kselftest: Add new test for detecting unprobed Devicetree devices

Introduce a new kselftest to detect devices that were declared in the
Devicetree, and are expected to be probed by a driver, but weren't.

The test uses two lists: a list of compatibles that can match a
Devicetree device to a driver, and a list of compatibles that should be
ignored. The first is automatically generated by the
dt-extract-compatibles script, and is run as part of building this test.
The list of compatibles to ignore is a hand-crafted list to capture the
few exceptions of compatibles that are expected to match a driver but
not be bound to it.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20230828211424.2964562-4-nfraprado@collabora.com
Signed-off-by: Rob Herring <robh@kernel.org>

MAINTAINERS

@@ -15971,6 +15971,7 @@ F:	Documentation/ABI/testing/sysfs-firmware-ofw
 F:	drivers/of/
 F:	include/linux/of*.h
 F:	scripts/dtc/
+F:	tools/testing/selftests/dt/
 K:	of_overlay_notifier_
 K:	of_overlay_fdt_apply
 K:	of_overlay_remove

tools/testing/selftests/Makefile

@@ -18,6 +18,7 @@ TARGETS += drivers/dma-buf
 TARGETS += drivers/s390x/uvdevice
 TARGETS += drivers/net/bonding
 TARGETS += drivers/net/team
+TARGETS += dt
 TARGETS += efivarfs
 TARGETS += exec
 TARGETS += fchmodat2

tools/testing/selftests/dt/.gitignore

@@ -0,0 +1 @@
+compatible_list

tools/testing/selftests/dt/Makefile

@@ -0,0 +1,21 @@
+PY3 = $(shell which python3 2>/dev/null)
+
+ifneq ($(PY3),)
+
+TEST_PROGS := test_unprobed_devices.sh
+TEST_GEN_FILES := compatible_list
+TEST_FILES := compatible_ignore_list ktap_helpers.sh
+
+include ../lib.mk
+
+$(OUTPUT)/compatible_list:
+	$(top_srcdir)/scripts/dtc/dt-extract-compatibles -d $(top_srcdir) > $@
+
+else
+
+all: no_py3_warning
+
+no_py3_warning:
+	@echo "Missing python3. This test will be skipped."
+
+endif

tools/testing/selftests/dt/compatible_ignore_list

@@ -0,0 +1 @@
+simple-mfd

tools/testing/selftests/dt/ktap_helpers.sh

@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (c) 2023 Collabora Ltd
+#
+# Helpers for outputting in KTAP format
+#
+KTAP_TESTNO=1
+KTAP_CNT_PASS=0
+KTAP_CNT_FAIL=0
+KTAP_CNT_SKIP=0
+
+ktap_print_header() {
+	echo "TAP version 13"
+}
+
+ktap_set_plan() {
+	num_tests="$1"
+
+	echo "1..$num_tests"
+}
+
+ktap_skip_all() {
+	echo -n "1..0 # SKIP "
+	echo $@
+}
+
+__ktap_test() {
+	result="$1"
+	description="$2"
+	directive="$3" # optional
+
+	local directive_str=
+	[[ ! -z "$directive" ]] && directive_str="# $directive"
+
+	echo $result $KTAP_TESTNO $description $directive_str
+
+	KTAP_TESTNO=$((KTAP_TESTNO+1))
+}
+
+ktap_test_pass() {
+	description="$1"
+
+	result="ok"
+	__ktap_test "$result" "$description"
+
+	KTAP_CNT_PASS=$((KTAP_CNT_PASS+1))
+}
+
+ktap_test_skip() {
+	description="$1"
+
+	result="ok"
+	directive="SKIP"
+	__ktap_test "$result" "$description" "$directive"
+
+	KTAP_CNT_SKIP=$((KTAP_CNT_SKIP+1))
+}
+
+ktap_test_fail() {
+	description="$1"
+
+	result="not ok"
+	__ktap_test "$result" "$description"
+
+	KTAP_CNT_FAIL=$((KTAP_CNT_FAIL+1))
+}
+
+ktap_print_totals() {
+	echo "# Totals: pass:$KTAP_CNT_PASS fail:$KTAP_CNT_FAIL xfail:0 xpass:0 skip:$KTAP_CNT_SKIP error:0"
+}

tools/testing/selftests/dt/test_unprobed_devices.sh

@@ -0,0 +1,83 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (c) 2023 Collabora Ltd
+#
+# Based on Frank Rowand's dt_stat script.
+#
+# This script tests for devices that were declared on the Devicetree and are
+# expected to bind to a driver, but didn't.
+#
+# To achieve this, two lists are used:
+# * a list of the compatibles that can be matched by a Devicetree node
+# * a list of compatibles that should be ignored
+#
+
+DIR="$(dirname $(readlink -f "$0"))"
+
+source "${DIR}"/ktap_helpers.sh
+
+PDT=/proc/device-tree/
+COMPAT_LIST="${DIR}"/compatible_list
+IGNORE_LIST="${DIR}"/compatible_ignore_list
+
+KSFT_PASS=0
+KSFT_FAIL=1
+KSFT_SKIP=4
+
+ktap_print_header
+
+if [[ ! -d "${PDT}" ]]; then
+	ktap_skip_all "${PDT} doesn't exist."
+	exit "${KSFT_SKIP}"
+fi
+
+nodes_compatible=$(
+	for node_compat in $(find ${PDT} -name compatible); do
+		node=$(dirname "${node_compat}")
+		# Check if node is available
+		if [[ -e "${node}"/status ]]; then
+			status=$(tr -d '\000' < "${node}"/status)
+			[[ "${status}" != "okay" && "${status}" != "ok" ]] && continue
+		fi
+		echo "${node}" | sed -e 's|\/proc\/device-tree||'
+	done | sort
+	)
+
+nodes_dev_bound=$(
+	IFS=$'\n'
+	for uevent in $(find /sys/devices -name uevent); do
+		if [[ -d "$(dirname "${uevent}")"/driver ]]; then
+			grep '^OF_FULLNAME=' "${uevent}" | sed -e 's|OF_FULLNAME=||'
+		fi
+	done
+	)
+
+num_tests=$(echo ${nodes_compatible} | wc -w)
+ktap_set_plan "${num_tests}"
+
+retval="${KSFT_PASS}"
+for node in ${nodes_compatible}; do
+	if ! echo "${nodes_dev_bound}" | grep -E -q "(^| )${node}( |\$)"; then
+		compatibles=$(tr '\000' '\n' < "${PDT}"/"${node}"/compatible)
+
+		for compatible in ${compatibles}; do
+			if grep -x -q "${compatible}" "${IGNORE_LIST}"; then
+				continue
+			fi
+
+			if grep -x -q "${compatible}" "${COMPAT_LIST}"; then
+				ktap_test_fail "${node}"
+				retval="${KSFT_FAIL}"
+				continue 2
+			fi
+		done
+		ktap_test_skip "${node}"
+	else
+		ktap_test_pass "${node}"
+	fi
+
+done
+
+ktap_print_totals
+exit "${retval}"