Re: [PATCH v2 02/29] Documentation: nvmem: document lookup entries

Brian Norris
2018-08-31T20:30:28Z

On Fri, Aug 10, 2018 at 10:04:59AM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> Describe the usage of nvmem cell lookup tables.
>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
> Documentation/nvmem/nvmem.txt | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
> diff --git a/Documentation/nvmem/nvmem.txt b/Documentation/nvmem/nvmem.txt
> index 8d8d8f58f96f..9d5e3ca2b4f3 100644
> --- a/Documentation/nvmem/nvmem.txt
> +++ b/Documentation/nvmem/nvmem.txt
> @@ -58,6 +58,34 @@ static int qfprom_probe(struct platform_device *pdev)
> It is mandatory that the NVMEM provider has a regmap associated with its
> struct device. Failure to do would return error code from nvmem_register().
>
> +Additionally it is possible to create nvmem cell lookup entries and register
> +them with the nvmem framework from machine code as shown in the example below:

Maybe it's partially a lacking in the existing documentation, but what
does the "name" and the "nvmem_name" mean here? AFAICT, "nvmem_name" is
akin to a provider identifier; and "name" is a key to match with the
consumer. It feels like this should be in either the header / kerneldoc
or this file. Or maybe both.

Does this mean there can only be a single "mac-address" cell in the
system? I have systems where there are multiple MACs provided in flash
storage, and we need to map them to ethernet0 and ethernet1. Is that
supported here?

Brian

> +static struct nvmem_cell_lookup foobar_lookup = {
> + .info = {
> + .name = "mac-address",
> + .offset = 0xd000,
> + .bytes = ERH_ALEN,
> + },
> + .nvmem_name = "foobar",
> +};
> +
> +static void foobar_register(void)
> +{
> + ...
> + nvmem_add_lookup_table(&foobar_lookup, 1);
> + ...
> +}
> +
> +A lookup entry table can be later removed if needed:
> +
> +static void foobar_fini(void)
> +{
> + ...
> + nvmem_del_lookup_table(&foobar_lookup, 1);
> + ...
> +}
> +
> NVMEM Consumers
> +++++++++++++++
>
> --
> 2.18.0
>