clk: fixed-factor: Introduce devm_clk_hw_register_fixed_factor_index()

Add an API for a fixed factor clk that uses an index for the parent
instead of a string name. This allows us to move drivers away from the
string based method of describing parents and use the DT/firmware based
method instead.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Michael Turquette <mturquette@baylibre.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Stephen Boyd <sboyd@kernel.org>
Cc: devicetree@vger.kernel.org
Link: https://lore.kernel.org/r/20220226040723.143705-2-marex@denx.de
[sboyd@kernel.org: Expose a new API instead of internal function]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/clk-fixed-factor.c

@@ -131,6 +131,28 @@ __clk_hw_register_fixed_factor(struct device *dev, struct device_node *np,
 	return hw;
 }
 
+/**
+ * devm_clk_hw_register_fixed_factor_index - Register a fixed factor clock with
+ * parent from DT index
+ * @dev: device that is registering this clock
+ * @name: name of this clock
+ * @index: index of phandle in @dev 'clocks' property
+ * @flags: fixed factor flags
+ * @mult: multiplier
+ * @div: divider
+ *
+ * Return: Pointer to fixed factor clk_hw structure that was registered or
+ * an error pointer.
+ */
+struct clk_hw *devm_clk_hw_register_fixed_factor_index(struct device *dev,
+		const char *name, unsigned int index, unsigned long flags,
+		unsigned int mult, unsigned int div)
+{
+	return __clk_hw_register_fixed_factor(dev, NULL, name, NULL, index,
+					      flags, mult, div, true);
+}
+EXPORT_SYMBOL_GPL(devm_clk_hw_register_fixed_factor_index);
+
 struct clk_hw *clk_hw_register_fixed_factor(struct device *dev,
 		const char *name, const char *parent_name, unsigned long flags,
 		unsigned int mult, unsigned int div)

include/linux/clk-provider.h

@@ -1003,6 +1003,9 @@ void clk_hw_unregister_fixed_factor(struct clk_hw *hw);
 struct clk_hw *devm_clk_hw_register_fixed_factor(struct device *dev,
 		const char *name, const char *parent_name, unsigned long flags,
 		unsigned int mult, unsigned int div);
+struct clk_hw *devm_clk_hw_register_fixed_factor_index(struct device *dev,
+		const char *name, unsigned int index, unsigned long flags,
+		unsigned int mult, unsigned int div);
 /**
  * struct clk_fractional_divider - adjustable fractional divider clock
  *