Re: Pull-up/down control via sysfs

[Gottfried Haider <gottfried.haider@xxxxxxxxx>]

> GPIOs have open source/open drain flags that I think can be used for
> what you want. The only problem is that these flags cannot be
> controlled from the sysfs interface. It should not be hard to add one
> entry to control these as well.
>
> What do you need to do exactly? Do you just want to set a pin as
> pull-up or pull-down? If so, using pinctrl seems more appropriate. My
> suggestion only applies if you need to control the GPIO's value after
> setting the open-source/open-drain property.

ARM boards such as the Raspberry Pi have internal pull-up & pull-down
resistors for their GPIO pins, that can be controlled via a set of
registers. I'd like to use them for input - i.e. giving the user
working with the board's exposed GPIO pins (pin header) the choice
whether to pull them high or low or leave them floating. I believe
that's quite handy, especially when learning about digital
electronics..

Is this what you had in mind with open source/open drain? Not so
familiar with that terminology but the pinctrl documentation mentions
an "input bias pull{up,down}".
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