workqueue: skip the node_nr_active update for non-unbound workqueuesgrafted

apply_wqattrs_commit() updates node_nr_active->max unconditionally.
wq->node_nr_active[] is only allocated for unbound workqueues, so guard
the call before per-cpu workqueues start using this path.

No functional change: only unbound workqueues reach apply_wqattrs_*()
today.

Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

12 files changed, 2305 insertions, 0 deletions

diff --git a/tools/testing/selftests/gpio/.gitignore b/tools/testing/selftests/gpio/.gitignore
new file mode 100644
index 000000000..ededb077a
--- /dev/null
+++ b/tools/testing/selftests/gpio/.gitignore
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
+gpio-mockup-cdev
+gpio-chip-info
+gpio-line-name
diff --git a/tools/testing/selftests/gpio/Makefile b/tools/testing/selftests/gpio/Makefile
new file mode 100644
index 000000000..741ab21e1
--- /dev/null
+++ b/tools/testing/selftests/gpio/Makefile
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0
+
+TEST_PROGS := gpio-mockup.sh gpio-sim.sh gpio-aggregator.sh gpio-cdev-uaf.sh
+TEST_FILES := gpio-mockup-sysfs.sh
+TEST_GEN_PROGS_EXTENDED := gpio-mockup-cdev gpio-chip-info gpio-line-name \
+			   gpio-cdev-uaf
+CFLAGS += -O2 -g -Wall $(KHDR_INCLUDES)
+
+include ../lib.mk
diff --git a/tools/testing/selftests/gpio/config b/tools/testing/selftests/gpio/config
new file mode 100644
index 000000000..1287abeaa
--- /dev/null
+++ b/tools/testing/selftests/gpio/config
@@ -0,0 +1,5 @@
+CONFIG_GPIOLIB=y
+CONFIG_GPIO_CDEV=y
+CONFIG_GPIO_MOCKUP=m
+CONFIG_GPIO_SIM=m
+CONFIG_GPIO_AGGREGATOR=m
diff --git a/tools/testing/selftests/gpio/gpio-aggregator.sh b/tools/testing/selftests/gpio/gpio-aggregator.sh
new file mode 100755
index 000000000..9b6f80ad9
--- /dev/null
+++ b/tools/testing/selftests/gpio/gpio-aggregator.sh
@@ -0,0 +1,727 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2025 Bartosz Golaszewski <brgl@bgdev.pl>
+# Copyright (C) 2025 Koichiro Den <koichiro.den@canonical.com>
+
+BASE_DIR=$(dirname "$0")
+CONFIGFS_SIM_DIR="/sys/kernel/config/gpio-sim"
+CONFIGFS_AGG_DIR="/sys/kernel/config/gpio-aggregator"
+SYSFS_AGG_DIR="/sys/bus/platform/drivers/gpio-aggregator"
+MODULE="gpio-aggregator"
+
+fail() {
+	echo "$*" >&2
+	echo "GPIO $MODULE test FAIL"
+	exit 1
+}
+
+skip() {
+	echo "$*" >&2
+	echo "GPIO $MODULE test SKIP"
+	exit 4
+}
+
+# gpio-sim
+sim_enable_chip() {
+	local CHIP=$1
+
+	echo 1 > "$CONFIGFS_SIM_DIR/$CHIP/live" || fail "Unable to enable the chip"
+}
+
+sim_disable_chip() {
+	local CHIP=$1
+
+	echo 0 > "$CONFIGFS_SIM_DIR/$CHIP/live" || fail "Unable to disable the chip"
+}
+
+sim_configfs_cleanup() {
+	local NOCHECK=${1:-0}
+
+	for CHIP_DIR in "$CONFIGFS_SIM_DIR"/*; do
+		[ -d "$CHIP_DIR" ] || continue
+		echo 0 > "$CHIP_DIR/live"
+		find "$CHIP_DIR" -depth -type d -exec rmdir {} \;
+	done
+	[ "$NOCHECK" -eq 1 ] && return;
+	remaining=$(find "$CONFIGFS_SIM_DIR" -mindepth 1 -type d 2> /dev/null)
+	if [ -n "$remaining" ]; then
+		fail "Directories remain in $CONFIGFS_SIM_DIR: $remaining"
+	fi
+}
+
+sim_get_chip_label() {
+	local CHIP=$1
+	local BANK=$2
+	local CHIP_NAME=$(cat "$CONFIGFS_SIM_DIR/$CHIP/$BANK/chip_name" 2> /dev/null) || \
+		fail "Unable to read the chip name from configfs"
+
+	$BASE_DIR/gpio-chip-info "/dev/$CHIP_NAME" label || \
+		fail "Unable to read the chip label from the character device"
+}
+
+# gpio-aggregator
+agg_create_chip() {
+	local CHIP=$1
+
+	mkdir "$CONFIGFS_AGG_DIR/$CHIP"
+}
+
+agg_remove_chip() {
+	local CHIP=$1
+
+	find "$CONFIGFS_AGG_DIR/$CHIP/" -depth -type d -exec rmdir {} \; || \
+		fail "Unable to remove $CONFIGFS_AGG_DIR/$CHIP"
+}
+
+agg_create_line() {
+	local CHIP=$1
+	local LINE=$2
+
+	mkdir "$CONFIGFS_AGG_DIR/$CHIP/$LINE"
+}
+
+agg_remove_line() {
+	local CHIP=$1
+	local LINE=$2
+
+	rmdir "$CONFIGFS_AGG_DIR/$CHIP/$LINE"
+}
+
+agg_set_key() {
+	local CHIP=$1
+	local LINE=$2
+	local KEY=$3
+
+	echo "$KEY" > "$CONFIGFS_AGG_DIR/$CHIP/$LINE/key" || fail "Unable to set the lookup key"
+}
+
+agg_set_offset() {
+	local CHIP=$1
+	local LINE=$2
+	local OFFSET=$3
+
+	echo "$OFFSET" > "$CONFIGFS_AGG_DIR/$CHIP/$LINE/offset" || \
+		fail "Unable to set the lookup offset"
+}
+
+agg_set_line_name() {
+	local CHIP=$1
+	local LINE=$2
+	local NAME=$3
+
+	echo "$NAME" > "$CONFIGFS_AGG_DIR/$CHIP/$LINE/name" || fail "Unable to set the line name"
+}
+
+agg_enable_chip() {
+	local CHIP=$1
+
+	echo 1 > "$CONFIGFS_AGG_DIR/$CHIP/live" || fail "Unable to enable the chip"
+}
+
+agg_disable_chip() {
+	local CHIP=$1
+
+	echo 0 > "$CONFIGFS_AGG_DIR/$CHIP/live" || fail "Unable to disable the chip"
+}
+
+agg_configfs_cleanup() {
+	local NOCHECK=${1:-0}
+
+	for CHIP_DIR in "$CONFIGFS_AGG_DIR"/*; do
+		[ -d "$CHIP_DIR" ] || continue
+		echo 0 > "$CHIP_DIR/live" 2> /dev/null
+		find "$CHIP_DIR" -depth -type d -exec rmdir {} \;
+	done
+	[ "$NOCHECK" -eq 1 ] && return;
+	remaining=$(find "$CONFIGFS_AGG_DIR" -mindepth 1 -type d 2> /dev/null)
+	if [ -n "$remaining" ]; then
+		fail "Directories remain in $CONFIGFS_AGG_DIR: $remaining"
+	fi
+}
+
+agg_configfs_dev_name() {
+	local CHIP=$1
+
+	cat "$CONFIGFS_AGG_DIR/$CHIP/dev_name" 2> /dev/null || \
+		fail "Unable to read the device name from configfs"
+}
+
+agg_configfs_chip_name() {
+	local CHIP=$1
+	local DEV_NAME=$(agg_configfs_dev_name "$CHIP")
+	local CHIP_LIST=$(find "/sys/devices/platform/$DEV_NAME" \
+		-maxdepth 1 -type d -name "gpiochip[0-9]*" 2> /dev/null)
+	local CHIP_COUNT=$(echo "$CHIP_LIST" | wc -l)
+
+	if [ -z "$CHIP_LIST" ]; then
+		fail "No gpiochip in /sys/devices/platform/$DEV_NAME/"
+	elif [ "$CHIP_COUNT" -ne 1 ]; then
+		fail "Multiple gpiochips unexpectedly found: $CHIP_LIST"
+	fi
+	basename "$CHIP_LIST"
+}
+
+agg_get_chip_num_lines() {
+	local CHIP=$1
+	local N_DIR=$(ls -d $CONFIGFS_AGG_DIR/$CHIP/line[0-9]* 2> /dev/null | wc -l)
+	local N_LINES
+
+	if [ "$(cat $CONFIGFS_AGG_DIR/$CHIP/live)" = 0 ]; then
+		echo "$N_DIR"
+	else
+		N_LINES=$(
+			$BASE_DIR/gpio-chip-info \
+				"/dev/$(agg_configfs_chip_name "$CHIP")" num-lines
+		) || fail "Unable to read the number of lines from the character device"
+		if [ $N_DIR != $N_LINES ]; then
+			fail "Discrepancy between two sources for the number of lines"
+		fi
+		echo "$N_LINES"
+	fi
+}
+
+agg_get_chip_label() {
+	local CHIP=$1
+
+	$BASE_DIR/gpio-chip-info "/dev/$(agg_configfs_chip_name "$CHIP")" label || \
+		fail "Unable to read the chip label from the character device"
+}
+
+agg_get_line_name() {
+	local CHIP=$1
+	local OFFSET=$2
+	local NAME_CONFIGFS=$(cat "$CONFIGFS_AGG_DIR/$CHIP/line${OFFSET}/name")
+	local NAME_CDEV
+
+	if [ "$(cat "$CONFIGFS_AGG_DIR/$CHIP/live")" = 0 ]; then
+		echo "$NAME_CONFIGFS"
+	else
+		NAME_CDEV=$(
+			$BASE_DIR/gpio-line-name \
+				"/dev/$(agg_configfs_chip_name "$CHIP")" "$OFFSET"
+		) || fail "Unable to read the line name from the character device"
+		if [ "$NAME_CONFIGFS" != "$NAME_CDEV" ]; then
+			fail "Discrepancy between two sources for the name of line"
+		fi
+		echo "$NAME_CDEV"
+	fi
+}
+
+
+# Load the modules. This will pull in configfs if needed too.
+modprobe gpio-sim || skip "unable to load the gpio-sim module"
+modprobe gpio-aggregator || skip "unable to load the gpio-aggregator module"
+
+# Make sure configfs is mounted at /sys/kernel/config. Wait a bit if needed.
