[PATCH v2 1/4] clk: Introduce clk_hw_set_spread_spectrum

["Peng Fan (OSS)" <peng.fan@oss.nxp.com>]

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

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            | 34 ++++++++++++++++++++++++++++++++++
 include/linux/clk-provider.h | 32 ++++++++++++++++++++++++++++++++
 include/linux/clk.h          | 22 ++++++++++++++++++++++
 3 files changed, 88 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index cf7720b9172ff223d86227aad144e15375ddfd86..e11f9615e683af52c719d4c8419bd30f369f301b 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2790,6 +2790,40 @@ 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, unsigned int modfreq,
+			       unsigned int spreaddepth, enum clk_ssc_method method,
+			       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..ac0270cc9ec133954b1f8dcffed015723bd1ff5d 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 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;
+	enum clk_ssc_method method;
+	bool enable;
+};
+
 /**
  * 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 +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
+ *		and method. This callback is optional for clocks that does not
+ *		support spread spectrum feature or no need to enable this feature.
+ *		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 +282,8 @@ 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);
@@ -1404,6 +1433,9 @@ 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, unsigned int modfreq,
+			       unsigned int spreaddepth, enum clk_ssc_method method,
+			       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..49a7f7eb8b03233e11cd3b92768896c4e45c4e7c 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);
  */
 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,
+			    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)
 	return 0;
 }
 
+static inline int clk_set_spread_spectrum(struct clk *clk, unsigned int modfreq,
+					  unsigned int spreadpercent,
+					  unsigned int method, bool enable)
+{
+	return 0;
+}
+
 static inline long clk_round_rate(struct clk *clk, unsigned long rate)
 {
 	return 0;

-- 
2.37.1