Re: [RFC 1/8] dt-bindings: mfd: Add Altera Arria10 System Resource Chip bindings

[Thor Thayer <tthayer@opensource.altera.com>]

Hi Lee,

On 04/18/2016 02:43 AM, Lee Jones wrote:
> On Fri, 15 Apr 2016, Thor Thayer wrote:
>> On 03/30/2016 06:35 AM, Lee Jones wrote:
>>> On Tue, 29 Mar 2016, tthayer@opensource.altera.com wrote:
>>>
>>>> From: Thor Thayer <tthayer@opensource.altera.com>
>>>>
>>>> The Altera Arria10 Devkit System Resource chip is a Multi-Function
>>>> Device, it has two subdevices:
>>>>       - GPIO
>>>>       - HWMON
>>>>
>>>> This patch adds documentation for the Altera A10-SR DT bindings.
>>>>
>>>> Signed-off-by: Thor Thayer <tthayer@opensource.altera.com>
>>>> ---
>>>>   .../devicetree/bindings/mfd/altera-a10sr.txt       |   35 ++++++++++++++++++++
>>>>   1 file changed, 35 insertions(+)
>>>>   create mode 100644 Documentation/devicetree/bindings/mfd/altera-a10sr.txt
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/mfd/altera-a10sr.txt b/Documentation/devicetree/bindings/mfd/altera-a10sr.txt
>>>> new file mode 100644
>>>> index 0000000..564c761
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/mfd/altera-a10sr.txt
>>>> @@ -0,0 +1,35 @@
>>>> +* Altera Arria10 Development Kit System Resource Chip
>>>> +
>>>> +Required parent device properties:
>>>> +- compatible : "altr,altr_a10sr"
>>>> +- spi-max-frequency : Maximum SPI frequency.
>>>> +- reg : the SPI Chip Select address for the Arria10 System Resource chip
>>>
>>> DT bindings are much easier to read in the following format:
>>>
>>> - compatible		: "altr,altr_a10sr"
>>> - spi-max-frequency	: Maximum SPI frequency.
>>> - reg			: the SPI Chip Select address for the Arria10 System Resource chip
>>>
>>> ... also, sentences start with an uppercase char.
>>>
>>>> +The A10SR consists of this varied group of sub-devices:
>>>> +
>>>> +Device                   Description
>>>> +------                   ----------
>>>> +altr_a10sr_gpio          GPIO Controller
>>>> +altr_a10sr_hwmon         Hardware Monitor
>>>> +
>>>> +The LEDs are implemented entirely in the device tree using
>>>> +the gpio-led framework.
>>>
>>> This is a Linuxisum and should not live in DT bindings.
>>>
>>>> +Example:
>>>> +
>>>> +        a10-sr: a10-sr@0 {
>>>
>>> Nodes should be named after their device 'type'.
>>>
>>> Does this device really start a address 0?
>>>
>>
>> I see in the documentation on device trees there are a number of
>> categories I can use. GPIO is easy because it is one of the
>> categories but I'm not sure about the new device I'm adding since
>> the a10sr is a new device.
>
> It's always difficult with MFDs as they are by their very nature, more
> than one device.  But how about 'resource-manager'?
>
OK. Yes, that would be a good name. Thanks.

>> I believe I should only call out the name and address on the SPI bus like:
>>
>> a10sr@0 {
>
> Correct.
>
>>>> +		compatible = "altr,altr-a10sr";
>>>> +		reg = <0>;
>>>> +		spi-max-frequency = <100000>;
>>>> +
>>>> +		a10sr_gpio: a10sr_gpio {
>>>
>>> Device type only please.
>>>
>>
>> and this would be a10sr_gpio: gpio-controller {
>>
>> Does that seem correct?
>
> Also correct.  No address though?
>

Thank you. It is at a fixed address inside the SPI device. When making 
this binding I followed the format of other gpio controllers like the 
tps65086 and lp3943 which didn't have an address.

Thanks for the clarification.

>>>> +			compatible = "altr,a10sr-gpio";
>>>> +			gpio-controller;
>>>> +			#gpio-cells = <2>;
>>>> +			ngpios = <16>;
>>>> +		};
>>>> +
>>>> +		a10sr_hwmon: a10sr_hwmon {
>>>
>>> Device type only please.
>>>
>> I need to revisit where this will live (hwmon does not seem to be
>> the correct place) so it will change but I can follow the format
>> above if it is correct.
>>
>> Thanks for reviewing.
>>
>>>> +			compatible = "altr,a10sr-hwmon";
>>>> +		};
>>>> +	};
>>>
>