From ad25a74ac0ea39855dfe36f0bab8014477401779 Mon Sep 17 00:00:00 2001
From: Bailey Stevens <me@mtxyz.me>
Date: Tue, 4 Apr 2023 13:51:16 -0400
Subject: [PATCH] Initial commit

---
 .gitignore |  1 +
 config.txt | 15 +++++++++
 flake.lock | 43 ++++++++++++++++++++++++++
 flake.nix  | 23 ++++++++++++++
 orange.nix | 90 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 rootfs.nix |  3 ++
 6 files changed, 175 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 config.txt
 create mode 100644 flake.lock
 create mode 100644 flake.nix
 create mode 100644 orange.nix
 create mode 100644 rootfs.nix

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..b2be92b
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+result
diff --git a/config.txt b/config.txt
new file mode 100644
index 0000000..36b0e3a
--- /dev/null
+++ b/config.txt
@@ -0,0 +1,15 @@
+[pi02]
+kernel=u-boot-rpi3.bin
+
+[all]
+# Boot in 64-bit mode.
+arm_64bit=1
+
+# U-Boot needs this to work, regardless of whether UART is actually used or not.
+# Look in arch/arm/mach-bcm283x/Kconfig in the U-Boot tree to see if this is still
+# a requirement in the future.
+enable_uart=1
+
+# Prevent the firmware from smashing the framebuffer setup done by the mainline kernel
+# when attempting to show low-voltage or overtemperature warnings.
+avoid_warnings=1
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..e43b1b8
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,43 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1678901627,
+        "narHash": "sha256-U02riOqrKKzwjsxc/400XnElV+UtPUQWpANPlyazjH0=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "93a2b84fc4b70d9e089d029deacc3583435c2ed6",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1680398059,
+        "narHash": "sha256-qtbKRe+pWuf5nNINdiCgn6EwOIQZxj0Ig/wybBpFNkQ=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "7c656856e9eb863c4d21c83e2601dd77f95f6941",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000..ea10b1c
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,23 @@
+{
+  description = "my project description";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = inputs@{self, nixpkgs, flake-utils, ...}:
+  flake-utils.lib.eachDefaultSystem (system:
+  let
+    pkgs = import nixpkgs {
+      inherit system;
+      crossSystem = nixpkgs.lib.systems.examples.aarch64-multiplatform;
+    };
+  in
+  {
+    packages = {
+      default = import ./orange.nix { inherit pkgs; };
+    };
+  }
+  );
+}
diff --git a/orange.nix b/orange.nix
new file mode 100644
index 0000000..7a904b1
--- /dev/null
+++ b/orange.nix
@@ -0,0 +1,90 @@
+{ pkgs }:
+
+let
+  imageName = "orange";
+  firmwarePartition = {
+    offset = 8;
+    id = "0xfeed3425";
+    name = "FIRMWARE";
+    size = 512;
+  };
+
+  rootfsImage = import ./rootfs.nix { inherit pkgs; };
+
+  configTxt = pkgs.writeText "config.txt" (builtins.readFile ./config.txt);
+  populateFirmwareCommands = ''
+    # Add config.txt
+    cp ${configTxt} firmware/config.txt
+
+    # Copy the firmware files
+    cp ${pkgs.raspberrypifw}/share/raspberrypi/boot/bootcode.bin firmware/
+    cp ${pkgs.raspberrypifw}/share/raspberrypi/boot/fixup*.dat firmware/
+    cp ${pkgs.raspberrypifw}/share/raspberrypi/boot/start*.elf firmware/
+
+    # Add pi3 specific files
+    cp ${pkgs.ubootRaspberryPi3_64bit}/u-boot.bin firmware/u-boot-rpi3.bin
+  '';
+in
+  pkgs.stdenv.mkDerivation {
+    name = imageName;
+
+    nativeBuildInputs = with pkgs; [ dosfstools e2fsprogs libfaketime mtools util-linux zstd ];
+
+    buildCommand = ''
+    mkdir -p $out/nix-support $out/sd-image
+    export img=$out/sd-image/${imageName}
+    echo "${pkgs.stdenv.buildPlatform.system}" > $out/nix-support/system
+    echo "file sd-image $img.zst" >> $out/nix-support/hydra-build-products
+    root_fs=${rootfsImage}
+
+    # Gap in front of the first partition, in MiB
+    gap=${toString firmwarePartition.offset}
+
+    # Create the image file sized to fit /boot/firmware and /, plus slack for the gap.
+    rootSizeBlocks=$(du -B 512 --apparent-size $root_fs | awk '{ print $1 }')
+    firmwareSizeBlocks=$((${toString firmwarePartition.size} * 1024 * 1024 / 512))
+    imageSize=$((rootSizeBlocks * 512 + firmwareSizeBlocks * 512 + gap * 1024 * 1024))
+    truncate -s $imageSize $img
+
+    # type=b is 'W95 FAT32', type=83 is 'Linux'.
+    # The "bootable" partition is where u-boot will look file for the bootloader
+    # information (dtbs, extlinux.conf file).
+    sfdisk $img <<EOF
+      label: dos
+      label-id: ${firmwarePartition.id}
+      start=''${gap}M, size=$firmwareSizeBlocks, type=b
+      start=$((gap + ${toString firmwarePartition.size}))M, type=83, bootable
+    EOF
+
+    # Copy the rootfs into the SD image
+    eval $(partx $img -o START,SECTORS --nr 2 --pairs)
+    dd conv=notrunc if=$root_fs of=$img seek=$START count=$SECTORS
+
+    # Create a FAT32 /boot/firmware partition of suitable size into firmware_part.img
+    eval $(partx $img -o START,SECTORS --nr 1 --pairs)
+    truncate -s $((SECTORS * 512)) firmware_part.img
+    mkfs.vfat --invariant -i ${toString firmwarePartition.size} -n ${firmwarePartition.name} firmware_part.img
+
+    # Populate the files intended for /boot/firmware
+    mkdir firmware
+    ${populateFirmwareCommands}
+    find firmware -exec touch --date=2000-01-01 {} +
+
+    # Copy the populated /boot/firmware into the SD image
+    cd firmware
+    # Force a fixed order in mcopy for better determinism, and avoid file globbing
+    for d in $(find . -type d -mindepth 1 | sort); do
+    faketime "2000-01-01 00:00:00" mmd -i ../firmware_part.img "::/$d"
+    done
+    for f in $(find . -type f | sort); do
+    mcopy -pvm -i ../firmware_part.img "$f" "::/$f"
+    done
+    cd ..
+
+    # Verify the FAT partition before copying it.
+    fsck.vfat -vn firmware_part.img
+
+    dd conv=notrunc if=firmware_part.img of=$img seek=$START count=$SECTORS
+    zstd -T$NIX_BUILD_CORES --rm $img
+    '';
+  }
diff --git a/rootfs.nix b/rootfs.nix
new file mode 100644
index 0000000..fd315fb
--- /dev/null
+++ b/rootfs.nix
@@ -0,0 +1,3 @@
+{ pkgs }:
+
+pkgs.runCommand "rootfs" {} "truncate -s 1M $out"