[PATCH 6/6] of: Add KUnit test to confirm DTB is loaded

[Stephen Boyd <sboyd@kernel.org>]

Add a KUnit test that confirms a DTB has been loaded, i.e. there is a
root node, and that the of_have_populated_dt() API works properly.

Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: David Gow <davidgow@google.com>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
---
 drivers/of/.kunitconfig |  3 ++
 drivers/of/Kconfig      |  9 ++++
 drivers/of/Makefile     |  2 +
 drivers/of/of_test.c    | 98 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 112 insertions(+)
 create mode 100644 drivers/of/.kunitconfig
 create mode 100644 drivers/of/of_test.c

diff --git a/drivers/of/.kunitconfig b/drivers/of/.kunitconfig
new file mode 100644
index 000000000000..5a8fee11978c
--- /dev/null
+++ b/drivers/of/.kunitconfig
@@ -0,0 +1,3 @@
+CONFIG_KUNIT=y
+CONFIG_OF=y
+CONFIG_OF_KUNIT_TEST=y
diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index 9628e48baa15..a527ba8451d9 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -37,6 +37,15 @@ config OF_UNITTEST
 
 	  If unsure, say N here. This option is not safe to enable.
 
+config OF_KUNIT_TEST
+	tristate "Devicetree KUnit DTB Test" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This option builds KUnit unit tests for device tree infrastructure.
+
+	  If unsure, say N here, but this option is safe to enable.
+
 config OF_ALL_DTBS
 	bool "Build all Device Tree Blobs"
 	depends on COMPILE_TEST
diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index df305348d1cb..251d33532148 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -19,4 +19,6 @@ obj-y	+= kexec.o
 endif
 endif
 
+obj-$(CONFIG_OF_KUNIT_TEST) += of_test.o
+
 obj-$(CONFIG_OF_UNITTEST) += unittest-data/
diff --git a/drivers/of/of_test.c b/drivers/of/of_test.c
new file mode 100644
index 000000000000..7609ad3081b9
--- /dev/null
+++ b/drivers/of/of_test.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit tests for OF APIs
+ */
+#include <linux/module.h>
+#include <linux/of.h>
+
+#include <kunit/test.h>
+
+/*
+ * Test that the root node "/" exists.
+ */
+static void dtb_root_node_found_by_path(struct kunit *test)
+{
+	struct device_node *np;
+
+	np = of_find_node_by_path("/");
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, np);
+	of_node_put(np);
+}
+
+/*
+ * Test that the of_root global variable is always populated when DT
+ * code is enabled.
+ */
+static void dtb_root_node_populates_of_root(struct kunit *test)
+{
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, of_root);
+}
+
+static struct kunit_case dtb_test_cases[] = {
+	KUNIT_CASE(dtb_root_node_found_by_path),
+	KUNIT_CASE(dtb_root_node_populates_of_root),
+	{}
+};
+
+/*
+ * Test suite to confirm a live DTB is loaded.
+ */
+static struct kunit_suite dtb_suite = {
+	.name = "dtb",
+	.test_cases = dtb_test_cases,
+};
+
+/*
+ * Test that calling of_have_populated_dt() returns false when
+ * the OF_EMPTY_ROOT flag isn't set.
+ */
+static void of_have_populated_dt_false_when_flag_set(struct kunit *test)
+{
+	bool was_set;
+
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, of_root);
+
+	was_set = of_node_test_and_set_flag(of_root, OF_EMPTY_ROOT);
+	KUNIT_EXPECT_FALSE(test, of_have_populated_dt());
+
+	if (!was_set)
+		of_node_clear_flag(of_root, OF_EMPTY_ROOT);
+}
+
+/*
+ * Test that calling of_have_populated_dt() returns false when
+ * the OF_EMPTY_ROOT flag isn't set.
+ */
+static void of_have_populated_dt_true_when_flag_clear(struct kunit *test)
+{
+	bool was_set;
+
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, of_root);
+
+	was_set = of_node_check_flag(of_root, OF_EMPTY_ROOT);
+	of_node_set_flag(of_root, OF_EMPTY_ROOT);
+	KUNIT_EXPECT_FALSE(test, of_have_populated_dt());
+
+	if (was_set)
+		of_node_set_flag(of_root, OF_EMPTY_ROOT);
+}
+
+static struct kunit_case of_have_populated_dt_test_cases[] = {
+	KUNIT_CASE(of_have_populated_dt_false_when_flag_set),
+	KUNIT_CASE(of_have_populated_dt_true_when_flag_clear),
+	{}
+};
+
+/*
+ * Test suite to confirm behavior of of_have_populated_dt().
+ */
+static struct kunit_suite of_have_populated_dt_suite = {
+	.name = "of_have_populated_dt",
+	.test_cases = of_have_populated_dt_test_cases,
+};
+
+kunit_test_suites(
+	&dtb_suite,
+	&of_have_populated_dt_suite,
+);
+MODULE_LICENSE("GPL");
-- 
https://git.kernel.org/pub/scm/linux/kernel/git/clk/linux.git/
https://git.kernel.org/pub/scm/linux/kernel/git/sboyd/spmi.git