dm: core: Allow obtaining a node offset in the same tree

In some cases we want to obtain an ofnode in the same tree as a different
ofnode, such as when looking up a subnode. At present this is trivial,
since there is only one tree. When there are multiple trees, this
implementation will change.

Also move the ofnode_to_offset() function up higher in the header file,
since we will need to provide a different implementation with multiple
trees.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/core/ofnode.c

@@ -278,7 +278,7 @@ ofnode ofnode_find_subnode(ofnode node, const char *subnode_name)
 	} else {
 		int ooffset = fdt_subnode_offset(ofnode_to_fdt(node),
 				ofnode_to_offset(node), subnode_name);
-		subnode = offset_to_ofnode(ooffset);
+		subnode = noffset_to_ofnode(node, ooffset);
 	}
 	debug("%s\n", ofnode_valid(subnode) ?
 	      ofnode_get_name(subnode) : "<none>");
@@ -330,7 +330,7 @@ ofnode ofnode_first_subnode(ofnode node)
 	if (ofnode_is_np(node))
 		return np_to_ofnode(node.np->child);
 
-	return offset_to_ofnode(
+	return noffset_to_ofnode(node,
 		fdt_first_subnode(ofnode_to_fdt(node), ofnode_to_offset(node)));
 }
 
@@ -340,7 +340,7 @@ ofnode ofnode_next_subnode(ofnode node)
 	if (ofnode_is_np(node))
 		return np_to_ofnode(node.np->sibling);
 
-	return offset_to_ofnode(
+	return noffset_to_ofnode(node,
 		fdt_next_subnode(ofnode_to_fdt(node), ofnode_to_offset(node)));
 }
 #endif /* !DM_INLINE_OFNODE */
@@ -1172,8 +1172,8 @@ ofnode ofnode_by_compatible(ofnode from, const char *compat)
 			(struct device_node *)ofnode_to_np(from), NULL,
 			compat));
 	} else {
-		return offset_to_ofnode(fdt_node_offset_by_compatible(
+		return noffset_to_ofnode(from,
-					ofnode_to_fdt(from),
+			fdt_node_offset_by_compatible(ofnode_to_fdt(from),
 					ofnode_to_offset(from), compat));
 	}
 }
@@ -1186,9 +1186,10 @@ ofnode ofnode_by_prop_value(ofnode from, const char *propname,
 			(struct device_node *)ofnode_to_np(from), propname,
 			propval, proplen));
 	} else {
-		return offset_to_ofnode(fdt_node_offset_by_prop_value(
+		return noffset_to_ofnode(from,
-				ofnode_to_fdt(from), ofnode_to_offset(from),
+			 fdt_node_offset_by_prop_value(ofnode_to_fdt(from),
-				propname, propval, proplen));
+				ofnode_to_offset(from), propname, propval,
+				proplen));
 	}
 }
 
@@ -1342,7 +1343,7 @@ int ofnode_add_subnode(ofnode node, const char *name, ofnode *subnodep)
 		}
 		if (offset < 0)
 			return -EINVAL;
-		subnode = offset_to_ofnode(offset);
+		subnode = noffset_to_ofnode(node, offset);
 	}
 
 	*subnodep = subnode;

include/dm/ofnode.h

@@ -54,6 +54,23 @@ static inline void *ofnode_to_fdt(ofnode node)
 	return (void *)gd->fdt_blob;
 }
 
+/**
+ * ofnode_to_offset() - convert an ofnode to a flat DT offset
+ *
+ * This cannot be called if the reference contains a node pointer.
+ *
+ * @node: Reference containing offset (possibly invalid)
+ * Return: DT offset (can be -1)
+ */
+static inline int ofnode_to_offset(ofnode node)
+{
+#ifdef OF_CHECKS
+	if (of_live_active())
+		return -1;
+#endif
+	return node.of_offset;
+}
+
 /**
  * ofnode_to_np() - convert an ofnode to a live DT node pointer
  *
@@ -72,20 +89,22 @@ static inline struct device_node *ofnode_to_np(ofnode node)
 }
 
 /**
- * ofnode_to_offset() - convert an ofnode to a flat DT offset
+ * noffset_to_ofnode() - convert a DT offset to an ofnode
  *
- * This cannot be called if the reference contains a node pointer.
+ * @other_node: Node in the same tree to use as a reference
- *
+ * @of_offset: DT offset (either valid, or -1)
- * @node: Reference containing offset (possibly invalid)
+ * Return: reference to the associated DT offset
- * Return: DT offset (can be -1)
  */
-static inline int ofnode_to_offset(ofnode node)
+static inline ofnode noffset_to_ofnode(ofnode other_node, int of_offset)
 {
-#ifdef OF_CHECKS
+	ofnode node;
+
 	if (of_live_active())
-		return -1;
+		node.np = NULL;
-#endif
+	else
-	return node.of_offset;
+		node.of_offset = of_offset;
+
+	return node;
 }
 
 /**
@@ -1175,8 +1194,9 @@ ofnode ofnode_by_compatible(ofnode from, const char *compat);
  * Find the next node after @from that has a @propname with a value
  * @propval and a length @proplen.
  *
- * @from: ofnode to start from (use ofnode_null() to start at the
+ * @from: ofnode to start from. Use ofnode_null() to start at the
- * beginning)
+ * beginning, or the return value from oftree_root() to start at the first
+ * child of the root
  * @propname: property name to check
  * @propval: property value to search for
  * @proplen: length of the value in propval