[PATCH v3 0/7] clk: Add support for clock nexus

[PATCH v3 0/7] clk: Add support for clock nexus

[Miquel Raynal (Schneider Electric)]

Adding support for clock nexus had some prerequisites requested by
Stephen, such as adding new selftests, the initial discussions come
from:

Link: https://lore.kernel.org/linux-clk/20260129201003.288605-1-miquel.raynal@bootlin.com/

Changes in v3:
- Prevent out-of-bounds clock-ranges fallback in of_parse_clkspec()
- tests: Check of_clk_add_hw_provider_kunit() return value and fix node
  ref leaks
- Link to v2: https://lore.kernel.org/r/20260710-schneider-v7-2-rc1-eip201-upstream-v2-0-b4680787377e@bootlin.com

Changes in v2:
- Collected tags.
- Rebased on top of v7.2-rc1
- Exported (test) clock symbols using the _IF_KUNIT() variant, and
  imported the NS in the test file.
- Fixed a leaking node reported by Brian in the tests. Also used
  existing helpers to simplify the test implementation as he wisely
  suggested.
- Reworded the nexus node binding description as suggested by Stephen.
- Dropped redundant and non restraining properties from the Nexus
  node as suggested by Rob.
- Assigned clock/clock-rate properties now traverse Nexus nodes.
- Rename helpers following Stephen proposals.
- Rework tests following Stephen hints.
- Link to v1: https://lore.kernel.org/r/20260327-schneider-v7-0-rc1-crypto-v1-0-5e6ff7853994@bootlin.com

Signed-off-by: Miquel Raynal (Schneider Electric) <miquel.raynal@bootlin.com>
---
Miquel Raynal (Schneider Electric) (7):
      dt-bindings: clock: Introduce nexus nodes
      clk: tests: Add clk_parse_clkspec() Kunit testing
      clk: tests: Add Kunit testing for of_clk_get_parent_name()
      clk: Improve a couple of comments
      clk: Use the generic OF phandle parsing in only one place
      clk: Add support for clock nexus dt bindings
      clk: tests: Add Kunit testing for nexus nodes

 .../bindings/clock/clock-nexus-node.yaml           |  30 +++++
 drivers/clk/Makefile                               |   1 +
 drivers/clk/clk-conf.c                             |  12 +-
 drivers/clk/clk.c                                  |  15 ++-
 drivers/clk/clk_kunit_helpers.c                    |  31 +++++
 drivers/clk/clk_test.c                             | 139 +++++++++++++++++++++
 drivers/clk/kunit_clk_parse_clkspec.dtso           |  31 +++++
 include/kunit/clk.h                                |   2 +
 8 files changed, 249 insertions(+), 12 deletions(-)
---
base-commit: 7f26e010764df304602f33912a0550dcf46e72c2
change-id: 20260710-schneider-v7-2-rc1-eip201-upstream-a470e5eab92d

Best regards,
-- 
Miquel Raynal (Schneider Electric) <miquel.raynal@bootlin.com>

[PATCH v3 1/7] dt-bindings: clock: Introduce nexus nodes

[Miquel Raynal (Schneider Electric)]

Hardware containers can just decouple external resources like clock
without any more control. Nexus nodes already exist for PWM and GPIOs,
add a binding to allow them for clocks as well.

No examples are given, the file is litteraly a copy-paste from Hervé
Codina's work on PWM Nexus nodes, hence we just point to the examples
there which already illustrate very clearly the concept of the various
properties.

Signed-off-by: Miquel Raynal (Schneider Electric) <miquel.raynal@bootlin.com>
---
 .../bindings/clock/clock-nexus-node.yaml           | 30 ++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/Documentation/devicetree/bindings/clock/clock-nexus-node.yaml b/Documentation/devicetree/bindings/clock/clock-nexus-node.yaml
new file mode 100644
index 000000000000..ff3283bd5fb1
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/clock-nexus-node.yaml
@@ -0,0 +1,30 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/clock/clock-nexus-node.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Clock Nexus
+
+description: >
+  A nexus node allows to remap a clock specifier list in a consumer node
+  through a container or a connector node in a generic way. With this
+  remapping, the consumer node needs to know only about the nexus
+  node. Resources behind the nexus node are decoupled by the nexus node
+  itself.
+
+maintainers:
+  - Miquel Raynal <miquel.raynal@bootlin.com>
+
+select: true
+
+properties:
+  clock-map:
+    $ref: /schemas/types.yaml#/definitions/uint32-matrix
+
+dependentRequired:
+  clock-map: ['#clock-cells']
+
+additionalProperties: true
+
+# See the original pwm-nexus-node.yaml description for examples

-- 
2.54.0

[PATCH v3 2/7] clk: tests: Add clk_parse_clkspec() Kunit testing

[Miquel Raynal (Schneider Electric)]

Create a new set of kunit tests to make sure clk_parse_clkspec() is
working as expected. We currently verify if we get a proper device when
using indexes and names. If we make an out of bounds request we expect
an error.

