Index: sys/dev/ofw/ofw_bus_subr.c
===================================================================
--- sys/dev/ofw/ofw_bus_subr.c
+++ sys/dev/ofw/ofw_bus_subr.c
@@ -629,9 +629,12 @@
  *  node - consumers device node
  *  list_name  - name of parsed list - "clocks"
  *  cells_name - name of size property - "#clock-cells"
+ *  idx - the index of the requested list entry, or, if -1, an indication
+ *        to return the number of entries in the parsed list.
  * Output arguments:
  *  producer - handle of producer
- *  ncells   - number of cells in result
+ *  ncells   - number of cells in result or the number of items in the list when
+ *             idx == -1.
  *  cells    - array of decoded cells
  */
 int
@@ -649,7 +652,7 @@
 	    (void **)&elems);
 	if (nelems <= 0)
 		return (ENOENT);
-	rv = ENOENT;
+	rv = (idx == -1) ? 0 : ENOENT;
 	for (i = 0, cnt = 0; i < nelems; i += pcells, cnt++) {
 		pnode = elems[i++];
 		if (OF_getencprop(OF_node_from_xref(pnode),
@@ -678,6 +681,8 @@
 	}
 	if (elems != NULL)
 		free(elems, M_OFWPROP);
+	if (idx == -1 && rv == 0)
+		*ncells = cnt;
 	return (rv);
 }