[PATCH v3 0/5] clk: Support spread spectrum and use it in clk-scmi

[PATCH v3 0/5] clk: Support spread spectrum and use it in clk-scmi

[Peng Fan]

Since the assigned-clock-sscs property [1] has been accepted into the device
tree schema, we can now support it in the Linux clock driver. Therefore,
I’ve picked up the previously submitted work [2] titled “clk: Support
spread spectrum and use it in clk-pll144x and clk-scmi.”
As more than six months have passed since [2] was posted, I’m treating this
patchset as a new submission rather than a v3.

- Introduce clk_set_spread_spectrum to set the parameters for enabling
  spread spectrum of a clock.
- Parse 'assigned-clock-sscs' and configure it by default before using the
  clock. This property is parsed before parsing clock rate.
- Enable this feature for clk-scmi on i.MX95.

Because SCMI spec will not include spread spectrum as a standard
extension, we still need to use NXP i.MX OEM extension.

[1] https://github.com/devicetree-org/dt-schema/pull/154
[2] https://lore.kernel.org/all/20250205-clk-ssc-v2-0-fa73083caa92@nxp.com/

Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
Changes in v3:
- New patch 1 for dt-bindings per comment from Brian
  https://lore.kernel.org/all/aLeEFzXkPog_dt2B@x1/
  This might not be good to add a new dt-binding file in v3. But this is
  quite a simple file that just has four macros to encode modulation
  method. So hope this is fine for DT maintainers.
- Add Brain's R-b for patch 2
- New patch 3 to add Kunit test per Brain. Since Brain helped
  draft part of the code, I added Co-developed-by tag from Brain.
- Link to v2: https://lore.kernel.org/r/20250901-clk-ssc-version1-v2-0-1d0a486dffe6@nxp.com

Changes in v2:
- Simplify the code in patch 2 per Dan Carpenter and Brian Masney
- Rebased to next-20250829
- Link to v1: https://lore.kernel.org/r/20250812-clk-ssc-version1-v1-0-cef60f20d770@nxp.com

---
Peng Fan (5):
      dt-bindings: clock: Add spread spectrum definition
      clk: Introduce clk_hw_set_spread_spectrum
      clk: conf: Support assigned-clock-sscs
      clk: Add KUnit tests for assigned-clock-sscs
      clk: scmi: Support Spread Spectrum for NXP i.MX95

 drivers/clk/Makefile                               |   6 +
 drivers/clk/clk-conf.c                             |  69 ++++++++++++
 drivers/clk/clk-scmi.c                             |  64 ++++++++++-
 drivers/clk/clk.c                                  |  26 +++++
 drivers/clk/clk_test.c                             | 121 ++++++++++++++++++++-
 drivers/clk/kunit_clk_assigned_rates.h             |  10 ++
 drivers/clk/kunit_clk_assigned_rates_multiple.dtso |   6 +
 ...kunit_clk_assigned_rates_multiple_consumer.dtso |   6 +
 drivers/clk/kunit_clk_assigned_rates_one.dtso      |   3 +
 .../clk/kunit_clk_assigned_rates_one_consumer.dtso |   3 +
 .../clk/kunit_clk_assigned_rates_u64_multiple.dtso |   6 +
 ...t_clk_assigned_rates_u64_multiple_consumer.dtso |   6 +
 drivers/clk/kunit_clk_assigned_rates_u64_one.dtso  |   3 +
 .../kunit_clk_assigned_rates_u64_one_consumer.dtso |   3 +
 .../kunit_clk_assigned_rates_zero_consumer.dtso    |   1 +
 drivers/clk/kunit_clk_assigned_sscs_null.dtso      |  16 +++
 .../clk/kunit_clk_assigned_sscs_null_consumer.dtso |  20 ++++
 drivers/clk/kunit_clk_assigned_sscs_without.dtso   |  15 +++
 .../kunit_clk_assigned_sscs_without_consumer.dtso  |  19 ++++
 drivers/clk/kunit_clk_assigned_sscs_zero.dtso      |  12 ++
 .../clk/kunit_clk_assigned_sscs_zero_consumer.dtso |  16 +++
 include/dt-bindings/clock/clock.h                  |  14 +++
 include/linux/clk-provider.h                       |  22 ++++
 include/linux/scmi_protocol.h                      |   5 +
 24 files changed, 465 insertions(+), 7 deletions(-)
---
base-commit: cd996742d7bc41dc968843b64e6af19ff32c72fa
change-id: 20250812-clk-ssc-version1-acf6f6efbd96

Best regards,
-- 
Peng Fan <peng.fan@nxp.com>

[PATCH v3 1/5] dt-bindings: clock: Add spread spectrum definition

[Peng Fan]

Per dt-schema, the modulation methods are: down-spread(3), up-spread(2),
center-spread(1), no-spread(0). So define them in dt-bindings to avoid
write the magic number in device tree.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
 include/dt-bindings/clock/clock.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/include/dt-bindings/clock/clock.h b/include/dt-bindings/clock/clock.h
new file mode 100644
index 0000000000000000000000000000000000000000..155e2653a120bf10747bd7f4d47f25e0493e0464
--- /dev/null
+++ b/include/dt-bindings/clock/clock.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-only OR MIT */
+/*
+ * Copyright 2025 NXP
+ */
+
+#ifndef __DT_BINDINGS_CLOCK_H
+#define __DT_BINDINGS_CLOCK_H
+
+#define CLK_SSC_NO_SPREAD	0
+#define CLK_SSC_CENTER_SPREAD	1
+#define CLK_SSC_UP_SPREAD	2
+#define CLK_SSC_DOWN_SPREAD	3
+
+#endif	/* __DT_BINDINGS_CLOCK_H */

-- 
2.37.1

[PATCH v3 2/5] clk: Introduce clk_hw_set_spread_spectrum

[Peng Fan]

Add clk_hw_set_spread_spectrum to configure a clock to enable spread
spectrum feature. set_spread_spectrum ops is added for clk drivers to
have their own hardware specific implementation.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
 drivers/clk/clk.c            | 26 ++++++++++++++++++++++++++
 include/linux/clk-provider.h | 22 ++++++++++++++++++++++
 2 files changed, 48 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index b821b2cdb155331c85fafbd2fac8ab3703a08e4d..06db8918a1b35e3280e565272bc4603a88295a92 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2802,6 +2802,32 @@ int clk_set_max_rate(struct clk *clk, unsigned long rate)
 }
 EXPORT_SYMBOL_GPL(clk_set_max_rate);
 
+int clk_hw_set_spread_spectrum(struct clk_hw *hw, struct clk_spread_spectrum *conf)
+{
+	struct clk_core *core;
+	int ret;
+
+	if (!hw)
+		return 0;
+
+	core = hw->core;
+
+	clk_prepare_lock();
+
+	ret = clk_pm_runtime_get(core);
+	if (ret)
+		goto fail;
+
+	if (core->ops->set_spread_spectrum)
+		ret = core->ops->set_spread_spectrum(hw, conf);
+
+	clk_pm_runtime_put(core);
+
+fail:
+	clk_prepare_unlock();
+	return ret;
+}
+
 /**
  * clk_get_parent - return the parent of a clk
  * @clk: the clk whose parent gets returned
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 630705a47129453c241f1b1755f2c2f2a7ed8f77..4f48a4df95a1c54638a0e91e0a449fcc8aa40b80 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -84,6 +84,19 @@ struct clk_duty {
 	unsigned int den;
 };
 
