linux-kernel - [PATCH] clk: tests: Add tests for clk lookup by name

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Message-ID: <20251002092036.2504858-1-wenst@chromium.org>
Date: Thu,  2 Oct 2025 17:20:35 +0800
From: Chen-Yu Tsai <wenst@...omium.org>
To: Stephen Boyd <sboyd@...nel.org>
Cc: Chen-Yu Tsai <wenst@...omium.org>,
	linux-clk@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] clk: tests: Add tests for clk lookup by name

Clk lookup (by name) recently gained some performance improvements at
the expense of more complexity within the lookup code.

To make sure that this works as intended and doesn't break, add some
basic tests for this part of the CCF.

A new "clk_hw_lookup()" function is added purely for running kunit
tests.

Signed-off-by: Chen-Yu Tsai <wenst@...omium.org>
---
 drivers/clk/clk.c      | 11 +++++++
 drivers/clk/clk.h      |  4 +++
 drivers/clk/clk_test.c | 66 +++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 80 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 85d2f2481acf..a17d0070d11f 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -778,6 +778,17 @@ struct clk *__clk_lookup(const char *name)
 	return !core ? NULL : core->hw->clk;
 }
 
+#if IS_ENABLED(CONFIG_CLK_KUNIT_TEST)
+/* This is only provided for kunit tests to test the core lookup functions. */
+struct clk_hw *clk_hw_lookup(const char *name)
+{
+	struct clk_core *core = clk_core_lookup(name);
+
+	return !core ? NULL : core->hw;
+}
+EXPORT_SYMBOL_GPL(clk_hw_lookup);
+#endif
+
 static void clk_core_get_boundaries(struct clk_core *core,
 				    unsigned long *min_rate,
 				    unsigned long *max_rate)
diff --git a/drivers/clk/clk.h b/drivers/clk/clk.h
index 2d801900cad5..a8ed54f5b572 100644
--- a/drivers/clk/clk.h
+++ b/drivers/clk/clk.h
@@ -8,6 +8,10 @@ struct clk_hw;
 struct device;
 struct of_phandle_args;
 
+#if IS_ENABLED(CONFIG_CLK_KUNIT_TEST)
+struct clk_hw *clk_hw_lookup(const char *name);
+#endif
+
 #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
 struct clk_hw *of_clk_get_hw(struct device_node *np,
 				    int index, const char *con_id);
diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c
index a268d7b5d4cb..b3b5ce0ad897 100644
--- a/drivers/clk/clk_test.c
+++ b/drivers/clk/clk_test.c
@@ -175,6 +175,8 @@ static const struct clk_ops clk_multiple_parents_no_reparent_mux_ops = {
 	.set_parent = clk_multiple_parents_mux_set_parent,
 };
 
+#define DUMMY_CLK_NAME	"test_dummy_rate"
+
 static int clk_test_init_with_ops(struct kunit *test, const struct clk_ops *ops)
 {
 	struct clk_dummy_context *ctx;
@@ -187,7 +189,7 @@ static int clk_test_init_with_ops(struct kunit *test, const struct clk_ops *ops)
 	ctx->rate = DUMMY_CLOCK_INIT_RATE;
 	test->priv = ctx;
 
-	init.name = "test_dummy_rate";
+	init.name = DUMMY_CLK_NAME;
 	init.ops = ops;
 	ctx->hw.init = &init;
 
@@ -3541,6 +3543,67 @@ static struct kunit_suite clk_hw_get_dev_of_node_test_suite = {
 	.test_cases = clk_hw_get_dev_of_node_test_cases,
 };
 
+/*
+ * Test that clk lookup with a name that is not registered returns NULL.
+ */
+static void clk_lookup_not_registered_clk_returns_NULL(struct kunit *test)
+{
+	KUNIT_EXPECT_PTR_EQ(test, NULL, clk_hw_lookup(DUMMY_CLK_NAME));
+}
+
+/*
+ * Test that clk lookup with a name that is registered returns the clk.
+ */
+static void clk_lookup_registered_clk_returns_clk(struct kunit *test)
+{
+	struct clk_hw *hw;
+	struct clk_init_data init = {
+		.name = DUMMY_CLK_NAME,
+		.ops = &empty_clk_ops,
+	};
+
+	hw = kunit_kzalloc(test, sizeof(*hw), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw);
+
+	hw->init = &init;
+	KUNIT_ASSERT_EQ(test, 0, clk_hw_register_kunit(test, NULL, hw));
+
+	KUNIT_EXPECT_PTR_EQ(test, hw, clk_hw_lookup(DUMMY_CLK_NAME));
+}
+
+/*
+ * Test that clk lookup with a name that was unregistered returns NULL.
+ */
+static void clk_lookup_unregistered_clk_returns_NULL(struct kunit *test)
+{
+	struct clk_hw *hw;
+	struct clk_init_data init = {
+		.name = DUMMY_CLK_NAME,
+		.ops = &empty_clk_ops,
+	};
+
+	hw = kunit_kzalloc(test, sizeof(*hw), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw);
+
+	hw->init = &init;
+	KUNIT_ASSERT_FALSE(test, clk_hw_register(NULL, hw));
+
+	clk_hw_unregister(hw);
+
+	KUNIT_EXPECT_PTR_EQ(test, NULL, clk_hw_lookup(DUMMY_CLK_NAME));
+}
+
+static struct kunit_case clk_lookup_test_cases[] = {
+	KUNIT_CASE(clk_lookup_not_registered_clk_returns_NULL),
+	KUNIT_CASE(clk_lookup_registered_clk_returns_clk),
+	KUNIT_CASE(clk_lookup_unregistered_clk_returns_NULL),
+	{}
+};
+
+static struct kunit_suite clk_lookup_test_suite = {
+	.name = "clk-lookup",
+	.test_cases = clk_lookup_test_cases,
+};
 
 kunit_test_suites(
 	&clk_assigned_rates_suite,
@@ -3560,6 +3623,7 @@ kunit_test_suites(
 	&clk_register_clk_parent_data_device_suite,
 	&clk_single_parent_mux_test_suite,
 	&clk_uncached_test_suite,
+	&clk_lookup_test_suite,
 );
 MODULE_DESCRIPTION("Kunit tests for clk framework");
 MODULE_LICENSE("GPL v2");
-- 
2.51.0.618.g983fd99d29-goog