+for IDX in $(seq 5); do
+	if [ "$IDX" -eq "5" ]; then
+		skip "configfs not mounted at /sys/kernel/config"
+	fi
+
+	mountpoint -q /sys/kernel/config && break
+	sleep 0.1
+done
+
+# If the module was already loaded: remove all previous chips
+agg_configfs_cleanup
+sim_configfs_cleanup
+
+trap "exit 1" SIGTERM SIGINT
+trap "agg_configfs_cleanup 1; sim_configfs_cleanup 1" EXIT
+
+# Use gpio-sim chips as the test backend
+for CHIP in $(seq -f "chip%g" 0 1); do
+	mkdir $CONFIGFS_SIM_DIR/$CHIP
+	for BANK in $(seq -f "bank%g" 0 1); do
+		mkdir -p "$CONFIGFS_SIM_DIR/$CHIP/$BANK"
+		echo "${CHIP}_${BANK}" > "$CONFIGFS_SIM_DIR/$CHIP/$BANK/label" || \
+			fail "unable to set the chip label"
+		echo 16 > "$CONFIGFS_SIM_DIR/$CHIP/$BANK/num_lines" || \
+			fail "unable to set the number of lines"
+		for IDX in $(seq 0 15); do
+			LINE_NAME="${CHIP}${BANK}_${IDX}"
+			LINE_DIR="$CONFIGFS_SIM_DIR/$CHIP/$BANK/line$IDX"
+			mkdir -p $LINE_DIR
+			echo "$LINE_NAME" > "$LINE_DIR/name" || fail "unable to set the line name"
+		done
+	done
+	sim_enable_chip "$CHIP"
+done
+
+echo "1. GPIO aggregator creation/deletion"
+
+echo "1.1. Creation/deletion via configfs"
+
+echo "1.1.1. Minimum creation/deletion"
+agg_create_chip   agg0
+agg_create_line   agg0 line0
+agg_set_key       agg0 line0 "$(sim_get_chip_label chip0 bank0)"
+agg_set_offset    agg0 line0 5
+agg_set_line_name agg0 line0 test0
+agg_enable_chip   agg0
+test "$(cat "$CONFIGFS_AGG_DIR/agg0/live")" = 1 || fail "chip unexpectedly dead"
+test "$(agg_get_chip_label agg0)" = "$(agg_configfs_dev_name agg0)" || \
+	fail "label is inconsistent"
+test "$(agg_get_chip_num_lines agg0)" = "1" || fail "number of lines is not 1"
+test "$(agg_get_line_name agg0 0)" = "test0" || fail "line name is unset"
+agg_disable_chip  agg0
+agg_remove_line   agg0 line0
+agg_remove_chip   agg0
+
+echo "1.1.2. Complex creation/deletion"
+agg_create_chip   agg0
+agg_create_line   agg0 line0
+agg_create_line   agg0 line1
+agg_create_line   agg0 line2
+agg_create_line   agg0 line3
+agg_set_key       agg0 line0 "$(sim_get_chip_label chip0 bank0)"
+agg_set_key       agg0 line1 "$(sim_get_chip_label chip0 bank1)"
+agg_set_key       agg0 line2 "$(sim_get_chip_label chip1 bank0)"
+agg_set_key       agg0 line3 "$(sim_get_chip_label chip1 bank1)"
+agg_set_offset    agg0 line0 1
+agg_set_offset    agg0 line1 3
+agg_set_offset    agg0 line2 5
+agg_set_offset    agg0 line3 7
+agg_set_line_name agg0 line0 test0
+agg_set_line_name agg0 line1 test1
+agg_set_line_name agg0 line2 test2
+agg_set_line_name agg0 line3 test3
+agg_enable_chip   agg0
+test "$(cat "$CONFIGFS_AGG_DIR/agg0/live")" = 1 || fail "chip unexpectedly dead"
+test "$(agg_get_chip_label agg0)" = "$(agg_configfs_dev_name agg0)" || \
+	fail "label is inconsistent"
+test "$(agg_get_chip_num_lines agg0)" = "4" || fail "number of lines is not 1"
+test "$(agg_get_line_name agg0 0)" = "test0" || fail "line name is unset"
+test "$(agg_get_line_name agg0 1)" = "test1" || fail "line name is unset"
+test "$(agg_get_line_name agg0 2)" = "test2" || fail "line name is unset"
+test "$(agg_get_line_name agg0 3)" = "test3" || fail "line name is unset"
+agg_disable_chip  agg0
+agg_remove_line   agg0 line0
+agg_remove_line   agg0 line1
+agg_remove_line   agg0 line2
+agg_remove_line   agg0 line3
+agg_remove_chip   agg0
+
+echo "1.1.3. Can't instantiate a chip without any line"
+agg_create_chip   agg0
+echo 1 > "$CONFIGFS_AGG_DIR/agg0/live" 2> /dev/null && fail "chip unexpectedly enabled"
+test "$(cat "$CONFIGFS_AGG_DIR/agg0/live")" = 0 || fail "chip unexpectedly alive"
+agg_remove_chip   agg0
+
+echo "1.1.4. Can't instantiate a chip with invalid configuration"
+agg_create_chip   agg0
+agg_create_line   agg0 line0
+agg_set_key       agg0 line0 "chipX_bankX"
+agg_set_offset    agg0 line0 99
+agg_set_line_name agg0 line0 test0
+echo 1 > "$CONFIGFS_AGG_DIR/agg0/live" 2> /dev/null && fail "chip unexpectedly enabled"
+test "$(cat "$CONFIGFS_AGG_DIR/agg0/live")" = 0 || fail "chip unexpectedly alive"
+agg_remove_line   agg0 line0
+agg_remove_chip   agg0
+
+echo "1.1.5. Can't instantiate a chip asynchronously via deferred probe"
+agg_create_chip   agg0
+agg_create_line   agg0 line0
+agg_set_key       agg0 line0 "chip0_bank0"
+agg_set_offset    agg0 line0 5
+agg_set_line_name agg0 line0 test0
+sim_disable_chip  chip0
+echo 1 > "$CONFIGFS_AGG_DIR/agg0/live" 2> /dev/null && fail "chip unexpectedly enabled"
+test "$(cat "$CONFIGFS_AGG_DIR/agg0/live")" = 0 || fail "chip unexpectedly alive"
+sim_enable_chip   chip0
+sleep 1
+test "$(cat "$CONFIGFS_AGG_DIR/agg0/live")" = 0 || \
+	fail "chip unexpectedly transitioned to 'live' state"
+agg_remove_line   agg0 line0
+agg_remove_chip   agg0
+
+echo "1.1.6. Can't instantiate a chip with _sysfs prefix"
+mkdir "$CONFIGFS_AGG_DIR/_sysfs" 2> /dev/null && fail "chip _sysfs unexpectedly created"
+mkdir "$CONFIGFS_AGG_DIR/_sysfs.foo" 2> /dev/null && fail "chip _sysfs.foo unexpectedly created"
+
+echo "1.2. Creation/deletion via sysfs"
+
+echo "1.2.1. Minimum creation/deletion"
+echo "chip0_bank0 0" > "$SYSFS_AGG_DIR/new_device"
+CHIPNAME=$(agg_configfs_chip_name _sysfs.0)
+test "$(cat "$CONFIGFS_AGG_DIR/_sysfs.0/live")" = 1 || fail "chip unexpectedly dead"
+test "$(agg_get_chip_label _sysfs.0)" = "$(agg_configfs_dev_name _sysfs.0)" || \
+	fail "label is inconsistent"
+test "$(agg_get_chip_num_lines _sysfs.0)" = "1" || fail "number of lines is not 1"
+test "$(agg_get_line_name _sysfs.0 0)" = "" || fail "line name is unset"
+echo "$(agg_configfs_dev_name _sysfs.0)" > "$SYSFS_AGG_DIR/delete_device"
+test -d $CONFIGFS_AGG_DIR/_sysfs.0 && fail "_sysfs.0 unexpectedly remains"
+test -d /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains"
+
+echo "1.2.2. Complex creation/deletion"
+echo "chip0bank0_0 chip1_bank1 10-11" > "$SYSFS_AGG_DIR/new_device"
+CHIPNAME=$(agg_configfs_chip_name _sysfs.0)
+test "$(cat "$CONFIGFS_AGG_DIR/_sysfs.0/live")" = 1 || fail "chip unexpectedly dead"
+test "$(agg_get_chip_label _sysfs.0)" = "$(agg_configfs_dev_name _sysfs.0)" || \
+	fail "label is inconsistent"
+test "$(agg_get_chip_num_lines _sysfs.0)" = "3" || fail "number of lines is not 3"
+test "$(agg_get_line_name _sysfs.0 0)" = "" || fail "line name is unset"
+test "$(agg_get_line_name _sysfs.0 1)" = "" || fail "line name is unset"
+test "$(agg_get_line_name _sysfs.0 2)" = "" || fail "line name is unset"
+echo "$(agg_configfs_dev_name _sysfs.0)" > "$SYSFS_AGG_DIR/delete_device"
+test -d $CONFIGFS_AGG_DIR/_sysfs.0 && fail "_sysfs.0 unexpectedly remains"
+test -d /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains"
+
+echo "1.2.3. Asynchronous creation with deferred probe"
+sim_disable_chip  chip0
+echo 'chip0_bank0 0' > $SYSFS_AGG_DIR/new_device
+sleep 1
+test "$(cat "$CONFIGFS_AGG_DIR/_sysfs.0/live")" = 0 || fail "chip unexpectedly alive"
+sim_enable_chip  chip0
+sleep 1
+CHIPNAME=$(agg_configfs_chip_name _sysfs.0)
+test "$(cat "$CONFIGFS_AGG_DIR/_sysfs.0/live")" = 1 || fail "chip unexpectedly remains dead"
+test "$(agg_get_chip_label _sysfs.0)" = "$(agg_configfs_dev_name _sysfs.0)" || \
+	fail "label is inconsistent"
+test "$(agg_get_chip_num_lines _sysfs.0)" = "1" || fail "number of lines is not 1"
+test "$(agg_get_line_name _sysfs.0 0)" = "" || fail "line name unexpectedly set"
+echo "$(agg_configfs_dev_name _sysfs.0)" > "$SYSFS_AGG_DIR/delete_device"
+test -d $CONFIGFS_AGG_DIR/_sysfs.0 && fail "_sysfs.0 unexpectedly remains"
+test -d /dev/${CHIPNAME} && fail "/dev/${CHIPNAME} unexpectedly remains"
+
+echo "1.2.4. Can't instantiate a chip with invalid configuration"
+echo "xyz 0" > "$SYSFS_AGG_DIR/new_device"
+test "$(cat $CONFIGFS_AGG_DIR/_sysfs.0/live)" = 0 || fail "chip unexpectedly alive"
+echo "$(agg_configfs_dev_name _sysfs.0)" > "$SYSFS_AGG_DIR/delete_device"
+
+echo "2. GPIO aggregator configuration"
+
+echo "2.1. Configuring aggregators instantiated via configfs"
+setup_2_1() {
+	agg_create_chip   agg0
+	agg_create_line   agg0 line0
+	agg_create_line   agg0 line1
+	agg_set_key       agg0 line0 "$(sim_get_chip_label chip0 bank0)"
+	agg_set_key       agg0 line1 "$(sim_get_chip_label chip1 bank0)"
+	agg_set_offset    agg0 line0 1
+	agg_set_offset    agg0 line1 3
+	agg_set_line_name agg0 line0 test0
+	agg_set_line_name agg0 line1 test1
+	agg_enable_chip   agg0
+}
+teardown_2_1() {
+	agg_configfs_cleanup
+}
+
+echo "2.1.1. While offline"
+
+echo "2.1.1.1. Line can be added/removed"
+setup_2_1
+agg_disable_chip  agg0
+agg_create_line   agg0 line2
+agg_set_key       agg0 line2 "$(sim_get_chip_label chip0 bank1)"
+agg_set_offset    agg0 line2 5
+agg_enable_chip   agg0
+test "$(agg_get_chip_num_lines agg0)" = "3" || fail "number of lines is not 1"
+teardown_2_1
+
+echo "2.1.1.2. Line key can be modified"
