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

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

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On Tue, May 31, 2016 at 10:47:19AM +1000, David Gibson wrote:
> 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.

Sorry, one other thing, as I noted on 2/4, I prefer the convention
where the loop counter (so the subnode offset in this case) is the
first argument to foreach style macros.

> 
> > ---
> >  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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