryPiTokenSpaceGuid.PcdDebugShowUEFIExit
   gRaspberryPiTokenSpaceGuid.PcdDisplayEnableScaledVModes
   gRaspberryPiTokenSpaceGuid.PcdDisplayEnableSShot
+  gRaspberryPiTokenSpaceGuid.PcdOptDeviceTree
   gRaspberryPiTokenSpaceGuid.PcdRamMoreThan3GB
   gRaspberryPiTokenSpaceGuid.PcdRamLimitTo3GB
 
diff --git a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.uni b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.uni
index 830533a9dc49..2e79e322e558 100644
--- a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.uni
+++ b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.uni
@@ -46,6 +46,11 @@
 #string STR_ADVANCED_3GB_OFF         #language en-US "Disabled"
 #string STR_ADVANCED_3GB_ON          #language en-US "Enabled"
 
+#string STR_ADVANCED_DT_PROMPT       #language en-US "Device Tree"
+#string STR_ADVANCED_DT_HELP         #language en-US "Disable this option to force OSes such as GNU/Linux to use ACPI"
+#string STR_ADVANCED_DT_OFF          #language en-US "Disabled (Force ACPI)"
+#string STR_ADVANCED_DT_ON           #language en-US "Enabled"
+
 /*
  * MMC/SD configuration.
  */
diff --git a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.vfr b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.vfr
index 483edd7459c5..d16058da4926 100644
--- a/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.vfr
+++ b/Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxeHii.vfr
@@ -85,6 +85,14 @@ typedef struct {
   UINT32 Enabled;
 } ADVANCED_RAM_LIMIT_TO_3GB_VARSTORE_DATA;
 
+typedef struct {
+  /*
+   * 0 - Do not provide a Device Tree to the OS
+   * 1 - Provide a Device Tree to the OS
+   */
+  UINT32 Enabled;
+} ADVANCED_DEVICE_TREE_VARSTORE_DATA;
+
 typedef struct {
   /*
    * 0 - Don't disable multi-block.
@@ -162,6 +170,11 @@ formset
       name  = RamLimitTo3GB,
       guid  = CONFIGDXE_FORM_SET_GUID;
 
+    efivarstore ADVANCED_DEVICE_TREE_VARSTORE_DATA,
+      attribute = EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,
+      name  = OptDeviceTree,
+      guid  = CONFIGDXE_FORM_SET_GUID;
+
     efivarstore MMC_DISMULTI_VARSTORE_DATA,
       attribute = EFI_VARIABLE_BOOTSERVICE_ACCESS | EFI_VARIABLE_RUNTIME_ACCESS | EFI_VARIABLE_NON_VOLATILE,
       name  = MmcDisableMulti,
@@ -279,6 +292,14 @@ formset
               option text = STRING_TOKEN(STR_ADVANCED_3GB_ON), value = 1, flags = 0;
           endoneof;
         endif;
+
+        oneof varid = OptDeviceTree.Enabled,
+            prompt      = STRING_TOKEN(STR_ADVANCED_DT_PROMPT),
+            help        = STRING_TOKEN(STR_ADVANCED_DT_HELP),
+            flags       = NUMERIC_SIZE_4 | INTERACTIVE | RESET_REQUIRED,
+            option text = STRING_TOKEN(STR_ADVANCED_DT_OFF), value = 0, flags = 0;
+            option text = STRING_TOKEN(STR_ADVANCED_DT_ON), value = 1, flags = DEFAULT;
+        endoneof;
     endform;
 
     form formid = 0x1003,
diff --git a/Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.c b/Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.c
index eb8048930c30..e7143f57b3b6 100644
--- a/Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.c
+++ b/Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.c
@@ -443,6 +443,11 @@ FdtDxeInitialize (
   UINT32     BoardRevision;
   BOOLEAN    Internal;
 
+  if (PcdGet32 (PcdOptDeviceTree) == 0) {
+    DEBUG ((DEBUG_INFO, "Device Tree disabled per user configuration\n"));
+    return EFI_SUCCESS;
+  }
+
   Status = gBS->LocateProtocol (&gRaspberryPiFirmwareProtocolGuid, NULL,
                   (VOID**)&mFwProtocol);
   ASSERT_EFI_ERROR (Status);
diff --git a/Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.inf b/Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.inf
index bf9912b4f7d8..fc37353f883f 100644
--- a/Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.inf
+++ b/Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.inf
@@ -48,3 +48,6 @@ [Depex]
 
