clk: tests: Add tests for mux with multiple parents

We'll need to test a few corner cases that occur when we have a mux
clock whose default parent is missing.

For now, let's create the context structure and the trivial ops, along
with a test suite that just tests trivial things for now, without
considering the orphan case.

Tested-by: Alexander Stein <alexander.stein@ew.tq-group.com> # imx8mp
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> # exynos4210, meson g12b
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220816112530.1837489-11-maxime@cerno.tech
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Author: mripard

drivers/clk/clk_test.c

@@ -108,6 +108,39 @@ static const struct clk_ops clk_dummy_single_parent_ops = {
 	.get_parent = clk_dummy_single_get_parent,
 };
 
+struct clk_multiple_parent_ctx {
+	struct clk_dummy_context parents_ctx[2];
+	struct clk_hw hw;
+	u8 current_parent;
+};
+
+static int clk_multiple_parents_mux_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct clk_multiple_parent_ctx *ctx =
+		container_of(hw, struct clk_multiple_parent_ctx, hw);
+
+	if (index >= clk_hw_get_num_parents(hw))
+		return -EINVAL;
+
+	ctx->current_parent = index;
+
+	return 0;
+}
+
+static u8 clk_multiple_parents_mux_get_parent(struct clk_hw *hw)
+{
+	struct clk_multiple_parent_ctx *ctx =
+		container_of(hw, struct clk_multiple_parent_ctx, hw);
+
+	return ctx->current_parent;
+}
+
+static const struct clk_ops clk_multiple_parents_mux_ops = {
+	.get_parent = clk_multiple_parents_mux_get_parent,
+	.set_parent = clk_multiple_parents_mux_set_parent,
+	.determine_rate = __clk_mux_determine_rate_closest,
+};
+
 static int clk_test_init_with_ops(struct kunit *test, const struct clk_ops *ops)
 {
 	struct clk_dummy_context *ctx;
@@ -360,6 +393,93 @@ static struct kunit_suite clk_uncached_test_suite = {
 	.test_cases = clk_uncached_test_cases,
 };
 
+static int
+clk_multiple_parents_mux_test_init(struct kunit *test)
+{
+	struct clk_multiple_parent_ctx *ctx;
+	const char *parents[2] = { "parent-0", "parent-1"};
+	int ret;
+
+	ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+	test->priv = ctx;
+
+	ctx->parents_ctx[0].hw.init = CLK_HW_INIT_NO_PARENT("parent-0",
+							    &clk_dummy_rate_ops,
+							    0);
+	ctx->parents_ctx[0].rate = DUMMY_CLOCK_RATE_1;
+	ret = clk_hw_register(NULL, &ctx->parents_ctx[0].hw);
+	if (ret)
+		return ret;
+
+	ctx->parents_ctx[1].hw.init = CLK_HW_INIT_NO_PARENT("parent-1",
+							    &clk_dummy_rate_ops,
+							    0);
+	ctx->parents_ctx[1].rate = DUMMY_CLOCK_RATE_2;
+	ret = clk_hw_register(NULL, &ctx->parents_ctx[1].hw);
+	if (ret)
+		return ret;
+
+	ctx->current_parent = 0;
+	ctx->hw.init = CLK_HW_INIT_PARENTS("test-mux", parents,
+					   &clk_multiple_parents_mux_ops,
+					   CLK_SET_RATE_PARENT);
+	ret = clk_hw_register(NULL, &ctx->hw);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static void
+clk_multiple_parents_mux_test_exit(struct kunit *test)
+{
+	struct clk_multiple_parent_ctx *ctx = test->priv;
+
+	clk_hw_unregister(&ctx->hw);
+	clk_hw_unregister(&ctx->parents_ctx[0].hw);
+	clk_hw_unregister(&ctx->parents_ctx[1].hw);
+}
+
+/*
+ * Test that for a clock with multiple parents, clk_get_parent()
+ * actually returns the current one.
+ */
+static void
+clk_test_multiple_parents_mux_get_parent(struct kunit *test)
+{
+	struct clk_multiple_parent_ctx *ctx = test->priv;
+	struct clk_hw *hw = &ctx->hw;
+	struct clk *clk = clk_hw_get_clk(hw, NULL);
+	struct clk *parent = clk_hw_get_clk(&ctx->parents_ctx[0].hw, NULL);
+
+	KUNIT_EXPECT_TRUE(test, clk_is_match(clk_get_parent(clk), parent));
+
+	clk_put(parent);
+	clk_put(clk);
+}
+
+static struct kunit_case clk_multiple_parents_mux_test_cases[] = {
+	KUNIT_CASE(clk_test_multiple_parents_mux_get_parent),
+	{}
+};
+
+/*
+ * Test suite for a basic mux clock with two parents, with
+ * CLK_SET_RATE_PARENT on the child.
+ *
+ * These tests exercise the consumer API and check that the state of the
+ * child and parents are sane and consistent.
+ */
+static struct kunit_suite
+clk_multiple_parents_mux_test_suite = {
+	.name = "clk-multiple-parents-mux-test",
+	.init = clk_multiple_parents_mux_test_init,
+	.exit = clk_multiple_parents_mux_test_exit,
+	.test_cases = clk_multiple_parents_mux_test_cases,
+};
+
 struct clk_single_parent_ctx {
 	struct clk_dummy_context parent_ctx;
 	struct clk_hw hw;
@@ -1339,6 +1459,7 @@ static struct kunit_suite clk_range_minimize_test_suite = {
 
 kunit_test_suites(
 	&clk_test_suite,
+	&clk_multiple_parents_mux_test_suite,
 	&clk_orphan_transparent_single_parent_test_suite,
 	&clk_range_test_suite,
 	&clk_range_maximize_test_suite,