For testing purposes, we must ensure of_clk_get_hw()'s symbol is
exported.

Suggested-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Miquel Raynal (Schneider Electric) <miquel.raynal@bootlin.com>
---
 drivers/clk/Makefile                     |   1 +
 drivers/clk/clk.c                        |   2 +
 drivers/clk/clk_test.c                   | 110 +++++++++++++++++++++++++++++++
 drivers/clk/kunit_clk_parse_clkspec.dtso |  21 ++++++
 4 files changed, 134 insertions(+)

diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index cc108a75a900..035b984db70d 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -19,6 +19,7 @@ clk-test-y			:= clk_test.o \
 				   kunit_clk_assigned_rates_zero.dtbo.o \
 				   kunit_clk_assigned_rates_zero_consumer.dtbo.o \
 				   kunit_clk_hw_get_dev_of_node.dtbo.o \
+				   kunit_clk_parse_clkspec.dtbo.o \
 				   kunit_clk_parent_data_test.dtbo.o
 obj-$(CONFIG_COMMON_CLK)	+= clk-divider.o
 obj-$(CONFIG_COMMON_CLK)	+= clk-fixed-factor.o
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 048adfa86a5d..08874cf9b561 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -24,6 +24,7 @@
 #include <linux/spinlock.h>
 #include <linux/string.h>
 #include <linux/stringhash.h>
+#include <kunit/visibility.h>
 
 #include "clk.h"
 
@@ -5300,6 +5301,7 @@ struct clk_hw *of_clk_get_hw(struct device_node *np, int index,
 
 	return hw;
 }
+EXPORT_SYMBOL_IF_KUNIT(of_clk_get_hw);
 
 static struct clk *__of_clk_get(struct device_node *np,
 				int index, const char *dev_id,
diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c
index b1961daac5e2..f47f81b7d72a 100644
--- a/drivers/clk/clk_test.c
+++ b/drivers/clk/clk_test.c
@@ -3541,10 +3541,119 @@ static struct kunit_suite clk_hw_get_dev_of_node_test_suite = {
 	.test_cases = clk_hw_get_dev_of_node_test_cases,
 };
 
+static const struct clk_init_data clk_parse_clkspec_1_init_data = {
+	.name = "clk_parse_clkspec_1",
+	.ops = &empty_clk_ops,
+};
+
+static const struct clk_init_data clk_parse_clkspec_2_init_data = {
+	.name = "clk_parse_clkspec_2",
+	.ops = &empty_clk_ops,
+};
+
+struct clk_parse_clkspec_ctx {
+	struct device_node *cons_np;
+};
+
+static int clk_parse_clkspec_init(struct kunit *test)
+{
+	struct device_node *prov1_np, *prov2_np;
+	struct clk_parse_clkspec_ctx *ctx;
+	struct clk_hw *hw1, *hw2;
+
+	ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
+	test->priv = ctx;
+
+	KUNIT_ASSERT_EQ(test, 0, of_overlay_apply_kunit(test, kunit_clk_parse_clkspec));
+
+	/* Register provider 1 */
+	hw1 = kunit_kzalloc(test, sizeof(*hw1), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw1);
+	hw1->init = &clk_parse_clkspec_1_init_data;
+
+	prov1_np = of_find_compatible_node(NULL, NULL, "test,clock-provider1");
+	KUNIT_ASSERT_NOT_NULL(test, prov1_np);
+	of_node_put_kunit(test, prov1_np);
+
+	KUNIT_ASSERT_EQ(test, 0, of_clk_hw_register_kunit(test, prov1_np, hw1));
+	KUNIT_ASSERT_EQ(test, 0, of_clk_add_hw_provider_kunit(test, prov1_np, of_clk_hw_simple_get, hw1));
+
+	/* Register provider 2 */
+	hw2 = kunit_kzalloc(test, sizeof(*hw2), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, hw2);
+	hw2->init = &clk_parse_clkspec_2_init_data;
+
+	prov2_np = of_find_compatible_node(NULL, NULL, "test,clock-provider2");
+	KUNIT_ASSERT_NOT_NULL(test, prov2_np);
+	of_node_put_kunit(test, prov2_np);
+
+	KUNIT_ASSERT_EQ(test, 0, of_clk_hw_register_kunit(test, prov2_np, hw2));
+	KUNIT_ASSERT_EQ(test, 0, of_clk_add_hw_provider_kunit(test, prov2_np, of_clk_hw_simple_get, hw2));
+
+	ctx->cons_np = of_find_compatible_node(NULL, NULL, "test,clock-consumer");
+	KUNIT_ASSERT_NOT_NULL(test, ctx->cons_np);
+	of_node_put_kunit(test, ctx->cons_np);
+
+	return 0;
+}
+
+/* Test DT phandle lookups using correct index or name succeed */
+static void clk_parse_clkspec_with_correct_index_and_name(struct kunit *test)
+{
+	struct clk_parse_clkspec_ctx *ctx = test->priv;
+	struct clk_hw *hw1, *hw2, *hw3, *hw4;
+
+	/* Get clocks by index */
+	hw1 = of_clk_get_hw(ctx->cons_np, 0, NULL);
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, hw1);
+
+	hw2 = of_clk_get_hw(ctx->cons_np, 1, NULL);
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, hw2);
+	KUNIT_EXPECT_PTR_NE(test, hw1, hw2);
+
+	/* Get clocks by name */
+	hw3 = of_clk_get_hw(ctx->cons_np, 0, "first_clock");
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, hw3);
+	KUNIT_EXPECT_PTR_EQ(test, hw1, hw3);
+
+	hw4 = of_clk_get_hw(ctx->cons_np, 0, "second_clock");
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, hw4);
+	KUNIT_EXPECT_PTR_EQ(test, hw2, hw4);
+}
+
+/* Test DT phandle lookups using wrong index or name fail */
+static void clk_parse_clkspec_with_incorrect_index_and_name(struct kunit *test)
+{
+	struct clk_parse_clkspec_ctx *ctx = test->priv;
+	struct clk_hw *hw;
+
+	/* Get clock by index */
+	hw = of_clk_get_hw(ctx->cons_np, 2, NULL);
+	KUNIT_EXPECT_TRUE(test, IS_ERR(hw));
+
+	/* Get clock by name */
+	hw = of_clk_get_hw(ctx->cons_np, 0, "third_clock");
+	KUNIT_EXPECT_TRUE(test, IS_ERR(hw));
+}
+
+static struct kunit_case clk_parse_clkspec_test_cases[] = {
+	KUNIT_CASE(clk_parse_clkspec_with_correct_index_and_name),
+	KUNIT_CASE(clk_parse_clkspec_with_incorrect_index_and_name),
+	{}
+};
+
+/* Test suite to verify clk_parse_clkspec() */
+static struct kunit_suite clk_parse_clkspec_test_suite = {
+	.name = "clk_parse_clkspec",
+	.init = clk_parse_clkspec_init,
+	.test_cases = clk_parse_clkspec_test_cases,
+};
 
