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Reply-To: wens@kernel.org
From:   Chen-Yu Tsai <wens@kernel.org>
Date:   Mon, 7 Jun 2021 16:35:52 +0800
Message-ID: <CAGb2v66GAOtF40o5XoK_K3bWPa2L8jGxH=R-YK8060TGeAKreQ@mail.gmail.com>
Subject: Re: [PATCH] arm64: dts: rockchip: add EEPROM node for NanoPi R4S
To:     Tianling Shen <cnsztl@gmail.com>
Cc:     Rob Herring <robh+dt@kernel.org>, Heiko Stuebner <heiko@sntech.de>,
        Marty Jones <mj8263788@gmail.com>, Pavel Machek <pavel@ucw.cz>,
        devicetree <devicetree@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@lists.infradead.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
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Hi,

On Mon, Jun 7, 2021 at 4:19 PM Tianling Shen <cnsztl@gmail.com> wrote:
>
> NanoPi R4S has a EEPROM attached to the 2nd I2C bus (U92), which
> stores the MAC address.
>
> Signed-off-by: Tianling Shen <cnsztl@gmail.com>
> ---
>  arch/arm64/boot/dts/rockchip/rk3399-nanopi-r4s.dts | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/rockchip/rk3399-nanopi-r4s.dts b/arch/arm64/boot/dts/rockchip/rk3399-nanopi-r4s.dts
> index cef4d18b599d..4a82f50a07c5 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3399-nanopi-r4s.dts
> +++ b/arch/arm64/boot/dts/rockchip/rk3399-nanopi-r4s.dts
> @@ -68,6 +68,15 @@
>         status = "disabled";
>  };
>
> +&i2c2 {
> +       eeprom@51 {
> +               compatible = "microchip,24c02", "atmel,24c02";

The actual part number is Microchip 24AA025E48, but I don't think
the way this device splits its storage area is easy to support
without additional modifications to the driver.

> +               reg = <0x51>;
> +               pagesize = <16>;
> +               read-only; /* This holds our MAC */

Please also add the size, as well as a cell defining the offset
and length to the MAC address. The gmac node can then reference
this with:

    nvmem-cells = <&mac_address>;
    nvmem-cells-names = "mac-address";

which will actually pick up the MAC address.


Regards
ChenYu

> +       };
> +};
> +
>  &i2c4 {
>         status = "disabled";
>  };
> --
> 2.17.1
>
>
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