+setup_2_1
+agg_disable_chip  agg0
+agg_set_key       agg0 line0 "$(sim_get_chip_label chip0 bank1)"
+agg_set_key       agg0 line1 "$(sim_get_chip_label chip1 bank1)"
+agg_enable_chip   agg0
+teardown_2_1
+
+echo "2.1.1.3. Line name can be modified"
+setup_2_1
+agg_disable_chip  agg0
+agg_set_line_name agg0 line0 new0
+agg_set_line_name agg0 line1 new1
+agg_enable_chip   agg0
+test "$(agg_get_line_name agg0 0)" = "new0" || fail "line name is unset"
+test "$(agg_get_line_name agg0 1)" = "new1" || fail "line name is unset"
+teardown_2_1
+
+echo "2.1.1.4. Line offset can be modified"
+setup_2_1
+agg_disable_chip  agg0
+agg_set_offset    agg0 line0 5
+agg_set_offset    agg0 line1 7
+agg_enable_chip   agg0
+teardown_2_1
+
+echo "2.1.1.5. Can re-enable a chip after valid reconfiguration"
+setup_2_1
+agg_disable_chip  agg0
+agg_set_key       agg0 line0 "$(sim_get_chip_label chip1 bank1)"
+agg_set_offset    agg0 line0 15
+agg_set_key       agg0 line1 "$(sim_get_chip_label chip0 bank1)"
+agg_set_offset    agg0 line0 14
+agg_create_line   agg0 line2
+agg_set_key       agg0 line2 "$(sim_get_chip_label chip0 bank1)"
+agg_set_offset    agg0 line2 13
+agg_enable_chip   agg0
+test "$(agg_get_chip_num_lines agg0)" = "3" || fail "number of lines is not 1"
+teardown_2_1
+
+echo "2.1.1.7. Can't re-enable a chip with invalid reconfiguration"
+setup_2_1
+agg_disable_chip  agg0
+agg_set_key       agg0 line0 invalidkey
+echo 1 > "$CONFIGFS_AGG_DIR/agg0/live" 2> /dev/null && fail "chip unexpectedly enabled"
+teardown_2_1
+setup_2_1
+agg_disable_chip  agg0
+agg_set_offset    agg0 line0 99
+echo 1 > "$CONFIGFS_AGG_DIR/agg0/live" 2> /dev/null && fail "chip unexpectedly enabled"
+teardown_2_1
+
+echo "2.1.2. While online"
+
+echo "2.1.2.1. Can't add/remove line"
+setup_2_1
+mkdir "$CONFIGFS_AGG_DIR/agg0/line2" 2> /dev/null && fail "line unexpectedly added"
+rmdir "$CONFIGFS_AGG_DIR/agg0/line1" 2> /dev/null && fail "line unexpectedly removed"
+teardown_2_1
+
+echo "2.1.2.2. Can't modify line key"
+setup_2_1
+echo "chip1_bank1" > "$CONFIGFS_AGG_DIR/agg0/line0/key" 2> /dev/null && \
+	fail "lookup key unexpectedly updated"
+teardown_2_1
+
+echo "2.1.2.3. Can't modify line name"
+setup_2_1
+echo "new0" > "$CONFIGFS_AGG_DIR/agg0/line0/name" 2> /dev/null && \
+	fail "name unexpectedly updated"
+teardown_2_1
+
+echo "2.1.2.4. Can't modify line offset"
+setup_2_1
+echo "5" > "$CONFIGFS_AGG_DIR/agg0/line0/offset" 2> /dev/null && \
+	fail "offset unexpectedly updated"
+teardown_2_1
+
+echo "2.2. Configuring aggregators instantiated via sysfs"
+setup_2_2() {
+	echo "chip0_bank0 1 chip1_bank0 3" > "$SYSFS_AGG_DIR/new_device"
+}
+teardown_2_2() {
+	echo "$(agg_configfs_dev_name _sysfs.0)" > "$SYSFS_AGG_DIR/delete_device"
+}
+
+echo "2.2.1. While online"
+
+echo "2.2.1.1. Can toggle live"
+setup_2_2
+agg_disable_chip  _sysfs.0
+agg_enable_chip   _sysfs.0
+teardown_2_2
+
+echo "2.2.1.2. Can't add/remove line"
+setup_2_2
+mkdir "$CONFIGFS_AGG_DIR/_sysfs.0/line2" 2> /dev/null && fail "line unexpectedly added"
+rmdir "$CONFIGFS_AGG_DIR/_sysfs.0/line1" 2> /dev/null && fail "line unexpectedly removed"
+teardown_2_2
+
+echo "2.2.1.3. Can't modify line key"
+setup_2_2
+echo "chip1_bank1" > "$CONFIGFS_AGG_DIR/_sysfs.0/line0/key" 2> /dev/null && \
+	fail "lookup key unexpectedly updated"
+teardown_2_2
+
+echo "2.2.1.4. Can't modify line name"
+setup_2_2
+echo "new0" > "$CONFIGFS_AGG_DIR/_sysfs.0/line0/name" 2> /dev/null && \
+	fail "name unexpectedly updated"
+teardown_2_2
+
+echo "2.2.1.5. Can't modify line offset"
+setup_2_2
+echo "5" > "$CONFIGFS_AGG_DIR/_sysfs.0/line0/offset" 2> /dev/null && \
+	fail "offset unexpectedly updated"
+teardown_2_2
+
+echo "2.2.2. While waiting for deferred probe"
+
+echo "2.2.2.1. Can't add/remove line despite live = 0"
+sim_disable_chip chip0
+setup_2_2
+mkdir "$CONFIGFS_AGG_DIR/_sysfs.0/line2" 2> /dev/null && fail "line unexpectedly added"
+rmdir "$CONFIGFS_AGG_DIR/_sysfs.0/line1" 2> /dev/null && fail "line unexpectedly removed"
+teardown_2_2
+sim_enable_chip chip0
+
+echo "2.2.2.2. Can't modify line key"
+sim_disable_chip chip0
+setup_2_2
+echo "chip1_bank1" > "$CONFIGFS_AGG_DIR/_sysfs.0/line0/key" 2> /dev/null && \
+	fail "lookup key unexpectedly updated"
+teardown_2_2
+sim_enable_chip chip0
+
+echo "2.2.2.3. Can't modify line name"
+sim_disable_chip chip0
+setup_2_2
+echo "new0" > "$CONFIGFS_AGG_DIR/_sysfs.0/line0/name" 2> /dev/null && \
+	fail "name unexpectedly updated"
+teardown_2_2
+sim_enable_chip chip0
+
+echo "2.2.2.4. Can't modify line offset"
+sim_disable_chip chip0
+setup_2_2
+echo 5 > "$CONFIGFS_AGG_DIR/_sysfs.0/line0/offset" 2> /dev/null && \
+	fail "offset unexpectedly updated"
+teardown_2_2
+sim_enable_chip chip0
+
+echo "2.2.2.5. Can't toggle live"
+sim_disable_chip chip0
+setup_2_2
+test "$(cat "$CONFIGFS_AGG_DIR/_sysfs.0/live")" = 0 || fail "chip unexpectedly alive"
+echo 1 > "$CONFIGFS_AGG_DIR/_sysfs.0/live" 2> /dev/null && fail "chip unexpectedly enabled"
+teardown_2_2
+sim_enable_chip chip0
+
+echo "2.2.3. While offline"
+
+echo "2.2.3.1. Can't add/remove line despite live = 0"
+setup_2_2
+agg_disable_chip _sysfs.0
+mkdir "$CONFIGFS_AGG_DIR/_sysfs.0/line2" 2> /dev/null && fail "line unexpectedly added"
+rmdir "$CONFIGFS_AGG_DIR/_sysfs.0/line1" 2> /dev/null && fail "line unexpectedly removed"
+teardown_2_2
+
+echo "2.2.3.2. Line key can be modified"
+setup_2_2
+agg_disable_chip  _sysfs.0
+agg_set_key       _sysfs.0 line0 "$(sim_get_chip_label chip0 bank1)"
+agg_set_key       _sysfs.0 line1 "$(sim_get_chip_label chip1 bank1)"
+agg_enable_chip   _sysfs.0
+teardown_2_2
+
+echo "2.2.3.3. Line name can be modified"
+setup_2_2
+agg_disable_chip  _sysfs.0
+agg_set_line_name _sysfs.0 line0 new0
+agg_set_line_name _sysfs.0 line1 new1
+agg_enable_chip   _sysfs.0
+test "$(agg_get_line_name _sysfs.0 0)" = "new0" || fail "line name is unset"
+test "$(agg_get_line_name _sysfs.0 1)" = "new1" || fail "line name is unset"
+teardown_2_2
+
+echo "2.2.3.4. Line offset can be modified"
+setup_2_2
+agg_disable_chip  _sysfs.0
+agg_set_offset    _sysfs.0 line0 5
+agg_set_offset    _sysfs.0 line1 7
+agg_enable_chip   _sysfs.0
+teardown_2_2
+
+echo "2.2.3.5. Can re-enable a chip with valid reconfiguration"
+setup_2_2
+agg_disable_chip  _sysfs.0
+agg_set_key       _sysfs.0 line0 "$(sim_get_chip_label chip1 bank1)"
+agg_set_offset    _sysfs.0 line0 15
+agg_set_key       _sysfs.0 line1 "$(sim_get_chip_label chip0 bank1)"
+agg_set_offset    _sysfs.0 line0 14
+agg_enable_chip   _sysfs.0
+teardown_2_2
+
+echo "2.2.3.6. Can't re-enable a chip with invalid reconfiguration"
+setup_2_2
+agg_disable_chip  _sysfs.0
+agg_set_key       _sysfs.0 line0 invalidkey
+echo 1 > "$CONFIGFS_AGG_DIR/_sysfs.0/live" 2> /dev/null && fail "chip unexpectedly enabled"
+teardown_2_2
+setup_2_2
+agg_disable_chip  _sysfs.0
+agg_set_offset    _sysfs.0 line0 99
+echo 1 > "$CONFIGFS_AGG_DIR/_sysfs.0/live" 2> /dev/null && fail "chip unexpectedly enabled"
+teardown_2_2
+
+echo "3. Module unload"
+
+echo "3.1. Can't unload module if there is at least one device created via configfs"
+agg_create_chip agg0
+modprobe -r gpio-aggregator 2> /dev/null
+test -d /sys/module/gpio_aggregator || fail "module unexpectedly unloaded"
+agg_remove_chip agg0
+
+echo "3.2. Can unload module if there is no device created via configfs"
+echo "chip0_bank0 1 chip1_bank0 3" > "$SYSFS_AGG_DIR/new_device"
+modprobe -r gpio-aggregator 2> /dev/null
+test -d /sys/module/gpio_aggregator && fail "module unexpectedly remains to be loaded"
+modprobe gpio-aggregator 2> /dev/null
+
+echo "4. GPIO forwarder functional"
+SETTINGS="chip0:bank0:2 chip0:bank1:4 chip1:bank0:6 chip1:bank1:8"
+setup_4() {
+	local OFFSET=0
+	agg_create_chip agg0
+	for SETTING in $SETTINGS; do
+		CHIP=$(echo "$SETTING" | cut -d: -f1)
+		BANK=$(echo "$SETTING" | cut -d: -f2)
+		LINE=$(echo "$SETTING" | cut -d: -f3)
+		agg_create_line agg0 "line${OFFSET}"
+		agg_set_key     agg0 "line${OFFSET}" "$(sim_get_chip_label "$CHIP" "$BANK")"
+		agg_set_offset  agg0 "line${OFFSET}" "$LINE"
+		OFFSET=$(expr $OFFSET + 1)
+	done
+	agg_enable_chip agg0
+}
+teardown_4() {
+	agg_configfs_cleanup
+}
+
+echo "4.1. Forwarding set values"
+setup_4
+OFFSET=0
+for SETTING in $SETTINGS; do
+	CHIP=$(echo "$SETTING" | cut -d: -f1)
+	BANK=$(echo "$SETTING" | cut -d: -f2)
+	LINE=$(echo "$SETTING" | cut -d: -f3)
+	DEVNAME=$(cat "$CONFIGFS_SIM_DIR/$CHIP/dev_name")
+	CHIPNAME=$(cat "$CONFIGFS_SIM_DIR/$CHIP/$BANK/chip_name")
+	VAL_PATH="/sys/devices/platform/$DEVNAME/$CHIPNAME/sim_gpio${LINE}/value"
+	test $(cat $VAL_PATH) = "0" || fail "incorrect value read from sysfs"
+	$BASE_DIR/gpio-mockup-cdev -s 1 "/dev/$(agg_configfs_chip_name agg0)" "$OFFSET" &
+	mock_pid=$!
