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Subject: Re: [RFC PATCH 1/4] nvmem: core: allow specifying of_node
To:     Michael Walle <michael@walle.cc>, linux-mtd@lists.infradead.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Rob Herring <robh+dt@kernel.org>,
        =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= <rafal@milecki.pl>
References: <20210322181949.2805-1-michael@walle.cc>
 <20210322181949.2805-2-michael@walle.cc>
From:   Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Message-ID: <835a8124-0a22-e885-0bd4-c7493520558e@linaro.org>
Date:   Tue, 30 Mar 2021 11:35:10 +0100
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On 22/03/2021 18:19, Michael Walle wrote:
> Until now, the of_node of the parent device is used. Some devices
> provide more than just the nvmem provider. To avoid name space clashes,
> add a way to allow specifying the nvmem cells in subnodes. Consider the
> following example:
> 
>      flash@0 {
>          compatible = "jedec,spi-nor";
> 
>          partitions {
>              compatible = "fixed-partitions";
>              #address-cells = <1>;
>              #size-cells = <1>;
> 
>              partition@0 {
>                  reg = <0x000000 0x010000>;
>              };
>          };
> 
>          otp {
>              compatible = "mtd-user-otp";

I would have expected this to come up as a proper device, but am not 
100% sure how MTD handles flashes and its partitions.

>              #address-cells = <1>;
>              #size-cells = <1>;
> 
>              serial-number@0 {
>                  reg = <0x0 0x8>;
>              };
>          };
>      };
> 
> There the nvmem provider might be the MTD partition or the OTP region of
> the flash.
> 
> Add a new config->of_node parameter, which if set, will be used instead
> of the parent's of_node.
> 
> Signed-off-by: Michael Walle <michael@walle.cc>
> ---

Patch is fine as it its.
If you plan to take this via mtd tree here is my Ack

Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>


--srini

>   drivers/nvmem/core.c           | 4 +++-
>   include/linux/nvmem-provider.h | 2 ++
>   2 files changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
> index bca671ff4e54..62d363a399d3 100644
> --- a/drivers/nvmem/core.c
> +++ b/drivers/nvmem/core.c
> @@ -789,7 +789,9 @@ struct nvmem_device *nvmem_register(const struct nvmem_config *config)
>   	nvmem->reg_write = config->reg_write;
>   	nvmem->keepout = config->keepout;
>   	nvmem->nkeepout = config->nkeepout;
> -	if (!config->no_of_node)
> +	if (config->of_node)
> +		nvmem->dev.of_node = config->of_node;
> +	else if (!config->no_of_node)
>   		nvmem->dev.of_node = config->dev->of_node;
>   
>   	switch (config->id) {
> diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h
> index e162b757b6d5..471cb7b9e896 100644
> --- a/include/linux/nvmem-provider.h
> +++ b/include/linux/nvmem-provider.h
> @@ -57,6 +57,7 @@ struct nvmem_keepout {
>    * @type:	Type of the nvmem storage
>    * @read_only:	Device is read-only.
>    * @root_only:	Device is accessibly to root only.
> + * @of_node:	If given, this will be used instead of the parent's of_node.
>    * @no_of_node:	Device should not use the parent's of_node even if it's !NULL.
>    * @reg_read:	Callback to read data.
>    * @reg_write:	Callback to write data.
> @@ -86,6 +87,7 @@ struct nvmem_config {
>   	enum nvmem_type		type;
>   	bool			read_only;
>   	bool			root_only;
> +	struct device_node	*of_node;
>   	bool			no_of_node;
>   	nvmem_reg_read_t	reg_read;
>   	nvmem_reg_write_t	reg_write;
>