[PATCH v11 2/6] clk: Introduce clk_hw_set_spread_spectrum

From: Peng Fan <[email protected]>

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.

Reviewed-by: Brian Masney <[email protected]>
Reviewed-by: Sebin Francis <[email protected]>
Signed-off-by: Peng Fan <[email protected]>
---
 drivers/clk/clk.c            | 27 +++++++++++++++++++++++++++
 include/linux/clk-provider.h | 31 +++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 048adfa86a5d0..8c78621cde253 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2774,6 +2774,33 @@ 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, const struct clk_spread_spectrum *ss_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, ss_conf);
+
+	clk_pm_runtime_put(core);
+
+fail:
+	clk_prepare_unlock();
+	return ret;
+}
+EXPORT_SYMBOL_GPL(clk_hw_set_spread_spectrum);
+
 /**
  * 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 aba71f5dcc216..ad57bd18b536e 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -6,6 +6,7 @@
 #ifndef __LINUX_CLK_PROVIDER_H
 #define __LINUX_CLK_PROVIDER_H
 
+#include <dt-bindings/clock/clock.h>
 #include <linux/of.h>
 #include <linux/of_clk.h>
 
@@ -84,6 +85,26 @@ struct clk_duty {
 	unsigned int den;
 };
 
+enum clk_ssc_method {
+	CLK_SPREAD_NO		= CLK_SSC_NO_SPREAD,
+	CLK_SPREAD_CENTER	= CLK_SSC_CENTER_SPREAD,
+	CLK_SPREAD_UP		= CLK_SSC_UP_SPREAD,
+	CLK_SPREAD_DOWN		= CLK_SSC_DOWN_SPREAD,
+};
+
+/**
+ * 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;
+	enum clk_ssc_method method;
+};
+
 /**
  * struct clk_ops -  Callback operations for hardware clocks; these are to
  * be provided by the clock implementation, and will be called by drivers
@@ -174,6 +195,12 @@ 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.
@@ -249,6 +276,8 @@ 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,
+					       const struct clk_spread_spectrum *ss_conf);
 	unsigned long	(*recalc_accuracy)(struct clk_hw *hw,
 					   unsigned long parent_accuracy);
 	int		(*get_phase)(struct clk_hw *hw);
@@ -1468,6 +1497,8 @@ 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,
+			       const struct clk_spread_spectrum *ss_conf);
 
 static inline void __clk_hw_set_clk(struct clk_hw *dst, struct clk_hw *src)
 {

-- 
2.34.1