+	sleep 0.1 # FIXME Any better way?
+	test "$(cat $VAL_PATH)" = "1" || fail "incorrect value read from sysfs"
+	kill "$mock_pid"
+	OFFSET=$(expr $OFFSET + 1)
+done
+teardown_4
+
+echo "4.2. Forwarding set config"
+setup_4
+OFFSET=0
+for SETTING in $SETTINGS; do
+	CHIP=$(echo "$SETTING" | cut -d: -f1)
+	BANK=$(echo "$SETTING" | cut -d: -f2)
+	LINE=$(echo "$SETTING" | cut -d: -f3)
+	DEVNAME=$(cat "$CONFIGFS_SIM_DIR/$CHIP/dev_name")
+	CHIPNAME=$(cat "$CONFIGFS_SIM_DIR/$CHIP/$BANK/chip_name")
+	VAL_PATH="/sys/devices/platform/$DEVNAME/$CHIPNAME/sim_gpio${LINE}/value"
+	$BASE_DIR/gpio-mockup-cdev -b pull-up "/dev/$(agg_configfs_chip_name agg0)" "$OFFSET"
+	test $(cat "$VAL_PATH") = "1" || fail "incorrect value read from sysfs"
+	OFFSET=$(expr $OFFSET + 1)
+done
+teardown_4
+
+echo "5. Race condition verification"
+
+echo "5.1. Stress test of new_device/delete_device and module load/unload"
+for _ in $(seq 1000); do
+	{
+		echo "dummy 0" > "$SYSFS_AGG_DIR/new_device"
+		cat "$CONFIGFS_AGG_DIR/_sysfs.0/dev_name" > "$SYSFS_AGG_DIR/delete_device"
+	} 2> /dev/null
+done &
+writer_pid=$!
+while kill -0 "$writer_pid" 2> /dev/null; do
+	{
+		modprobe gpio-aggregator
+		modprobe -r gpio-aggregator
+	} 2> /dev/null
+done
+
+echo "GPIO $MODULE test PASS"
diff --git a/tools/testing/selftests/gpio/gpio-cdev-uaf.c b/tools/testing/selftests/gpio/gpio-cdev-uaf.c
new file mode 100644
index 000000000..765d3cc4f
--- /dev/null
+++ b/tools/testing/selftests/gpio/gpio-cdev-uaf.c
@@ -0,0 +1,292 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * GPIO character device helper for UAF tests.
+ *
+ * Copyright 2026 Google LLC
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/gpio.h>
+#include <poll.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#define CONFIGFS_DIR "/sys/kernel/config/gpio-sim"
+#define PROCFS_DIR "/proc"
+
+static void print_usage(void)
+{
+	printf("usage:\n");
+	printf("  gpio-cdev-uaf [chip|handle|event|req] [poll|read|ioctl]\n");
+}
+
+static int _create_chip(const char *name, int create)
+{
+	char path[64];
+
+	snprintf(path, sizeof(path), CONFIGFS_DIR "/%s", name);
+
+	if (create)
+		return mkdir(path, 0755);
+	else
+		return rmdir(path);
+}
+
+static int create_chip(const char *name)
+{
+	return _create_chip(name, 1);
+}
+
+static void remove_chip(const char *name)
+{
+	_create_chip(name, 0);
+}
+
+static int _create_bank(const char *chip_name, const char *name, int create)
+{
+	char path[64];
+
+	snprintf(path, sizeof(path), CONFIGFS_DIR "/%s/%s", chip_name, name);
+
+	if (create)
+		return mkdir(path, 0755);
+	else
+		return rmdir(path);
+}
+
+static int create_bank(const char *chip_name, const char *name)
+{
+	return _create_bank(chip_name, name, 1);
+}
+
+static void remove_bank(const char *chip_name, const char *name)
+{
+	_create_bank(chip_name, name, 0);
+}
+
+static int _enable_chip(const char *name, int enable)
+{
+	char path[64];
+	int fd, ret;
+
+	snprintf(path, sizeof(path), CONFIGFS_DIR "/%s/live", name);
+
+	fd = open(path, O_WRONLY);
+	if (fd == -1)
+		return fd;
+
+	if (enable)
+		ret = write(fd, "1", 1);
+	else
+		ret = write(fd, "0", 1);
+
+	close(fd);
+	return ret == 1 ? 0 : -1;
+}
+
+static int enable_chip(const char *name)
+{
+	return _enable_chip(name, 1);
+}
+
+static void disable_chip(const char *name)
+{
+	_enable_chip(name, 0);
+}
+
+static int open_chip(const char *chip_name, const char *bank_name)
+{
+	char path[64], dev_name[32];
+	int ret, fd;
+
+	ret = create_chip(chip_name);
+	if (ret) {
+		fprintf(stderr, "failed to create chip\n");
+		return ret;
+	}
+
+	ret = create_bank(chip_name, bank_name);
+	if (ret) {
+		fprintf(stderr, "failed to create bank\n");
+		goto err_remove_chip;
+	}
+
+	ret = enable_chip(chip_name);
+	if (ret) {
+		fprintf(stderr, "failed to enable chip\n");
+		goto err_remove_bank;
+	}
+
+	snprintf(path, sizeof(path), CONFIGFS_DIR "/%s/%s/chip_name",
+		 chip_name, bank_name);
+
+	fd = open(path, O_RDONLY);
+	if (fd == -1) {
+		ret = fd;
+		fprintf(stderr, "failed to open %s\n", path);
+		goto err_disable_chip;
+	}
+
+	ret = read(fd, dev_name, sizeof(dev_name) - 1);
+	close(fd);
+	if (ret == -1) {
+		fprintf(stderr, "failed to read %s\n", path);
+		goto err_disable_chip;
+	}
+	dev_name[ret] = '\0';
+	if (ret && dev_name[ret - 1] == '\n')
+		dev_name[ret - 1] = '\0';
+
+	snprintf(path, sizeof(path), "/dev/%s", dev_name);
+
+	fd = open(path, O_RDWR);
+	if (fd == -1) {
+		ret = fd;
+		fprintf(stderr, "failed to open %s\n", path);
+		goto err_disable_chip;
+	}
+
+	return fd;
+err_disable_chip:
+	disable_chip(chip_name);
+err_remove_bank:
+	remove_bank(chip_name, bank_name);
+err_remove_chip:
+	remove_chip(chip_name);
+	return ret;
+}
+
+static void close_chip(const char *chip_name, const char *bank_name)
+{
+	disable_chip(chip_name);
+	remove_bank(chip_name, bank_name);
+	remove_chip(chip_name);
+}
+
+static int test_poll(int fd)
+{
+	struct pollfd pfds;
+
+	pfds.fd = fd;
+	pfds.events = POLLIN;
+	pfds.revents = 0;
+
+	if (poll(&pfds, 1, 0) == -1)
+		return -1;
+
+	return (pfds.revents & ~(POLLHUP | POLLERR)) ? -1 : 0;
+}
+
+static int test_read(int fd)
+{
+	char data;
+
+	if (read(fd, &data, 1) == -1 && errno == ENODEV)
+		return 0;
+	return -1;
+}
+
+static int test_ioctl(int fd)
+{
+	if (ioctl(fd, 0, NULL) == -1 && errno == ENODEV)
+		return 0;
+	return -1;
+}
+
+int main(int argc, char **argv)
+{
+	int cfd, fd, ret;
+	int (*test_func)(int);
+
+	if (argc != 3) {
+		print_usage();
+		return EXIT_FAILURE;
+	}
+
+	if (strcmp(argv[1], "chip") == 0 ||
+	    strcmp(argv[1], "event") == 0 ||
+	    strcmp(argv[1], "req") == 0) {
+		if (strcmp(argv[2], "poll") &&
+		    strcmp(argv[2], "read") &&
+		    strcmp(argv[2], "ioctl")) {
+			fprintf(stderr, "unknown command: %s\n", argv[2]);
+			return EXIT_FAILURE;
+		}
+	} else if (strcmp(argv[1], "handle") == 0) {
+		if (strcmp(argv[2], "ioctl")) {
+			fprintf(stderr, "unknown command: %s\n", argv[2]);
+			return EXIT_FAILURE;
+		}
+	} else {
+		fprintf(stderr, "unknown command: %s\n", argv[1]);
+		return EXIT_FAILURE;
+	}
+
+	if (strcmp(argv[2], "poll") == 0)
+		test_func = test_poll;
+	else if (strcmp(argv[2], "read") == 0)
+		test_func = test_read;
+	else	/* strcmp(argv[2], "ioctl") == 0 */
+		test_func = test_ioctl;
+
+	cfd = open_chip("chip", "bank");
+	if (cfd == -1) {
+		fprintf(stderr, "failed to open chip\n");
+		return EXIT_FAILURE;
+	}
+
+	/* Step 1: Hold a FD to the test target. */
+	if (strcmp(argv[1], "chip") == 0) {
+		fd = cfd;
+	} else if (strcmp(argv[1], "handle") == 0) {
+		struct gpiohandle_request req = {0};
+
+		req.lines = 1;
+		if (ioctl(cfd, GPIO_GET_LINEHANDLE_IOCTL, &req) == -1) {
+			fprintf(stderr, "failed to get handle FD\n");
+			goto err_close_chip;
+		}
+
+		close(cfd);
+		fd = req.fd;
+	} else if (strcmp(argv[1], "event") == 0) {
+		struct gpioevent_request req = {0};
+
+		if (ioctl(cfd, GPIO_GET_LINEEVENT_IOCTL, &req) == -1) {
+			fprintf(stderr, "failed to get event FD\n");
+			goto err_close_chip;
+		}
+
+		close(cfd);
+		fd = req.fd;
+	} else {	/* strcmp(argv[1], "req") == 0 */
+		struct gpio_v2_line_request req = {0};
+
+		req.num_lines = 1;
+		if (ioctl(cfd, GPIO_V2_GET_LINE_IOCTL, &req) == -1) {
+			fprintf(stderr, "failed to get req FD\n");
+			goto err_close_chip;
+		}
+
+		close(cfd);
+		fd = req.fd;
+	}
+
+	/* Step 2: Free the chip. */
+	close_chip("chip", "bank");
+
+	/* Step 3: Access the dangling FD to trigger UAF. */
+	ret = test_func(fd);
+	close(fd);
+	return ret ? EXIT_FAILURE : EXIT_SUCCESS;
+err_close_chip:
+	close(cfd);
+	close_chip("chip", "bank");
+	return EXIT_FAILURE;
+}
diff --git a/tools/testing/selftests/gpio/gpio-cdev-uaf.sh b/tools/testing/selftests/gpio/gpio-cdev-uaf.sh
new file mode 100755
index 000000000..6e4753301
--- /dev/null
+++ b/tools/testing/selftests/gpio/gpio-cdev-uaf.sh
@@ -0,0 +1,63 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# Copyright 2026 Google LLC
+
+BASE_DIR=`dirname $0`
+MODULE="gpio-cdev-uaf"
+
+fail() {
+	echo "$*" >&2
+	echo "GPIO $MODULE test FAIL"
+	exit 1
+}
+
+skip() {
+	echo "$*" >&2
+	echo "GPIO $MODULE test SKIP"
+	exit 4
+}
+
+# Load the gpio-sim module. This will pull in configfs if needed too.
