flash: Clean up/add support for RPi 3

Although the official Fedora CoreOS documentation only provides
instructions for running CoreOS on a Raspberry Pi 4, it does actually
work on older boards as well.  `coreos-installer` creates a GPT disk
label, which the older devices do not support, but this can be worked
around using a hybrid MBR label.

Unfortunately, after I put all the effort into refactoring this script
and adding support for the older devices, I realized that it was rather
pointless as those boards simply do not have enough memory to be useful
Kubernetes nodes.  I was hoping to move the Zigbee and ZWave controllers
to a Raspberry Pi 3, but these processes take way too much memory for
that.

.gitignore

@@ -1,3 +1,4 @@
 *.ign
 frigate.env
 *.token
+RPi4boot

flash.sh

@@ -1,35 +0,0 @@
-#!/bin/sh
-# vim: set sw=4 ts=4 sts=4 et :
-
-set -eu
-
-ignition=${1}
-dev=${2:-/dev/disk/by-id/usb-Generic_STORAGE_DEVICE_000000001206-0:0}
-
-if [ -z "${ignition}" ]; then
-    printf 'usage: %s ignition\n' "${0##*/}" >&2
-    exit 2
-fi
-
-if [ $(id -u) -ne 0 ]; then
-    sudo=sudo
-fi
-
-${sudo} coreos-installer install \
-    -a aarch64 \
-    -s stable \
-    -i "${ignition}" \
-    --console ttyS0,115200n8 \
-    "${dev}"
-sync; sync; sync
-
-until [ -n "${efi_part}" ]; do
-    efi_part=$(
-        lsblk -o LABEL,PATH \
-        | awk '$1=="EFI-SYSTEM"{print $2}'
-    )
-done
-pmount "${efi_part}" coreos-efi
-rsync -ah --ignore-existing RPi4boot/boot/efi/ /media/coreos-efi/
-sync; sync; sync
-pumount coreos-efi

flash.zsh

@@ -0,0 +1,139 @@
+#!/bin/zsh
+# vim: set ft=sh sw=4 ts=4 sts=4 et :
+
+set -eu
+
+function copy_firmware() {
+    local dev="$1"
+    local efi_part
+    local mountpoint=/run/media/coreos-efi
+
+    if [ ! -d RPi4boot ]; then
+        download_firmware
+    fi
+
+    printf 'Waiting for device to settle ...' >&2
+    until [ -n "${efi_part-}" ]; do
+        printf '.'
+        efi_part=$(
+            lsblk -o LABEL,PATH "${dev}" \
+            | awk '$1=="EFI-SYSTEM"{print $2}'
+        )
+        sleep 0.25
+    done
+    printf '\n'
+
+    mkdir -p "${mountpoint}"
+    mount "${efi_part}" "${mountpoint}"
+    rsync -rtiOh --ignore-existing RPi4boot/boot/efi/ "${mountpoint}"
+    sync; sync; sync
+    umount "${mountpoint}"
+    rmdir "${mountpoint}"
+}
+
+function download_firmware() {
+    local rpm
+
+    echo 'Downloading Raspberry Pi Firmware blobs ...'
+    mkdir RPi4boot
+    podman run --rm -it \
+        -v $(PWD)/RPi4boot:/RPi4boot:rw,z \
+        registry.fedoraproject.org/fedora:38 \
+        dnf install -y \
+            --downloadonly \
+            --forcearch=aarch64 \
+            --destdir=/RPi4boot \
+            uboot-images-armv8 \
+            bcm283x-firmware \
+            bcm283x-overlays
+            --
+    for rpm in RPi4boot/*.rpm; do
+        rpm2cpio "${rpm}" | cpio -idv -D RPi4boot/
+    done
+
+    cp RPi4boot/usr/share/uboot/rpi_3/u-boot.bin RPi4boot/boot/efi/rpi3-u-boot.bin
+    cp RPi4boot/usr/share/uboot/rpi_4/u-boot.bin RPi4boot/boot/efi/rpi4-u-boot.bin
+    cp RPi4boot/usr/share/uboot/rpi_arm64/u-boot.bin RPi4boot/boot/efi/rpi-u-boot.bin
+}
+
+function hybridize_gpt() {
+    local dev="$1"
+
+    echo 'Creating Hybrid MBR partition table ...'
+    sgdisk -h 2:EE "${dev}"
+    echo type=0c,bootable | sfdisk -Y mbr -N 1 "${dev}"
+}
+
+function install_coreos() {
+    local ignition="$1"
+    local dev="$2"
+
+    coreos-installer install \
+        -a aarch64 \
+        -s stable \
+        -i "${ignition}" \
+        --console ttyS0,115200n8 \
+        "${dev}"
+    sync; sync; sync
+}
+
+function parse_args() {
+    pi=4
+    while [ $# -gt 0 ]; do
+        case "$1" in
+        --pi)
+            shift
+            pi=${1}
+            ;;
+        --pi=*)
+            pi=${1#--pi=}
+            ;;
+        *)
+            if [ -z "${ignition-}" ]; then
+                ignition="${1}"
+            elif [ -z "${dev-}" ]; then
+                dev="${1}"
+            else
+                usage >&2
+                exit 2
+            fi
+            ;;
+        esac
+        shift
+    done
+
+    if [ -z "${ignition-}" ]; then
+        usage >&2
+        exit 2
+    fi
+    if [ -z "${dev-}" ]; then
+        dev=/dev/disk/by-id/usb-Generic_STORAGE_DEVICE_000000001206-0:0
+    fi
+}
+
+function usage() {
+    printf 'usage: %s [--pi PI] ignition [device]\n' "${0##*/}"
+}
+
+parse_args "$@"
+
+case "${pi}" in
+0*|1)
+    printf 'Raspberry Pi model %s is not supported\n' "${pi}" >&2
+    exit 1
+    ;;
+esac
+
+if [ $(id -u) -ne 0 ]; then
+    exec sudo "$0" "$@"
+fi
+
+install_coreos "${ignition}" "${dev}"
+
+case "${pi}" in
+2|3)
+    hybridize_gpt "${dev}"
+    ;;
+esac
+
+copy_firmware "${dev}"