+/**
+ * struct clk_spread_spectrum - Structure encoding spread spectrum of a clock
+ *
+ * @modfreq_hz:		Modulation frequency
+ * @spread_bp:		Modulation percent in permyriad
+ * @method:		Modulation method
+ */
+struct clk_spread_spectrum {
+	u32 modfreq_hz;
+	u32 spread_bp;
+	u32 method;
+};
+
 /**
  * struct clk_ops -  Callback operations for hardware clocks; these are to
  * be provided by the clock implementation, and will be called by drivers
@@ -178,6 +191,12 @@ struct clk_duty {
  *		separately via calls to .set_parent and .set_rate.
  *		Returns 0 on success, -EERROR otherwise.
  *
+ * @set_spread_spectrum: Optional callback used to configure the spread
+ *		spectrum modulation frequency, percentage, and method
+ *		to reduce EMI by spreading the clock frequency over a
+ *		wider range.
+ *		Returns 0 on success, -EERROR otherwise.
+ *
  * @recalc_accuracy: Recalculate the accuracy of this clock. The clock accuracy
  *		is expressed in ppb (parts per billion). The parent accuracy is
  *		an input parameter.
@@ -255,6 +274,8 @@ struct clk_ops {
 	int		(*set_rate_and_parent)(struct clk_hw *hw,
 				    unsigned long rate,
 				    unsigned long parent_rate, u8 index);
+	int		(*set_spread_spectrum)(struct clk_hw *hw,
+					       struct clk_spread_spectrum *clk_ss);
 	unsigned long	(*recalc_accuracy)(struct clk_hw *hw,
 					   unsigned long parent_accuracy);
 	int		(*get_phase)(struct clk_hw *hw);
@@ -1430,6 +1451,7 @@ void clk_hw_get_rate_range(struct clk_hw *hw, unsigned long *min_rate,
 			   unsigned long *max_rate);
 void clk_hw_set_rate_range(struct clk_hw *hw, unsigned long min_rate,
 			   unsigned long max_rate);
+int clk_hw_set_spread_spectrum(struct clk_hw *hw, struct clk_spread_spectrum *conf);
 
 static inline void __clk_hw_set_clk(struct clk_hw *dst, struct clk_hw *src)
 {

-- 
2.37.1

[PATCH v3 3/5] clk: conf: Support assigned-clock-sscs

[Peng Fan]

Parse the Spread Spectrum Configuration(SSC) from device tree and configure
them before using the clock.

Each SSC is three u32 elements which means '<modfreq spreaddepth
modmethod>', so assigned-clock-sscs is an array of multiple three u32
elements.

Reviewed-by: Brian Masney <bmasney@redhat.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
 drivers/clk/clk-conf.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)

diff --git a/drivers/clk/clk-conf.c b/drivers/clk/clk-conf.c
index 303a0bb26e54a95655ce094a35b989c97ebc6fd8..dd6083597db3f8f27d86abf5640dfc3fb39a9b88 100644
--- a/drivers/clk/clk-conf.c
+++ b/drivers/clk/clk-conf.c
@@ -155,6 +155,71 @@ static int __set_clk_rates(struct device_node *node, bool clk_supplier)
 	return 0;
 }
 
+static int __set_clk_spread_spectrum(struct device_node *node, bool clk_supplier)
+{
+	struct clk_spread_spectrum *sscs __free(kfree) = NULL;
+	u32 elem_size = sizeof(struct clk_spread_spectrum);
+	struct of_phandle_args clkspec;
+	int rc, count, index;
+	struct clk *clk;
+
+	/* modfreq, spreadPercent, modmethod */
+	count = of_property_count_elems_of_size(node, "assigned-clock-sscs", elem_size);
+	if (count <= 0)
+		return 0;
+
+	sscs = kcalloc(count, elem_size, GFP_KERNEL);
+	if (!sscs)
+		return -ENOMEM;
+
+	rc = of_property_read_u32_array(node, "assigned-clock-sscs", (u32 *)sscs,
+					count * 3);
+	if (rc)
+		return rc;
+
+	for (index = 0; index < count; index++) {
+		struct clk_spread_spectrum *conf = &sscs[index];
+		struct clk_hw *hw;
+
+		if (!conf->modfreq_hz && !conf->spread_bp && !conf->method)
+			continue;
+
+		rc = of_parse_phandle_with_args(node, "assigned-clocks", "#clock-cells",
+						index, &clkspec);
+		if (rc < 0) {
+			/* skip empty (null) phandles */
+			if (rc == -ENOENT)
+				continue;
+			else
+				return rc;
+		}
+
+		if (clkspec.np == node && !clk_supplier) {
+			of_node_put(clkspec.np);
+			return 0;
+		}
+
+		clk = of_clk_get_from_provider(&clkspec);
+		of_node_put(clkspec.np);
+		if (IS_ERR(clk)) {
+			if (PTR_ERR(clk) != -EPROBE_DEFER)
+				pr_warn("clk: couldn't get clock %d for %pOF\n",
+					index, node);
+			return PTR_ERR(clk);
+		}
+
+		hw = __clk_get_hw(clk);
+		rc = clk_hw_set_spread_spectrum(hw, conf);
+		if (rc < 0)
+			pr_err("clk: couldn't set %s clk spread spectrum %u %u %u: %d\n",
+			       __clk_get_name(clk), conf->modfreq_hz, conf->spread_bp,
+			       conf->method, rc);
+		clk_put(clk);
+	}
+
+	return 0;
+}
+
 /**
  * of_clk_set_defaults() - parse and set assigned clocks configuration
  * @node: device node to apply clock settings for
@@ -174,6 +239,10 @@ int of_clk_set_defaults(struct device_node *node, bool clk_supplier)
 	if (!node)
 		return 0;
 
+	rc = __set_clk_spread_spectrum(node, clk_supplier);
+	if (rc < 0)
+		return rc;
+
 	rc = __set_clk_parents(node, clk_supplier);
 	if (rc < 0)
 		return rc;

-- 
2.37.1

[PATCH v3 4/5] clk: Add KUnit tests for assigned-clock-sscs

[Peng Fan]

Spread spectrum configuration is part of clock frequency settings,
and its behavior can be validated similarly to assigned clock rates.

Extend the existing KUnit tests for assigned-clock-rates to cover
assigned-clock-sscs by reusing the test framework. Add new test
device trees:
  - kunit_clk_assigned_sscs_null.dtso
  - kunit_clk_assigned_sscs_null_consumer.dtso
  - kunit_clk_assigned_sscs_without.dtso
  - kunit_clk_assigned_sscs_without_consumer.dtso
  - kunit_clk_assigned_sscs_zero.dtso
  - kunit_clk_assigned_sscs_zero_consumer.dtso

These tests cover various invalid configurations of assigned-clock-sscs,
ensuring robustness and consistent error handling, similar to the coverage
provided for assigned-clock-rates.