+modprobe gpio-sim || skip "unable to load the gpio-sim module"
+# Make sure configfs is mounted at /sys/kernel/config. Wait a bit if needed.
+for _ in `seq 5`; do
+	mountpoint -q /sys/kernel/config && break
+	mount -t configfs none /sys/kernel/config
+	sleep 0.1
+done
+mountpoint -q /sys/kernel/config || \
+	skip "configfs not mounted at /sys/kernel/config"
+
+echo "1. GPIO"
+
+echo "1.1. poll"
+$BASE_DIR/gpio-cdev-uaf chip poll || fail "failed to test chip poll"
+echo "1.2. read"
+$BASE_DIR/gpio-cdev-uaf chip read || fail "failed to test chip read"
+echo "1.3. ioctl"
+$BASE_DIR/gpio-cdev-uaf chip ioctl || fail "failed to test chip ioctl"
+
+echo "2. linehandle"
+
+echo "2.1. ioctl"
+$BASE_DIR/gpio-cdev-uaf handle ioctl || fail "failed to test handle ioctl"
+
+echo "3. lineevent"
+
+echo "3.1. read"
+$BASE_DIR/gpio-cdev-uaf event read || fail "failed to test event read"
+echo "3.2. poll"
+$BASE_DIR/gpio-cdev-uaf event poll || fail "failed to test event poll"
+echo "3.3. ioctl"
+$BASE_DIR/gpio-cdev-uaf event ioctl || fail "failed to test event ioctl"
+
+echo "4. linereq"
+
+echo "4.1. read"
+$BASE_DIR/gpio-cdev-uaf req read || fail "failed to test req read"
+echo "4.2. poll"
+$BASE_DIR/gpio-cdev-uaf req poll || fail "failed to test req poll"
+echo "4.3. ioctl"
+$BASE_DIR/gpio-cdev-uaf req ioctl || fail "failed to test req ioctl"
+
+echo "GPIO $MODULE test PASS"
diff --git a/tools/testing/selftests/gpio/gpio-chip-info.c b/tools/testing/selftests/gpio/gpio-chip-info.c
new file mode 100644
index 000000000..fdc07e742
--- /dev/null
+++ b/tools/testing/selftests/gpio/gpio-chip-info.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * GPIO character device helper for reading chip information.
+ *
+ * Copyright (C) 2021 Bartosz Golaszewski <brgl@bgdev.pl>
+ */
+
+#include <fcntl.h>
+#include <linux/gpio.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+
+static void print_usage(void)
+{
+	printf("usage:\n");
+	printf("  gpio-chip-info <chip path> [name|label|num-lines]\n");
+}
+
+int main(int argc, char **argv)
+{
+	struct gpiochip_info info;
+	int fd, ret;
+
+	if (argc != 3) {
+		print_usage();
+		return EXIT_FAILURE;
+	}
+
+	fd = open(argv[1], O_RDWR);
+	if (fd < 0) {
+		perror("unable to open the GPIO chip");
+		return EXIT_FAILURE;
+	}
+
+	memset(&info, 0, sizeof(info));
+	ret = ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &info);
+	if (ret) {
+		perror("chip info ioctl failed");
+		return EXIT_FAILURE;
+	}
+
+	if (strcmp(argv[2], "name") == 0) {
+		printf("%s\n", info.name);
+	} else if (strcmp(argv[2], "label") == 0) {
+		printf("%s\n", info.label);
+	} else if (strcmp(argv[2], "num-lines") == 0) {
+		printf("%u\n", info.lines);
+	} else {
+		fprintf(stderr, "unknown command: %s\n", argv[2]);
+		return EXIT_FAILURE;
+	}
+
+	return EXIT_SUCCESS;
+}
diff --git a/tools/testing/selftests/gpio/gpio-line-name.c b/tools/testing/selftests/gpio/gpio-line-name.c
new file mode 100644
index 000000000..e635cfadb
--- /dev/null
+++ b/tools/testing/selftests/gpio/gpio-line-name.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * GPIO character device helper for reading line names.
+ *
+ * Copyright (C) 2021 Bartosz Golaszewski <brgl@bgdev.pl>
+ */
+
+#include <fcntl.h>
+#include <linux/gpio.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+
+static void print_usage(void)
+{
+	printf("usage:\n");
+	printf("  gpio-line-name <chip path> <line offset>\n");
+}
+
+int main(int argc, char **argv)
+{
+	struct gpio_v2_line_info info;
+	int fd, ret;
+	char *endp;
+
+	if (argc != 3) {
+		print_usage();
+		return EXIT_FAILURE;
+	}
+
+	fd = open(argv[1], O_RDWR);
+	if (fd < 0) {
+		perror("unable to open the GPIO chip");
+		return EXIT_FAILURE;
+	}
+
+	memset(&info, 0, sizeof(info));
+	info.offset = strtoul(argv[2], &endp, 10);
+	if (*endp != '\0') {
+		print_usage();
+		return EXIT_FAILURE;
+	}
+
+	ret = ioctl(fd, GPIO_V2_GET_LINEINFO_IOCTL, &info);
+	if (ret) {
+		perror("line info ioctl failed");
+		return EXIT_FAILURE;
+	}
+
+	printf("%s\n", info.name);
+
+	return EXIT_SUCCESS;
+}
diff --git a/tools/testing/selftests/gpio/gpio-mockup-cdev.c b/tools/testing/selftests/gpio/gpio-mockup-cdev.c
new file mode 100644
index 000000000..d1640f44f
--- /dev/null
+++ b/tools/testing/selftests/gpio/gpio-mockup-cdev.c
@@ -0,0 +1,198 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * GPIO mockup cdev test helper
+ *
+ * Copyright (C) 2020 Kent Gibson
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <linux/gpio.h>
+
+#define CONSUMER	"gpio-mockup-cdev"
+
+static int request_line_v2(int cfd, unsigned int offset,
+			   uint64_t flags, unsigned int val)
+{
+	struct gpio_v2_line_request req;
+	int ret;
+
+	memset(&req, 0, sizeof(req));
+	req.num_lines = 1;
+	req.offsets[0] = offset;
+	req.config.flags = flags;
+	strcpy(req.consumer, CONSUMER);
+	if (flags & GPIO_V2_LINE_FLAG_OUTPUT) {
+		req.config.num_attrs = 1;
+		req.config.attrs[0].mask = 1;
+		req.config.attrs[0].attr.id = GPIO_V2_LINE_ATTR_ID_OUTPUT_VALUES;
+		if (val)
+			req.config.attrs[0].attr.values = 1;
+	}
+	ret = ioctl(cfd, GPIO_V2_GET_LINE_IOCTL, &req);
+	if (ret == -1)
+		return -errno;
+	return req.fd;
+}
+
+
+static int get_value_v2(int lfd)
+{
+	struct gpio_v2_line_values vals;
+	int ret;
+
+	memset(&vals, 0, sizeof(vals));
+	vals.mask = 1;
+	ret = ioctl(lfd, GPIO_V2_LINE_GET_VALUES_IOCTL, &vals);
+	if (ret == -1)
+		return -errno;
+	return vals.bits & 0x1;
+}
+
+static int request_line_v1(int cfd, unsigned int offset,
+			   uint32_t flags, unsigned int val)
+{
+	struct gpiohandle_request req;
+	int ret;
+
+	memset(&req, 0, sizeof(req));
+	req.lines = 1;
+	req.lineoffsets[0] = offset;
+	req.flags = flags;
+	strcpy(req.consumer_label, CONSUMER);
+	if (flags & GPIOHANDLE_REQUEST_OUTPUT)
+		req.default_values[0] = val;
+
+	ret = ioctl(cfd, GPIO_GET_LINEHANDLE_IOCTL, &req);
+	if (ret == -1)
+		return -errno;
+	return req.fd;
+}
+
+static int get_value_v1(int lfd)
+{
+	struct gpiohandle_data vals;
+	int ret;
+
+	memset(&vals, 0, sizeof(vals));
+	ret = ioctl(lfd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, &vals);
+	if (ret == -1)
+		return -errno;
+	return vals.values[0];
+}
+
+static void usage(char *prog)
+{
+	printf("Usage: %s [-l] [-b <bias>] [-s <value>] [-u <uAPI>] <gpiochip> <offset>\n", prog);
+	printf("        -b: set line bias to one of pull-down, pull-up, disabled\n");
+	printf("               (default is to leave bias unchanged):\n");
+	printf("        -l: set line active low (default is active high)\n");
+	printf("        -s: set line value (default is to get line value)\n");
+	printf("        -u: uAPI version to use (default is 2)\n");
+	exit(-1);
+}
+
+static int wait_signal(void)
+{
+	int sig;
+	sigset_t wset;
+
+	sigemptyset(&wset);
+	sigaddset(&wset, SIGHUP);
+	sigaddset(&wset, SIGINT);
+	sigaddset(&wset, SIGTERM);
+	sigwait(&wset, &sig);
+
+	return sig;
+}
+
+int main(int argc, char *argv[])
+{
+	char *chip;
+	int opt, ret, cfd, lfd;
+	unsigned int offset, val = 0, abiv;
+	uint32_t flags_v1;
+	uint64_t flags_v2;
+
+	abiv = 2;
+	ret = 0;
+	flags_v1 = GPIOHANDLE_REQUEST_INPUT;
+	flags_v2 = GPIO_V2_LINE_FLAG_INPUT;
+
+	while ((opt = getopt(argc, argv, "lb:s:u:")) != -1) {
+		switch (opt) {
+		case 'l':
+			flags_v1 |= GPIOHANDLE_REQUEST_ACTIVE_LOW;
+			flags_v2 |= GPIO_V2_LINE_FLAG_ACTIVE_LOW;
+			break;
+		case 'b':
+			if (strcmp("pull-up", optarg) == 0) {
+				flags_v1 |= GPIOHANDLE_REQUEST_BIAS_PULL_UP;
+				flags_v2 |= GPIO_V2_LINE_FLAG_BIAS_PULL_UP;
+			} else if (strcmp("pull-down", optarg) == 0) {
+				flags_v1 |= GPIOHANDLE_REQUEST_BIAS_PULL_DOWN;
+				flags_v2 |= GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN;
