[PATCH] Proposal for new GPIO API and example implementation for STM32F4 BSP

[Duc Doan]

Hello Christian,

I have been writing the complete API and also implementation for
STM32F4. A patch is coming soon.

On Mon, 2022-06-27 at 13:33 +0200, Christian MAUDERER wrote:
> Regarding pin groups: I think it's worth to think a bit about how the
> structure could be extended. You don't have to implement it right now
> but you should have a plan what could be possible.
> 
>  From my point of view, there are two directions how that could be 
> implemented: Masks or lists.
> 
> If you have a mask (like 0x00108 for pin 3 and pin 8) it has the 
> advantage that it works fast for most controllers. Difficult is that
> it 
> adds a limit to the maximum pin number depending on the size of the 
> mask. With that it works only for a few hardware models.
> 
> The other option is to add a list of pins instead of a mask. That
> makes 
> it inefficient because most controllers will have to collect pins
> into 
> masks and work with that.
> 
> Hm. Difficult. Maybe someone else has a good idea for that in the
> next 
> few days.

I am thinking of later adding separate functions that handle pin
groups. I think it's quite hard to integrate into current functions
because of using virtual pin.

I have an assumption that needs confirmation: all microcontrollers (or
most of them) have register size equal to word size, and pin masks
should be at word size. Is that assumption correct? If so, maybe we can
just use unsigned int (or uintptr_t) for pin masks?

Best,

Duc Doan