On Wed, Aug 26, 2026 at 10:31:43AM +0200, Herve Codina wrote:
> Future operations, such as handling unknown tags on dtb modifications,
> need to get an offset to a property based on the node offset and the
> property name.
> 
> Several function exists to get a property based on the node offset
> and the property name but none of them allows to get the property
> offset.
> 
> Fill the lack and introduce fdt_getprop_offset_namelen() and its
> simple variant fdt_getprop_offset().
> 
> Signed-off-by: Herve Codina <herve.codina@bootlin.com>

This seems redundant with fdt_ptr_offset_(), which can trivially get
this information when combined with fdt_get_property().

> ---
>  libfdt/fdt_ro.c          | 13 +++++++++++++
>  libfdt/libfdt_internal.h |  8 ++++++++
>  2 files changed, 21 insertions(+)
> 
> diff --git a/libfdt/fdt_ro.c b/libfdt/fdt_ro.c
> index 856c62f1..50c0a8bc 100644
> --- a/libfdt/fdt_ro.c
> +++ b/libfdt/fdt_ro.c
> @@ -536,6 +536,19 @@ const void *fdt_getprop(const void *fdt, int nodeoffset,
>  	return fdt_getprop_namelen(fdt, nodeoffset, name, strlen(name), lenp);
>  }
>  
> +int fdt_getprop_offset_namelen(const void *fdt, int nodeoffset,
> +			       const char *name, int namelen)
> +{
> +	const struct fdt_property *prop;
> +	int lenp, offset;
> +
> +	prop = fdt_get_property_namelen_(fdt, nodeoffset, name, namelen,
> +					 &lenp, &offset);
> +	if (!prop)
> +		return lenp;
> +	return offset;
> +}
> +
>  uint32_t fdt_get_phandle(const void *fdt, int nodeoffset)
>  {
>  	const fdt32_t *php;
> diff --git a/libfdt/libfdt_internal.h b/libfdt/libfdt_internal.h
> index 3c83d9a7..e3923629 100644
> --- a/libfdt/libfdt_internal.h
> +++ b/libfdt/libfdt_internal.h
> @@ -26,6 +26,14 @@ uint32_t fdt_next_tag_(const void *fdt, int startoffset, int *nextoffset,
>  int fdt_check_node_offset_(const void *fdt, int offset);
>  int fdt_check_prop_offset_(const void *fdt, int offset);
>  
> +int fdt_getprop_offset_namelen(const void *fdt, int nodeoffset,
> +			       const char *name, int namelen);
> +static inline int fdt_getprop_offset(const void *fdt, int nodeoffset,
> +				     const char *name)
> +{
> +	return fdt_getprop_offset_namelen(fdt, nodeoffset, name, strlen(name));
> +}
> +
>  const char *fdt_find_string_len_(const char *strtab, int tabsize, const char *s,
>  				 int s_len);
>  static inline const char *fdt_find_string_(const char *strtab, int tabsize,
> -- 
> 2.55.0
> 
> 

-- 
David Gibson (he or they)	| 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