uboot-tools/10-devicetree.install

#!/bin/bash

# set -x

COMMAND="$1"
KERNEL_VERSION="$2"
#BOOT_DIR_ABS="$3"
#KERNEL_IMAGE="$4"

# Setup a /boot/dtb -> /boot/dtb-$newest_kernel_version symlink so that
# u-boot can find the correct dtb to load.
#
# If invoked to 'add' a new kernel, find the newest based on `sort`ing
# the kernel versions dtb.  If 'remove', then follow basically the same
# procedure but exclude the version currently being removed.
#
# The theory of operation here is that, while newer kernels may add new
# dtb nodes and fields, as upstreaming hw support for some particular
# device progresses, it should never make backward incompatible changes.
# So it should always be safe to use a newer dtb with an older kernel.

if [[ "$(uname -m)" == arm* || "$(uname -m)" == aarch64 ]]; then

    list_dtb_versions() {
        excluded_version="$1"
        for dtbdir in /boot/dtb-*; do
            dtbver=${dtbdir#*-}
            if [ "$dtbver" != "$excluded_version" ]; then
                echo $dtbver
            fi
        done
    }

    setup_dtb_link() {
        ver=`list_dtb_versions $1 | sort -r --sort=version | head -1`
        if [ -h /boot/dtb ]; then
            rm -f /boot/dtb
        fi
        ln -s dtb-$ver /boot/dtb
    }

    ret=0
    case "$COMMAND" in
        add)
            setup_dtb_link
            ret=$?
	    ;;
        remove)
            setup_dtb_link $KERNEL_VERSION
            ret=$?
	    ;;
    esac
    exit $ret
fi