 kunit_test_suites(
 	&clk_assigned_rates_suite,
 	&clk_hw_get_dev_of_node_test_suite,
+	&clk_parse_clkspec_test_suite,
 	&clk_leaf_mux_set_rate_parent_test_suite,
 	&clk_test_suite,
 	&clk_multiple_parents_mux_test_suite,
@@ -3562,4 +3671,5 @@ kunit_test_suites(
 	&clk_uncached_test_suite,
 );
 MODULE_DESCRIPTION("Kunit tests for clk framework");
+MODULE_IMPORT_NS("EXPORTED_FOR_KUNIT_TESTING");
 MODULE_LICENSE("GPL v2");
diff --git a/drivers/clk/kunit_clk_parse_clkspec.dtso b/drivers/clk/kunit_clk_parse_clkspec.dtso
new file mode 100644
index 000000000000..c93feb93e101
--- /dev/null
+++ b/drivers/clk/kunit_clk_parse_clkspec.dtso
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&{/} {
+	kunit_clock_provider1: kunit-clock-provider1 {
+		compatible = "test,clock-provider1";
+		#clock-cells = <1>;
+	};
+
+	kunit_clock_provider2: kunit-clock-provider2 {
+		compatible = "test,clock-provider2";
+		#clock-cells = <1>;
+	};
+
+	kunit-clock-consumer {
+		compatible = "test,clock-consumer";
+		clocks = <&kunit_clock_provider1 0>, <&kunit_clock_provider2 0>;
+		clock-names = "first_clock", "second_clock";
+	};
+};

-- 
2.54.0

[PATCH v3 3/7] clk: tests: Add Kunit testing for of_clk_get_parent_name()

[Miquel Raynal (Schneider Electric)]

Make sure this helper is never broken, especially since we will soon
make some changes in it.

Signed-off-by: Miquel Raynal (Schneider Electric) <miquel.raynal@bootlin.com>
---
 drivers/clk/clk_test.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c
index f47f81b7d72a..4084559e157d 100644
--- a/drivers/clk/clk_test.c
+++ b/drivers/clk/clk_test.c
@@ -3637,9 +3637,23 @@ static void clk_parse_clkspec_with_incorrect_index_and_name(struct kunit *test)
 	KUNIT_EXPECT_TRUE(test, IS_ERR(hw));
 }
 