Co-developed-by: Brian Masney <bmasney@redhat.com>
Signed-off-by: Brian Masney <bmasney@redhat.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
 drivers/clk/Makefile                               |   6 +
 drivers/clk/clk_test.c                             | 121 ++++++++++++++++++++-
 drivers/clk/kunit_clk_assigned_rates.h             |  10 ++
 drivers/clk/kunit_clk_assigned_rates_multiple.dtso |   6 +
 ...kunit_clk_assigned_rates_multiple_consumer.dtso |   6 +
 drivers/clk/kunit_clk_assigned_rates_one.dtso      |   3 +
 .../clk/kunit_clk_assigned_rates_one_consumer.dtso |   3 +
 .../clk/kunit_clk_assigned_rates_u64_multiple.dtso |   6 +
 ...t_clk_assigned_rates_u64_multiple_consumer.dtso |   6 +
 drivers/clk/kunit_clk_assigned_rates_u64_one.dtso  |   3 +
 .../kunit_clk_assigned_rates_u64_one_consumer.dtso |   3 +
 .../kunit_clk_assigned_rates_zero_consumer.dtso    |   1 +
 drivers/clk/kunit_clk_assigned_sscs_null.dtso      |  16 +++
 .../clk/kunit_clk_assigned_sscs_null_consumer.dtso |  20 ++++
 drivers/clk/kunit_clk_assigned_sscs_without.dtso   |  15 +++
 .../kunit_clk_assigned_sscs_without_consumer.dtso  |  19 ++++
 drivers/clk/kunit_clk_assigned_sscs_zero.dtso      |  12 ++
 .../clk/kunit_clk_assigned_sscs_zero_consumer.dtso |  16 +++
 18 files changed, 269 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 18ed29cfdc1133b6c254190c6092eb263366d5ac..ea93e16c5a0080f610c8cfaccc1ac68fefa481c2 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -18,6 +18,12 @@ clk-test-y			:= clk_test.o \
 				   kunit_clk_assigned_rates_without_consumer.dtbo.o \
 				   kunit_clk_assigned_rates_zero.dtbo.o \
 				   kunit_clk_assigned_rates_zero_consumer.dtbo.o \
+				   kunit_clk_assigned_sscs_null.dtbo.o \
+				   kunit_clk_assigned_sscs_null_consumer.dtbo.o \
+				   kunit_clk_assigned_sscs_without.dtbo.o \
+				   kunit_clk_assigned_sscs_without_consumer.dtbo.o \
+				   kunit_clk_assigned_sscs_zero.dtbo.o \
+				   kunit_clk_assigned_sscs_zero_consumer.dtbo.o \
 				   kunit_clk_hw_get_dev_of_node.dtbo.o \
 				   kunit_clk_parent_data_test.dtbo.o
 obj-$(CONFIG_COMMON_CLK)	+= clk-divider.o
diff --git a/drivers/clk/clk_test.c b/drivers/clk/clk_test.c
index a268d7b5d4cb28ec1f029f828c31107f8e130556..eb28f0a61ef0057bcc9c1d75653357a442bff81d 100644
--- a/drivers/clk/clk_test.c
+++ b/drivers/clk/clk_test.c
@@ -28,6 +28,7 @@ static const struct clk_ops empty_clk_ops = { };
 struct clk_dummy_context {
 	struct clk_hw hw;
 	unsigned long rate;
+	struct clk_spread_spectrum sscs;
 };
 
 static unsigned long clk_dummy_recalc_rate(struct clk_hw *hw,
@@ -83,6 +84,17 @@ static int clk_dummy_set_rate(struct clk_hw *hw,
 	return 0;
 }
 
+static int clk_dummy_set_spread_spectrum(struct clk_hw *hw,
+					 struct clk_spread_spectrum *conf)
+{
+	struct clk_dummy_context *ctx =
+		container_of(hw, struct clk_dummy_context, hw);
+
+	ctx->sscs = *conf;
+
+	return 0;
+}
+
 static int clk_dummy_single_set_parent(struct clk_hw *hw, u8 index)
 {
 	if (index >= clk_hw_get_num_parents(hw))
@@ -100,18 +112,21 @@ static const struct clk_ops clk_dummy_rate_ops = {
 	.recalc_rate = clk_dummy_recalc_rate,
 	.determine_rate = clk_dummy_determine_rate,
 	.set_rate = clk_dummy_set_rate,
+	.set_spread_spectrum = clk_dummy_set_spread_spectrum,
 };
 
 static const struct clk_ops clk_dummy_maximize_rate_ops = {
 	.recalc_rate = clk_dummy_recalc_rate,
 	.determine_rate = clk_dummy_maximize_rate,
 	.set_rate = clk_dummy_set_rate,
+	.set_spread_spectrum = clk_dummy_set_spread_spectrum,
 };
 
 static const struct clk_ops clk_dummy_minimize_rate_ops = {
 	.recalc_rate = clk_dummy_recalc_rate,
 	.determine_rate = clk_dummy_minimize_rate,
 	.set_rate = clk_dummy_set_rate,
+	.set_spread_spectrum = clk_dummy_set_spread_spectrum,
 };
 
 static const struct clk_ops clk_dummy_single_parent_ops = {
@@ -3097,6 +3112,7 @@ struct clk_assigned_rates_context {
  * @overlay_end: Pointer to end of DT overlay to apply for test
  * @rate0: Initial rate of first clk
  * @rate1: Initial rate of second clk
+ * @sscs: Initial spread spectrum settings
  * @consumer_test: true if a consumer is being tested
  */
 struct clk_assigned_rates_test_param {
@@ -3105,6 +3121,7 @@ struct clk_assigned_rates_test_param {
 	u8 *overlay_end;
 	unsigned long rate0;
 	unsigned long rate1;
+	struct clk_spread_spectrum sscs;
 	bool consumer_test;
 };
 
@@ -3116,7 +3133,7 @@ static void
 clk_assigned_rates_register_clk(struct kunit *test,
 				struct clk_dummy_context *ctx,
 				struct device_node *np, const char *name,
-				unsigned long rate)
+				unsigned long rate, const struct clk_spread_spectrum *sscs)
 {
 	struct clk_init_data init = { };
 
@@ -3124,6 +3141,7 @@ clk_assigned_rates_register_clk(struct kunit *test,
 	init.ops = &clk_dummy_rate_ops;
 	ctx->hw.init = &init;
 	ctx->rate = rate;
+	ctx->sscs = *sscs;
 
 	KUNIT_ASSERT_EQ(test, 0, of_clk_hw_register_kunit(test, np, &ctx->hw));
 	KUNIT_ASSERT_EQ(test, ctx->rate, rate);
@@ -3167,14 +3185,16 @@ static int clk_assigned_rates_test_init(struct kunit *test)
 	KUNIT_ASSERT_LT(test, clk_cells, 2);
 
 	clk_assigned_rates_register_clk(test, &ctx->clk0, np,
-					"test_assigned_rate0", test_param->rate0);
+					"test_assigned_rate0", test_param->rate0,
+					&test_param->sscs);
 	if (clk_cells == 0) {
 		KUNIT_ASSERT_EQ(test, 0,
 				of_clk_add_hw_provider_kunit(test, np, of_clk_hw_simple_get,
 							     &ctx->clk0.hw));
 	} else if (clk_cells == 1) {
 		clk_assigned_rates_register_clk(test, &ctx->clk1, np,
-						"test_assigned_rate1", test_param->rate1);
+						"test_assigned_rate1", test_param->rate1,
+						&test_param->sscs);
 
 		KUNIT_ASSERT_NOT_ERR_OR_NULL(test,
 			data = kunit_kzalloc(test, struct_size(data, hws, 2), GFP_KERNEL));
@@ -3203,6 +3223,9 @@ static void clk_assigned_rates_assigns_one(struct kunit *test)
 	struct clk_assigned_rates_context *ctx = test->priv;
 
