Create selftests for PCIe BW control through the PCIe cooling device
sysfs interface.

First, the BW control selftest finds the PCIe Port to test with. By
default, the PCIe Port with the highest Link Speed is selected but
another PCIe Port can be provided with -d parameter.

The actual test steps the cur_state of the cooling device one-by-one
from max_state to what the cur_state was initially. The speed change
is confirmed by observing the current_link_speed for the corresponding
PCIe Port.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
---
 MAINTAINERS                                   |   1 +
 tools/testing/selftests/Makefile              |   1 +
 tools/testing/selftests/pcie_bwctrl/Makefile  |   2 +
 .../pcie_bwctrl/set_pcie_cooling_state.sh     | 122 ++++++++++++++++++
 .../selftests/pcie_bwctrl/set_pcie_speed.sh   |  67 ++++++++++
 5 files changed, 193 insertions(+)
 create mode 100644 tools/testing/selftests/pcie_bwctrl/Makefile
 create mode 100755 tools/testing/selftests/pcie_bwctrl/set_pcie_cooling_state.sh
 create mode 100755 tools/testing/selftests/pcie_bwctrl/set_pcie_speed.sh

diff --git a/MAINTAINERS b/MAINTAINERS
index 47542dcb9259..dc601dcab8c6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17676,6 +17676,7 @@ S:	Supported
 F:	drivers/pci/pcie/bwctrl.c
 F:	drivers/thermal/pcie_cooling.c
 F:	include/linux/pci-bwctrl.h
+F:	tools/testing/selftests/pcie_bwctrl/
 