+/*
+ * Verify that of_clk_get_parent_name() returns the correct clock name when
+ * looking up by index through the consumer's clocks property.
+ */
+static void of_clk_get_parent_name_gets_parent_name(struct kunit *test)
+{
+	struct clk_parse_clkspec_ctx *ctx = test->priv;
+	const char *expected_name = "clk_parse_clkspec_1";
+
+	KUNIT_EXPECT_STREQ(test, expected_name,
+			   of_clk_get_parent_name(ctx->cons_np, 0));
+}
+
 static struct kunit_case clk_parse_clkspec_test_cases[] = {
 	KUNIT_CASE(clk_parse_clkspec_with_correct_index_and_name),
 	KUNIT_CASE(clk_parse_clkspec_with_incorrect_index_and_name),
+	KUNIT_CASE(of_clk_get_parent_name_gets_parent_name),
 	{}
 };
 

-- 
2.54.0

[PATCH v3 4/7] clk: Improve a couple of comments

[Miquel Raynal (Schneider Electric)]

Avoid mentioning the function names directly in the comments, it makes
them easily out of sync with the rest of the code. Use a more generic
wording.

Suggested-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Miquel Raynal (Schneider Electric) <miquel.raynal@bootlin.com>
Reviewed-by: Brian Masney <bmasney@redhat.com>
---
 drivers/clk/clk.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 08874cf9b561..7d63d81ebc09 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -5202,7 +5202,7 @@ static int of_parse_clkspec(const struct device_node *np, int index,
 		/*
 		 * For named clocks, first look up the name in the
 		 * "clock-names" property.  If it cannot be found, then index
-		 * will be an error code and of_parse_phandle_with_args() will
+		 * will be an error code and the OF phandle parser will
 		 * return -EINVAL.
 		 */
 		if (name)
@@ -5275,7 +5275,7 @@ of_clk_get_hw_from_clkspec(struct of_phandle_args *clkspec)
  *
  * This function looks up a struct clk from the registered list of clock
  * providers, an input is a clock specifier data structure as returned
- * from the of_parse_phandle_with_args() function call.
+ * from the OF phandle parser.
  */
 struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec)
 {

-- 
2.54.0

[PATCH v3 5/7] clk: Use the generic OF phandle parsing in only one place

[Miquel Raynal (Schneider Electric)]

There should be one single entry in the OF world, so that the way we
parse the DT is always the same. make sure this is the case by avoid
calling of_parse_phandle_with_args() from of_clk_get_parent_name(). This
is even more relevant as we currently fail to parse clock-ranges. As a
result, it seems to be safer to directly call of_parse_clkspec() there,
but doing so implies that we do not try the "clock-ranges" path if we
already found a "clocks" property..

Suggested-by: Stephen Boyd <sboyd@kernel.org>
Fixes: 4472287a3b2f5 ("clk: Introduce of_clk_get_hw_from_clkspec()")
Signed-off-by: Miquel Raynal (Schneider Electric) <miquel.raynal@bootlin.com>
Reviewed-by: Brian Masney <bmasney@redhat.com>
---
 drivers/clk/clk.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 7d63d81ebc09..45f5d7a4ccc1 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -5219,6 +5219,8 @@ static int of_parse_clkspec(const struct device_node *np, int index,
 		 * has a "clock-ranges" property, then we can try one of its
 		 * clocks.
 		 */
+		if (of_property_present(np, "clocks"))
+			break;
 		np = np->parent;
 		if (np && !of_property_present(np, "clock-ranges"))
 			break;
@@ -5364,8 +5366,7 @@ const char *of_clk_get_parent_name(const struct device_node *np, int index)
 	int count;
 	struct clk *clk;
 
-	rc = of_parse_phandle_with_args(np, "clocks", "#clock-cells", index,
-					&clkspec);
+	rc = of_parse_clkspec(np, index, NULL, &clkspec);
 	if (rc)
 		return NULL;
 

-- 
2.54.0

[PATCH v3 6/7] clk: Add support for clock nexus dt bindings

[Miquel Raynal (Schneider Electric)]

A nexus node is some kind of parent device abstracting the outer
connections. They are particularly useful for describing connectors-like
interfaces but not only. Certain IP blocks will typically include inner
blocks and distribute resources to them.

In the case of clocks, there is already the concept of clock controller,
but this usually indicates some kind of control over the said clock,
ie. gate or rate control. When there is none of this, an existing
approach is to reference the upper clock, which is wrong from a hardware
point of view.