 	KUNIT_EXPECT_EQ(test, ctx->clk0.rate, ASSIGNED_RATES_0_RATE);
+	KUNIT_EXPECT_EQ(test, ctx->clk0.sscs.modfreq_hz, ASSIGNED_SSCS_0_MODFREQ);
+	KUNIT_EXPECT_EQ(test, ctx->clk0.sscs.spread_bp, ASSIGNED_SSCS_0_SPREAD);
+	KUNIT_EXPECT_EQ(test, ctx->clk0.sscs.method, ASSIGNED_SSCS_0_METHOD);
 }
 
 static void clk_assigned_rates_assigns_multiple(struct kunit *test)
@@ -3210,7 +3233,13 @@ static void clk_assigned_rates_assigns_multiple(struct kunit *test)
 	struct clk_assigned_rates_context *ctx = test->priv;
 
 	KUNIT_EXPECT_EQ(test, ctx->clk0.rate, ASSIGNED_RATES_0_RATE);
+	KUNIT_EXPECT_EQ(test, ctx->clk0.sscs.modfreq_hz, ASSIGNED_SSCS_0_MODFREQ);
+	KUNIT_EXPECT_EQ(test, ctx->clk0.sscs.spread_bp, ASSIGNED_SSCS_0_SPREAD);
+	KUNIT_EXPECT_EQ(test, ctx->clk0.sscs.method, ASSIGNED_SSCS_0_METHOD);
 	KUNIT_EXPECT_EQ(test, ctx->clk1.rate, ASSIGNED_RATES_1_RATE);
+	KUNIT_EXPECT_EQ(test, ctx->clk1.sscs.modfreq_hz, ASSIGNED_SSCS_1_MODFREQ);
+	KUNIT_EXPECT_EQ(test, ctx->clk1.sscs.spread_bp, ASSIGNED_SSCS_1_SPREAD);
+	KUNIT_EXPECT_EQ(test, ctx->clk1.sscs.method, ASSIGNED_SSCS_1_METHOD);
 }
 
 static void clk_assigned_rates_skips(struct kunit *test)
@@ -3222,6 +3251,19 @@ static void clk_assigned_rates_skips(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, ctx->clk0.rate, test_param->rate0);
 }
 
+static void clk_assigned_sscs_skips(struct kunit *test)
+{
+	struct clk_assigned_rates_context *ctx = test->priv;
+	const struct clk_assigned_rates_test_param *test_param = test->param_value;
+
+	KUNIT_EXPECT_NE(test, ctx->clk0.sscs.modfreq_hz, ASSIGNED_SSCS_0_MODFREQ);
+	KUNIT_EXPECT_NE(test, ctx->clk0.sscs.spread_bp, ASSIGNED_SSCS_0_SPREAD);
+	KUNIT_EXPECT_NE(test, ctx->clk0.sscs.method, ASSIGNED_SSCS_0_METHOD);
+	KUNIT_EXPECT_EQ(test, ctx->clk0.sscs.modfreq_hz, test_param->sscs.modfreq_hz);
+	KUNIT_EXPECT_EQ(test, ctx->clk0.sscs.spread_bp, test_param->sscs.spread_bp);
+	KUNIT_EXPECT_EQ(test, ctx->clk0.sscs.method, test_param->sscs.method);
+}
+
 OF_OVERLAY_DECLARE(kunit_clk_assigned_rates_one);
 OF_OVERLAY_DECLARE(kunit_clk_assigned_rates_one_consumer);
 OF_OVERLAY_DECLARE(kunit_clk_assigned_rates_u64_one);
@@ -3384,6 +3426,77 @@ KUNIT_ARRAY_PARAM_DESC(clk_assigned_rates_skips,
 		       clk_assigned_rates_skips_test_params,
 		       desc)
 
+OF_OVERLAY_DECLARE(kunit_clk_assigned_sscs_without);
+OF_OVERLAY_DECLARE(kunit_clk_assigned_sscs_without_consumer);
+OF_OVERLAY_DECLARE(kunit_clk_assigned_sscs_zero);
+OF_OVERLAY_DECLARE(kunit_clk_assigned_sscs_zero_consumer);
+OF_OVERLAY_DECLARE(kunit_clk_assigned_sscs_null);
+OF_OVERLAY_DECLARE(kunit_clk_assigned_sscs_null_consumer);
+
+/* Test cases that skip changing the sscs due to malformed DT */
+static const struct clk_assigned_rates_test_param clk_assigned_sscs_skips_test_params[] = {
+	{
+		/*
+		 * Test that an assigned-clock-sscs property without an assigned-clocks
+		 * property fails when the property is in the provider.
+		 */
+		.desc = "provider missing assigned-clocks",
+		TEST_PARAM_OVERLAY(kunit_clk_assigned_sscs_without),
+		.sscs = {50000, 60000, 3},
+	},
+	{
+		/*
+		 * Test that an assigned-clock-rates property without an assigned-clocks
+		 * property fails when the property is in the consumer.
+		 */
+		.desc = "consumer missing assigned-clocks",
+		TEST_PARAM_OVERLAY(kunit_clk_assigned_sscs_without_consumer),
+		.sscs = {50000, 60000, 3},
+		.consumer_test = true,
+	},
+	{
+		/*
+		 * Test that an assigned-clock-rates property of zero doesn't
+		 * set a rate when the property is in the provider.
+		 */
+		.desc = "provider assigned-clock-sscs of zero",
+		TEST_PARAM_OVERLAY(kunit_clk_assigned_sscs_zero),
+		.sscs = {50000, 60000, 3},
+	},
+	{
+		/*
+		 * Test that an assigned-clock-rates property of zero doesn't
+		 * set a rate when the property is in the consumer.
+		 */
+		.desc = "consumer assigned-clock-sscs of zero",
+		TEST_PARAM_OVERLAY(kunit_clk_assigned_sscs_zero_consumer),
+		.sscs = {50000, 60000, 3},
+		.consumer_test = true,
+	},
+	{
+		/*
+		 * Test that an assigned-clocks property with a null phandle
+		 * doesn't set a rate when the property is in the provider.
+		 */
+		.desc = "provider assigned-clocks null phandle",
+		TEST_PARAM_OVERLAY(kunit_clk_assigned_sscs_null),
+		.sscs = {50000, 60000, 3},
+	},
+	{
+		/*
+		 * Test that an assigned-clocks property with a null phandle
+		 * doesn't set a rate when the property is in the consumer.
+		 */
+		.desc = "provider assigned-clocks null phandle",
+		TEST_PARAM_OVERLAY(kunit_clk_assigned_sscs_null_consumer),
+		.sscs = {50000, 60000, 3},
+		.consumer_test = true,
+	},
+};
+KUNIT_ARRAY_PARAM_DESC(clk_assigned_sscs_skips,
+		       clk_assigned_sscs_skips_test_params,
+		       desc)
+
 static struct kunit_case clk_assigned_rates_test_cases[] = {
 	KUNIT_CASE_PARAM(clk_assigned_rates_assigns_one,
 			 clk_assigned_rates_assigns_one_gen_params),
@@ -3391,6 +3504,8 @@ static struct kunit_case clk_assigned_rates_test_cases[] = {
 			 clk_assigned_rates_assigns_multiple_gen_params),
 	KUNIT_CASE_PARAM(clk_assigned_rates_skips,
 			 clk_assigned_rates_skips_gen_params),
+	KUNIT_CASE_PARAM(clk_assigned_sscs_skips,
+			 clk_assigned_sscs_skips_gen_params),
 	{}
 };
 
diff --git a/drivers/clk/kunit_clk_assigned_rates.h b/drivers/clk/kunit_clk_assigned_rates.h
index df2d84dcaa93511694b6da842debdc3cfd3a6c19..d7ae5ec2d25bed79b8438e8ce580872131ce4286 100644
--- a/drivers/clk/kunit_clk_assigned_rates.h
+++ b/drivers/clk/kunit_clk_assigned_rates.h
@@ -1,8 +1,18 @@
 /* SPDX-License-Identifier: GPL-2.0 */
+
+#include <dt-bindings/clock/clock.h>
+
 #ifndef _KUNIT_CLK_ASSIGNED_RATES_H
 #define _KUNIT_CLK_ASSIGNED_RATES_H
 
