linux-kernel - Re: [PATCH v2 2/2] i2c: aspeed: added documentation for Aspeed I2C driver

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Date:   Tue, 20 Sep 2016 16:03:48 -0700
From:   Brendan Higgins <brendanhiggins@...gle.com>
To:     Rob Herring <robh@...nel.org>
Cc:     Wolfram Sang <wsa@...-dreams.de>, mark.rutland@....com,
        linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        OpenBMC Maillist <openbmc@...ts.ozlabs.org>,
        Joel Stanley <joel@....id.au>, Jeremy Kerr <jk@...abs.org>
Subject: Re: [PATCH v2 2/2] i2c: aspeed: added documentation for Aspeed I2C driver

To be clear, these bus numbers are defined as part of the hardware
specification. I am not sure if that was clear before.

On Tue, Sep 20, 2016 at 11:08 AM, Brendan Higgins
<brendanhiggins@...gle.com> wrote:
> (sorry if you get a duplicate, I forgot to send plain text)
>
> First off, someone pointed out to me that the mapping that I used
> between addresses and bus numbers is not actually valid for busses
> 8-14.
>
> This could be fixed by checking the offset, but I am wondering if that
> is the right way to do it. It seems like this is not completely
> trivial so maybe this should be specified in the device tree? If that
> is the case, should I do this as another reg entry or go back to the
> way I was doing it before?
>
> On Mon, Sep 19, 2016 at 4:26 PM, Brendan Higgins
> <brendanhiggins@...gle.com> wrote:
>> Addressed in v3.
>>
>> Thanks!
>>
>> On Mon, Sep 19, 2016 at 2:35 PM, Rob Herring <robh@...nel.org> wrote:
>>> On Fri, Sep 09, 2016 at 06:55:51PM -0700, Brendan Higgins wrote:
>>>> Added device tree binding documentation for Aspeed I2C controller and
>>>> busses.
>>>>
>>>> Signed-off-by: Brendan Higgins <brendanhiggins@...gle.com>
>>>> ---
>>>> Changes for v2:
>>>>   - None
>>>> ---
>>>>  .../devicetree/bindings/i2c/i2c-aspeed.txt         | 63 ++++++++++++++++++++++
>>>>  1 file changed, 63 insertions(+)
>>>>  create mode 100644 Documentation/devicetree/bindings/i2c/i2c-aspeed.txt
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/i2c/i2c-aspeed.txt b/Documentation/devicetree/bindings/i2c/i2c-aspeed.txt
>>>> new file mode 100644
>>>> index 0000000..df68f2a
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/i2c/i2c-aspeed.txt
>>>> @@ -0,0 +1,63 @@
>>>> +Device tree configuration for the I2C controller and busses on the AST24XX
>>>> +and AST25XX SoCs.
>>>> +
>>>> +Controller:
>>>> +
>>>> +     Required Properties:
>>>> +     - #address-cells        : should be 1
>>>> +     - #size-cells           : should be 1
>>>> +     - #interrupt-cells      : should be 1
>>>> +     - compatible            : should be "aspeed,ast2400-i2c-controller"
>>>> +                               or "aspeed,ast2500-i2c-controller"
>>>> +     - reg                   : address start and range of controller
>>>> +     - ranges                : defines address offset and range for busses
>>>> +     - interrupts            : interrupt number
>>>> +     - clocks                : root clock of bus, should reference the APB
>>>> +                               clock
>>>> +     - clock-ranges          : specifies that child busses can inherit clocks
>>>> +     - interrupt-controller  : denotes that the controller receives and fires
>>>> +                               new interrupts for child busses
>>>> +
>>>> +Bus:
>>>> +
>>>> +     Required Properties:
>>>> +     - #address-cells        : should be 1
>>>> +     - #size-cells           : should be 0
>>>> +     - reg                   : address offset and range of bus
>>>> +     - compatible            : should be "aspeed,ast2400-i2c-bus"
>>>> +                               or "aspeed,ast2500-i2c-bus"
>>>> +     - bus                   : the bus's number
>>>
>>> Don't use indexes. The reg property is enough to id which bus is which.