Nexus nodes are already part of the device-tree specification and clocks
are already mentioned:
https://github.com/devicetree-org/devicetree-specification/blob/v0.4/source/chapter2-devicetree-basics.rst#nexus-nodes-and-specifier-mapping

Following the introductions of nexus nodes support for interrupts, gpios
and pwms, here is the same logic applied again to the clk subsystem,
just by transitioning from of_parse_phandle_with_args() to
of_parse_phandle_with_args_map():

* Nexus OF support:
commit bd6f2fd5a1d5 ("of: Support parsing phandle argument lists through a nexus node")
* GPIO adoption:
commit c11e6f0f04db ("gpio: Support gpio nexus dt bindings")
* PWM adoption:
commit e71e46a6f19c ("pwm: Add support for pwm nexus dt bindings")

Only expected Nexus property:
- clock-map: maps inner clocks to inlet clocks
(the other properties have been judged not relevant for clocks)

Here is an example:

Example:
    soc_clk: clock-controller {
        #clock-cells = <1>;
    };

    container: container {
        #clock-cells = <1>;
        clock-map = <0 &soc_clk 2>,
                    <1 &soc_clk 6>;

        child-device {
            clocks = <&container 1>;
	    /* This is equivalent to <&soc_clk 6> */
        };
    };

The child device does not need to know about the outer implementation,
and only knows about what the nexus provides. The nexus acts as a
pass-through, with no extra control.

Signed-off-by: Miquel Raynal (Schneider Electric) <miquel.raynal@bootlin.com>
Reviewed-by: Herve Codina <herve.codina@bootlin.com>
Reviewed-by: Brian Masney <bmasney@redhat.com>
---
 drivers/clk/clk-conf.c | 12 ++++++------
 drivers/clk/clk.c      |  4 ++--
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/clk/clk-conf.c b/drivers/clk/clk-conf.c
index 303a0bb26e54..5380d43b56a4 100644
--- a/drivers/clk/clk-conf.c
+++ b/drivers/clk/clk-conf.c
@@ -25,8 +25,8 @@ static int __set_clk_parents(struct device_node *node, bool clk_supplier)
 		       node);
 
 	for (index = 0; index < num_parents; index++) {
-		rc = of_parse_phandle_with_args(node, "assigned-clock-parents",
-					"#clock-cells",	index, &clkspec);
+		rc = of_parse_phandle_with_args_map(node, "assigned-clock-parents",
+						    "clock", index, &clkspec);
 		if (rc < 0) {
 			/* skip empty (null) phandles */
 			if (rc == -ENOENT)
@@ -47,8 +47,8 @@ static int __set_clk_parents(struct device_node *node, bool clk_supplier)
 			return PTR_ERR(pclk);
 		}
 
-		rc = of_parse_phandle_with_args(node, "assigned-clocks",
-					"#clock-cells", index, &clkspec);
+		rc = of_parse_phandle_with_args_map(node, "assigned-clocks",
+						    "clock", index, &clkspec);
 		if (rc < 0)
 			goto err;
 		if (clkspec.np == node && !clk_supplier) {
@@ -121,8 +121,8 @@ static int __set_clk_rates(struct device_node *node, bool clk_supplier)
 			rate = rates[index];
 
 		if (rate) {
-			rc = of_parse_phandle_with_args(node, "assigned-clocks",
-					"#clock-cells",	index, &clkspec);
+			rc = of_parse_phandle_with_args_map(node, "assigned-clocks",
+							    "clock", index, &clkspec);
 			if (rc < 0) {
 				/* skip empty (null) phandles */
 				if (rc == -ENOENT)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 45f5d7a4ccc1..6acf042673c3 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -5207,8 +5207,8 @@ static int of_parse_clkspec(const struct device_node *np, int index,
 		 */
 		if (name)
 			index = of_property_match_string(np, "clock-names", name);
-		ret = of_parse_phandle_with_args(np, "clocks", "#clock-cells",
-						 index, out_args);
+		ret = of_parse_phandle_with_args_map(np, "clocks", "clock",
+						     index, out_args);
 		if (!ret)
 			break;
 		if (name && index >= 0)

-- 
2.54.0

[PATCH v3 7/7] clk: tests: Add Kunit testing for nexus nodes

[Miquel Raynal (Schneider Electric)]

Add a nexus node with a child requesting a mapped clock in the fake DT
overlay to verify that the parsing is also correctly working.

Suggested-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Miquel Raynal (Schneider Electric) <miquel.raynal@bootlin.com>
---
 drivers/clk/clk_kunit_helpers.c          | 31 +++++++++++++++++++++++++++++++
 drivers/clk/clk_test.c                   | 15 +++++++++++++++
 drivers/clk/kunit_clk_parse_clkspec.dtso | 10 ++++++++++
 include/kunit/clk.h                      |  2 ++
 4 files changed, 58 insertions(+)

diff --git a/drivers/clk/clk_kunit_helpers.c b/drivers/clk/clk_kunit_helpers.c
index 68a28e70bb61..151f62ab57c1 100644
--- a/drivers/clk/clk_kunit_helpers.c
+++ b/drivers/clk/clk_kunit_helpers.c
@@ -233,5 +233,36 @@ int of_clk_add_hw_provider_kunit(struct kunit *test, struct device_node *np,
 }
 EXPORT_SYMBOL_GPL(of_clk_add_hw_provider_kunit);
 
