Re: [PATCH 1/2] mtd: spi-nor: sst: register SFDP region into NVMEM framework to read MAC Address

Miquel Raynal
2025-03-06T08:34:44Z

>>> +static int sst26vf_nor_post_sfdp(struct spi_nor *nor)
>>> +{
>>> + struct nvmem_device *nvmem;
>>> +
>>> + sst26vf_sfdp_nvmem_config.dev = nor->dev;
>>> + sst26vf_sfdp_nvmem_config.size = nor->sfdp->num_dwords * sizeof(*nor->sfdp->dwords);
>>> + sst26vf_sfdp_nvmem_config.priv = nor;
>>> + sst26vf_sfdp_nvmem_config.reg_read = sst26vf_sfdp_mac_addr_read;
>>> +
>>> + nvmem = devm_nvmem_register(nor->dev, &sst26vf_sfdp_nvmem_config);
>>> + if (IS_ERR(nvmem)) {
>>> + dev_err(nor->dev, "failed to register NVMEM device: %ld\n", PTR_ERR(nvmem));
>>> + return PTR_ERR(nvmem);
>>
>> I don't think it makes sense to have this one-off in a particular
>> driver. If at all, this should be handled in the core. Sorry, but
>> this really looks like an ugly hack.
>>
>
> Because the EUI identifier within the SFDP is unique to the
> SST26VF064BEUI flash, I opted to handle it here rather than in the core.
>
> Also here the MAC address data resides within the 0x260-0x26F range, I
> will resize the nvmem_config.size to 0x10 instead of registering the
> full SFDP region as NVMEM.

Open question to all parties in this thread: how do we give an offset in
the device tree that is relative to the sfdp region and not the data
region? I believe we care not to mix these areas while describing.

Thanks,
Miquèl