#! /bin/sh# SPDX-License-Identifier: GPL-2.0# Copyright (c) 2020, Google LLC. All rights reserved.# Author: Saravana Kannan <saravanak@google.com> function help() {	cat << EOFUsage: $(basename $0) [-c|-d|-m|-f] [filter options] <list of devices> This script needs to be run on the target device once it has booted to ashell. The script takes as input a list of one or more device directories under/sys/devices and then lists the probe dependency chain (suppliers andparents) of these devices. It does a breadth first search of the dependencychain, so the last entry in the output is close to the root of thedependency chain. By default it lists the full path to the devices under /sys/devices. It also takes an optional modifier flag as the first parameter to changewhat information is listed in the output. If the requested information isnot available, the device name is printed.   -c	lists the compatible string of the dependencies  -d	lists the driver name of the dependencies that have probed  -m	lists the module name of the dependencies that have a module  -f	list the firmware node path of the dependencies  -g	list the dependencies as edges and nodes for graphviz  -t	list the dependencies as edges for tsort The filter options provide a way to filter out some dependencies:  --allow-no-driver	By default dependencies that don't have a driver			attached are ignored. This is to avoid following			device links to "class" devices that are created			when the consumer probes (as in, not a probe			dependency). If you want to follow these links			anyway, use this flag.   --exclude-devlinks	Don't follow device links when tracking probe			dependencies.   --exclude-parents	Don't follow parent devices when tracking probe			dependencies. EOF} function dev_to_detail() {	local i=0	while [ $i -lt ${#OUT_LIST[@]} ]	do		local C=${OUT_LIST[i]}		local S=${OUT_LIST[i+1]}		local D="'$(detail_chosen $C $S)'"		if [ ! -z "$D" ]		then			# This weirdness is needed to work with toybox when			# using the -t option.			printf '%05u\t%s\n' ${i} "$D" | tr -d \'		fi		i=$((i+2))	done} function already_seen() {	local i=0	while [ $i -lt ${#OUT_LIST[@]} ]	do		if [ "$1" = "${OUT_LIST[$i]}" ]		then			# if-statement treats 0 (no-error) as true			return 0		fi		i=$(($i+2))	done 	# if-statement treats 1 (error) as false	return 1} # Return 0 (no-error/true) if parent was addedfunction add_parent() { 	if [ ${ALLOW_PARENTS} -eq 0 ]	then		return 1	fi 	local CON=$1	# $CON could be a symlink path. So, we need to find the real path and	# then go up one level to find the real parent.	local PARENT=$(realpath $CON/..) 	while [ ! -e ${PARENT}/driver ]	do		if [ "$PARENT" = "/sys/devices" ]		then			return 1		fi		PARENT=$(realpath $PARENT/..)	done 	CONSUMERS+=($PARENT)	OUT_LIST+=(${CON} ${PARENT})	return 0} # Return 0 (no-error/true) if one or more suppliers were addedfunction add_suppliers() {	local CON=$1	local RET=1 	if [ ${ALLOW_DEVLINKS} -eq 0 ]	then		return 1	fi 	SUPPLIER_LINKS=$(ls -1d $CON/supplier:* 2>/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_deviceALLOW_NO_DRIVER=0ALLOW_DEVLINKS=1ALLOW_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	shiftdone function detail_chosen() {	detail $1 $2} if [ $# -eq 0 ]then	help	exit 1fi CONSUMERS=($@)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=0while [ $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")	fidone # 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