Re: [PATCH 1/4] libfdt: Add a subnodes iterator macro

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

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On Fri, May 27, 2016 at 10:28:46AM +0200, Maxime Ripard wrote:
> From: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> 
> 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-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>

Looks good, but needs a testcase.  Extending subnode_iterate would
probably make sense.

> ---
>  libfdt/libfdt.h | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
> index 36222fd4a6f4..331f32dd04b5 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
> + *
> + * This is actually a wrapper around a for loop and would be used like so:
> + *
> + *	fdt_for_each_subnode(fdt, node, parent) {
> + *		...
> + *		use node
> + *		...
> + *	}
> + *
> + * Note that this is implemented as a macro and node is used as iterator in
> + * the loop. It should therefore be a locally allocated variable. The parent
> + * variable on the other hand is never modified, so it can be constant or
> + * even a literal.
> + *
> + * @fdt:	FDT blob (const void *)
> + * @node:	child node (int)
> + * @parent:	parent node (int)
> + */
> +#define fdt_for_each_subnode(fdt, node, parent)		\
> +	for (node = fdt_first_subnode(fdt, parent);	\
> +	     node >= 0;					\
> +	     node = fdt_next_subnode(fdt, node))
> +
>  /**********************************************************************/
>  /* General functions                                                  */
>  /**********************************************************************/

-- 
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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