 PCIE DRIVER FOR AMAZON ANNAPURNA LABS
 M:	Jonathan Chocron <jonnyc@amazon.com>
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index bc8fe9e8f7f2..086af950930c 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -69,6 +69,7 @@ TARGETS += net/openvswitch
 TARGETS += net/tcp_ao
 TARGETS += net/netfilter
 TARGETS += nsfs
+TARGETS += pcie_bwctrl
 TARGETS += perf_events
 TARGETS += pidfd
 TARGETS += pid_namespace
diff --git a/tools/testing/selftests/pcie_bwctrl/Makefile b/tools/testing/selftests/pcie_bwctrl/Makefile
new file mode 100644
index 000000000000..3e84e26341d1
--- /dev/null
+++ b/tools/testing/selftests/pcie_bwctrl/Makefile
@@ -0,0 +1,2 @@
+TEST_PROGS = set_pcie_cooling_state.sh
+include ../lib.mk
diff --git a/tools/testing/selftests/pcie_bwctrl/set_pcie_cooling_state.sh b/tools/testing/selftests/pcie_bwctrl/set_pcie_cooling_state.sh
new file mode 100755
index 000000000000..9df606552af3
--- /dev/null
+++ b/tools/testing/selftests/pcie_bwctrl/set_pcie_cooling_state.sh
@@ -0,0 +1,122 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+SYSFS=
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+retval=0
+skipmsg="skip all tests:"
+
+PCIEPORTTYPE="PCIe_Port_Link_Speed"
+
+prerequisite()
+{
+	local ports
+
+	if [ $UID != 0 ]; then
+		echo $skipmsg must be run as root >&2
+		exit $ksft_skip
+	fi
+
+	SYSFS=`mount -t sysfs | head -1 | awk '{ print $3 }'`
+
+	if [ ! -d "$SYSFS" ]; then
+		echo $skipmsg sysfs is not mounted >&2
+		exit $ksft_skip
+	fi
+
+	if ! ls $SYSFS/class/thermal/cooling_device* > /dev/null 2>&1; then
+		echo $skipmsg thermal cooling devices missing >&2
+		exit $ksft_skip
+	fi
+
+	ports=`grep -e "^$PCIEPORTTYPE" $SYSFS/class/thermal/cooling_device*/type | wc -l`
+	if [ $ports -eq 0 ]; then
+		echo $skipmsg pcie cooling devices missing >&2
+		exit $ksft_skip
+	fi
+}
+
+testport=
+find_pcie_port()
+{
+	local patt="$1"
+	local pcieports
+	local max
+	local cur
+	local delta
+	local bestdelta=-1
+
+	pcieports=`grep -l -F -e "$patt" /sys/class/thermal/cooling_device*/type`
+	if [ -z "$pcieports" ]; then
+		return
+	fi
+	pcieports=${pcieports//\/type/}
+	# Find the port with the highest PCIe Link Speed
+	for port in $pcieports; do
+		max=`cat $port/max_state`
+		cur=`cat $port/cur_state`
+		delta=$((max-cur))
+		if [ $delta -gt $bestdelta ]; then
+			testport="$port"
+			bestdelta=$delta
+		fi
+	done
+}
+
+sysfspcidev=
+find_sysfs_pci_dev()
+{
+	local typefile="$1/type"
+	local pcidir
+
+	pcidir="$SYSFS/bus/pci/devices/`sed -e "s|^${PCIEPORTTYPE}_||g" $typefile`"
+
+	if [ -r "$pcidir/current_link_speed" ]; then
+		sysfspcidev="$pcidir/current_link_speed"
+	fi
+}
+
+usage()
+{
+	echo "Usage $0 [ -d dev ]"
+	echo -e "\t-d: PCIe port BDF string (e.g., 0000:00:04.0)"
+}
+
+pattern="$PCIEPORTTYPE"
+parse_arguments()
+{
+	while getopts d:h opt; do
+		case $opt in
+			h)
+				usage "$0"
+				exit 0
+				;;
+			d)
+				pattern="$PCIEPORTTYPE_$OPTARG"
+				;;
+			*)
+				usage "$0"
+				exit 0
+				;;
+		esac
+	done
+}
+
+parse_arguments "$@"
+prerequisite
+find_pcie_port "$pattern"
+if [ -z "$testport" ]; then
+	echo $skipmsg "pcie cooling device not found from sysfs" >&2
+	exit $ksft_skip
+fi
+find_sysfs_pci_dev "$testport"
+if [ -z "$sysfspcidev" ]; then
+	echo $skipmsg "PCIe port device not found from sysfs" >&2
+	exit $ksft_skip
+fi
+
+./set_pcie_speed.sh "$testport" "$sysfspcidev"
+retval=$?
+
+exit $retval
diff --git a/tools/testing/selftests/pcie_bwctrl/set_pcie_speed.sh b/tools/testing/selftests/pcie_bwctrl/set_pcie_speed.sh
new file mode 100755
index 000000000000..584596949312
--- /dev/null
+++ b/tools/testing/selftests/pcie_bwctrl/set_pcie_speed.sh
@@ -0,0 +1,67 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+set -e
+
+TESTNAME=set_pcie_speed
+
+declare -a PCIELINKSPEED=(
+	"2.5 GT/s PCIe"
+	"5.0 GT/s PCIe"
+	"8.0 GT/s PCIe"
+	"16.0 GT/s PCIe"
+	"32.0 GT/s PCIe"
+	"64.0 GT/s PCIe"
+)
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+retval=0
+
+coolingdev="$1"
+statefile="$coolingdev/cur_state"
+maxfile="$coolingdev/max_state"
+linkspeedfile="$2"
+
+oldstate=`cat $statefile`
+maxstate=`cat $maxfile`
+
+set_state()
+{
+	local state=$1
+	local linkspeed
+	local expected_linkspeed
+
+	echo $state > $statefile
+
+	sleep 1
+
+	linkspeed="`cat $linkspeedfile`"
+	expected_linkspeed=$((maxstate-state))
+	expected_str="${PCIELINKSPEED[$expected_linkspeed]}"
+	if [ ! "${expected_str}" = "${linkspeed}" ]; then
+		echo "$TESTNAME failed: expected: ${expected_str}; got ${linkspeed}"
+		retval=1
+	fi
+}
+
+cleanup_skip ()
+{
+	set_state $oldstate
+	exit $ksft_skip
+}
+
+trap cleanup_skip EXIT
+
+echo "$TESTNAME: testing states $maxstate .. $oldstate with $coolingdev"
+for i in $(seq $maxstate -1 $oldstate); do
+	set_state "$i"
+done
+
+trap EXIT
+if [ $retval -eq 0 ]; then
+	echo "$TESTNAME [PASS]"
+else
+	echo "$TESTNAME [FAIL]"
+fi
+exit $retval
-- 
2.39.2