 #define ASSIGNED_RATES_0_RATE		1600000
 #define ASSIGNED_RATES_1_RATE		9700000
 
+#define ASSIGNED_SSCS_0_MODFREQ		10000
+#define ASSIGNED_SSCS_0_SPREAD		30000
+#define ASSIGNED_SSCS_0_METHOD		CLK_SSC_CENTER_SPREAD
+#define ASSIGNED_SSCS_1_MODFREQ		20000
+#define ASSIGNED_SSCS_1_SPREAD		40000
+#define ASSIGNED_SSCS_1_METHOD		CLK_SSC_UP_SPREAD
+
 #endif
diff --git a/drivers/clk/kunit_clk_assigned_rates_multiple.dtso b/drivers/clk/kunit_clk_assigned_rates_multiple.dtso
index e600736e70f5041ddeb1bfb0d6074746a064e08a..6c54d65444d5d779c9fa4bb2a79c4742dd88f6d0 100644
--- a/drivers/clk/kunit_clk_assigned_rates_multiple.dtso
+++ b/drivers/clk/kunit_clk_assigned_rates_multiple.dtso
@@ -12,5 +12,11 @@ clk: kunit-clock {
 				  <&clk 1>;
 		assigned-clock-rates = <ASSIGNED_RATES_0_RATE>,
 				       <ASSIGNED_RATES_1_RATE>;
+		assigned-clock-sscs = <ASSIGNED_SSCS_0_MODFREQ
+				       ASSIGNED_SSCS_0_SPREAD
+				       ASSIGNED_SSCS_0_METHOD>,
+				      <ASSIGNED_SSCS_1_MODFREQ
+				       ASSIGNED_SSCS_1_SPREAD
+				       ASSIGNED_SSCS_1_METHOD>;
 	};
 };
diff --git a/drivers/clk/kunit_clk_assigned_rates_multiple_consumer.dtso b/drivers/clk/kunit_clk_assigned_rates_multiple_consumer.dtso
index 260aba458daf2bc57fde46b5442453e7de10faac..b1fee396c4b1e51341a411168569d8351bb23b12 100644
--- a/drivers/clk/kunit_clk_assigned_rates_multiple_consumer.dtso
+++ b/drivers/clk/kunit_clk_assigned_rates_multiple_consumer.dtso
@@ -16,5 +16,11 @@ kunit-clock-consumer {
 				  <&clk 1>;
 		assigned-clock-rates = <ASSIGNED_RATES_0_RATE>,
 				       <ASSIGNED_RATES_1_RATE>;
+		assigned-clock-sscs = <ASSIGNED_SSCS_0_MODFREQ
+				       ASSIGNED_SSCS_0_SPREAD
+				       ASSIGNED_SSCS_0_METHOD>,
+				      <ASSIGNED_SSCS_1_MODFREQ
+				       ASSIGNED_SSCS_1_SPREAD
+				       ASSIGNED_SSCS_1_METHOD>;
 	};
 };
diff --git a/drivers/clk/kunit_clk_assigned_rates_one.dtso b/drivers/clk/kunit_clk_assigned_rates_one.dtso
index dd95ec9b1cf977883f71564a94602ae518937132..da6e91b9e6bda0ef2c8f601a08aef1f10fda4baa 100644
--- a/drivers/clk/kunit_clk_assigned_rates_one.dtso
+++ b/drivers/clk/kunit_clk_assigned_rates_one.dtso
@@ -10,5 +10,8 @@ clk: kunit-clock {
 		#clock-cells = <0>;
 		assigned-clocks = <&clk>;
 		assigned-clock-rates = <ASSIGNED_RATES_0_RATE>;
+		assigned-clock-sscs = <ASSIGNED_SSCS_0_MODFREQ
+				       ASSIGNED_SSCS_0_SPREAD
+				       ASSIGNED_SSCS_0_METHOD>;
 	};
 };
diff --git a/drivers/clk/kunit_clk_assigned_rates_one_consumer.dtso b/drivers/clk/kunit_clk_assigned_rates_one_consumer.dtso
index a41dca806318b031187c1b8739fcf71eb088a480..4b6e06048f863d014aed8222652d6d9d38e9238b 100644
--- a/drivers/clk/kunit_clk_assigned_rates_one_consumer.dtso
+++ b/drivers/clk/kunit_clk_assigned_rates_one_consumer.dtso
@@ -14,5 +14,8 @@ kunit-clock-consumer {
 		compatible = "test,clk-consumer";
 		assigned-clocks = <&clk>;
 		assigned-clock-rates = <ASSIGNED_RATES_0_RATE>;
+		assigned-clock-sscs = <ASSIGNED_SSCS_0_MODFREQ
+				       ASSIGNED_SSCS_0_SPREAD
+				       ASSIGNED_SSCS_0_METHOD>;
 	};
 };
diff --git a/drivers/clk/kunit_clk_assigned_rates_u64_multiple.dtso b/drivers/clk/kunit_clk_assigned_rates_u64_multiple.dtso
index 389b4e2eb7f74f1770ff5f5c4be5b45dd344dc9c..3a717dab2d00b7fdaff580e30ed2cc520683ef95 100644
--- a/drivers/clk/kunit_clk_assigned_rates_u64_multiple.dtso
+++ b/drivers/clk/kunit_clk_assigned_rates_u64_multiple.dtso
@@ -12,5 +12,11 @@ clk: kunit-clock {
 				  <&clk 1>;
 		assigned-clock-rates-u64 = /bits/ 64 <ASSIGNED_RATES_0_RATE>,
 					   /bits/ 64 <ASSIGNED_RATES_1_RATE>;
+		assigned-clock-sscs = <ASSIGNED_SSCS_0_MODFREQ
+				       ASSIGNED_SSCS_0_SPREAD
+				       ASSIGNED_SSCS_0_METHOD>,
+				      <ASSIGNED_SSCS_1_MODFREQ
+				       ASSIGNED_SSCS_1_SPREAD
+				       ASSIGNED_SSCS_1_METHOD>;
 	};
 };
diff --git a/drivers/clk/kunit_clk_assigned_rates_u64_multiple_consumer.dtso b/drivers/clk/kunit_clk_assigned_rates_u64_multiple_consumer.dtso
index 3e117fd59b7da19cd8a603af77eff29175ce6900..cbee7cbad068f3336f0c8997a5b3e9af4db565c9 100644
--- a/drivers/clk/kunit_clk_assigned_rates_u64_multiple_consumer.dtso
+++ b/drivers/clk/kunit_clk_assigned_rates_u64_multiple_consumer.dtso
@@ -16,5 +16,11 @@ kunit-clock-consumer {
 				  <&clk 1>;
 		assigned-clock-rates-u64 = /bits/ 64 <ASSIGNED_RATES_0_RATE>,
 					   /bits/ 64 <ASSIGNED_RATES_1_RATE>;
+		assigned-clock-sscs = <ASSIGNED_SSCS_0_MODFREQ
+				       ASSIGNED_SSCS_0_SPREAD
+				       ASSIGNED_SSCS_0_METHOD>,
+				      <ASSIGNED_SSCS_1_MODFREQ
+				       ASSIGNED_SSCS_1_SPREAD
+				       ASSIGNED_SSCS_1_METHOD>;
 	};
 };
diff --git a/drivers/clk/kunit_clk_assigned_rates_u64_one.dtso b/drivers/clk/kunit_clk_assigned_rates_u64_one.dtso
index 87041264e8f544dafddf2e905efc89dc1f917c54..9b04d6927f0830a5621af1cbea503a427b46bee0 100644
--- a/drivers/clk/kunit_clk_assigned_rates_u64_one.dtso
+++ b/drivers/clk/kunit_clk_assigned_rates_u64_one.dtso
@@ -10,5 +10,8 @@ clk: kunit-clock {
 		#clock-cells = <0>;
 		assigned-clocks = <&clk>;
 		assigned-clock-rates-u64 = /bits/ 64 <ASSIGNED_RATES_0_RATE>;
+		assigned-clock-sscs = <ASSIGNED_SSCS_0_MODFREQ
