[PATCH RFC v5 4/4] clk: test: add kunit test for coordinated rate change
From: Brian Masney
Date: Fri Mar 06 2026 - 18:23:26 EST
Add kunit tests to demonstrate how to use the coordinated rate change
clk APIs, and to validate that they are working as expected.
Link: https://lore.kernel.org/linux-clk/aUSWU7UymULCXOeF@xxxxxxxxxx/
Link: https://lpc.events/event/19/contributions/2152/
Signed-off-by: Brian Masney <bmasney@xxxxxxxxxx>
---
drivers/clk/clk_test.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 101 insertions(+), 2 deletions(-)
diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c
index 97cbf9dd16ee504d7687d8f0729b6e6e22a21afb..886190408545635926689046f6237260303b2271 100644
--- a/drivers/clk/clk_test.c
+++ b/drivers/clk/clk_test.c
@@ -5,6 +5,7 @@
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/clk/clk-conf.h>
+#include <linux/lcm.h>
#include <linux/of.h>
#include <linux/platform_device.h>
@@ -180,6 +181,46 @@ static const struct clk_ops clk_dummy_div_ops = {
.set_rate = clk_dummy_div_set_rate,
};
+static int clk_dummy_div_coordinating_determine_rate(struct clk_hw *hw,
+ struct clk_rate_request *req)
+{
+ struct clk_hw *parent_hw = clk_hw_get_parent(hw);
+ struct clk_rate_change *child_node;
+ unsigned long lcm_rate = 0;
+ LIST_HEAD(stable_clks);
+ int ret;
+
+ ret = clk_hw_get_v2_stable_clks(req, parent_hw, &stable_clks);
+ if (ret)
+ return ret;
+
+ list_for_each_entry(child_node, &stable_clks, node) {
+ if (child_node->target_rate == 0)
+ continue;
+ if (lcm_rate == 0)
+ lcm_rate = child_node->target_rate;
+ else
+ lcm_rate = lcm(lcm_rate, child_node->target_rate);
+ }
+
+ ret = clk_hw_add_coordinated_rate_changes(req, parent_hw,
+ clk_hw_get_rate(parent_hw),
+ lcm_rate, &stable_clks);
+ if (ret)
+ return ret;
+
+ req->best_parent_rate = lcm_rate;
+ req->best_parent_hw = parent_hw;
+
+ return 0;
+}
+
+static const struct clk_ops clk_dummy_div_coordinating_ops = {
+ .recalc_rate = clk_dummy_div_recalc_rate,
+ .determine_rate = clk_dummy_div_coordinating_determine_rate,
+ .set_rate = clk_dummy_div_set_rate,
+};
+
struct clk_multiple_parent_ctx {
struct clk_dummy_context parents_ctx[2];
struct clk_hw hw;
@@ -671,6 +712,14 @@ clk_rate_change_sibling_div_div_test_regular_ops_params[] = {
KUNIT_ARRAY_PARAM_DESC(clk_rate_change_sibling_div_div_test_regular_ops,
clk_rate_change_sibling_div_div_test_regular_ops_params, desc)
+static const struct clk_rate_change_sibling_div_div_test_param
+clk_rate_change_sibling_div_div_test_coord_ops_params[] = {
+ { .desc = "coordinating_ops", .ops = &clk_dummy_div_coordinating_ops },
+};
+
+KUNIT_ARRAY_PARAM_DESC(clk_rate_change_sibling_div_div_test_coord_ops,
+ clk_rate_change_sibling_div_div_test_coord_ops_params, desc)
+
static int clk_rate_change_sibling_div_div_test_init(struct kunit *test)
{
const struct clk_rate_change_sibling_div_div_test_param *param = test->param_value;
@@ -689,14 +738,16 @@ static int clk_rate_change_sibling_div_div_test_init(struct kunit *test)
return ret;
ctx->child1.hw.init = CLK_HW_INIT_HW("child1", &ctx->parent.hw,
- param->ops, CLK_SET_RATE_PARENT);
+ param->ops,
+ CLK_SET_RATE_PARENT | CLK_V2_RATE_NEGOTIATION);
ctx->child1.div = 1;
ret = clk_hw_register_kunit(test, NULL, &ctx->child1.hw);
if (ret)
return ret;
ctx->child2.hw.init = CLK_HW_INIT_HW("child2", &ctx->parent.hw,
- param->ops, CLK_SET_RATE_PARENT);
+ param->ops,
+ CLK_SET_RATE_PARENT | CLK_V2_RATE_NEGOTIATION);
ctx->child2.div = 1;
ret = clk_hw_register_kunit(test, NULL, &ctx->child2.hw);
if (ret)
@@ -803,6 +854,48 @@ static void clk_test_rate_change_sibling_div_div_3(struct kunit *test)
KUNIT_EXPECT_EQ(test, ctx->child2.div, 1);
}
+static void clk_test_rate_change_sibling_div_div_4(struct kunit *test)
+{
+ struct clk_rate_change_sibling_div_div_context *ctx = test->priv;
+ int ret;
+
+ ret = clk_set_rate(ctx->child1_clk, 48 * HZ_PER_MHZ);
+ KUNIT_ASSERT_EQ(test, ret, 0);
+
+ /*
+ * With coordinated rate changes, the parent should be at 48 MHz,
+ * child1 at 48 MHz (div=1), and child2 at 24 MHz (div=2). Child2's
+ * keeps the same frequency, and the divider is changed from 1 to 2.