+KUNIT_DEFINE_ACTION_WRAPPER(of_node_put_wrapper, of_node_put, struct device_node *);
+
+/**
+ * of_find_node_by_name_kunit() - Test managed of_find_node_by_name()
+ * @test: The test context
+ * @from: Parent device node to start searching from, or NULL to search from root
+ * @name: The name string to match against
+ *
+ * Just like of_find_node_by_name(), except the device_noded is managed by
+ * the test case and is automatically put after the test case concludes.
+ *
+ * Return: the device_node on success or a negative errno value on failure.
+ */
+struct device_node *of_find_node_by_name_kunit(struct kunit *test, struct device_node *from,
+					       const char *name)
+{
+	struct device_node *np;
+	int ret;
+
+	np = of_find_node_by_name(from, name);
+	if (!np)
+		return NULL;
+
+	ret = kunit_add_action_or_reset(test, of_node_put_wrapper, np);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return np;
+}
+EXPORT_SYMBOL_GPL(of_find_node_by_name_kunit);
+
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("KUnit helpers for clk providers and consumers");
diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c
index 4084559e157d..0c2f1efdaa8e 100644
--- a/drivers/clk/clk_test.c
+++ b/drivers/clk/clk_test.c
@@ -3650,10 +3650,25 @@ static void of_clk_get_parent_name_gets_parent_name(struct kunit *test)
 			   of_clk_get_parent_name(ctx->cons_np, 0));
 }
 
+static void of_clk_get_hw_maps_thru_nexus(struct kunit *test)
+{
+	struct clk_parse_clkspec_ctx *ctx = test->priv;
+	struct clk_hw *expected;
+	struct device_node *np;
+
+	np = of_find_node_by_name_kunit(test, NULL, "kunit-clock-nexus-child");
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, np);
+	expected = of_clk_get_hw(ctx->cons_np, 1, NULL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, expected);
+
+	KUNIT_EXPECT_PTR_EQ(test, expected, of_clk_get_hw(np, 0, NULL));
+}
+
 static struct kunit_case clk_parse_clkspec_test_cases[] = {
 	KUNIT_CASE(clk_parse_clkspec_with_correct_index_and_name),
 	KUNIT_CASE(clk_parse_clkspec_with_incorrect_index_and_name),
 	KUNIT_CASE(of_clk_get_parent_name_gets_parent_name),
+	KUNIT_CASE(of_clk_get_hw_maps_thru_nexus),
 	{}
 };
 
diff --git a/drivers/clk/kunit_clk_parse_clkspec.dtso b/drivers/clk/kunit_clk_parse_clkspec.dtso
index c93feb93e101..a4115216d2aa 100644
--- a/drivers/clk/kunit_clk_parse_clkspec.dtso
+++ b/drivers/clk/kunit_clk_parse_clkspec.dtso
@@ -18,4 +18,14 @@ kunit-clock-consumer {
 		clocks = <&kunit_clock_provider1 0>, <&kunit_clock_provider2 0>;
 		clock-names = "first_clock", "second_clock";
 	};
+
+	kunit_clock_nexus: kunit-clock-nexus {
+		clocks = <&kunit_clock_provider2 0>;
+		clock-map = <&kunit_clock_provider2 0>;
+		#clock-cells = <0>;
+
+		kunit-clock-nexus-child {
+			clocks = <&kunit_clock_nexus>;
+		};
+	};
 };
diff --git a/include/kunit/clk.h b/include/kunit/clk.h
index f226044cc78d..ab24f7747516 100644
--- a/include/kunit/clk.h
+++ b/include/kunit/clk.h
@@ -29,5 +29,7 @@ int of_clk_hw_register_kunit(struct kunit *test, struct device_node *node,
 int of_clk_add_hw_provider_kunit(struct kunit *test, struct device_node *np,
 				 struct clk_hw *(*get)(struct of_phandle_args *clkspec, void *data),
 				 void *data);
+struct device_node *of_find_node_by_name_kunit(struct kunit *test, struct device_node *from,
+					       const char *name);
 
 #endif

-- 
2.54.0

Re: [PATCH v3 1/7] dt-bindings: clock: Introduce nexus nodes

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] The clock nexus node schema omits definitions and constraints for `clock-map-mask`, `clock-map-pass-thru`, and `#clock-cells`.
- [Medium] The Linux core clock framework does not support nexus node translation, making the `clock-map` property silently ignored at runtime.
--

--- Patch [1]: [PATCH v3 1/7] dt-bindings: clock: Introduce nexus nodes ---
commit 30cf1cc96ffba77a6f8ef9429e05ed6f37f38c53
Author: Miquel Raynal (Schneider Electric) <miquel.raynal@bootlin.com>

dt-bindings: clock: Introduce nexus nodes

This commit introduces a new device tree binding for clock nexus nodes,
allowing the remapping of clock specifier lists through a container or
connector node in a generic way.