+			} else if (strcmp("disabled", optarg) == 0) {
+				flags_v1 |= GPIOHANDLE_REQUEST_BIAS_DISABLE;
+				flags_v2 |= GPIO_V2_LINE_FLAG_BIAS_DISABLED;
+			}
+			break;
+		case 's':
+			val = atoi(optarg);
+			flags_v1 &= ~GPIOHANDLE_REQUEST_INPUT;
+			flags_v1 |= GPIOHANDLE_REQUEST_OUTPUT;
+			flags_v2 &= ~GPIO_V2_LINE_FLAG_INPUT;
+			flags_v2 |= GPIO_V2_LINE_FLAG_OUTPUT;
+			break;
+		case 'u':
+			abiv = atoi(optarg);
+			break;
+		default:
+			usage(argv[0]);
+		}
+	}
+
+	if (argc < optind + 2)
+		usage(argv[0]);
+
+	chip = argv[optind];
+	offset = atoi(argv[optind + 1]);
+
+	cfd = open(chip, 0);
+	if (cfd == -1) {
+		fprintf(stderr, "Failed to open %s: %s\n", chip, strerror(errno));
+		return -errno;
+	}
+
+	if (abiv == 1)
+		lfd = request_line_v1(cfd, offset, flags_v1, val);
+	else
+		lfd = request_line_v2(cfd, offset, flags_v2, val);
+
+	close(cfd);
+
+	if (lfd < 0) {
+		fprintf(stderr, "Failed to request %s:%d: %s\n", chip, offset, strerror(-lfd));
+		return lfd;
+	}
+
+	if (flags_v2 & GPIO_V2_LINE_FLAG_OUTPUT) {
+		wait_signal();
+	} else {
+		if (abiv == 1)
+			ret = get_value_v1(lfd);
+		else
+			ret = get_value_v2(lfd);
+	}
+
+	close(lfd);
+
+	return ret;
+}
diff --git a/tools/testing/selftests/gpio/gpio-mockup-sysfs.sh b/tools/testing/selftests/gpio/gpio-mockup-sysfs.sh
new file mode 100755
index 000000000..2d2e5d876
--- /dev/null
+++ b/tools/testing/selftests/gpio/gpio-mockup-sysfs.sh
@@ -0,0 +1,77 @@
+
+# SPDX-License-Identifier: GPL-2.0
+
+# Overrides functions in gpio-mockup.sh to test using the GPIO SYSFS uAPI
+
+SYSFS=`grep -w sysfs /proc/mounts | cut -f2 -d' '`
+[ -d "$SYSFS" ] || skip "sysfs is not mounted"
+
+GPIO_SYSFS="${SYSFS}/class/gpio"
+[ -d "$GPIO_SYSFS" ] || skip "CONFIG_GPIO_SYSFS is not selected"
+
+PLATFORM_SYSFS=$SYSFS/devices/platform
+
+sysfs_nr=
+sysfs_ldir=
+
+# determine the sysfs GPIO number given the $chip and $offset
+# e.g. gpiochip1:32
+find_sysfs_nr()
+{
+	# e.g. /sys/devices/platform/gpio-mockup.1/gpiochip1
+	local platform=$(find $PLATFORM_SYSFS -mindepth 2 -maxdepth 2 -type d -name $chip)
+	[ "$platform" ] || fail "can't find platform of $chip"
+	# e.g. /sys/devices/platform/gpio-mockup.1/gpio/gpiochip508/base
+	local base=$(find ${platform%/*}/gpio/ -mindepth 2 -maxdepth 2 -type f -name base)
+	[ "$base" ] || fail "can't find base of $chip"
+	sysfs_nr=$(($(< "$base") + $offset))
+	sysfs_ldir="$GPIO_SYSFS/gpio$sysfs_nr"
+}
+
+acquire_line()
+{
+	[ "$sysfs_nr" ] && return
+	find_sysfs_nr
+	echo "$sysfs_nr" > "$GPIO_SYSFS/export"
+}
+
+# The helpers being overridden...
+get_line()
+{
+	[ -e "$sysfs_ldir/value" ] && echo $(< "$sysfs_ldir/value")
+}
+
+set_line()
+{
+	acquire_line
+
+	for option in $*; do
+		case $option in
+		active-high)
+			echo 0 > "$sysfs_ldir/active_low"
+			;;
+		active-low)
+			echo 1 > "$sysfs_ldir/active_low"
+			;;
+		input)
+			echo "in" > "$sysfs_ldir/direction"
+			;;
+		0)
+			echo "out" > "$sysfs_ldir/direction"
+			echo 0 > "$sysfs_ldir/value"
+			;;
+		1)
+			echo "out" > "$sysfs_ldir/direction"
+			echo 1 > "$sysfs_ldir/value"
+			;;
+		esac
+	done
+}
+
+release_line()
+{
+	[ "$sysfs_nr" ] || return 0
+	echo "$sysfs_nr" > "$GPIO_SYSFS/unexport"
+	sysfs_nr=
+	sysfs_ldir=
+}
diff --git a/tools/testing/selftests/gpio/gpio-mockup.sh b/tools/testing/selftests/gpio/gpio-mockup.sh
new file mode 100755
index 000000000..fc2dd4c24
--- /dev/null
+++ b/tools/testing/selftests/gpio/gpio-mockup.sh
@@ -0,0 +1,400 @@
+#!/bin/bash -efu
+# SPDX-License-Identifier: GPL-2.0
+
+#exit status
+#0: success
+#1: fail
+#4: skip test - including run as non-root user
+
+BASE=${0%/*}
+DEBUGFS=
+GPIO_DEBUGFS=
+dev_type="cdev"
+module="gpio-mockup"
+verbose=
+full_test=
+random=
+uapi_opt=
+active_opt=
+bias_opt=
+line_set_pid=
+
+# Kselftest return codes
+ksft_fail=1
+ksft_skip=4
+
+usage()
+{
+	echo "Usage:"
+	echo "$0 [-frv] [-t type]"
+	echo "-f:  full test (minimal set run by default)"
+	echo "-r:  test random lines as well as fence posts"
+	echo "-t:  interface type:"
+	echo "      cdev (character device ABI) - default"
+	echo "      cdev_v1 (deprecated character device ABI)"
+	echo "      sysfs (deprecated SYSFS ABI)"
+	echo "-v:  verbose progress reporting"
+	exit $ksft_fail
+}
+
+skip()
+{
+	echo "$*" >&2
+	echo "GPIO $module test SKIP"
+	exit $ksft_skip
+}
+
+prerequisite()
+{
+	[ $(id -u) -eq 0 ] || skip "must be run as root"
+
+	DEBUGFS=$(grep -w debugfs /proc/mounts | cut -f2 -d' ')
+	[ -d "$DEBUGFS" ] || skip "debugfs is not mounted"
+
+	GPIO_DEBUGFS=$DEBUGFS/$module
+}
+
+remove_module()
+{
+	modprobe -r -q $module
+}
+
+cleanup()
+{
+	set +e
+	release_line
+	remove_module
+	jobs -p | xargs -r kill > /dev/null 2>&1
+}
+
+fail()
+{
+	echo "test failed: $*" >&2
+	echo "GPIO $module test FAIL"
+	exit $ksft_fail
+}
+
+try_insert_module()
+{
+	modprobe -q $module "$1" || fail "insert $module failed with error $?"
+}
+
+log()
+{
+	[ -z "$verbose" ] || echo "$*"
+}
+
+# The following line helpers, release_Line, get_line and set_line, all
+# make use of the global $chip and $offset variables.
+#
+# This implementation drives the GPIO character device (cdev) uAPI.
+# Other implementations may override these to test different uAPIs.
+
+# Release any resources related to the line
+release_line()
+{
+	[ "$line_set_pid" ] && kill $line_set_pid && wait $line_set_pid || true
+	line_set_pid=
+}
+
+# Read the current value of the line
+get_line()
+{
+	release_line
+
+	local cdev_opts=${uapi_opt}${active_opt}
+	$BASE/gpio-mockup-cdev $cdev_opts /dev/$chip $offset
+	echo $?
+}
+
+# Set the state of the line
+#
+# Changes to line configuration are provided as parameters.
+# The line is assumed to be an output if the line value 0 or 1 is
+# specified, else an input.
+set_line()
+{
+	local val=
+
+	release_line
+
+	# parse config options...
+	for option in $*; do
+		case $option in
+		active-low)
+			active_opt="-l "
+			;;
+		active-high)
+			active_opt=
+			;;
+		bias-none)
+			bias_opt=
+			;;
+		pull-down)
+			bias_opt="-bpull-down "
+			;;
+		pull-up)
+			bias_opt="-bpull-up "
+			;;
+		0)
+			val=0
+			;;
+		1)
+			val=1
+			;;
+		esac
+	done
+
+	local cdev_opts=${uapi_opt}${active_opt}
+	if [ "$val" ]; then
+		$BASE/gpio-mockup-cdev $cdev_opts -s$val /dev/$chip $offset &
+		# failure to set is detected by reading mockup and toggling values
+		line_set_pid=$!
+		# allow for gpio-mockup-cdev to launch and request line
+		# (there is limited value in checking if line has been requested)
+		sleep 0.01
+	elif [ "$bias_opt" ]; then
+		cdev_opts=${cdev_opts}${bias_opt}
+		$BASE/gpio-mockup-cdev $cdev_opts /dev/$chip $offset || true
+	fi
+}
+
+assert_line()
+{
+	local val
+	# don't need any retry here as set_mock allows for propagation
+	val=$(get_line)
+	[ "$val" = "$1" ] || fail "line value is ${val:-empty} when $1 was expected"
+}
+
+# The following mockup helpers all make use of the $mock_line
+assert_mock()
+{
+	local backoff_wait=10
+	local retry=0
+	local val
+	# retry allows for set propagation from uAPI to mockup
+	while true; do
+		val=$(< $mock_line)
+		[ "$val" = "$1" ] && break
+		retry=$((retry + 1))
+		[ $retry -lt 5 ] || fail "mockup $mock_line value ${val:-empty} when $1 expected"
+		sleep $(printf "%0.2f" $((backoff_wait))e-3)
+		backoff_wait=$((backoff_wait * 2))
+	done
+}
+
+set_mock()
+{
+	echo "$1" > $mock_line
+	# allow for set propagation - so we won't be in a race with set_line
+	assert_mock "$1"
+}
+
+# test the functionality of a line
+#
+# The line is set from the mockup side and is read from the userspace side
+# (input), and is set from the userspace side and is read from the mockup side
+# (output).
