[RFC PATCH 2/2] kselftest: Add test to detect unprobed devices on ACPI platforms

[Laura Nao]

Add new kselftest that tests whether devices declared in the ACPI
namespace and supported by the kernel are correctly bound
to a driver.

The test runs the acpi-extract-ids script to generate a list
of all the ACPI device IDs present in the kernel sources.
The list is then used as a reference to determine which of the
devices declared in the ACPI namespace are supported by the kernel
and therefore expected to bind to a driver.

Signed-off-by: Laura Nao <laura.nao@xxxxxxxxxxxxx>
---
 MAINTAINERS                                   |  1 +
 tools/testing/selftests/Makefile              |  1 +
 tools/testing/selftests/acpi/.gitignore       |  2 +
 tools/testing/selftests/acpi/Makefile         | 23 ++++++
 .../selftests/acpi/test_unprobed_devices.sh   | 75 +++++++++++++++++++
 5 files changed, 102 insertions(+)
 create mode 100644 tools/testing/selftests/acpi/.gitignore
 create mode 100644 tools/testing/selftests/acpi/Makefile
 create mode 100755 tools/testing/selftests/acpi/test_unprobed_devices.sh

diff --git a/MAINTAINERS b/MAINTAINERS
index 7540316d82f5..5c83b36f26ed 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -295,6 +295,7 @@ F:	include/acpi/
 F:	include/linux/acpi.h
 F:	include/linux/fwnode.h
 F:	scripts/acpi/acpi-extract-ids
+F:	tools/testing/selftests/acpi/
 F:	tools/power/acpi/
 
 ACPI APEI
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 11aa8a834794..bb95daf9ae91 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
+TARGETS += acpi
 TARGETS += alsa
 TARGETS += amd-pstate
 TARGETS += arm64
diff --git a/tools/testing/selftests/acpi/.gitignore b/tools/testing/selftests/acpi/.gitignore
new file mode 100644
index 000000000000..2526540468f4
--- /dev/null
+++ b/tools/testing/selftests/acpi/.gitignore
@@ -0,0 +1,2 @@
+supported_id_list
+ktap_helpers.sh
\ No newline at end of file
diff --git a/tools/testing/selftests/acpi/Makefile b/tools/testing/selftests/acpi/Makefile
new file mode 100644
index 000000000000..806e75f15824
--- /dev/null
+++ b/tools/testing/selftests/acpi/Makefile
@@ -0,0 +1,23 @@
+PY3 = $(shell which python3 2>/dev/null)
+
+ifneq ($(PY3),)
+
+TEST_PROGS := test_unprobed_devices.sh
+TEST_GEN_FILES := supported_id_list ktap_helpers.sh
+
+include ../lib.mk
+
+$(OUTPUT)/supported_id_list:
+	$(top_srcdir)/scripts/acpi/acpi-extract-ids $(top_srcdir) > $@
+
+$(OUTPUT)/ktap_helpers.sh:
+	cp $(top_srcdir)/tools/testing/selftests/dt/ktap_helpers.sh $@
+
+else
+
+all: no_py3_warning
+
+no_py3_warning:
+	@echo "Missing python3. This test will be skipped."
+
+endif
\ No newline at end of file
diff --git a/tools/testing/selftests/acpi/test_unprobed_devices.sh b/tools/testing/selftests/acpi/test_unprobed_devices.sh
new file mode 100755
index 000000000000..aa8c62166b4d
--- /dev/null
+++ b/tools/testing/selftests/acpi/test_unprobed_devices.sh
@@ -0,0 +1,75 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (c) 2023 Collabora Ltd
+#
+# Inspired by the tools/testing/selftests/dt/test_unprobed_devices.sh
+# script, adapted for the ACPI use case.
+#
+# This script checks whether devices declared in the ACPI namespace
+# and supported by the kernel are correctly bound to a driver.
+#
+# A list of all the ACPI device IDs present in the kernel sources
+# is used as reference to determine which of the devices declared
+# in the ACPI tables are supported.
+#
+
+DIR="$(dirname "$(readlink -f "$0")")"
+
+source "${DIR}"/ktap_helpers.sh
+
+ACPI_SYSTEM_DIR="/sys/devices/LNXSYSTM:00"
+SUPPORTED_ID_LIST="${DIR}"/supported_id_list
+
+KSFT_PASS=0
+KSFT_FAIL=1
+KSFT_SKIP=4
+
+ktap_print_header
+
+if [[ ! -d "${ACPI_SYSTEM_DIR}" ]]; then
+	ktap_skip_all "${ACPI_SYSTEM_DIR} doesn't exist."
+	exit "${KSFT_SKIP}"
+fi
+
+# The ACPI specification mandates that ACPI objects representing devices on
+# non-enumerable and enumerable busses contain a _HID or an _ADR identification
+# object respectively.
+# Get a list of devices of both types, by searching the ACPI sysfs subtree for
+# directories containing a hid or adr attribute.
+supp_dev_paths=$(while IFS=$'\n' read -r dev_path; do
+	if [ ! -f "${dev_path}"/hid ] && [ ! -f "${dev_path}"/adr ]; then
+		continue
+	fi
+
+	if [ -f "${dev_path}"/hid ]; then
+		if ! grep -x -q -i "$(cat "${dev_path}"/hid)" "${SUPPORTED_ID_LIST}"; then
+			continue
+		fi
+	fi
+
+	echo "${dev_path}"
+done < <(find ${ACPI_SYSTEM_DIR} -name uevent -exec dirname {} \;))
+
+supp_dev_paths_num=$(echo "${supp_dev_paths}" | wc -w)
+ktap_set_plan "${supp_dev_paths_num}"
+
+ret="${KSFT_PASS}"
+for dev_path in ${supp_dev_paths}; do
+	desc="$(cat "${dev_path}"/path)"
+	[ -f "${dev_path}"/hid ] && desc+=" $(cat "${dev_path}"/hid)"
+
+	# ACPI device objects might be linked to other objects in the device
+	# hierarchy (e.g. devices on the PCI bus).
+	# In these cases, the driver folder will be in the companion object's sysfs
+	# directory, linked by physical_node.
+	if [ -d "${dev_path}"/physical_node/driver ] || [ -d "${dev_path}"/driver ]; then
+		ktap_test_pass "${desc}"
+	else
+		ret="${KSFT_FAIL}"
+		ktap_test_fail "${desc}"
+	fi
+done
+
+ktap_print_totals
+exit "${ret}"
-- 
2.30.2