Hi Andrew,
On 10/29/2014 08:32 PM, Andrew Bresticker wrote:
> Hi Ezequiel,
>
>> From: James Hogan <james.hogan@xxxxxxxxxx>
>>
>> Introduce a devicetree binding for Imagination Technologies
>> I2C SCB controller.
>>
>> Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
>
> This should have your S-o-B as well.
>
Sure, although I haven't written a single line of this file and
I'm not sure what's the value of having my S-o-B in addition
to James Hogan's.
>> diff --git a/Documentation/devicetree/bindings/i2c/i2c-img-scb.txt b/Documentation/devicetree/bindings/i2c/i2c-img-scb.txt
>
>> @@ -0,0 +1,14 @@
>> +IMG Serial Control Bus (SCB) I2C Controller
>> +
>> +Required Properties:
>> +- compatible: "img,scb-i2c"
>
> Is there no difference between the controller present on TZ1090 and Pistachio?
>
As James Hogan explained, the revision register should be enough to
distinguish different IP block revisions. So for now no need for different
compatibles.
>> +- reg: Physical base address and length of controller registers
>> +- interrupts: Interrupt number used by the controller
>> +- clocks : Clock specifier to the SCB clock node
>
> On Pistachio there are two clocks per controller, the I2C operating
> clock and I2C "system" clock (which I assume is the system interface
> gate clock). There should also be a "clock-names" property with an
> entry for each clock.
>
Right.
>> +- clock-frequency: The I2C bus frequency in Hz
>> +- bus-delay : Bus delay in ms
>
> Probably should list #address-cells and #size-cells here as well.
>
OK.
>> +Optional properties:
>> +- linux,i2c-index: Can be used to override the I2C bus number. This is useful
>> + when some of the I2C adapters are used by other non-Linux cores so would get
>> + numbered incorrectly by default.
>
> I don't think this is necessary. Aliases can be used to set the
> adapter number instead.
>
Yes, just did a quick test and adding the following:
aliases {
i2c2 = &i2c0;
i2c3 = &i2c1;
};
Is enough to get the devices numbered:
$ ls /sys/class/i2c-adapter/*
/sys/class/i2c-adapter/i2c-2@ /sys/class/i2c-adapter/i2c-3@
> Also, it's generally good to include an example node.
>
Ah, forgot about that.
I'll cook a v2. Thanks a lot for the review.
--
Ezequiel
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