libfdt: Add iterator over properties

Implement a macro based on fdt_first_property_offset and
fdt_next_property_offset that provides a convenience to iterate over all
the properties of a given node.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Simon Glass <sjg@chromium.org>

diff --git a/include/libfdt.h b/include/libfdt.h
index 74b1d14..fbbe58c 100644 (file)
--- a/include/libfdt.h
+++ b/include/libfdt.h
@@ -440,6 +440,30 @@ int fdt_first_property_offset(const void *fdt, int nodeoffset);
  */
 int fdt_next_property_offset(const void *fdt, int offset);
 
+/**
+ * fdt_for_each_property - iterate over all properties of a node
+ * @property_offset:   property offset (int)
+ * @fdt:               FDT blob (const void *)
+ * @node:              node offset (int)
+ *
+ * This is actually a wrapper around a for loop and would be used like so:
+ *
+ *     fdt_for_each_property(fdt, node, property) {
+ *             ...
+ *             use property
+ *             ...
+ *     }
+ *
+ * Note that this is implemented as a macro and property is used as
+ * iterator in the loop. It should therefore be a locally allocated
+ * variable. The node variable on the other hand is never modified, so
+ * it can be constant or even a literal.
+ */
+#define fdt_for_each_property_offset(property, fdt, node)      \
+       for (property = fdt_first_property_offset(fdt, node);   \
+            property >= 0;                                     \
+            property = fdt_next_property_offset(fdt, property))
+
 /**
  * fdt_get_property_by_offset - retrieve the property at a given offset
  * @fdt: pointer to the device tree blob