[PATCH v2 1/2] clk: divider: prepare for minimum divider

[Afzal Mohammed]

Some of clocks can have a limit on minimum divider value that can be
programmed, prepare for such a support.

Add a new field min_div for the basic divider clock and a new dynamic
clock divider registration function where minimum divider value can
be specified. Keep behaviour of existing divider clock registration
functions, static initialization helpers as was earlier.

Signed-off-by: Afzal Mohammed <afzal at ti.com>
---

v2: create a new registration function for those that needs to
    constrain minimum divider value instead of modifying existing
    registration functions and hence remove modification in other
    clock files.
    

 drivers/clk/clk-divider.c    | 37 ++++++++++++++++++++++++++++++++++---
 include/linux/clk-private.h  |  6 +++++-
 include/linux/clk-provider.h |  7 +++++++
 3 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
index a9204c6..4025c5a 100644
--- a/drivers/clk/clk-divider.c
+++ b/drivers/clk/clk-divider.c
@@ -236,7 +236,7 @@ EXPORT_SYMBOL_GPL(clk_divider_ops);
 
 static struct clk *_register_divider(struct device *dev, const char *name,
 		const char *parent_name, unsigned long flags,
-		void __iomem *reg, u8 shift, u8 width,
+		void __iomem *reg, u8 shift, u8 width, u8 min_div,
 		u8 clk_divider_flags, const struct clk_div_table *table,
 		spinlock_t *lock)
 {
@@ -244,6 +244,11 @@ static struct clk *_register_divider(struct device *dev, const char *name,
 	struct clk *clk;
 	struct clk_init_data init;
 
+	if (!min_div) {
+		pr_err("%s: minimum divider cannot be zero\n", __func__);
+		return ERR_PTR(-EINVAL);
+	}
+
 	/* allocate the divider */
 	div = kzalloc(sizeof(struct clk_divider), GFP_KERNEL);
 	if (!div) {
@@ -261,6 +266,7 @@ static struct clk *_register_divider(struct device *dev, const char *name,
 	div->reg = reg;
 	div->shift = shift;
 	div->width = width;
+	div->min_div = min_div;
 	div->flags = clk_divider_flags;
 	div->lock = lock;
 	div->hw.init = &init;
@@ -276,6 +282,29 @@ static struct clk *_register_divider(struct device *dev, const char *name,
 }
 
 /**
+ * clk_register_min_divider - register a divider clock having minimum divider
+ * constraints with clock framework
+ * @dev: device registering this clock
+ * @name: name of this clock
+ * @parent_name: name of clock's parent
+ * @flags: framework-specific flags
+ * @reg: register address to adjust divider
+ * @shift: number of bits to shift the bitfield
+ * @width: width of the bitfield
+ * @min_div: minimum allowable divider
+ * @clk_divider_flags: divider-specific flags for this clock
+ * @lock: shared register lock for this clock
+ */
+struct clk *clk_register_min_divider(struct device *dev, const char *name,
+		const char *parent_name, unsigned long flags,
+		void __iomem *reg, u8 shift, u8 width, u8 min_div,
+		u8 clk_divider_flags, spinlock_t *lock)
+{
+	return _register_divider(dev, name, parent_name, flags, reg, shift,
+			width, min_div, clk_divider_flags, NULL, lock);
+}
+
+/**
  * clk_register_divider - register a divider clock with the clock framework
  * @dev: device registering this clock
  * @name: name of this clock
@@ -293,7 +322,8 @@ struct clk *clk_register_divider(struct device *dev, const char *name,
 		u8 clk_divider_flags, spinlock_t *lock)
 {
 	return _register_divider(dev, name, parent_name, flags, reg, shift,
-			width, clk_divider_flags, NULL, lock);
+			width, CLK_DIVIDER_MIN_DIV_DEFAULT, clk_divider_flags,
+			NULL, lock);
 }
 
 /**
@@ -317,5 +347,6 @@ struct clk *clk_register_divider_table(struct device *dev, const char *name,
 		spinlock_t *lock)
 {
 	return _register_divider(dev, name, parent_name, flags, reg, shift,
-			width, clk_divider_flags, table, lock);
+			width, CLK_DIVIDER_MIN_DIV_DEFAULT, clk_divider_flags,
+			table, lock);
 }
diff --git a/include/linux/clk-private.h b/include/linux/clk-private.h
index 9c7f580..942a1be 100644
--- a/include/linux/clk-private.h
+++ b/include/linux/clk-private.h
@@ -105,7 +105,8 @@ struct clk {
 
 #define _DEFINE_CLK_DIVIDER(_name, _parent_name, _parent_ptr,	\
 				_flags, _reg, _shift, _width,	\
-				_divider_flags, _table, _lock)	\
+				_min_div, _divider_flags,	\
+				_table, _lock)			\
 	static struct clk _name;				\
 	static const char *_name##_parent_names[] = {		\
 		_parent_name,					\
@@ -120,6 +121,7 @@ struct clk {
 		.reg = _reg,					\
 		.shift = _shift,				\
 		.width = _width,				\
+		.min_div = _min_div,				\
 		.flags = _divider_flags,			\
 		.table = _table,				\
 		.lock = _lock,					\
@@ -132,6 +134,7 @@ struct clk {
 				_divider_flags, _lock)		\
 	_DEFINE_CLK_DIVIDER(_name, _parent_name, _parent_ptr,	\
 				_flags, _reg, _shift, _width,	\
+				CLK_DIVIDER_MIN_DIV_DEFAULT,	\
 				_divider_flags, NULL, _lock)
 
 #define DEFINE_CLK_DIVIDER_TABLE(_name, _parent_name,		\
@@ -140,6 +143,7 @@ struct clk {
 				_table, _lock)			\
 	_DEFINE_CLK_DIVIDER(_name, _parent_name, _parent_ptr,	\
 				_flags, _reg, _shift, _width,	\
+				CLK_DIVIDER_MIN_DIV_DEFAULT,	\
 				_divider_flags, _table, _lock)	\
 
 #define DEFINE_CLK_MUX(_name, _parent_names, _parents, _flags,	\
diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
index 4989b8a..1c09481 100644
--- a/include/linux/clk-provider.h
+++ b/include/linux/clk-provider.h
@@ -248,15 +248,22 @@ struct clk_divider {
 	void __iomem	*reg;
 	u8		shift;
 	u8		width;
+	u8		min_div;
 	u8		flags;
 	const struct clk_div_table	*table;
 	spinlock_t	*lock;
 };
 
+#define	CLK_DIVIDER_MIN_DIV_DEFAULT	1
+
 #define CLK_DIVIDER_ONE_BASED		BIT(0)
 #define CLK_DIVIDER_POWER_OF_TWO	BIT(1)
 
 extern const struct clk_ops clk_divider_ops;
+struct clk *clk_register_min_divider(struct device *dev, const char *name,
+		const char *parent_name, unsigned long flags,
+		void __iomem *reg, u8 shift, u8 width, u8 min_div,
+		u8 clk_divider_flags, spinlock_t *lock);
 struct clk *clk_register_divider(struct device *dev, const char *name,
 		const char *parent_name, unsigned long flags,
 		void __iomem *reg, u8 shift, u8 width,
-- 
1.7.12