 [FixedPcd]
   gRaspberryPiTokenSpaceGuid.PcdFdtBaseAddress
+
+[Pcd]
+  gRaspberryPiTokenSpaceGuid.PcdOptDeviceTree
diff --git a/Platform/RaspberryPi/RPi3/RPi3.dsc b/Platform/RaspberryPi/RPi3/RPi3.dsc
index 48e1a32e1d24..91d5738afbc6 100644
--- a/Platform/RaspberryPi/RPi3/RPi3.dsc
+++ b/Platform/RaspberryPi/RPi3/RPi3.dsc
@@ -445,6 +445,11 @@ [PcdsDynamicHii.common.DEFAULT]
   gRaspberryPiTokenSpaceGuid.PcdRamMoreThan3GB|L"RamMoreThan3GB"|gConfigDxeFormSetGuid|0x0|0
   gRaspberryPiTokenSpaceGuid.PcdRamLimitTo3GB|L"RamLimitTo3GB"|gConfigDxeFormSetGuid|0x0|0
 
+  #
+  # Device Tree
+  #
+  gRaspberryPiTokenSpaceGuid.PcdOptDeviceTree|L"OptDeviceTree"|gConfigDxeFormSetGuid|0x0|1
+
   #
   # Common UEFI ones.
   #
diff --git a/Platform/RaspberryPi/RPi4/RPi4.dsc b/Platform/RaspberryPi/RPi4/RPi4.dsc
index 3ce2c3e4d519..79295729f6ee 100644
--- a/Platform/RaspberryPi/RPi4/RPi4.dsc
+++ b/Platform/RaspberryPi/RPi4/RPi4.dsc
@@ -38,7 +38,6 @@ [Defines]
   DEFINE SECURE_BOOT_ENABLE      = FALSE
   DEFINE INCLUDE_TFTP_COMMAND    = FALSE
   DEFINE DEBUG_PRINT_ERROR_LEVEL = 0x8000004F
-  DEFINE ACPI_BASIC_MODE_ENABLE  = FALSE
 
 !ifndef TFA_BUILD_ARTIFACTS
   #
@@ -271,8 +270,6 @@ [PcdsFeatureFlag.common]
   gEfiMdeModulePkgTokenSpaceGuid.PcdConOutGopSupport|TRUE
   gEfiMdeModulePkgTokenSpaceGuid.PcdConOutUgaSupport|FALSE
 
-  gRaspberryPiTokenSpaceGuid.PcdAcpiBasicMode|$(ACPI_BASIC_MODE_ENABLE)
-
 [PcdsFixedAtBuild.common]
   gEfiMdePkgTokenSpaceGuid.PcdMaximumUnicodeStringLength|1000000
   gEfiMdePkgTokenSpaceGuid.PcdMaximumAsciiStringLength|1000000
@@ -483,6 +480,11 @@ [PcdsDynamicHii.common.DEFAULT]
   gRaspberryPiTokenSpaceGuid.PcdRamMoreThan3GB|L"RamMoreThan3GB"|gConfigDxeFormSetGuid|0x0|0
   gRaspberryPiTokenSpaceGuid.PcdRamLimitTo3GB|L"RamLimitTo3GB"|gConfigDxeFormSetGuid|0x0|1
 
+  #
+  # Device Tree
+  #
+  gRaspberryPiTokenSpaceGuid.PcdOptDeviceTree|L"OptDeviceTree"|gConfigDxeFormSetGuid|0x0|0
+
   #
   # Common UEFI ones.
   #
@@ -575,9 +577,7 @@ [Components.common]
 
   ArmPkg/Drivers/ArmGic/ArmGicDxe.inf
   Platform/RaspberryPi/Drivers/RpiFirmwareDxe/RpiFirmwareDxe.inf
-!if $(ACPI_BASIC_MODE_ENABLE) == FALSE
   Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.inf
-!endif
   Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf
   ArmPkg/Drivers/TimerDxe/TimerDxe.inf
   MdeModulePkg/Universal/WatchdogTimerDxe/WatchdogTimer.inf
diff --git a/Platform/RaspberryPi/RPi4/RPi4.fdf b/Platform/RaspberryPi/RPi4/RPi4.fdf
index cb5e8e9ae92e..c38320350213 100644
--- a/Platform/RaspberryPi/RPi4/RPi4.fdf
+++ b/Platform/RaspberryPi/RPi4/RPi4.fdf
@@ -208,9 +208,7 @@ [FV.FvMain]
 
