dm: core: support reading a single indexed u32 value

The patch adds helper functions to allow reading a single indexed u32
value from a device-tree property containing multiple u32 values, that
is an array of integers.

Signed-off-by: Dario Binacchi <dariobin@libero.it>
Reviewed-by: Simon Glass <sjg@chromium.org>

include/dm/ofnode.h

@@ -202,6 +202,18 @@ static inline ofnode ofnode_null(void)
  */
 int ofnode_read_u32(ofnode node, const char *propname, u32 *outp);
 
+/**
+ * ofnode_read_u32_index() - Read a 32-bit integer from a multi-value property
+ *
+ * @ref:	valid node reference to read property from
+ * @propname:	name of the property to read from
+ * @index:	index of the integer to return
+ * @outp:	place to put value (if found)
+ * @return 0 if OK, -ve on error
+ */
+int ofnode_read_u32_index(ofnode node, const char *propname, int index,
+			  u32 *outp);
+
 /**
  * ofnode_read_s32() - Read a 32-bit integer from a property
  *
@@ -226,6 +238,19 @@ static inline int ofnode_read_s32(ofnode node, const char *propname,
  */
 u32 ofnode_read_u32_default(ofnode ref, const char *propname, u32 def);
 
+/**
+ * ofnode_read_u32_index_default() - Read a 32-bit integer from a multi-value
+ *                                   property
+ *
+ * @ref:	valid node reference to read property from
+ * @propname:	name of the property to read from
+ * @index:	index of the integer to return
+ * @def:	default value to return if the property has no value
+ * @return property value, or @def if not found
+ */
+u32 ofnode_read_u32_index_default(ofnode ref, const char *propname, int index,
+				  u32 def);
+
 /**
  * ofnode_read_s32_default() - Read a 32-bit integer from a property
  *