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

[Sascha Hauer]

On Wed, Aug 20, 2025 at 11:11:19AM +0200, Marco Felsch wrote:
> On 25-08-20, Sascha Hauer wrote:
> > 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.
> 
> Thanks for testing and spotting this. I ran tests but of course all my
> nvmem devices had an of_node :(

In this case you would have noticed it by running

labgrid-pytest --lg-env test/sandbox/sandbox_defconfig.yaml

Sascha

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