linux-kernel - RE: [PATCH v1 1/3] dt-bindings: nvmem: add description for UniPhier eFuse

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Message-ID: <000001d32615$38e1b0c0$aaa51240$@socionext.com>
Date:   Tue, 5 Sep 2017 16:04:31 +0900
From:   "Keiji Hayashibara" <hayashibara.keiji@...ionext.com>
To:     "'Masahiro Yamada'" <yamada.masahiro@...ionext.com>
Cc:     "Srinivas Kandagatla" <srinivas.kandagatla@...aro.org>,
        "Rob Herring" <robh+dt@...nel.org>, <devicetree@...r.kernel.org>,
        "linux-arm-kernel" <linux-arm-kernel@...ts.infradead.org>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
        "Masami Hiramatsu" <masami.hiramatsu@...aro.org>,
        "Jassi Brar" <jaswinder.singh@...aro.org>,
        Hayashi, Kunihiko/林 邦彦 
        <hayashi.kunihiko@...ionext.com>,
        Owada, Kiyoshi/大和田 清志 
        <owada.kiyoshi@...ionext.com>
Subject: RE: [PATCH v1 1/3] dt-bindings: nvmem: add description for UniPhier eFuse

Hello Yamada-san,

Thank you for your comment.

> From: Masahiro Yamada [mailto:yamada.masahiro@...ionext.com]
> Sent: Monday, September 4, 2017 9:56 PM
> 
> 2017-09-01 8:20 GMT+09:00 Keiji Hayashibara
> <hayashibara.keiji@...ionext.com>:
> > Add uniphier-efuse dt-bindings documentation.
> >
> > Signed-off-by: Keiji Hayashibara <hayashibara.keiji@...ionext.com>
> > ---
> >  .../devicetree/bindings/nvmem/uniphier-efuse.txt   | 45
> ++++++++++++++++++++++
> >  1 file changed, 45 insertions(+)
> >  create mode 100644
> > Documentation/devicetree/bindings/nvmem/uniphier-efuse.txt
> >
> > diff --git
> > a/Documentation/devicetree/bindings/nvmem/uniphier-efuse.txt
> > b/Documentation/devicetree/bindings/nvmem/uniphier-efuse.txt
> > new file mode 100644
> > index 0000000..09024a2
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/nvmem/uniphier-efuse.txt
> > @@ -0,0 +1,45 @@
> > += UniPhier eFuse device tree bindings =
> > +
> > +This UniPhier eFuse must be under soc-glue.
> > +
> > +Required properties:
> > +- compatible: should be "socionext,uniphier-efuse"
> > +- reg: should contain the register base and length
> > +
> > += Data cells =
> > +Are child nodes of efuse, bindings of which as described in
> > +bindings/nvmem/nvmem.txt
> > +
> > +Example:
> > +
> > +       soc-glue@...00000 {
> > +               compatible = "socionext,uniphier-ld20-soc-glue-debug",
> > +                            "simple-mfd";
> > +               #address-cells = <1>;
> > +               #size-cells = <1>;
> > +               ranges = <0x0 0x5f900000 0x2000>;
> 
> 
> IMHO, I think an empty "ranges;" will clarify the code, but it is up to
> your taste.
> 
> 
> > +
> > +               efuse {
> > +                       compatible = "socionext,uniphier-efuse",
> > +                                    "syscon";
> 
> 
> You are adding a dedicated driver for "socionext,uniphier-efuse".
> 
> Then, "syscon" as well?
> 

Since I was using the syscon interface to implement the driver,
I specified "syscon". It's interface is syscon_node_to_regmap().

I will rethink this in v2.

> 
> 
> > +                       reg = <0x100 0xf00>;
> 
> 
> Not so many efuse registers exist on the SoC.
> 
> reg = <0x100 0x200>; will be enough.
> 
> 
> Or if you want to be strict to the hw spec, you can write as follows:
> 
>         soc-glue@...00000 {
>                compatible = "socionext,uniphier-ld20-soc-glue-debug";
>                             "simple-mfd";
>                #address-cells = <1>;
>                #size-cells = <1>;
>                ranges = <0x0 0x5f900000 0x2000>;
> 
>                efuse@100 {
>                            compatible = "socionext,uniphier-efuse";
>                            reg = <0x100 0x28>;
>                };
> 
>                efuse@200 {
>                            compatible = "socionext,uniphier-efuse";
>                            reg = <0x200 0x68>;
>                };
>        };
> 
> 
> 
> 
> > +                       #address-cells = <1>;
> > +                       #size-cells = <1>;
> > +
> > +                       /* Data cells */
> > +                       usb_mon: usb_mon {
> > +                               reg = <0x154 0xc>;
> > +                       };
> 
> 
> This <0x154 0xc> represents 0x5f900254 in CPU address view.
> (0x5f900000 + 0x100 + 0x154)
> 
> So many ranges conversion, and how error-prone..
> 

Yes, indeed...
I will modify as below.

        soc-glue@...00000 {
                compatible = "socionext,uniphier-ld20-soc-glue-debug",
                             "simple-mfd";
                #address-cells = <1>;
                #size-cells = <1>;
                ranges;

                efuse@...00100 {
                        compatible = "socionext,uniphier-efuse";
                        reg = <0x5f900100 0x28>;
                };

                efuse@...00200 {
                        compatible = "socionext,uniphier-efuse";
                        reg = <0x5f900200 0x68>;
                };
        };


> 
> 
> 
> > +       };
> > +
> > += Data consumers =
> > +Are device nodes which consume nvmem data cells.
> > +
> > +Example:
> > +
> > +       usb {
> > +               ...
> > +               nvmem-cells = <&usb_mon>;
> > +               nvmem-cell-names = "usb_mon";
> > +       }
> > --
> > 2.7.4
> >
> > --
> > To unsubscribe from this list: send the line "unsubscribe devicetree"
> > in the body of a message to majordomo@...r.kernel.org More majordomo
> > info at  http://vger.kernel.org/majordomo-info.html
> 
> 
> 
> --
> Best Regards
> Masahiro Yamada

Best Regards,
Keiji Hayashibara