dm: core: Add functions to get strings and the string count from a stringlist

dev_read_string_count() is used to get the number of strings in a
stringlist.
dev_read_string_index() is used to get a string in the stringlist based on
its position in the list.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>

drivers/core/read.c

@@ -81,6 +81,17 @@ int dev_read_stringlist_search(struct udevice *dev, const char *property,
 	return ofnode_stringlist_search(dev_ofnode(dev), property, string);
 }
 
+int dev_read_string_index(struct udevice *dev, const char *propname, int index,
+			  const char **outp)
+{
+	return ofnode_read_string_index(dev_ofnode(dev), propname, index, outp);
+}
+
+int dev_read_string_count(struct udevice *dev, const char *propname)
+{
+	return ofnode_read_string_count(dev_ofnode(dev), propname);
+}
+
 int dev_read_phandle_with_args(struct udevice *dev, const char *list_name,
 				const char *cells_name, int cell_count,
 				int index,

include/dm/read.h

@@ -165,6 +165,29 @@ const char *dev_read_name(struct udevice *dev);
 int dev_read_stringlist_search(struct udevice *dev, const char *property,
 			  const char *string);
 
+/**
+ * dev_read_string_index() - obtain an indexed string from a string list
+ *
+ * @dev: device to examine
+ * @propname: name of the property containing the string list
+ * @index: index of the string to return
+ * @out: return location for the string
+ *
+ * @return:
+ *   length of string, if found or -ve error value if not found
+ */
+int dev_read_string_index(struct udevice *dev, const char *propname, int index,
+			  const char **outp);
+
+/**
+ * dev_read_string_count() - find the number of strings in a string list
+ *
+ * @dev: device to examine
+ * @propname: name of the property containing the string list
+ * @return:
+ *   number of strings in the list, or -ve error value if not found
+ */
+int dev_read_string_count(struct udevice *dev, const char *propname);
 /**
  * dev_read_phandle_with_args() - Find a node pointed by phandle in a list
  *
@@ -451,6 +474,19 @@ static inline int dev_read_stringlist_search(struct udevice *dev,
 	return ofnode_stringlist_search(dev_ofnode(dev), propname, string);
 }
 
+static inline int dev_read_string_index(struct udevice *dev,
+					const char *propname, int index,
+					const char **outp)
+{
+	return ofnode_read_string_index(dev_ofnode(dev), propname, index, outp);
+}
+
+static inline int dev_read_string_count(struct udevice *dev,
+					const char *propname)
+{
+	return ofnode_read_string_count(dev_ofnode(dev), propname);
+}
+
 static inline int dev_read_phandle_with_args(struct udevice *dev,
 		const char *list_name, const char *cells_name, int cell_count,
 		int index, struct ofnode_phandle_args *out_args)