+				       ASSIGNED_SSCS_0_SPREAD
+				       ASSIGNED_SSCS_0_METHOD>;
 	};
 };
diff --git a/drivers/clk/kunit_clk_assigned_rates_u64_one_consumer.dtso b/drivers/clk/kunit_clk_assigned_rates_u64_one_consumer.dtso
index 3259c003aec0be3269ab60a4a3a95df69f8de1f8..4784d40520f4193e4f08c8981386f0772a063452 100644
--- a/drivers/clk/kunit_clk_assigned_rates_u64_one_consumer.dtso
+++ b/drivers/clk/kunit_clk_assigned_rates_u64_one_consumer.dtso
@@ -14,5 +14,8 @@ kunit-clock-consumer {
 		compatible = "test,clk-consumer";
 		assigned-clocks = <&clk>;
 		assigned-clock-rates-u64 = /bits/ 64 <ASSIGNED_RATES_0_RATE>;
+		assigned-clock-sscs = <ASSIGNED_SSCS_0_MODFREQ
+				       ASSIGNED_SSCS_0_SPREAD
+				       ASSIGNED_SSCS_0_METHOD>;
 	};
 };
diff --git a/drivers/clk/kunit_clk_assigned_rates_zero_consumer.dtso b/drivers/clk/kunit_clk_assigned_rates_zero_consumer.dtso
index 1d964672e8553a90263af400367a2d947f755015..d62c7522c92461245d45f8ac0ebd26fa2850be98 100644
--- a/drivers/clk/kunit_clk_assigned_rates_zero_consumer.dtso
+++ b/drivers/clk/kunit_clk_assigned_rates_zero_consumer.dtso
@@ -12,5 +12,6 @@ kunit-clock-consumer {
 		compatible = "test,clk-consumer";
 		assigned-clocks = <&clk>;
 		assigned-clock-rates = <0>;
+		assigned-clock-sscs = <0 0 0>;
 	};
 };
diff --git a/drivers/clk/kunit_clk_assigned_sscs_null.dtso b/drivers/clk/kunit_clk_assigned_sscs_null.dtso
new file mode 100644
index 0000000000000000000000000000000000000000..43b2068c845dea53ea1328bb63a2f58a4b8ef339
--- /dev/null
+++ b/drivers/clk/kunit_clk_assigned_sscs_null.dtso
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+#include "kunit_clk_assigned_rates.h"
+
+&{/} {
+	clk: kunit-clock {
+		compatible = "test,clk-assigned-rates";
+		#clock-cells = <0>;
+		assigned-clocks = <0>;
+		assigned-clock-sscs = <ASSIGNED_SSCS_0_MODFREQ
+				       ASSIGNED_SSCS_0_SPREAD
+				       ASSIGNED_SSCS_0_METHOD>;
+	};
+};
diff --git a/drivers/clk/kunit_clk_assigned_sscs_null_consumer.dtso b/drivers/clk/kunit_clk_assigned_sscs_null_consumer.dtso
new file mode 100644
index 0000000000000000000000000000000000000000..bda008f5aaa35e53af97863e4f2e6d8a168cc053
--- /dev/null
+++ b/drivers/clk/kunit_clk_assigned_sscs_null_consumer.dtso
@@ -0,0 +1,20 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+#include "kunit_clk_assigned_rates.h"
+
+&{/} {
+	clk: kunit-clock {
+		compatible = "test,clk-assigned-rates";
+		#clock-cells = <0>;
+	};
+
+	kunit-clock-consumer {
+		compatible = "test,clk-consumer";
+		assigned-clocks = <0>;
+		assigned-clock-sscs = <ASSIGNED_SSCS_0_MODFREQ
+				       ASSIGNED_SSCS_0_SPREAD
+				       ASSIGNED_SSCS_0_METHOD>;
+	};
+};
diff --git a/drivers/clk/kunit_clk_assigned_sscs_without.dtso b/drivers/clk/kunit_clk_assigned_sscs_without.dtso
new file mode 100644
index 0000000000000000000000000000000000000000..08660846b55c12122bfb211c01c377a3a45223c9
--- /dev/null
+++ b/drivers/clk/kunit_clk_assigned_sscs_without.dtso
@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+#include "kunit_clk_assigned_rates.h"
+
+&{/} {
+	clk: kunit-clock {
+		compatible = "test,clk-assigned-rates";
+		#clock-cells = <0>;
+		assigned-clock-sscs = <ASSIGNED_SSCS_0_MODFREQ
+				       ASSIGNED_SSCS_0_SPREAD
+				       ASSIGNED_SSCS_0_METHOD>;
+	};
+};
diff --git a/drivers/clk/kunit_clk_assigned_sscs_without_consumer.dtso b/drivers/clk/kunit_clk_assigned_sscs_without_consumer.dtso
new file mode 100644
index 0000000000000000000000000000000000000000..e1c089c6f0c0223f16f7ac9a396e7ac7b821c967
--- /dev/null
+++ b/drivers/clk/kunit_clk_assigned_sscs_without_consumer.dtso
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+#include "kunit_clk_assigned_rates.h"
+
+&{/} {
+	clk: kunit-clock {
+		compatible = "test,clk-assigned-rates";
+		#clock-cells = <0>;
+	};
+
+	kunit-clock-consumer {
+		compatible = "test,clk-consumer";
+		assigned-clock-sscs = <ASSIGNED_SSCS_0_MODFREQ
+				       ASSIGNED_SSCS_0_SPREAD
+				       ASSIGNED_SSCS_0_METHOD>;
+	};
+};
diff --git a/drivers/clk/kunit_clk_assigned_sscs_zero.dtso b/drivers/clk/kunit_clk_assigned_sscs_zero.dtso
new file mode 100644
index 0000000000000000000000000000000000000000..f39f4e754e532c9c1b1fdf034700e5af1f3f0779
--- /dev/null
+++ b/drivers/clk/kunit_clk_assigned_sscs_zero.dtso
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&{/} {
+	clk: kunit-clock {
+		compatible = "test,clk-assigned-rates";
+		#clock-cells = <0>;
+		assigned-clocks = <&clk>;
+		assigned-clock-sscs = <0 0 0>;
+	};
+};
diff --git a/drivers/clk/kunit_clk_assigned_sscs_zero_consumer.dtso b/drivers/clk/kunit_clk_assigned_sscs_zero_consumer.dtso
new file mode 100644
index 0000000000000000000000000000000000000000..d6bd7dfada7e2f455cb23e483b9bd6ce24839e3a
--- /dev/null
+++ b/drivers/clk/kunit_clk_assigned_sscs_zero_consumer.dtso
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+/dts-v1/;
+/plugin/;
+
+&{/} {
+	clk: kunit-clock {
+		compatible = "test,clk-assigned-rates";
+		#clock-cells = <0>;
+	};
+
+	kunit-clock-consumer {
+		compatible = "test,clk-consumer";
+		assigned-clocks = <&clk>;
+		assigned-clock-sscs = <0 0 0>;
+	};
+};

