[PATCH v2 10/15] nvmem: core: add nvmem-layout support

[Sascha Hauer]

On Mon, Aug 18, 2025 at 07:44:44PM +0200, Marco Felsch wrote:
> This ports the Linux nvmem-layout core infrastructure required for the
> actual nvmem-layout drivers. This commit doesn't add any specific
> nvmem-layout driver.
> 
> A nvmem-layout is the new way to describe the nvmem storage format. The
> nvmem-layout driver parses the nvmem sotrage format and provides the
> information via nvmem-cells.
> 
> Signed-off-by: Marco Felsch <m.felsch at pengutronix.de>
> ---
>  drivers/nvmem/Kconfig          |   7 ++
>  drivers/nvmem/Makefile         |   3 +
>  drivers/nvmem/core.c           | 100 +++++++++++++++++++++++-
>  drivers/nvmem/internals.h      |  22 ++++++
>  drivers/nvmem/layouts.c        | 173 +++++++++++++++++++++++++++++++++++++++++
>  drivers/nvmem/layouts/Kconfig  |  13 ++++
>  drivers/nvmem/layouts/Makefile |   7 ++
>  include/linux/nvmem-provider.h |  63 +++++++++++++++
>  8 files changed, 385 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/nvmem/Kconfig b/drivers/nvmem/Kconfig
> +struct device_node *of_nvmem_layout_get_container(struct nvmem_device *nvmem)
> +{
> +	return of_get_child_by_name(nvmem->dev.of_node, "nvmem-layout");

This also needs an additional

	if (!nvmem->dev.of_node)
		return NULL;

check. This also goes down to of_get_child_by_name doing a
for_each_child_of_node() which is defines as:

#define for_each_child_of_node(parent, child) \
	list_for_each_entry(child, &parent->children, parent_list)

list_for_each_entry() does not work with NULL pointers. We might want to
change this for Linux compatibility.

Sascha

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