Subject: Re: [PATCH v2 1/4] clk: Introduce
clk_hw_set_spread_spectrum

Hi Peng,

On 25-02-05, Peng Fan (OSS) wrote:

quoted

From: Peng Fan <peng.fan@nxp.com>

Add clk_hw_set_spread_spectrum to configure a clock to enable

spread

quoted

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            | 34 ++++++++++++++++++++++++++++++++++
 include/linux/clk-provider.h | 32

++++++++++++++++++++++++++++++++

quoted

 include/linux/clk.h          | 22 ++++++++++++++++++++++
 3 files changed, 88 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index

cf7720b9172ff223d86227aad144e15375ddfd86..e11f9615e683af52c7
19d4c8419b

quoted

d30f369f301b 100644

--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c

@@ -2790,6 +2790,40 @@ int clk_set_max_rate(struct clk *clk,

unsigned

quoted

long rate)  }  EXPORT_SYMBOL_GPL(clk_set_max_rate);

+int clk_hw_set_spread_spectrum(struct clk_hw *hw, unsigned int

modfreq,

quoted

+			       unsigned int spreaddepth, enum

clk_ssc_method method,

quoted

+			       bool enable)
+{
+	struct clk_spread_spectrum clk_ss;
+	struct clk_core *core;
+	int ret;
+
+	if (!hw)
+		return 0;
+
+	core = hw->core;
+
+	clk_ss.modfreq = modfreq;
+	clk_ss.spreaddepth = spreaddepth;
+	clk_ss.method = method;
+	clk_ss.enable = enable;
+
+	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, &clk_ss);
+
+	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

2e6e603b749342931c0d0693c3e72b62c000791b..ac0270cc9ec13395
4b1f8dcffed0

quoted

15723bd1ff5d 100644

--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h

@@ -84,6 +84,28 @@ struct clk_duty {
 	unsigned int den;
 };

+/* Aligned with dtschema/schemas/clock/clock.yaml */ enum
+clk_ssc_method {
+	CLK_SSC_CENTER_SPREAD,
+	CLK_SSC_UP_SPREAD,
+	CLK_SSC_DOWN_SPREAD,
+};
+
+/**
+ * struct clk_spread_spectrum - Structure encoding spread spectrum

of

quoted

+a clock
+ *
+ * @modfreq:		Modulation frequency
+ * @spreadpercent:	Modulation percent
+ * @method:		Modulation method
+ * @enable:		Modulation enable or disable
+ */
+struct clk_spread_spectrum {
+	unsigned int modfreq;
+	unsigned int spreaddepth;

Please use per mil as unit since I noticed that 0.x% is a common value
too.

I use " The modulation depth in permyriad " in dt-schema, since
Dario said ST chips has permyriad.

So change it to moddepth_per_myriad?

Thanks,
Peng.

Regards,
  Marco

quoted

+	enum clk_ssc_method method;
+	bool enable;
+};
+
 /**
  * struct clk_ops -  Callback operations for hardware clocks; these are

to

quoted

  * be provided by the clock implementation, and will be called by
drivers @@ -178,6 +200,11 @@ struct clk_duty {
  *		separately via calls to .set_parent and .set_rate.
  *		Returns 0 on success, -EERROR otherwise.
  *
+ * @set_spread_spectrum: Configure the modulation frequency,

modulation percentage

quoted

+ *		and method. This callback is optional for clocks that

does not

quoted

+ *		support spread spectrum feature or no need to enable

this feature.

quoted

+ *		Returns 0 on success, -EERROR otherwise.
+ *
  * @recalc_accuracy: Recalculate the accuracy of this clock. The

clock accuracy

quoted

  *		is expressed in ppb (parts per billion). The parent

accuracy is

quoted

  *		an input parameter.

@@ -255,6 +282,8 @@ struct clk_ops {
 	int		(*set_rate_and_parent)(struct clk_hw *hw,
 				    unsigned long rate,
 				    unsigned long parent_rate, u8

index);

quoted

+	int		(*set_spread_spectrum)(struct clk_hw *hw,
+					       struct

clk_spread_spectrum *clk_ss);

quoted

 	unsigned long	(*recalc_accuracy)(struct clk_hw *hw,
 					   unsigned long

parent_accuracy);

quoted

 	int		(*get_phase)(struct clk_hw *hw);

@@ -1404,6 +1433,9 @@ void clk_hw_get_rate_range(struct clk_hw

*hw, unsigned long *min_rate,

quoted

 			   unsigned long *max_rate);
 void clk_hw_set_rate_range(struct clk_hw *hw, unsigned long

min_rate,

quoted

 			   unsigned long max_rate);
+int clk_hw_set_spread_spectrum(struct clk_hw *hw, unsigned int

modfreq,

quoted

+			       unsigned int spreaddepth, enum

clk_ssc_method method,

quoted

+			       bool enable);

 static inline void __clk_hw_set_clk(struct clk_hw *dst, struct clk_hw
*src)  { diff --git a/include/linux/clk.h b/include/linux/clk.h index

b607482ca77e987b9344c38f25ebb5c8d35c1d39..49a7f7eb8b03233e
11cd3b927688

quoted

96c4e45c4e7c 100644

--- a/include/linux/clk.h
+++ b/include/linux/clk.h

@@ -858,6 +858,21 @@ int clk_set_rate(struct clk *clk, unsigned

long rate);

quoted

  */
 int clk_set_rate_exclusive(struct clk *clk, unsigned long rate);

+/**
+ * clk_set_spread_spectrum - set the spread spectrum for a clock
+ * @clk: clock source
+ * @modfreq: modulation freq
+ * @spreadpercent: modulation percentage
+ * @method: down spread, up spread, center spread or else
+ * @enable: enable or disable
+ *
+ * Configure the spread spectrum parameters for a clock.
+ *
+ * Returns success (0) or negative errno.
+ */
+int clk_set_spread_spectrum(struct clk *clk, unsigned int modfreq,
+			    unsigned int spreadpercent, unsigned int

method,

quoted

+			    bool enable);
 /**
  * clk_has_parent - check if a clock is a possible parent for another
  * @clk: clock source

@@ -1088,6 +1103,13 @@ static inline int

clk_set_rate_exclusive(struct clk *clk, unsigned long rate)

quoted

 	return 0;
 }

+static inline int clk_set_spread_spectrum(struct clk *clk, unsigned

int modfreq,

quoted

+					  unsigned int spreadpercent,
+					  unsigned int method, bool

enable) {

quoted

+	return 0;
+}
+
 static inline long clk_round_rate(struct clk *clk, unsigned long
rate)  {
 	return 0;

--
2.37.1