-- 
2.37.1

[PATCH v3 5/5] clk: scmi: Support Spread Spectrum for NXP i.MX95

[Peng Fan]

The PLL clocks on NXP i.MX95 SoCs support Spread Spectrum (SS).
This patch introduces scmi_clk_imx_set_spread_spectrum to pass SS
configuration to the SCMI firmware, which handles the actual
implementation.

To ensure this feature is only enabled on NXP platforms,
scmi_clk_imx_extended_config_oem is added. Since SS is only applicable
to PLL clocks, config_oem_get is used to verify SS support for a given
clock.

i.MX95 SCMI firmware Spread Spectrum extConfigValue definition is as
below, no modulation method because firmware forces to use down spread.
	 extConfigValue[7:0]   - spread percentage (%)
	 extConfigValue[23:8]  - Modulation Frequency (KHz)
	 extConfigValue[24]    - Enable/Disable
	 extConfigValue[31:25] - Reserved

Signed-off-by: Peng Fan <peng.fan@nxp.com>
---
 drivers/clk/clk-scmi.c        | 64 ++++++++++++++++++++++++++++++++++++++++---
 include/linux/scmi_protocol.h |  5 ++++
 2 files changed, 65 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/clk-scmi.c b/drivers/clk/clk-scmi.c
index d2408403283fc72f0cf902e65f4c08bcbc7b4b0b..bb5e20dab18e92932ab4b99192b496e0c4d96417 100644
--- a/drivers/clk/clk-scmi.c
+++ b/drivers/clk/clk-scmi.c
@@ -12,6 +12,7 @@
 #include <linux/of.h>
 #include <linux/module.h>
 #include <linux/scmi_protocol.h>
+#include <linux/scmi_imx_protocol.h>
 #include <asm/div64.h>
 
 #define NOT_ATOMIC	false
@@ -23,6 +24,7 @@ enum scmi_clk_feats {
 	SCMI_CLK_RATE_CTRL_SUPPORTED,
 	SCMI_CLK_PARENT_CTRL_SUPPORTED,
 	SCMI_CLK_DUTY_CYCLE_SUPPORTED,
+	SCMI_CLK_IMX_SSC_SUPPORTED,
 	SCMI_CLK_FEATS_COUNT
 };
 
@@ -98,6 +100,35 @@ static int scmi_clk_set_parent(struct clk_hw *hw, u8 parent_index)
 	return scmi_proto_clk_ops->parent_set(clk->ph, clk->id, parent_index);
 }
 
+static int scmi_clk_imx_set_spread_spectrum(struct clk_hw *hw,
+					    struct clk_spread_spectrum *clk_ss)
+{
+	struct scmi_clk *clk = to_scmi_clk(hw);
+	int ret;
+	u32 val;
+
+	/*
+	 * extConfigValue[7:0]   - spread percentage (%)
+	 * extConfigValue[23:8]  - Modulation Frequency
+	 * extConfigValue[24]    - Enable/Disable
+	 * extConfigValue[31:25] - Reserved
+	 */
+	val = FIELD_PREP(SCMI_CLOCK_IMX_SS_PERCENTAGE_MASK, clk_ss->spread_bp / 10000);
+	val |= FIELD_PREP(SCMI_CLOCK_IMX_SS_MOD_FREQ_MASK, clk_ss->modfreq_hz);
+	if (clk_ss->method != CLK_SSC_NO_SPREAD)
+		val |= SCMI_CLOCK_IMX_SS_ENABLE_MASK;
+	ret = scmi_proto_clk_ops->config_oem_set(clk->ph, clk->id,
+						 SCMI_CLOCK_CFG_IMX_SSC,
+						 val, false);
+	if (ret)
+		dev_warn(clk->dev,
+			 "Failed to set spread spectrum(%u,%u,%u) for clock ID %d\n",
+			 clk_ss->modfreq_hz, clk_ss->spread_bp, clk_ss->method,
+			 clk->id);
+
+	return ret;
+}
+
 static u8 scmi_clk_get_parent(struct clk_hw *hw)
 {
 	struct scmi_clk *clk = to_scmi_clk(hw);
@@ -316,11 +347,33 @@ scmi_clk_ops_alloc(struct device *dev, unsigned long feats_key)
 		ops->set_duty_cycle = scmi_clk_set_duty_cycle;
 	}
 
+	if (feats_key & BIT(SCMI_CLK_IMX_SSC_SUPPORTED))
+		ops->set_spread_spectrum = scmi_clk_imx_set_spread_spectrum;
+
 	return ops;
 }
 
+static void scmi_clk_imx_extended_config_oem(const struct scmi_handle *handle,
+					     struct scmi_clk *sclk,
+					     unsigned int *feats_key)
+{
+	int ret;
+	u32 val;
+
+	if (strcmp(handle->version->vendor_id, SCMI_IMX_VENDOR) ||
+	    strcmp(handle->version->sub_vendor_id, SCMI_IMX_SUBVENDOR))
+		return;
+
+	ret = scmi_proto_clk_ops->config_oem_get(sclk->ph, sclk->id,
+						 SCMI_CLOCK_CFG_IMX_SSC,
+						 &val, NULL, false);
+	if (!ret)
+		*feats_key |= BIT(SCMI_CLK_IMX_SSC_SUPPORTED);
+}
+
 /**
  * scmi_clk_ops_select() - Select a proper set of clock operations
+ * @handle: A reference to an SCMI entity
  * @sclk: A reference to an SCMI clock descriptor
  * @atomic_capable: A flag to indicate if atomic mode is supported by the
  *		    transport
@@ -345,8 +398,8 @@ scmi_clk_ops_alloc(struct device *dev, unsigned long feats_key)
  *	   NULL otherwise.
  */
 static const struct clk_ops *
-scmi_clk_ops_select(struct scmi_clk *sclk, bool atomic_capable,
-		    unsigned int atomic_threshold_us,
+scmi_clk_ops_select(const struct scmi_handle *handle, struct scmi_clk *sclk,
+		    bool atomic_capable, unsigned int atomic_threshold_us,
 		    const struct clk_ops **clk_ops_db, size_t db_size)
 {
 	const struct scmi_clock_info *ci = sclk->info;
@@ -370,9 +423,12 @@ scmi_clk_ops_select(struct scmi_clk *sclk, bool atomic_capable,
 	if (!ci->parent_ctrl_forbidden)
 		feats_key |= BIT(SCMI_CLK_PARENT_CTRL_SUPPORTED);
 
