#! /bin/sh
# SPDX-License-Identifier: GPL-2.0
# Copyright (c) 2020, Google LLC. All rights reserved.
# Author: Saravana Kannan <[email protected]>
function help() {
cat << EOF
Usage: $(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 a
shell.
The script takes as input a list of one or more device directories under
/sys/devices and then lists the probe dependency chain (suppliers and
parents) of these devices. It does a breadth first search of the dependency
chain, so the last entry in the output is close to the root of the
dependency 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 change
what information is listed in the output. If the requested information is
not 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 added
function 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 added
function 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_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
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