Iterating through subnodes with libfdt is a little painful to write as we need something like this:
for (depth = 0, count = 0, offset = fdt_next_node(fdt, parent_offset, &depth); (offset >= 0) && (depth > 0); offset = fdt_next_node(fdt, offset, &depth)) { if (depth == 1) { /* code body */ } }
Using fdt_next_subnode() we can instead write this, which is shorter and easier to get right:
for (offset = fdt_first_subnode(fdt, parent_offset); offset >= 0; offset = fdt_next_subnode(fdt, offset)) { /* code body */ }
Also, it doesn't require two levels of indentation for the loop body.
Signed-off-by: Simon Glass sjg@chromium.org (Cherry-picked from dtc commit 4e76ec79) --- Changes in v4: - Bring in upstream version of fdt_first/next_subnode()
Changes in v3: None Changes in v2: None
include/libfdt.h | 22 ++++++++++++++++++++++ lib/libfdt/fdt.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 50 insertions(+)
diff --git a/include/libfdt.h b/include/libfdt.h index fc7f75b..3721a90 100644 --- a/include/libfdt.h +++ b/include/libfdt.h @@ -136,6 +136,28 @@ uint32_t fdt_next_tag(const void *fdt, int offset, int *nextoffset);
int fdt_next_node(const void *fdt, int offset, int *depth);
+/** + * fdt_first_subnode() - get offset of first direct subnode + * + * @fdt: FDT blob + * @offset: Offset of node to check + * @return offset of first subnode, or -FDT_ERR_NOTFOUND if there is none + */ +int fdt_first_subnode(const void *fdt, int offset); + +/** + * fdt_next_subnode() - get offset of next direct subnode + * + * After first calling fdt_first_subnode(), call this function repeatedly to + * get direct subnodes of a parent node. + * + * @fdt: FDT blob + * @offset: Offset of previous subnode + * @return offset of next subnode, or -FDT_ERR_NOTFOUND if there are no more + * subnodes + */ +int fdt_next_subnode(const void *fdt, int offset); + /**********************************************************************/ /* General functions */ /**********************************************************************/ diff --git a/lib/libfdt/fdt.c b/lib/libfdt/fdt.c index 387e354..154e9a4 100644 --- a/lib/libfdt/fdt.c +++ b/lib/libfdt/fdt.c @@ -202,6 +202,34 @@ int fdt_next_node(const void *fdt, int offset, int *depth) return offset; }
+int fdt_first_subnode(const void *fdt, int offset) +{ + int depth = 0; + + offset = fdt_next_node(fdt, offset, &depth); + if (offset < 0 || depth != 1) + return -FDT_ERR_NOTFOUND; + + return offset; +} + +int fdt_next_subnode(const void *fdt, int offset) +{ + int depth = 1; + + /* + * With respect to the parent, the depth of the next subnode will be + * the same as the last. + */ + do { + offset = fdt_next_node(fdt, offset, &depth); + if (offset < 0 || depth < 1) + return -FDT_ERR_NOTFOUND; + } while (depth > 1); + + return offset; +} + const char *_fdt_find_string(const char *strtab, int tabsize, const char *s) { int len = strlen(s) + 1;