Suggested content for /etc/initramfs-tools/hooks/devicetree-firmware

devicetree-firmware

#!/bin/sh -e

# Copyright (C) Linaro Ltd, 2024
# SPDX-License-Identifier: GPL-2.0-or-later

# Add firmware whose names are dictated by the devicetree. Such firmware cannot
# be described in a MODULE_FIRMWARE() meaning modinfo based discovery tools are
# insufficient to handle these cases.

# No prereq
if [ "$1" = "prereqs" ]; then exit 0; fi

. /usr/share/initramfs-tools/hook-functions

# Only run if this system is booted with a devicetree
if [ ! -d /sys/firmware/devicetree ]; then exit 0; fi

# Scan for appropriately named devicetree nodes and add any firmware
# we discover this way to the initramfs. Sadly we cannot tell the difference
# between boot-critical firmware and any other so we have to be over-zealous.
# However the impact on initramfs size should be acceptable because we only
# scan the devicetree of the booted system.
for node in $(find /sys/firmware/devicetree -name firmware-name); do
        firmware="$(cat "${node}")"
        if ! add_firmware "${firmware}"; then
                echo "W: Possible missing firmware /lib/firmware/${firmware} found in devicetree" >&2
        fi
done