[U-Boot] [PATCH 1/2] gpio: Add DW APB GPIO driver

Simon Glass
2015-08-07T20:37:54Z

Hi Marek,

On 7 August 2015 at 14:35, Marek Vasut <marex@denx.de> wrote:
> On Friday, August 07, 2015 at 09:13:45 PM, Simon Glass wrote:
>> Hi Marek,
>
> Hi!
>
>> On 5 August 2015 at 19:49, Marek Vasut <marex@denx.de> wrote:
>> > On Wednesday, August 05, 2015 at 04:39:33 PM, Simon Glass wrote:
>> >> Hi Marek,
>> >
>> > Hi Simon,
>
> [...]
>
>> >> It's up to you. Normally each bank has a name and the datasheet
>> >> specifies it. In your case if not you could think about a naming
>> >> scheme.
>> >
>> > Can you please take a look into arch/arm/dts/socfpga.dtsi ?
>> > The system has three GPIO controllers (look for gpio0, gpio1, gpio2)
>> > and each of these controllers has one bank (porta, portb, portc) .
>> >
>> > I can name my gpios portxN , where x is either of a,b,c and N is the
>> > GPIO number. The problem is, I cannot determine in dwapb_gpio_bind()
>> > which one is "porta", "portb" and "portc" because all I have is the
>> > physical addess of the GPIO controller and the index of the bank in
>> > the namespace of that controller.
>> >
>> > Sure, I can do some sort of global counting in the driver, but I would
>> > like to avoid that sort of thing. I can also add some kind of ad-hoc DT
>> > prop, but that's also not a good idea I think. Do you have any suggestion
>> > for me please ?
>>
>> One option is to use the device tree node name but it isn't very
>> friendly - gpio0 at xxxxx.
>
> That's what I do now pretty much.
>
>> You could perhaps add a new property like 'bank-name'?
>
> Do we want to add ad-hoc DT nodes which are
> a) Not describing hardware
> b) Not part of the official DT bindings for that platform
> ?
>
> Is that really a way to go ?
>
> [...]
>

It needs to be part of the official binding. Naming the hardware is
part of the hardware definition - see for example the regulator-name
property for regulators.

Another option is to use an alias:

aliases {
gpio0 = &gpio_0;
gpio1 = &gpio_1;
gpio2 = &gpio_2;
}

Then you can turn gpio0 into bank A, gpio1 into bank B, etc.

Regards,
Simon