#! /bin/sh
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2020, Google LLC. All rights reserved.
# Author: Saravana Kannan 

function help() {
	cat /dev/null)
	for SL in $SUPPLIER_LINKS;
	do
		SYNC_STATE=$(cat $SL/sync_state_only)

		# sync_state_only links are proxy dependencies.
		# They can also have cycles. So, don't follow them.
		if [ "$SYNC_STATE" != '0' ]
		then
			continue
		fi

		SUPPLIER=$(realpath $SL/supplier)

		if [ ! -e $SUPPLIER/driver -a ${ALLOW_NO_DRIVER} -eq 0 ]
		then
			continue
		fi

		CONSUMERS+=($SUPPLIER)
		OUT_LIST+=(${CON} ${SUPPLIER})
		RET=0
	done

	return $RET
}

function detail_compat() {
	f=$1/of_node/compatible
	if [ -e $f ]
	then
		echo -n $(cat $f)
	else
		echo -n $1
	fi
}

function detail_module() {
	f=$1/driver/module
	if [ -e $f ]
	then
		echo -n $(basename $(realpath $f))
	else
		echo -n $1
	fi
}

function detail_driver() {
	f=$1/driver
	if [ -e $f ]
	then
		echo -n $(basename $(realpath $f))
	else
		echo -n $1
	fi
}

function detail_fwnode() {
	f=$1/firmware_node
	if [ ! -e $f ]
	then
		f=$1/of_node
	fi

	if [ -e $f ]
	then
		echo -n $(realpath $f)
	else
		echo -n $1
	fi
}

function detail_graphviz() {
	if [ "$2" != "ROOT" ]
	then
		echo -n "\"$(basename $2)\"->\"$(basename $1)\""
	else
		echo -n "\"$(basename $1)\""
	fi
}

function detail_tsort() {
	echo -n "\"$2\" \"$1\""
}

function detail_device() { echo -n $1; }

alias detail=detail_device
ALLOW_NO_DRIVER=0
ALLOW_DEVLINKS=1
ALLOW_PARENTS=1

while [ $# -gt 0 ]
do
	ARG=$1
	case $ARG in
		--help)
			help
			exit 0
			;;
		-c)
			alias detail=detail_compat
			;;
		-m)
			alias detail=detail_module
			;;
		-d)
			alias detail=detail_driver
			;;
		-f)
			alias detail=detail_fwnode
			;;
		-g)
			alias detail=detail_graphviz
			;;
		-t)
			alias detail=detail_tsort
			;;
		--allow-no-driver)
			ALLOW_NO_DRIVER=1
			;;
		--exclude-devlinks)
			ALLOW_DEVLINKS=0
			;;
		--exclude-parents)
			ALLOW_PARENTS=0
			;;
		*)
			# Stop at the first argument that's not an option.
			break
			;;
	esac
	shift
done

function detail_chosen() {
	detail $1 $2
}

if [ $# -eq 0 ]
then
	help
	exit 1
fi

CONSUMERS=($@)
OUT_LIST=()

# Do a breadth first, non-recursive tracking of suppliers. The parent is also
# considered a "supplier" as a device can't probe without its parent.
i=0
while [ $i -lt ${#CONSUMERS[@]} ]
do
	CONSUMER=$(realpath ${CONSUMERS[$i]})
	i=$(($i+1))

	if already_seen ${CONSUMER}
	then
		continue
	fi

	# If this is not a device with a driver, we don't care about its
	# suppliers.
	if [ ! -e ${CONSUMER}/driver -a ${ALLOW_NO_DRIVER} -eq 0 ]
	then
		continue
	fi

	ROOT=1

	# Add suppliers to CONSUMERS list and output the consumer details.
	#
	# We don't need to worry about a cycle in the dependency chain causing
	# infinite loops. That's because the kernel doesn't allow cycles in
	# device links unless it's a sync_state_only device link. And we ignore
	# sync_state_only device links inside add_suppliers.
	if add_suppliers ${CONSUMER}
	then
		ROOT=0
	fi

	if add_parent ${CONSUMER}
	then
		ROOT=0
	fi

	if [ $ROOT -eq 1 ]
	then
		OUT_LIST+=(${CONSUMER} "ROOT")
	fi
done

# Can NOT combine sort and uniq using sort -suk2 because stable sort in toybox
# isn't really stable.
dev_to_detail | sort -k2 -k1 | uniq -f 1 | sort | cut -f2-

exit 0