+#
+# Setting the mockup pull using the userspace interface bias settings is
+# tested where supported by the userspace interface (cdev).
+test_line()
+{
+	chip=$1
+	offset=$2
+	log "test_line $chip $offset"
+	mock_line=$GPIO_DEBUGFS/$chip/$offset
+	[ -e "$mock_line" ] || fail "missing line $chip:$offset"
+
+	# test input active-high
+	set_mock 1
+	set_line input active-high
+	assert_line 1
+	set_mock 0
+	assert_line 0
+	set_mock 1
+	assert_line 1
+
+	if [ "$full_test" ]; then
+		if [ "$dev_type" != "sysfs" ]; then
+			# test pulls
+			set_mock 0
+			set_line input pull-up
+			assert_line 1
+			set_mock 0
+			assert_line 0
+
+			set_mock 1
+			set_line input pull-down
+			assert_line 0
+			set_mock 1
+			assert_line 1
+
+			set_line bias-none
+		fi
+
+		# test input active-low
+		set_mock 0
+		set_line active-low
+		assert_line 1
+		set_mock 1
+		assert_line 0
+		set_mock 0
+		assert_line 1
+
+		# test output active-high
+		set_mock 1
+		set_line active-high 0
+		assert_mock 0
+		set_line 1
+		assert_mock 1
+		set_line 0
+		assert_mock 0
+	fi
+
+	# test output active-low
+	set_mock 0
+	set_line active-low 0
+	assert_mock 1
+	set_line 1
+	assert_mock 0
+	set_line 0
+	assert_mock 1
+
+	release_line
+}
+
+test_no_line()
+{
+	log test_no_line "$*"
+	[ ! -e "$GPIO_DEBUGFS/$1/$2" ] || fail "unexpected line $1:$2"
+}
+
+# Load the module and check that the expected number of gpiochips, with the
+# expected number of lines, are created and are functional.
+#
+# $1 is the gpio_mockup_ranges parameter for the module
+# The remaining parameters are the number of lines, n, expected for each of
+# the gpiochips expected to be created.
+#
+# For each gpiochip the fence post lines, 0 and n-1, are tested, and the
+# line on the far side of the fence post, n, is tested to not exist.
+#
+# If the $random flag is set then a random line in the middle of the
+# gpiochip is tested as well.
+insmod_test()
+{
+	local ranges=
+	local gc=
+	local width=
+
+	[ "${1:-}" ] || fail "missing ranges"
+	ranges=$1 ; shift
+	try_insert_module "gpio_mockup_ranges=$ranges"
+	log "GPIO $module test with ranges: <$ranges>:"
+	# e.g. /sys/kernel/debug/gpio-mockup/gpiochip1
+	gpiochip=$(find "$DEBUGFS/$module/" -name gpiochip* -type d | sort)
+	for chip in $gpiochip; do
+		gc=${chip##*/}
+		[ "${1:-}" ] || fail "unexpected chip - $gc"
+		width=$1 ; shift
+		test_line $gc 0
+		if [ "$random" -a $width -gt 2 ]; then
+			test_line $gc $((RANDOM % ($width - 2) + 1))
+		fi
+		test_line $gc $(($width - 1))
+		test_no_line $gc $width
+	done
+	[ "${1:-}" ] && fail "missing expected chip of width $1"
+	remove_module || fail "failed to remove module with error $?"
+}
+
+while getopts ":frvt:" opt; do
+	case $opt in
+	f)
+		full_test=true
+		;;
+	r)
+		random=true
+		;;
+	t)
+		dev_type=$OPTARG
+		;;
+	v)
+		verbose=true
+		;;
+	*)
+		usage
+		;;
+	esac
+done
+shift $((OPTIND - 1))
+
+[ "${1:-}" ] && fail "unknown argument '$1'"
+
+prerequisite
+
+trap 'exit $ksft_fail' SIGTERM SIGINT
+trap cleanup EXIT
+
+case "$dev_type" in
+sysfs)
+	source $BASE/gpio-mockup-sysfs.sh
+	echo "WARNING: gpio sysfs ABI is deprecated."
+	;;
+cdev_v1)
+	echo "WARNING: gpio cdev ABI v1 is deprecated."
+	uapi_opt="-u1 "
+	;;
+cdev)
+	;;
+*)
+	fail "unknown interface type: $dev_type"
+	;;
+esac
+
+remove_module || fail "can't remove existing $module module"
+
+# manual gpio allocation tests fail if a physical chip already exists
+[ "$full_test" -a -e "/dev/gpiochip0" ] && skip "full tests conflict with gpiochip0"
+
+echo "1.  Module load tests"
+echo "1.1.  dynamic allocation of gpio"
+insmod_test "-1,32" 32
+insmod_test "-1,23,-1,32" 23 32
+insmod_test "-1,23,-1,26,-1,32" 23 26 32
+if [ "$full_test" ]; then
+	echo "1.2.  manual allocation of gpio"
+	insmod_test "0,32" 32
+	insmod_test "0,32,32,60" 32 28
+	insmod_test "0,32,40,64,64,96" 32 24 32
+	echo "1.3.  dynamic and manual allocation of gpio"
+	insmod_test "-1,32,32,62" 32 30
+	insmod_test "-1,22,-1,23,0,24,32,64" 22 23 24 32
+	insmod_test "-1,32,32,60,-1,29" 32 28 29
+	insmod_test "-1,32,40,64,-1,5" 32 24 5
+	insmod_test "0,32,32,44,-1,22,-1,31" 32 12 22 31
+fi
+echo "2.  Module load error tests"
+echo "2.1 no lines defined"
+insmod_test "0,0"
+if [ "$full_test" ]; then
+	echo "2.2 ignore range overlap"
+	insmod_test "0,32,0,1" 32
+	insmod_test "0,32,1,5" 32
+	insmod_test "0,32,30,35" 32
+	insmod_test "0,32,31,32" 32
+	insmod_test "10,32,30,35" 22
+	insmod_test "10,32,9,14" 22
+	insmod_test "0,32,20,21,40,56" 32 16
+	insmod_test "0,32,32,64,32,40" 32 32
+	insmod_test "0,32,32,64,36,37" 32 32
+	insmod_test "0,32,35,64,34,36" 32 29
+	insmod_test "0,30,35,64,35,45" 30 29
+	insmod_test "0,32,40,56,30,33" 32 16
+	insmod_test "0,32,40,56,30,41" 32 16
+	insmod_test "0,32,40,56,39,45" 32 16
+fi
+
+echo "GPIO $module test PASS"
diff --git a/tools/testing/selftests/gpio/gpio-sim.sh b/tools/testing/selftests/gpio/gpio-sim.sh
new file mode 100755
index 000000000..bbc29ed9c
--- /dev/null
+++ b/tools/testing/selftests/gpio/gpio-sim.sh
@@ -0,0 +1,418 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2021 Bartosz Golaszewski <brgl@bgdev.pl>
+
+BASE_DIR=`dirname $0`
+CONFIGFS_DIR="/sys/kernel/config/gpio-sim"
+MODULE="gpio-sim"
+
+fail() {
+	echo "$*" >&2
+	echo "GPIO $MODULE test FAIL"
+	exit 1
+}
+
+skip() {
+	echo "$*" >&2
+	echo "GPIO $MODULE test SKIP"
+	exit 4
+}
+
+remove_chip() {
+	local CHIP=$1
+
+	for FILE in $CONFIGFS_DIR/$CHIP/*; do
+		BANK=`basename $FILE`
+		if [ "$BANK" = "live" -o "$BANK" = "dev_name" ]; then
+			continue
+		fi
+
+		LINES=`ls $CONFIGFS_DIR/$CHIP/$BANK/ | grep -E ^line`
+		if [ "$?" = 0 ]; then
+			for LINE in $LINES; do
+				if [ -e $CONFIGFS_DIR/$CHIP/$BANK/$LINE/hog ]; then
+					rmdir $CONFIGFS_DIR/$CHIP/$BANK/$LINE/hog || \
+						fail "Unable to remove the hog"
+				fi
+
+				rmdir $CONFIGFS_DIR/$CHIP/$BANK/$LINE || \
+					fail "Unable to remove the line"
+			done
+		fi
+
+		rmdir $CONFIGFS_DIR/$CHIP/$BANK
+	done
+
+	rmdir $CONFIGFS_DIR/$CHIP || fail "Unable to remove the chip"
+}
+
+create_chip() {
+	local CHIP=$1
+
+	mkdir $CONFIGFS_DIR/$CHIP
+}
+
+create_bank() {
+	local CHIP=$1
+	local BANK=$2
+
+	mkdir $CONFIGFS_DIR/$CHIP/$BANK
+}
+
+set_label() {
+	local CHIP=$1
+	local BANK=$2
+	local LABEL=$3
+
+	echo $LABEL > $CONFIGFS_DIR/$CHIP/$BANK/label || fail "Unable to set the chip label"
+}
+
+set_num_lines() {
+	local CHIP=$1
+	local BANK=$2
+	local NUM_LINES=$3
+
+	echo $NUM_LINES > $CONFIGFS_DIR/$CHIP/$BANK/num_lines || \
+		fail "Unable to set the number of lines"
+}
+
+set_line_name() {
+	local CHIP=$1
+	local BANK=$2
+	local OFFSET=$3
+	local NAME=$4
+	local LINE_DIR=$CONFIGFS_DIR/$CHIP/$BANK/line$OFFSET
+
+	test -d $LINE_DIR || mkdir $LINE_DIR
+	echo $NAME > $LINE_DIR/name || fail "Unable to set the line name"
+}
+
+enable_chip() {
+	local CHIP=$1
+
+	echo 1 > $CONFIGFS_DIR/$CHIP/live || fail "Unable to enable the chip"
+}
+
+disable_chip() {
+	local CHIP=$1
+
+	echo 0 > $CONFIGFS_DIR/$CHIP/live || fail "Unable to disable the chip"
+}
+
+configfs_cleanup() {
+	for CHIP in `ls $CONFIGFS_DIR/`; do
+		disable_chip $CHIP
+		remove_chip $CHIP
+	done
+}
+
+configfs_chip_name() {
+	local CHIP=$1
+	local BANK=$2
+
+	cat $CONFIGFS_DIR/$CHIP/$BANK/chip_name 2> /dev/null || \
+		fail "unable to read the chip name from configfs"
+}
+
+configfs_dev_name() {
+	local CHIP=$1
+
+	cat $CONFIGFS_DIR/$CHIP/dev_name 2> /dev/null || \
+		fail "unable to read the device name from configfs"
+}
+
+get_chip_num_lines() {
+	local CHIP=$1
+	local BANK=$2
+
+	$BASE_DIR/gpio-chip-info /dev/`configfs_chip_name $CHIP $BANK` num-lines || \
+		fail "unable to read the number of lines from the character device"
+}
+
+get_chip_label() {
+	local CHIP=$1
+	local BANK=$2
+
+	$BASE_DIR/gpio-chip-info /dev/`configfs_chip_name $CHIP $BANK` label || \
+		fail "unable to read the chip label from the character device"
+}
+
+get_line_name() {
+	local CHIP=$1
+	local BANK=$2
+	local OFFSET=$3
+
+	$BASE_DIR/gpio-line-name /dev/`configfs_chip_name $CHIP $BANK` $OFFSET || \
+		fail "unable to read the line name from the character device"
+}
+
+sysfs_set_pull() {
+	local DEV=$1
+	local BANK=$2
+	local OFFSET=$3
+	local PULL=$4
+	local DEVNAME=`configfs_dev_name $DEV`
+	local CHIPNAME=`configfs_chip_name $DEV $BANK`
+	local SYSFS_PATH="/sys/devices/platform/$DEVNAME/$CHIPNAME/sim_gpio$OFFSET/pull"
+
+	echo $PULL > $SYSFS_PATH || fail "Unable to set line pull in sysfs"
+}
+
+# Load the gpio-sim module. This will pull in configfs if needed too.
