Re: [PATCH v6 3/7] mtd: spi-nor: sfdp: expose the SFDP as a read-only NVMEM device

--===============7165828398680673433==
Content-Type: multipart/signed;
 boundary=a369d9f282471ab4613f2d34b9edebaf16481b78715d95de6253cba98872;
 micalg=pgp-sha384; protocol="application/pgp-signature"

--a369d9f282471ab4613f2d34b9edebaf16481b78715d95de6253cba98872
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain; charset=UTF-8

On Wed Jul 29, 2026 at 6:30 AM CEST, Manikandan Muralidharan wrote:
..

> +static void spi_nor_sfdp_nvmem_put_np(void *data)
> +{
> +	of_node_put(data);
> +}
> +
> +/**
> + * spi_nor_register_sfdp_nvmem() - expose the SFDP as a read-only NVMEM =
device
> + * @nor:	pointer to a 'struct spi_nor'
> + *
> + * Expose the whole SFDP, in on-flash byte order, as a read-only NVMEM d=
evice
> + * rooted at the flash's SFDP child node (compatible "jedec,sfdp"). This=
 lets
> + * generic (fixed-layout) or vendor (nvmem-layout) cells reference any S=
FDP
> + * data. The device is only registered when a child node with the "jedec=
,sfdp"
> + * compatible is described in the device tree.
> + *
> + * Return: 0 on success or if there is nothing to do, -errno otherwise.
> + */
> +static int spi_nor_register_sfdp_nvmem(struct spi_nor *nor)
> +{
> +	struct device *dev =3D nor->dev;
> +	struct nvmem_config config =3D { };
> +	struct nvmem_device *nvmem;
> +	struct device_node *np;
> +	int ret;
> +
> +	if (!nor->sfdp)
> +		return 0;
> +
> +	np =3D of_get_compatible_child(dev_of_node(dev), "jedec,sfdp");
> +	if (!np)
> +		return 0;
> +
> +	/*
> +	 * Register the put before devm_nvmem_register() so it runs last on
> +	 * detach, after the NVMEM device that uses the node is gone.
> +	 */
> +	ret =3D devm_add_action_or_reset(dev, spi_nor_sfdp_nvmem_put_np, np);
> +	if (ret)
> +		return ret;

Sorry I've missed that in the previous version. I guess we do that
because we hand the device_node to nvmem. But shouldn't it be part
of the NVMEM framework to do a of_node_get()?

> +
> +	config.dev =3D dev;
> +	config.of_node =3D np;
> +	config.name =3D "sfdp";
> +	config.id =3D NVMEM_DEVID_AUTO;
> +	config.owner =3D THIS_MODULE;
> +	config.read_only =3D true;
> +	config.word_size =3D 1;
> +	config.stride =3D 1;
> +	config.size =3D (int)(nor->sfdp->num_dwords * sizeof(*nor->sfdp->dwords=
));
> +	config.reg_read =3D spi_nor_sfdp_reg_read;
> +	config.priv =3D nor;
> +
> +	nvmem =3D devm_nvmem_register(dev, &config);
> +	if (IS_ERR(nvmem)) {
> +		/* NVMEM support is optional. */
> +		if (PTR_ERR(nvmem) =3D=3D -EOPNOTSUPP)
> +			return 0;
> +		return dev_err_probe(dev, PTR_ERR(nvmem),
> +				     "failed to register SFDP NVMEM device\n");
> +	}
> +

so we can do a of_node_put() here?

-michael

> +	dev_dbg(dev, "exposed %d-byte SFDP as an NVMEM device\n", config.size);
> +
> +	return 0;
> +}
> +

--a369d9f282471ab4613f2d34b9edebaf16481b78715d95de6253cba98872
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----

iKgEABMJADAWIQTIVZIcOo5wfU/AngkSJzzuPgIf+AUCammzdxIcbXdhbGxlQGtl
cm5lbC5vcmcACgkQEic87j4CH/it6gF/V3GubkwpHoS9P9IU244sBsKtytRavuvh
hXPhPMqXriH2cB1f70x+LBiHYBye74L+AYDkK5z86ahoo8Muf+vFJGWwpFHZziaa
0bbnosqgeVloCl0urxpv75kT0JbgJEHN8es=
=fp/9
-----END PGP SIGNATURE-----

--a369d9f282471ab4613f2d34b9edebaf16481b78715d95de6253cba98872--


--===============7165828398680673433==
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: inline

______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/

--===============7165828398680673433==--