[rtems commit] libfdt: Add a subnodes iterator macro

[Sebastian Huber]

Module:    rtems
Branch:    master
Commit:    da8eff9943780d1e294da14f096398196316f6d6
Changeset: http://git.rtems.org/rtems/commit/?id=da8eff9943780d1e294da14f096398196316f6d6

Author:    Thierry Reding <treding at nvidia.com>
Date:      Wed Jul 27 14:55:53 2016 +0200

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 at nvidia.com>
Signed-off-by: Maxime Ripard <maxime.ripard at free-electrons.com>
Signed-off-by: David Gibson <david at gibson.dropbear.id.au>

---

 cpukit/include/libfdt.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/cpukit/include/libfdt.h b/cpukit/include/libfdt.h
index 36222fd..911e548 100644
--- a/cpukit/include/libfdt.h
+++ b/cpukit/include/libfdt.h
@@ -168,6 +168,34 @@ int fdt_first_subnode(const void *fdt, int offset);
  */
 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                                                  */
 /**********************************************************************/