linux-kernel - Re: [PATCH v2 v2 1/3] dt-bindings: i2c: extend existing opencore bindings.

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Date:   Tue, 14 May 2019 18:20:17 +0530
From:   Sagar Kadam <sagar.kadam@...ive.com>
To:     Rob Herring <robh@...nel.org>
Cc:     mark.rutland@....com, peter@...sgaard.com,
        Andrew Lunn <andrew@...n.ch>,
        Palmer Dabbelt <palmer@...ive.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 v2 1/3] dt-bindings: i2c: extend existing opencore bindings.

Hello Rob,

Thank you for the review.

On Tue, May 14, 2019 at 2:26 AM Rob Herring <robh@...nel.org> wrote:
>
> On Tue, May 07, 2019 at 08:45:06PM +0530, Sagar Shrikant Kadam wrote:
> > Add FU540-C000 specific device tree bindings to already
> > available i2-ocores file. This device is available on
> > HiFive Unleashed Rev A00 board.
> >
> > Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@...ive.com>
> > ---
> >  Documentation/devicetree/bindings/i2c/i2c-ocores.txt | 20 ++++++++++++++++++++
> >  1 file changed, 20 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> > index 17bef9a..f6bcf90 100644
> > --- a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> > +++ b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt
> > @@ -2,6 +2,7 @@ Device tree configuration for i2c-ocores
> >
> >  Required properties:
> >  - compatible      : "opencores,i2c-ocores" or "aeroflexgaisler,i2cmst"
> > +                    "sifive,fu540-c000-i2c" or "sifive,i2c0"
>
> If this is Opencores IP, does it really follow the Sifive versioning
> convention? If so, please reference sifive-blocks-ip-versioning.txt
> (which appears to have missed going upstream). Also, referencing the IP
> repository would be good too. If this IP block doesn't follow the same
> convention, then don't try using it for this binding.
>
Yes, the sifive,fu540-c000-i2c is a SoC specific compatibility string,
this way SoC specific
workaround's or bugs, can be handled in the software and the ip-block
specific compatibility
string "sifive,<ip-block-name><integer version number>" i.e.
sifive,i2c0 is IP block specific compatibility
string. Please let me know if I need some correction here?
I will also update reference for sifive-blocks-ip-versioning and the
ip repository into next version of patch.

> >  - reg             : bus address start and address range size of device
> >  - interrupts      : interrupt number
> >  - clocks          : handle to the controller clock; see the note below.
> > @@ -67,3 +68,22 @@ or
> >                       reg = <0x60>;
> >               };
> >       };
> > +or
>
> Just a new compatible isn't really a reason to add an example.
>
> > +     /*
> > +       An Opencore based I2C node in FU540-C000 chip from SiFive
> > +       This chip has a hardware erratum for broken IRQ
> > +       so it's recommended not to define interrupt in the device node
>
> Then interrupts needs to be optional.
True, I will move interrupts and interrupt parent into optional section
>
> > +     */
> > +     i2c@...30000 {
> > +                     compatible = "sifive,i2c0","sifive,fu540-c000-i2c";
> > +                     reg = <0x0 0x10030000 0x0 0x1000>;
> > +                     reg-names = "i2c-control";
>
> Not doucmented.
In v1, I had added a new binding file as sifive-i2c-ocores.txt for
SiFive i2c core.
After Andrew's suggestion,  extending the available i2c-ocores.txt
seemed to be a better idea rather than adding a new file.
so added an example node which is HiFive specific in the existing file.
Please let me know if I need to handle this in a different way.

>
> > +                     clocks = <&tlclk>;
> > +                     clock-frequency = <100000>;
> > +
> > +                     reg-shift = <2>;
> > +                     reg-io-width = <1>;
> > +
> > +                     #address-cells = <1>;
> > +                     #size-cells = <0>;
> > +     };
> > --
> > 1.9.1
> >
> >
> > --
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