libfdt: Add a subnodes iterator macro
The fdt_for_each_subnode() iterator macro provided by this patch can be
used to iterate over a device tree node's subnodes. At each iteration a
loop variable will be set to the next subnode.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
index 36222fd..911e548 100644
--- a/libfdt/libfdt.h
+++ b/libfdt/libfdt.h
@@ -168,6 +168,34 @@
*/
int fdt_next_subnode(const void *fdt, int offset);
+/**
+ * fdt_for_each_subnode - iterate over all subnodes of a parent
+ *
+ * @node: child node (int, lvalue)
+ * @fdt: FDT blob (const void *)
+ * @parent: parent node (int)
+ *
+ * This is actually a wrapper around a for loop and would be used like so:
+ *
+ * fdt_for_each_subnode(node, fdt, parent) {
+ * Use node
+ * ...
+ * }
+ *
+ * if ((node < 0) && (node != -FDT_ERR_NOT_FOUND)) {
+ * Error handling
+ * }
+ *
+ * Note that this is implemented as a macro and @node is used as
+ * iterator in the loop. The parent variable be constant or even a
+ * literal.
+ *
+ */
+#define fdt_for_each_subnode(node, fdt, parent) \
+ for (node = fdt_first_subnode(fdt, parent); \
+ node >= 0; \
+ node = fdt_next_subnode(fdt, node))
+
/**********************************************************************/
/* General functions */
/**********************************************************************/
diff --git a/tests/subnode_iterate.c b/tests/subnode_iterate.c
index b9f379d..0fb5c90 100644
--- a/tests/subnode_iterate.c
+++ b/tests/subnode_iterate.c
@@ -48,9 +48,7 @@
subnodes = cpu_to_fdt32(*prop);
count = 0;
- for (offset = fdt_first_subnode(fdt, parent_offset);
- offset >= 0;
- offset = fdt_next_subnode(fdt, offset))
+ fdt_for_each_subnode(offset, fdt, parent_offset)
count++;
if (count != subnodes) {
@@ -65,9 +63,7 @@
int offset;
int count = 0;
- for (offset = fdt_first_subnode(fdt, 0);
- offset >= 0;
- offset = fdt_next_subnode(fdt, offset)) {
+ fdt_for_each_subnode(offset, fdt, 0) {
test_node(fdt, offset);
count++;
}