-	if (ci->extended_config)
+	if (ci->extended_config) {
 		feats_key |= BIT(SCMI_CLK_DUTY_CYCLE_SUPPORTED);
 
+		scmi_clk_imx_extended_config_oem(handle, sclk, &feats_key);
+	}
+
 	if (WARN_ON(feats_key >= db_size))
 		return NULL;
 
@@ -459,7 +515,7 @@ static int scmi_clocks_probe(struct scmi_device *sdev)
 		 * to avoid sharing the devm_ allocated clk_ops between multiple
 		 * SCMI clk driver instances.
 		 */
-		scmi_ops = scmi_clk_ops_select(sclk, transport_is_atomic,
+		scmi_ops = scmi_clk_ops_select(handle, sclk, transport_is_atomic,
 					       atomic_threshold_us,
 					       scmi_clk_ops_db,
 					       ARRAY_SIZE(scmi_clk_ops_db));
diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
index aafaac1496b06a6e4f0ca32eee58a9edf7d4a70f..37f422b4b1ef2af2b4231a1677161aa24e07d0e2 100644
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -80,9 +80,14 @@ enum scmi_clock_oem_config {
 	SCMI_CLOCK_CFG_DUTY_CYCLE = 0x1,
 	SCMI_CLOCK_CFG_PHASE,
 	SCMI_CLOCK_CFG_OEM_START = 0x80,
+	SCMI_CLOCK_CFG_IMX_SSC = 0x80,
 	SCMI_CLOCK_CFG_OEM_END = 0xFF,
 };
 
+#define SCMI_CLOCK_IMX_SS_PERCENTAGE_MASK	GENMASK(7, 0)
+#define SCMI_CLOCK_IMX_SS_MOD_FREQ_MASK		GENMASK(23, 8)
+#define SCMI_CLOCK_IMX_SS_ENABLE_MASK		BIT(24)
+
 /**
  * struct scmi_clk_proto_ops - represents the various operations provided
  *	by SCMI Clock Protocol

-- 
2.37.1

Re: [PATCH v3 2/5] clk: Introduce clk_hw_set_spread_spectrum

[Brian Masney]

On Fri, Sep 12, 2025 at 11:35:51AM +0800, Peng Fan wrote:
> Add clk_hw_set_spread_spectrum to configure a clock to enable spread
> spectrum feature. set_spread_spectrum ops is added for clk drivers to
> have their own hardware specific implementation.
> 
> Signed-off-by: Peng Fan <peng.fan@nxp.com>

Reviewed-by: Brian Masney <bmasney@redhat.com>

Re: [PATCH v3 4/5] clk: Add KUnit tests for assigned-clock-sscs

[Brian Masney]

On Fri, Sep 12, 2025 at 11:35:53AM +0800, Peng Fan wrote:
> Spread spectrum configuration is part of clock frequency settings,
> and its behavior can be validated similarly to assigned clock rates.
> 
> Extend the existing KUnit tests for assigned-clock-rates to cover
> assigned-clock-sscs by reusing the test framework. Add new test
> device trees:
>   - kunit_clk_assigned_sscs_null.dtso
>   - kunit_clk_assigned_sscs_null_consumer.dtso
>   - kunit_clk_assigned_sscs_without.dtso
>   - kunit_clk_assigned_sscs_without_consumer.dtso
>   - kunit_clk_assigned_sscs_zero.dtso
>   - kunit_clk_assigned_sscs_zero_consumer.dtso
> 
> These tests cover various invalid configurations of assigned-clock-sscs,
> ensuring robustness and consistent error handling, similar to the coverage
> provided for assigned-clock-rates.
> 
> Co-developed-by: Brian Masney <bmasney@redhat.com>
> Signed-off-by: Brian Masney <bmasney@redhat.com>
> Signed-off-by: Peng Fan <peng.fan@nxp.com>
> ---

There's no need to add a Co-developed-by for me. I just gave you a very
rough starting point.

> diff --git a/drivers/clk/kunit_clk_assigned_rates_zero_consumer.dtso b/drivers/clk/kunit_clk_assigned_rates_zero_consumer.dtso
> index 1d964672e8553a90263af400367a2d947f755015..d62c7522c92461245d45f8ac0ebd26fa2850be98 100644
> --- a/drivers/clk/kunit_clk_assigned_rates_zero_consumer.dtso
> +++ b/drivers/clk/kunit_clk_assigned_rates_zero_consumer.dtso
> @@ -12,5 +12,6 @@ kunit-clock-consumer {
>  		compatible = "test,clk-consumer";
>  		assigned-clocks = <&clk>;
>  		assigned-clock-rates = <0>;
> +		assigned-clock-sscs = <0 0 0>;
>  	};
>  };

kunit_clk_assigned_rates_zero_consumer.dtso is modified, however
kunit_clk_assigned_rates_zero.dtso was not. The underlying test doesn't
check for this, so you can drop the change to this dtso file.

Everything else looks good to me.

Brian

Re: [PATCH v3 1/5] dt-bindings: clock: Add spread spectrum definition

[Brian Masney]

On Fri, Sep 12, 2025 at 11:35:50AM +0800, Peng Fan wrote:
> Per dt-schema, the modulation methods are: down-spread(3), up-spread(2),
> center-spread(1), no-spread(0). So define them in dt-bindings to avoid
> write the magic number in device tree.
> 
> Signed-off-by: Peng Fan <peng.fan@nxp.com>

Reviewed-by: Brian Masney <bmasney@redhat.com>

Re: [PATCH v3 4/5] clk: Add KUnit tests for assigned-clock-sscs

[Peng Fan]

Hi Brian,

On Fri, Sep 12, 2025 at 10:50:39AM -0400, Brian Masney wrote:
>On Fri, Sep 12, 2025 at 11:35:53AM +0800, Peng Fan wrote:
>> ---
>
>There's no need to add a Co-developed-by for me. I just gave you a very
>rough starting point.

I honor your support, otherwise it would take me more time on write
the kunit test.

>
>> diff --git a/drivers/clk/kunit_clk_assigned_rates_zero_consumer.dtso b/drivers/clk/kunit_clk_assigned_rates_zero_consumer.dtso
>> index 1d964672e8553a90263af400367a2d947f755015..d62c7522c92461245d45f8ac0ebd26fa2850be98 100644
>> --- a/drivers/clk/kunit_clk_assigned_rates_zero_consumer.dtso
>> +++ b/drivers/clk/kunit_clk_assigned_rates_zero_consumer.dtso
>> @@ -12,5 +12,6 @@ kunit-clock-consumer {
>>  		compatible = "test,clk-consumer";
>>  		assigned-clocks = <&clk>;
>>  		assigned-clock-rates = <0>;
>> +		assigned-clock-sscs = <0 0 0>;
>>  	};
>>  };
>
>kunit_clk_assigned_rates_zero_consumer.dtso is modified, however
>kunit_clk_assigned_rates_zero.dtso was not. The underlying test doesn't
>check for this, so you can drop the change to this dtso file.

Right. I will drop this change.

Thanks,
Peng