Subject: [PATCH 0/2] dt-bindings: nvmem: support describing cells

From: Rafał Miłecki <[email-masked]>
Date: Tue, 25 Jan 2022 19:01:12 +0100

From: Rafał Miłecki <[email-masked]>

Michael has recently posted a cleaned up patchset for NVMEM
transformations support:
[PATCH 0/8] nvmem: add ethernet address offset support
https://lore.kernel.org/lkml/[email-masked]/T/
https://patchwork.ozlabs.org/project/linux-mtd/list/?series=278644&state=*

I find it very important & fully support it. In home routers we very
often deal with just one MAC address that:
1. Is a base for calculating multiple Ethernet addresses
2. Can be stored in binary as well as ASCII format

I'd like to suggest just a slightly different solution though. I think
that using something like:

otp-1 {
        compatible = "kontron,sl28-vpd", "user-otp";
        #address-cells = <1>;
        #size-cells = <1>;

        base_mac_address: base-mac-address@17 {
                #nvmem-cell-cells = <1>;
                reg = <17 6>;
        };
};

isn't clear enough and requires too much conditional code in Linux /
whatever implementation. DT doesn't make it clear which NVMEM cells
are used for what and how should be handled. That has to be hardcoded in
a Linux / whatever driver.

My idea is to add "compatible" & additional flags to NVMEM cells.
Example:

otp-1 {
        compatible = "user-otp";
        #address-cells = <1>;
        #size-cells = <1>;

        base_mac_address: base-mac-address@17 {
                compatible = "mac-address";
                reg = <17 6>;
                #nvmem-cell-cells = <1>;
        };
};

(for more examples see PATCH 2/2 and its mac-address.yaml .

Rafał Miłecki (2):
  dt-bindings: nvmem: extract NVMEM cell to separated file
  dt-bindings: nvmem: cells: add MAC address cell

 .../devicetree/bindings/nvmem/cells/cell.yaml | 35 +++++++
 .../bindings/nvmem/cells/mac-address.yaml     | 94 +++++++++++++++++++
 .../devicetree/bindings/nvmem/nvmem.yaml      | 25 +----
 3 files changed, 131 insertions(+), 23 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/nvmem/cells/cell.yaml
 create mode 100644 Documentation/devicetree/bindings/nvmem/cells/mac-address.yaml

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