1 files changed, 124 insertions, 0 deletions
diff --git a/tools/testing/selftests/firmware/fw_fallback.sh b/tools/testing/selftests/firmware/fw_fallback.sh
new file mode 100755
index 000000000000..f694afb7d12d
--- /dev/null
+++ b/tools/testing/selftests/firmware/fw_fallback.sh
@@ -0,0 +1,124 @@
+#!/bin/sh
+# This validates that the kernel will fall back to using the fallback mechanism
+# to load firmware it can't find on disk itself. We must request a firmware
+# that the kernel won't find, and any installed helper (e.g. udev) also
+# won't find so that we can do the load ourself manually.
+set -e
+
+modprobe test_firmware
+
+DIR=/sys/devices/virtual/misc/test_firmware
+
+# CONFIG_FW_LOADER_USER_HELPER has a sysfs class under /sys/class/firmware/
+# These days no one enables CONFIG_FW_LOADER_USER_HELPER so check for that
+# as an indicator for CONFIG_FW_LOADER_USER_HELPER.
+HAS_FW_LOADER_USER_HELPER=$(if [ -d /sys/class/firmware/ ]; then echo yes; else echo no; fi)
+
+if [ "$HAS_FW_LOADER_USER_HELPER" = "yes" ]; then
+       OLD_TIMEOUT=$(cat /sys/class/firmware/timeout)
+else
+	echo "usermode helper disabled so ignoring test"
+	exit 0
+fi
+
+FWPATH=$(mktemp -d)
+FW="$FWPATH/test-firmware.bin"
+
+test_finish()
+{
+	echo "$OLD_TIMEOUT" >/sys/class/firmware/timeout
+	rm -f "$FW"
+	rmdir "$FWPATH"
+}
+
+load_fw()
+{
+	local name="$1"
+	local file="$2"
+
+	# This will block until our load (below) has finished.
+	echo -n "$name" >"$DIR"/trigger_request &
+
+	# Give kernel a chance to react.
+	local timeout=10
+	while [ ! -e "$DIR"/"$name"/loading ]; do
+		sleep 0.1
+		timeout=$(( $timeout - 1 ))
+		if [ "$timeout" -eq 0 ]; then
+			echo "$0: firmware interface never appeared" >&2
+			exit 1
+		fi
+	done
+
+	echo 1 >"$DIR"/"$name"/loading
+	cat "$file" >"$DIR"/"$name"/data
+	echo 0 >"$DIR"/"$name"/loading
+
+	# Wait for request to finish.
+	wait
+}
+
+trap "test_finish" EXIT
+
+# This is an unlikely real-world firmware content. :)
+echo "ABCD0123" >"$FW"
+NAME=$(basename "$FW")
+
+DEVPATH="$DIR"/"nope-$NAME"/loading
+
+# Test failure when doing nothing (timeout works).
+echo -n 2 >/sys/class/firmware/timeout
+echo -n "nope-$NAME" >"$DIR"/trigger_request 2>/dev/null &
+
+# Give the kernel some time to load the loading file, must be less
+# than the timeout above.
+sleep 1
+if [ ! -f $DEVPATH ]; then
+	echo "$0: fallback mechanism immediately cancelled"
+	echo ""
+	echo "The file never appeared: $DEVPATH"
+	echo ""
+	echo "This might be a distribution udev rule setup by your distribution"
+	echo "to immediately cancel all fallback requests, this must be"
+	echo "removed before running these tests. To confirm look for"
+	echo "a firmware rule like /lib/udev/rules.d/50-firmware.rules"
+	echo "and see if you have something like this:"
+	echo ""
+	echo "SUBSYSTEM==\"firmware\", ACTION==\"add\", ATTR{loading}=\"-1\""
+	echo ""
+	echo "If you do remove this file or comment out this line before"
+	echo "proceeding with these tests."
+	exit 1
+fi
+
+if diff -q "$FW" /dev/test_firmware >/dev/null ; then
+	echo "$0: firmware was not expected to match" >&2
+	exit 1
+else
+	echo "$0: timeout works"
+fi
+
+# Put timeout high enough for us to do work but not so long that failures
+# slow down this test too much.
+echo 4 >/sys/class/firmware/timeout
+
+# Load this script instead of the desired firmware.
+load_fw "$NAME" "$0"
+if diff -q "$FW" /dev/test_firmware >/dev/null ; then
+	echo "$0: firmware was not expected to match" >&2
+	exit 1
+else
+	echo "$0: firmware comparison works"
+fi
+
+# Do a proper load, which should work correctly.
+load_fw "$NAME" "$FW"
+if ! diff -q "$FW" /dev/test_firmware >/dev/null ; then
+	echo "$0: firmware was not loaded" >&2
+	exit 1
+else
+	echo "$0: fallback mechanism works"
+
+fi
+
+exit 0