> diff --git a/Documentation/devicetree/bindings/clock/clock-nexus-node.yaml b/Documentation/devicetree/bindings/clock/clock-nexus-node.yaml
> new file mode 100644
> index 0000000000000..ff3283bd5fb11
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/clock-nexus-node.yaml
> @@ -0,0 +1,30 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/clock/clock-nexus-node.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Clock Nexus
> +
> +description: >
> +  A nexus node allows to remap a clock specifier list in a consumer node
> +  through a container or a connector node in a generic way. With this
> +  remapping, the consumer node needs to know only about the nexus
> +  node. Resources behind the nexus node are decoupled by the nexus node
> +  itself.

[Severity: Medium]
Does the Linux clock framework currently support traversing nexus nodes?

Looking at of_parse_clkspec() in drivers/clk/clk.c, it hardcodes a call to
of_parse_phandle_with_args():

drivers/clk/clk.c:of_parse_clkspec() {
    ...
    ret = of_parse_phandle_with_args(np, "clocks", "#clock-cells",
                                     index, out_args);
    ...
}

Because there isn't a call to of_parse_phandle_with_args_map() here, will
device tree consumers attempting to acquire a clock routed through a nexus
node fail to resolve it during driver probe?

Is there a companion patch for the clock framework to add this mapping
support?

[ ... ]

> +properties:
> +  clock-map:
> +    $ref: /schemas/types.yaml#/definitions/uint32-matrix
> +
> +dependentRequired:
> +  clock-map: ['#clock-cells']
> +
> +additionalProperties: true

[Severity: Medium]
Since this schema sets additionalProperties to true, are we missing the
definitions and constraints for #clock-cells, clock-map-mask, and
clock-map-pass-thru in the properties block?

Without defining them here, it appears device trees can use incorrectly
formatted properties for the mask and pass-through fields, and validation
will silently accept them since they are not constrained to standard
types.

Could we add these properties to ensure the schema enforces the correct
formats and dependencies?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260716-schneider-v7-2-rc1-eip201-upstream-v3-0-98454e83845c@bootlin.com?part=1

Re: [PATCH v3 2/7] clk: tests: Add clk_parse_clkspec() Kunit testing

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Pre-existing race condition in `__of_clk_get()` exposing a time-of-check to time-of-use (TOCTOU) use-after-free vulnerability during concurrent clock provider unregistration.
--

--- Patch [2]: [PATCH v3 2/7] clk: tests: Add clk_parse_clkspec() Kunit testing ---
commit b17a28133ab40253da7bfbaf67521eac37a7e21a
Author: Miquel Raynal (Schneider Electric) <miquel.raynal@bootlin.com>

clk: tests: Add clk_parse_clkspec() Kunit testing

Create a new set of kunit tests to make sure clk_parse_clkspec() is
working as expected. We currently verify if we get a proper device when
using indexes and names.

> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index 048adfa86a5d0..08874cf9b5617 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c

[ ... ]

> @@ -5300,6 +5301,7 @@ struct clk_hw *of_clk_get_hw(struct device_node *np, int index,
>  
>  	return hw;
>  }
> +EXPORT_SYMBOL_IF_KUNIT(of_clk_get_hw);
>  
>  static struct clk *__of_clk_get(struct device_node *np,
>  				int index, const char *dev_id,

[Severity: High]
This is a pre-existing issue, but exposing of_clk_get_hw() brings attention
to how the returned pointer is managed in the surrounding code.

Could a concurrent clock provider unregistration cause a use-after-free
vulnerability here?

Looking at how __of_clk_get() uses the hardware pointer:

__of_clk_get() {
    ...
    hw = of_clk_get_hw(np, index, con_id);
    return clk_hw_create_clk(NULL, hw, dev_id, con_id);
}

When of_clk_get_hw() calls of_clk_get_hw_from_clkspec(), it retrieves the hw
pointer under of_clk_mutex but returns it without incrementing any
underlying reference count.

Once the mutex is released, another thread could unregister the clock
provider, freeing both hw and hw->core.

If that happens before clk_hw_create_clk() executes, does it dereference
the freed pointer when evaluating hw->core and attempting try_module_get()
on core->owner?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260716-schneider-v7-2-rc1-eip201-upstream-v3-0-98454e83845c@bootlin.com?part=2

Re: [PATCH v3 6/7] clk: Add support for clock nexus dt bindings

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Unconditional dereference of optional `out_args` pointer in `of_parse_phandle_with_args_map()`.
--

--- Patch [6]: [PATCH v3 6/7] clk: Add support for clock nexus dt bindings ---
commit 6c00bcac0a2f79ec97235472147341c2654575cc
Author: Miquel Raynal (Schneider Electric) <miquel.raynal@bootlin.com>

clk: Add support for clock nexus dt bindings

This commit introduces support for clock nexus device tree bindings, allowing
inner clocks to be mapped to inlet clocks via the clock-map property. It
accomplishes this by transitioning the clock subsystem to use
of_parse_phandle_with_args_map() instead of of_parse_phandle_with_args().