+ */
+ KUNIT_EXPECT_EQ(test, clk_get_rate(ctx->parent_clk), 48 * HZ_PER_MHZ);
+ KUNIT_EXPECT_EQ(test, clk_get_rate(ctx->child1_clk), 48 * HZ_PER_MHZ);
+ KUNIT_EXPECT_EQ(test, ctx->child1.div, 1);
+ KUNIT_EXPECT_EQ(test, clk_get_rate(ctx->child2_clk), 24 * HZ_PER_MHZ);
+ KUNIT_EXPECT_EQ(test, ctx->child2.div, 2);
+}
+
+static void clk_test_rate_change_sibling_div_div_5(struct kunit *test)
+{
+ struct clk_rate_change_sibling_div_div_context *ctx = test->priv;
+ int ret;
+
+ ret = clk_set_rate(ctx->child1_clk, 32 * HZ_PER_MHZ);
+ KUNIT_ASSERT_EQ(test, ret, 0);
+
+ ret = clk_set_rate(ctx->child2_clk, 48 * HZ_PER_MHZ);
+ KUNIT_ASSERT_EQ(test, ret, 0);
+
+ /*
+ * With coordinated rate changes, the parent should be at 96 MHz,
+ * child1 at 32 MHz (div=3), and child2 at 48 MHz (div=2).
+ */
+ KUNIT_EXPECT_EQ(test, clk_get_rate(ctx->parent_clk), 96 * HZ_PER_MHZ);
+ KUNIT_EXPECT_EQ(test, clk_get_rate(ctx->child1_clk), 32 * HZ_PER_MHZ);
+ KUNIT_EXPECT_EQ(test, ctx->child1.div, 3);
+ KUNIT_EXPECT_EQ(test, clk_get_rate(ctx->child2_clk), 48 * HZ_PER_MHZ);
+ KUNIT_EXPECT_EQ(test, ctx->child2.div, 2);
+}
+
static struct kunit_case clk_rate_change_sibling_div_div_cases[] = {
KUNIT_CASE_PARAM(clk_test_rate_change_sibling_div_div_1,
clk_rate_change_sibling_div_div_test_regular_ops_gen_params),
@@ -810,6 +903,12 @@ static struct kunit_case clk_rate_change_sibling_div_div_cases[] = {
clk_rate_change_sibling_div_div_test_regular_ops_gen_params),
KUNIT_CASE_PARAM(clk_test_rate_change_sibling_div_div_3,
clk_rate_change_sibling_div_div_test_regular_ops_gen_params),
+ KUNIT_CASE_PARAM(clk_test_rate_change_sibling_div_div_1,
+ clk_rate_change_sibling_div_div_test_coord_ops_gen_params),
+ KUNIT_CASE_PARAM(clk_test_rate_change_sibling_div_div_4,
+ clk_rate_change_sibling_div_div_test_coord_ops_gen_params),
+ KUNIT_CASE_PARAM(clk_test_rate_change_sibling_div_div_5,
+ clk_rate_change_sibling_div_div_test_coord_ops_gen_params),
{}
};
--
2.53.0