[PATCH linux 2/2] ARM: dts: aspeed: zaius: Add I2C master selector and hotswap controller

[Xo Wang]

Hi Joel,

On Wed, Nov 16, 2016 at 8:59 PM, Joel Stanley <joel at jms.id.au> wrote:
> Hi Xo,
>
> On Thu, Nov 17, 2016 at 9:59 AM, Xo Wang <xow at google.com> wrote:
>> Add device-tree bindings to instantiate the PCA9541A I2C master
>> selector. This driver allows mastering downstream devices after sending
>> an arbitration request to the PCA9541A. Downstream devices go into the
>> 'i2c-arb' child node.
>
> I took a look at the bindings document for i2c-mux[1] and it suggests
> something different.
>
> Is there a reason why you didn't follow what it says?
>
> [1] https://www.kernel.org/doc/Documentation/devicetree/bindings/i2c/i2c-mux.txt
>

I was following the I2C arbitration bus doc, which has its i2c slave
device nodes in an "i2c-arb" child node. I'm not sure why it was
written differently from "i2c-mux" bindings.

To be clear, I haven't 100% tested the LM5066I instantiation since the
motherboard I have actually has an ADI ADM1272 at address 0x10
downstream of the NXP PCA9541A.

https://www.kernel.org/doc/Documentation/devicetree/bindings/i2c/i2c-arb.txt

cheers
xo

> Cheers,
>
> Joel
>
>
>>
>> Instantiate the HWMON client driver for the TI LM5066I hotswap
>> controller present on Zaius EVT2 downstream of the master selector.
>>
>> Signed-off-by: Xo Wang <xow at google.com>
>> ---
>>  arch/arm/boot/dts/aspeed-bmc-opp-zaius.dts | 19 +++++++++++++++++--
>>  1 file changed, 17 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm/boot/dts/aspeed-bmc-opp-zaius.dts b/arch/arm/boot/dts/aspeed-bmc-opp-zaius.dts
>> index 3d997d9..136eb1d 100644
>> --- a/arch/arm/boot/dts/aspeed-bmc-opp-zaius.dts
>> +++ b/arch/arm/boot/dts/aspeed-bmc-opp-zaius.dts
>> @@ -210,8 +210,23 @@
>>  &i2c7 {
>>         status = "okay";
>>
>> -       /* MUX PCA9541A (other master: CPU0 PCIe 1)
>> -        *   ADM1272 PMBUS @10h
>> +       pca9541a at 70 {
>> +               compatible = "nxp,pca9541";
>> +               reg = <0x70>;
>> +
>> +               i2c-arb {
>> +                       #address-cells = <1>;
>> +                       #size-cells = <0>;
>> +
>> +                       hotswap at 10 {
>> +                               compatible = "ti,lm5066";
>> +                               reg = <0x10>;
>> +                       };
>> +               };
>> +       };
>> +
>> +       /* Master selector PCA9541A @70h (other master: CPU0)
>> +        *   LM5066I PMBUS @10h
>>          */
>>         /* 12V SMPS Q54SH12050NNDH @61h */
>>         /* CPU0 VR ISL68137 0.7V, 0.96V PMBUS @64h */
>> --
>> 2.8.0.rc3.226.g39d4020
>>
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