Re: gpio-omap: add support gpiolib bias (pull-up/down) flags?

[Linus Walleij <linus.walleij@xxxxxxxxxx>]

Hi Drew,

On Sun, Mar 8, 2020 at 2:07 PM Drew Fustini <drew@xxxxxxxx> wrote:

> I would like the BeagleBone, which has the TI AM3358 SoC, to be able
> to use the bias flags as well.   The AM3358 uses the gpio-omap GPIO
> driver.  However, gpio-omap does not support these flags [8].
>
> Do you have any feedback on whether this is possible to implement?

Do we have a datasheet for this GPIO block somewhere? Should
be the datasheet for the ASIC.

We already have the required .set_config() callback on the OMAP
driver, it's just that it only uses it for debounce.

The driver is a bit convoluted with register offsets in a struct
omap_gpio_reg_offs depending on variant, but if they have
a register for this I'd say just get hacking.

If the GPIO driver is using pin control as back-end you are
looking at something more complex similar to what Intel is
doing inside drivers/pinctrl/intel/pinctrl-intel.c: this driver
is just calling up to gpiochip_generic_config() which will
try to configure the lines behind the GPIO using pin config,
which works if the proper ranges are defined so the
framework can map a GPIO line to a pin control pin.

Yours,
Linus Walleij