   INF ArmPkg/Drivers/ArmGic/ArmGicDxe.inf
   INF Platform/RaspberryPi/Drivers/RpiFirmwareDxe/RpiFirmwareDxe.inf
-!if $(ACPI_BASIC_MODE_ENABLE) == FALSE
   INF Platform/RaspberryPi/Drivers/FdtDxe/FdtDxe.inf
-!endif
   INF Platform/RaspberryPi/Drivers/ConfigDxe/ConfigDxe.inf
   INF ArmPkg/Drivers/TimerDxe/TimerDxe.inf
   INF MdeModulePkg/Universal/WatchdogTimerDxe/WatchdogTimer.inf
diff --git a/Platform/RaspberryPi/RPi4/Readme.md b/Platform/RaspberryPi/RPi4/Readme.md
index 758d0124a6cf..21c9fd4f0a4a 100644
--- a/Platform/RaspberryPi/RPi4/Readme.md
+++ b/Platform/RaspberryPi/RPi4/Readme.md
@@ -16,9 +16,12 @@ Raspberry Pi is a trademark of the [Raspberry Pi Foundation](https://www.raspber
 This firmware is still in development stage, meaning that it comes with the
 following __major__ limitations:
 
-- USB may only work in pre-OS phase at this stage due to nonstandard ECAM,
-  missing/incomplete ACPI tables as well as other factors. For Linux, using
-  the `ACPI_BASIC_MODE_ENABLE` build option may help.
+- xHCI USB may only work in pre-OS phase due to nonstandard DMA constraints.
+  For 4 GB models running Linux, limiting the RAM to 3 GB should help.
+  The 3 GB limitation is currently enabled by default in the user settings.
+- Device Tree boot of OSes such as Linux may not work at all.
+  For this reason, the provision of a Device Tree is disabled by default in
+  the user settings, in order to enforce ACPI boot.
 - Serial I/O from the OS may not work due to CPU throttling affecting the
   miniUART baudrate. This can be worked around by using the PL011 UART
   through the device tree overlays.
@@ -27,12 +30,6 @@ following __major__ limitations:
 
 Build instructions from the top level edk2-platforms Readme.md apply.
 
-The following additional build options are also available:
-- `-D ACPI_BASIC_MODE_ENABLE=1`: Limits OS visible memory to 3 GB and forces
-  ACPI (by disabling the Device Tree driver altogether). This may be required
-  to boot Operating Systems such as Linux on account of the current PCIe/xHCI
-  limitations.
-
 # Booting the firmware
 
 1. Format a uSD card as FAT16 or FAT32
diff --git a/Platform/RaspberryPi/RaspberryPi.dec b/Platform/RaspberryPi/RaspberryPi.dec
index 7f2c37ac9a7f..25058ccc7783 100644
--- a/Platform/RaspberryPi/RaspberryPi.dec
+++ b/Platform/RaspberryPi/RaspberryPi.dec
@@ -57,8 +57,6 @@ [PcdsFixedAtBuild, PcdsPatchableInModule, PcdsDynamic, PcdsDynamicEx]
   gRaspberryPiTokenSpaceGuid.PcdCustomCpuClock|0|UINT32|0x00000016
   gRaspberryPiTokenSpaceGuid.PcdDisplayEnableScaledVModes|0|UINT8|0x00000017
   gRaspberryPiTokenSpaceGuid.PcdDisplayEnableSShot|0|UINT32|0x00000018
+  gRaspberryPiTokenSpaceGuid.PcdOptDeviceTree|1|UINT32|0x0000001B
   gRaspberryPiTokenSpaceGuid.PcdRamMoreThan3GB|0|UINT32|0x00000019
   gRaspberryPiTokenSpaceGuid.PcdRamLimitTo3GB|0|UINT32|0x0000001A
-
-[PcdsFeatureFlag.common]
-  gRaspberryPiTokenSpaceGuid.PcdAcpiBasicMode|FALSE|BOOLEAN|0x0000001B
-- 
2.21.0.windows.1