+modprobe gpio-sim || skip "unable to load the gpio-sim module"
+# Make sure configfs is mounted at /sys/kernel/config. Wait a bit if needed.
+for IDX in `seq 5`; do
+	if [ "$IDX" -eq "5" ]; then
+		skip "configfs not mounted at /sys/kernel/config"
+	fi
+
+	mountpoint -q /sys/kernel/config && break
+	sleep 0.1
+done
+# If the module was already loaded: remove all previous chips
+configfs_cleanup
+
+trap "exit 1" SIGTERM SIGINT
+trap configfs_cleanup EXIT
+
+echo "1. chip_name and dev_name attributes"
+
+echo "1.1. Chip name is communicated to user"
+create_chip chip
+create_bank chip bank
+enable_chip chip
+test -n `cat $CONFIGFS_DIR/chip/bank/chip_name` || fail "chip_name doesn't work"
+disable_chip chip
+remove_chip chip
+
+echo "1.2. chip_name returns 'none' if the chip is still pending"
+create_chip chip
+create_bank chip bank
+test "`cat $CONFIGFS_DIR/chip/bank/chip_name`" = "none" || \
+	fail "chip_name doesn't return 'none' for a pending chip"
+remove_chip chip
+
+echo "1.3. Device name is communicated to user"
+create_chip chip
+create_bank chip bank
+enable_chip chip
+test -n `cat $CONFIGFS_DIR/chip/dev_name` || fail "dev_name doesn't work"
+disable_chip chip
+remove_chip chip
+
+echo "2. Creating and configuring simulated chips"
+
+echo "2.1. Default number of lines is 1"
+create_chip chip
+create_bank chip bank
+enable_chip chip
+test "`get_chip_num_lines chip bank`" = "1" || fail "default number of lines is not 1"
+disable_chip chip
+remove_chip chip
+
+echo "2.2. Number of lines can be specified"
+create_chip chip
+create_bank chip bank
+set_num_lines chip bank 16
+enable_chip chip
+test "`get_chip_num_lines chip bank`" = "16" || fail "number of lines is not 16"
+disable_chip chip
+remove_chip chip
+
+echo "2.3. Label can be set"
+create_chip chip
+create_bank chip bank
+set_label chip bank foobar
+enable_chip chip
+test "`get_chip_label chip bank`" = "foobar" || fail "label is incorrect"
+disable_chip chip
+remove_chip chip
+
+echo "2.4. Label can be left empty"
+create_chip chip
+create_bank chip bank
+enable_chip chip
+test -z "`cat $CONFIGFS_DIR/chip/bank/label`" || fail "label is not empty"
+disable_chip chip
+remove_chip chip
+
+echo "2.5. Line names can be configured"
+create_chip chip
+create_bank chip bank
+set_num_lines chip bank 16
+set_line_name chip bank 0 foo
+set_line_name chip bank 2 bar
+enable_chip chip
+test "`get_line_name chip bank 0`" = "foo" || fail "line name is incorrect"
+test "`get_line_name chip bank 2`" = "bar" || fail "line name is incorrect"
+disable_chip chip
+remove_chip chip
+
+echo "2.6. Line config can remain unused if offset is greater than number of lines"
+create_chip chip
+create_bank chip bank
+set_num_lines chip bank 2
+set_line_name chip bank 5 foobar
+enable_chip chip
+test "`get_line_name chip bank 0`" = "" || fail "line name is incorrect"
+test "`get_line_name chip bank 1`" = "" || fail "line name is incorrect"
+disable_chip chip
+remove_chip chip
+
+echo "2.7. Line configfs directory names are sanitized"
+create_chip chip
+create_bank chip bank
+mkdir $CONFIGFS_DIR/chip/bank/line12foobar 2> /dev/null && \
+	fail "invalid configfs line name accepted"
+mkdir $CONFIGFS_DIR/chip/bank/line_no_offset 2> /dev/null && \
+	fail "invalid configfs line name accepted"
+remove_chip chip
+
+echo "2.8. Multiple chips can be created"
+CHIPS="chip0 chip1 chip2"
+for CHIP in $CHIPS; do
+	create_chip $CHIP
+	create_bank $CHIP bank
+	enable_chip $CHIP
+done
+for CHIP in $CHIPS; do
+  disable_chip $CHIP
+	remove_chip $CHIP
+done
+
+echo "2.9. Can't modify settings when chip is live"
+create_chip chip
+create_bank chip bank
+enable_chip chip
+echo foobar > $CONFIGFS_DIR/chip/bank/label 2> /dev/null && \
+	fail "Setting label of a live chip should fail"
+echo 8 > $CONFIGFS_DIR/chip/bank/num_lines 2> /dev/null && \
+	fail "Setting number of lines of a live chip should fail"
+disable_chip chip
+remove_chip chip
+
+echo "2.10. Can't create line items when chip is live"
+create_chip chip
+create_bank chip bank
+enable_chip chip
+mkdir $CONFIGFS_DIR/chip/bank/line0 2> /dev/null && fail "Creating line item should fail"
+disable_chip chip
+remove_chip chip
+
+echo "2.11. Probe errors are propagated to user-space"
+create_chip chip
+create_bank chip bank
+set_num_lines chip bank 99999
+echo 1 > $CONFIGFS_DIR/chip/live 2> /dev/null && fail "Probe error was not propagated"
+remove_chip chip
+
+echo "2.12. Cannot enable a chip without any GPIO banks"
+create_chip chip
+echo 1 > $CONFIGFS_DIR/chip/live 2> /dev/null && fail "Chip enabled without any GPIO banks"
+remove_chip chip
+
+echo "2.13. Duplicate chip labels are not allowed"
+create_chip chip
+create_bank chip bank0
+set_label chip bank0 foobar
+create_bank chip bank1
+set_label chip bank1 foobar
+echo 1 > $CONFIGFS_DIR/chip/live 2> /dev/null && fail "Duplicate chip labels were not rejected"
+remove_chip chip
+
+echo "2.14. Lines can be hogged"
+create_chip chip
+create_bank chip bank
+set_num_lines chip bank 8
+mkdir -p $CONFIGFS_DIR/chip/bank/line4/hog
+enable_chip chip
+$BASE_DIR/gpio-mockup-cdev -s 1 /dev/`configfs_chip_name chip bank` 4 2> /dev/null && \
+	fail "Setting the value of a hogged line shouldn't succeed"
+disable_chip chip
+remove_chip chip
+
+echo "3. Controlling simulated chips"
+
+echo "3.1. Pull can be set over sysfs"
+create_chip chip
+create_bank chip bank
+set_num_lines chip bank 8
+enable_chip chip
+sysfs_set_pull chip bank 0 pull-up
+$BASE_DIR/gpio-mockup-cdev /dev/`configfs_chip_name chip bank` 0
+test "$?" = "1" || fail "pull set incorrectly"
+sysfs_set_pull chip bank 0 pull-down
+$BASE_DIR/gpio-mockup-cdev /dev/`configfs_chip_name chip bank` 1
+test "$?" = "0" || fail "pull set incorrectly"
+disable_chip chip
+remove_chip chip
+
+echo "3.2. Pull can be read from sysfs"
+create_chip chip
+create_bank chip bank
+set_num_lines chip bank 8
+enable_chip chip
+DEVNAME=`configfs_dev_name chip`
+CHIPNAME=`configfs_chip_name chip bank`
+SYSFS_PATH=/sys/devices/platform/$DEVNAME/$CHIPNAME/sim_gpio0/pull
+test `cat $SYSFS_PATH` = "pull-down" || fail "reading the pull failed"
+sysfs_set_pull chip bank 0 pull-up
+test `cat $SYSFS_PATH` = "pull-up" || fail "reading the pull failed"
+disable_chip chip
+remove_chip chip
+
+echo "3.3. Incorrect input in sysfs is rejected"
+create_chip chip
+create_bank chip bank
+set_num_lines chip bank 8
+enable_chip chip
+DEVNAME=`configfs_dev_name chip`
+CHIPNAME=`configfs_chip_name chip bank`
+SYSFS_PATH="/sys/devices/platform/$DEVNAME/$CHIPNAME/sim_gpio0/pull"
+echo foobar > $SYSFS_PATH 2> /dev/null && fail "invalid input not detected"
+disable_chip chip
+remove_chip chip
+
+echo "3.4. Can't write to value"
+create_chip chip
+create_bank chip bank
+enable_chip chip
+DEVNAME=`configfs_dev_name chip`
+CHIPNAME=`configfs_chip_name chip bank`
+SYSFS_PATH="/sys/devices/platform/$DEVNAME/$CHIPNAME/sim_gpio0/value"
+echo 1 > $SYSFS_PATH 2> /dev/null && fail "writing to 'value' succeeded unexpectedly"
+disable_chip chip
+remove_chip chip
+
+echo "4. Simulated GPIO chips are functional"
+
+echo "4.1. Values can be read from sysfs"
+create_chip chip
+create_bank chip bank
+set_num_lines chip bank 8
+enable_chip chip
+DEVNAME=`configfs_dev_name chip`
+CHIPNAME=`configfs_chip_name chip bank`
+SYSFS_PATH="/sys/devices/platform/$DEVNAME/$CHIPNAME/sim_gpio0/value"
+test `cat $SYSFS_PATH` = "0" || fail "incorrect value read from sysfs"
+$BASE_DIR/gpio-mockup-cdev -s 1 /dev/`configfs_chip_name chip bank` 0 &
+sleep 0.1 # FIXME Any better way?
+test `cat $SYSFS_PATH` = "1" || fail "incorrect value read from sysfs"
+kill $!
+disable_chip chip
+remove_chip chip
+
+echo "4.2. Bias settings work correctly"
+create_chip chip
+create_bank chip bank
+set_num_lines chip bank 8
+enable_chip chip
+DEVNAME=`configfs_dev_name chip`
+CHIPNAME=`configfs_chip_name chip bank`
+SYSFS_PATH="/sys/devices/platform/$DEVNAME/$CHIPNAME/sim_gpio0/value"
+$BASE_DIR/gpio-mockup-cdev -b pull-up /dev/`configfs_chip_name chip bank` 0
+test `cat $SYSFS_PATH` = "1" || fail "bias setting does not work"
+disable_chip chip
+remove_chip chip
+
+echo "GPIO $MODULE test PASS"