libfdt: Add and use a node iteration helper function.

This patch adds an fdt_next_node() function which can be used to
iterate through nodes of the tree while keeping track of depth.  This
function is used to simplify the iteration code in a lot of other
functions, and is also exported for use by library users.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

1 files changed, 41 insertions, 0 deletions

diff --git a/libfdt/fdt.c b/libfdt/fdt.c
index 071470dc94..660e2c1baf 100644
--- a/libfdt/fdt.c
+++ b/libfdt/fdt.c
@@ -133,6 +133,47 @@ uint32_t fdt_next_tag(const void *fdt, int offset, int *nextoffset)
 	return tag;
 }
 
+int fdt_next_node(const void *fdt, int offset, int *depth)
+{
+	int nextoffset = 0;
+	uint32_t tag;
+
+	if (offset >= 0) {
+		tag = fdt_next_tag(fdt, offset, &nextoffset);
+		if (tag != FDT_BEGIN_NODE)
+			return -FDT_ERR_BADOFFSET;
+	}
+
+	do {
+		offset = nextoffset;
+		tag = fdt_next_tag(fdt, offset, &nextoffset);
+
+		switch (tag) {
+		case FDT_PROP:
+		case FDT_NOP:
+			break;
+
+		case FDT_BEGIN_NODE:
+			if (depth)
+				(*depth)++;
+			break;
+
+		case FDT_END_NODE:
+			if (depth)
+				(*depth)--;
+			break;
+
+		case FDT_END:
+			return -FDT_ERR_NOTFOUND;
+
+		default:
+			return -FDT_ERR_BADSTRUCTURE;
+		}
+	} while (tag != FDT_BEGIN_NODE);
+
+	return offset;
+}
+
 const char *_fdt_find_string(const char *strtab, int tabsize, const char *s)
 {
 	int len = strlen(s) + 1;