edk-firmware-tegra: Support A/B redundancy

When USE_REDUNDANT_FLASH_LAYOUT is specified, add the
.dtbo file to the build which enables RootfsA/B suport
in UEFI based on discussion at [1].

This content of the variable is set based on the corresponding
logic found in nvidia's flash.sh.  The usage for this variable
can be found at [2].

1: https://github.com/OE4T/meta-tegra/discussions/1182#discussioncomment-5067058
2: 71fc2f6de4/Silicon/NVIDIA/Application/L4TLauncher/L4TRootfsValidation.c (L464-L466)

Signed-off-by: Dan Walkes <danwalkes@trellis-logic.com>

conf/machine/include/tegra-common.inc

@@ -13,6 +13,7 @@ UBOOT_EXTLINUX_KERNEL_ARGS ?= "${KERNEL_ARGS}"
 UBOOT_EXTLINUX_INITRD ?= "${@'/boot/initrd' if d.getVar('INITRAMFS_IMAGE') != '' and d.getVar('INITRAMFS_IMAGE_BUNDLE') != '1' else ''}"
 
 TEGRA_BOOTCONTROL_OVERLAYS ?= "L4TConfiguration.dtbo"
+TEGRA_BOOTCONTROL_OVERLAYS += "${@'L4TConfiguration-RootfsRedundancyLevelABEnable.dtbo' if bb.utils.to_boolean(d.getVar('USE_REDUNDANT_FLASH_LAYOUT')) else ''}"
 TEGRA_PLUGIN_MANAGER_OVERLAYS ??= ""
 # The following variable is deprecated; add new overlays
 # to one of the above instead.

recipes-bsp/uefi/edk2-firmware-tegra_35.4.1.bb

@@ -20,6 +20,8 @@ NVDISPLAY_INIT ?= "${NVDISPLAY_INIT_DEFAULT}"
 NVDISPLAY_INIT_DEPS = ""
 NVDISPLAY_INIT_DEPS:tegra194 = "nvdisp-init:do_deploy"
 
+SRC_URI += "${@'file://L4TConfiguration-RootfsRedundancyLevelABEnable.dtsi' if bb.utils.to_boolean(d.getVar('USE_REDUNDANT_FLASH_LAYOUT')) else ''}"
+
 do_compile:append() {
     rm -rf ${B}/images
     mkdir ${B}/images
@@ -42,6 +44,9 @@ do_compile:append() {
     done
     cp ${B}/images/L4TConfiguration.dtbo ${B}/images/L4TConfiguration-rcmboot.dtbo
     fdtput -t s ${B}/images/L4TConfiguration-rcmboot.dtbo /fragment@0/__overlay__/firmware/uefi/variables/gNVIDIATokenSpaceGuid/DefaultBootPriority data boot.img
+    if [ ${USE_REDUNDANT_FLASH_LAYOUT} -eq 1 ]; then
+       dtc -Idts -Odtb -o ${B}/images/L4TConfiguration-RootfsRedundancyLevelABEnable.dtbo ${WORKDIR}/L4TConfiguration-RootfsRedundancyLevelABEnable.dtsi
+    fi
 }
 do_compile[depends] += "${NVDISPLAY_INIT_DEPS}"
 

recipes-bsp/uefi/files/L4TConfiguration-RootfsRedundancyLevelABEnable.dtsi

@@ -0,0 +1,36 @@
+/dts-v1/;
+
+/ {
+        overlay-name = "L4T Configuration Settings";
+
+        fragment@0 {
+                target-path = "/";
+
+                board_config {
+                        sw-modules = "uefi";
+                };
+
+                __overlay__ {
+
+                        firmware {
+
+                                uefi {
+
+                                        variables {
+
+                                                gNVIDIAPublicVariableGuid {
+
+                                                        RootfsRedundancyLevel {
+                                                                data = [01 00 00 00];
+                                                                runtime;
+                                                                locked;
+                                                        };
+
+                                                };
+
+                                        };
+                                };
+                        };
+                };
+        };
+};