> diff --git a/drivers/clk/clk-conf.c b/drivers/clk/clk-conf.c
> --- a/drivers/clk/clk-conf.c
> +++ b/drivers/clk/clk-conf.c
> @@ -25,8 +25,8 @@ static int __set_clk_parents(struct device_node *node, bool clk_supplier)
>  		       node);
>  
>  	for (index = 0; index < num_parents; index++) {
> -		rc = of_parse_phandle_with_args(node, "assigned-clock-parents",
> -					"#clock-cells",	index, &clkspec);
> +		rc = of_parse_phandle_with_args_map(node, "assigned-clock-parents",
> +						    "clock", index, &clkspec);

[Severity: High]
This is a pre-existing issue, but since this patch transitions the subsystem
to use of_parse_phandle_with_args_map(), it seems worth noting a flaw in the
underlying API.

Looking at of_parse_phandle_with_args_map() in drivers/of/base.c, there is an
unconditional dereference of the out_args pointer:

drivers/of/base.c:of_parse_phandle_with_args_map() {
	...
	ret = __of_parse_phandle_with_args(np, list_name, cells_name, -1, index,
					   out_args);
	if (ret)
		return ret;

	/* Get the #<list>-cells property */
	cur = out_args->np;
	...
}

Since out_args is documented as an optional pointer for this exported symbol,
would a caller passing null immediately trigger a kernel panic here due to a
null pointer dereference?

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260716-schneider-v7-2-rc1-eip201-upstream-v3-0-98454e83845c@bootlin.com?part=6

Re: [PATCH v3 7/7] clk: tests: Add Kunit testing for nexus nodes

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [Medium] The `of_find_node_by_name_kunit` helper creates a double-free vulnerability if a KUnit-managed node is passed as the `from` argument.
- [Low] The `of_find_node_by_name_kunit` kernel-doc incorrectly states the return value is only a node or negative errno, omitting the NULL case when a node is not found.
--

--- Patch [7]: [PATCH v3 7/7] clk: tests: Add Kunit testing for nexus nodes ---
commit 5c005eb5dfe6aeb07b97b34ac1e15ba0def6eeae
Author: Miquel Raynal (Schneider Electric) <miquel.raynal@bootlin.com>

clk: tests: Add Kunit testing for nexus nodes

This commit adds a fake DT overlay with a nexus node to verify clock parsing
in KUnit tests. It also introduces of_find_node_by_name_kunit() to manage
device node lifetimes during tests.

> diff --git a/drivers/clk/clk_kunit_helpers.c b/drivers/clk/clk_kunit_helpers.c
> index 68a28e70bb61c..151f62ab57c1a 100644
> --- a/drivers/clk/clk_kunit_helpers.c
> +++ b/drivers/clk/clk_kunit_helpers.c
[ ... ]
> +/**
> + * of_find_node_by_name_kunit() - Test managed of_find_node_by_name()
> + * @test: The test context
> + * @from: Parent device node to start searching from, or NULL to search from root
> + * @name: The name string to match against
> + *
> + * Just like of_find_node_by_name(), except the device_noded is managed by
> + * the test case and is automatically put after the test case concludes.
> + *
> + * Return: the device_node on success or a negative errno value on failure.

[Severity: Low]
This isn't a bug, but the kernel-doc states the function returns a device_node
on success or a negative errno on failure.

However, the implementation also returns NULL if the node is not found.

Could the documentation be updated to mention the NULL return case, so
callers don't assume IS_ERR() is sufficient?

> + */
> +struct device_node *of_find_node_by_name_kunit(struct kunit *test, struct device_node *from,
> +					       const char *name)
> +{
> +	struct device_node *np;
> +	int ret;
> +
> +	np = of_find_node_by_name(from, name);

[Severity: Medium]
Could this result in a double-free if a KUnit-managed node is passed as the
'from' argument?

of_find_node_by_name() automatically consumes and drops the reference to the
'from' node. If a developer chains KUnit-managed lookups:

    parent = of_find_node_by_name_kunit(test, NULL, "parent_name");
    child = of_find_node_by_name_kunit(test, parent, "child_name");

The inner of_find_node_by_name() will drop the 'parent' reference.

Since KUnit is unaware of this consumption, won't the deferred test cleanup
still call of_node_put() on 'parent' at test exit, resulting in a guaranteed
double-free?

> +	if (!np)
> +		return NULL;
> +
> +	ret = kunit_add_action_or_reset(test, of_node_put_wrapper, np);
> +	if (ret)
> +		return ERR_PTR(ret);
> +
> +	return np;
> +}

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260716-schneider-v7-2-rc1-eip201-upstream-v3-0-98454e83845c@bootlin.com?part=7