clk: Add clk_resolve_parent_clk()

Add clk_resolve_parent_clk() to resolve parent clock udevice name
based on clock-names DT property. This is used in SoC clock drivers
to look up the clock name in clock tables, which matches a clock
name in DT clock-names property, and convert it into udevice name
which is used by U-Boot clock framework to look up parent clock in
e.g. clk_register() using uclass_get_device_by_name(UCLASS_CLK,
parent_name, &parent);

Signed-off-by: Marek Vasut <marex@denx.de>

drivers/clk/clk-uclass.c

@@ -420,6 +420,24 @@ int clk_get_by_name_nodev(ofnode node, const char *name, struct clk *clk)
 	return clk_get_by_index_nodev(node, index, clk);
 }
 
+const char *
+clk_resolve_parent_clk(struct udevice *dev, const char *name)
+{
+	struct udevice *parent;
+	struct clk clk;
+	int ret;
+
+	ret = uclass_get_device_by_name(UCLASS_CLK, name, &parent);
+	if (!ret)
+		return name;
+
+	ret = clk_get_by_name(dev, name, &clk);
+	if (!clk.dev)
+		return name;
+
+	return clk.dev->name;
+}
+
 int clk_release_all(struct clk *clk, unsigned int count)
 {
 	unsigned int i;

include/clk.h

@@ -350,6 +350,15 @@ static inline int clk_get_by_name_nodev_optional(ofnode node, const char *name,
 	return ret;
 }
 
+/**
+ * clk_resolve_parent_clk - Determine name of clock udevice based on clock-names
+ * @dev:	The client udevice.
+ * @name:	The name of the clock to look up.
+ *
+ * Return name of the clock udevice which represents clock with clock-names name.
+ */
+const char *clk_resolve_parent_clk(struct udevice *dev, const char *name);
+
 /**
  * enum clk_defaults_stage - What stage clk_set_defaults() is called at
  * @CLK_DEFAULTS_PRE: Called before probe. Setting of defaults for clocks owned