On Mon, Jul 11, 2016 at 09:56:18PM +0200, Maxime Ripard wrote:
> From: Thierry Reding <treding@xxxxxxxxxx>
>
> 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@xxxxxxxxxx>
> Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
Code looks ok, but there are some nits in the comments.
> ---
> libfdt/libfdt.h | 25 +++++++++++++++++++++++++
> tests/subnode_iterate.c | 8 ++------
> 2 files changed, 27 insertions(+), 6 deletions(-)
>
> diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
> index 36222fd4a6f4..0cf46872b54e 100644
> --- a/libfdt/libfdt.h
> +++ b/libfdt/libfdt.h
> @@ -168,6 +168,31 @@ 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
Parameter descriptions should go here.
> + *
> + * This is actually a wrapper around a for loop and would be used like so:
> + *
> + * fdt_for_each_subnode(fdt, node, parent) {
Parameter order hasn't been updated for code revisions.
> + * ...
> + * use node
> + * ...
> + * }
One gotcha with this is what happens if there's an error during the
iteration. I suggest adding something like:
if ((node < 0) && (node != -FDT_ERR_NOTFOUND)) {
/* error handling */
}
to the example, to remind users that they should check for this.
> + *
> + * Note that this is implemented as a macro and node is used as iterator in
s/node/@node/ - makes it stand out as a parameter.
> + * the loop. It should therefore be a locally allocated variable. The parent
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Remove for brevity.
> + * variable on the other hand is never modified, so it can be constant or
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Remove for brevity.
> + * even a literal.
> + *
> + * @node: child node (int)
> + * @fdt: FDT blob (const void *)
> + * @parent: parent node (int)
> + */
> +#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 b9f379d5963c..0fb5c901ebd7 100644
> --- a/tests/subnode_iterate.c
> +++ b/tests/subnode_iterate.c
> @@ -48,9 +48,7 @@ static void test_node(void *fdt, int parent_offset)
> 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 @@ static void check_fdt_next_subnode(void *fdt)
> 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++;
> }
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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