[PATCH 1/3] firewire: core: add KUnit test skeleton for node tree

Some issues have been reported in node tree management. Refactoring
the topology-related code in the core is required. Adding unit tests
would help ensure that the refactoring does not introduce regressions.

This commit adds a KUnit test skeleton for this purpose.

Signed-off-by: Takashi Sakamoto <[email protected]>
---
 drivers/firewire/.kunitconfig     |  1 +
 drivers/firewire/Kconfig          | 15 +++++++++++++++
 drivers/firewire/core-topology.c  |  4 ++++
 drivers/firewire/node-tree-test.c | 19 +++++++++++++++++++
 4 files changed, 39 insertions(+)
 create mode 100644 drivers/firewire/node-tree-test.c

diff --git a/drivers/firewire/.kunitconfig b/drivers/firewire/.kunitconfig
index 21b7e9eef63d..7406acb00478 100644
--- a/drivers/firewire/.kunitconfig
+++ b/drivers/firewire/.kunitconfig
@@ -6,3 +6,4 @@ CONFIG_FIREWIRE_KUNIT_DEVICE_ATTRIBUTE_TEST=y
 CONFIG_FIREWIRE_KUNIT_PACKET_SERDES_TEST=y
 CONFIG_FIREWIRE_KUNIT_SELF_ID_SEQUENCE_HELPER_TEST=y
 CONFIG_FIREWIRE_KUNIT_OHCI_SERDES_TEST=y
+CONFIG_FIREWIRE_KUNIT_NODE_TREE_TEST=y
diff --git a/drivers/firewire/Kconfig b/drivers/firewire/Kconfig
index a5f5e250223a..b5abe00accc9 100644
--- a/drivers/firewire/Kconfig
+++ b/drivers/firewire/Kconfig
@@ -81,6 +81,21 @@ config FIREWIRE_KUNIT_SELF_ID_SEQUENCE_HELPER_TEST
 	  For more information on KUnit and unit tests in general, refer
 	  to the KUnit documentation in Documentation/dev-tools/kunit/.
 
+config FIREWIRE_KUNIT_NODE_TREE_TEST
+	tristate "KUnit tests for node tree" if !KUNIT_ALL_TESTS
+	depends on FIREWIRE && KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the KUnit tests for node tree.
+
+	  KUnit tests run during boot and output the results to the debug
+	  log in TAP format (https://testanything.org/). Only useful for
+	  kernel devs running KUnit test harness and are not for inclusion
+	  into a production build.
+
+	  For more information on KUnit and unit tests in general, refer
+	  to the KUnit documentation in Documentation/dev-tools/kunit/.
+
 config FIREWIRE_OHCI
 	tristate "OHCI-1394 controllers"
 	depends on PCI && FIREWIRE
diff --git a/drivers/firewire/core-topology.c b/drivers/firewire/core-topology.c
index df2ac0dab106..1d3a4419f554 100644
--- a/drivers/firewire/core-topology.c
+++ b/drivers/firewire/core-topology.c
@@ -507,3 +507,7 @@ void fw_core_handle_bus_reset(struct fw_card *card, int node_id, int generation,
 	}
 }
 EXPORT_SYMBOL(fw_core_handle_bus_reset);
+
+#ifdef CONFIG_FIREWIRE_KUNIT_NODE_TREE_TEST
+#include "node-tree-test.c"
+#endif
diff --git a/drivers/firewire/node-tree-test.c b/drivers/firewire/node-tree-test.c
new file mode 100644
index 000000000000..fca71dd99b25
--- /dev/null
+++ b/drivers/firewire/node-tree-test.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// node-tree-test.c - An application of Kunit to test node tree.
+//
+// Copyright (c) 2026 Takashi Sakamoto
+//
+// This file can not be built independently since it is intentionally included in core-topology.c.
+
+#include <kunit/test.h>
+
+static struct kunit_case node_tree_test_cases[] = {
+	{}
+};
+
+static struct kunit_suite node_tree_test_suite = {
+	.name = "firewire-node-tree",
+	.test_cases = node_tree_test_cases,
+};
+kunit_test_suite(node_tree_test_suite);
-- 
2.53.0