Using Pull-up resistors on gpio-pca953x expander

Using Pull-up resistors on gpio-pca953x expander

[Adam Ford]

The pca953x can support pull-up resistors, and I have a pcal6416 that
I'd like to enable them.

Ideally, I was hoping there would be a way to add enable to the device
tree, because the expander is connected to some buttons which are
grounded when pressed.  Without pull-up resistors enabled, the buttons
always appear to be pressed.

Is there some way to enable them?  I see the functionality is
available and called through gc->set_config = pca953x_gpio_set_config;

I don't know enough about the API to know how to enable this.  Can
someone give me some pointers?

Would you entertain my adding some device tree hooks to enable them?

adam

Re: Using Pull-up resistors on gpio-pca953x expander

[Linus Walleij]

On Wed, Jan 15, 2020 at 9:26 PM Adam Ford <aford173@gmail.com> wrote:

> The pca953x can support pull-up resistors, and I have a pcal6416 that
> I'd like to enable them.

OK this is supported in the driver since
commit 15add06841a3b0b4734a72847a73c71fd09ebe52
"gpio: pca953x: add ->set_config implementation"

> Ideally, I was hoping there would be a way to add enable to the device
> tree, because the expander is connected to some buttons which are
> grounded when pressed.  Without pull-up resistors enabled, the buttons
> always appear to be pressed.
>
> Is there some way to enable them?  I see the functionality is
> available and called through gc->set_config = pca953x_gpio_set_config;
(...)
> Would you entertain my adding some device tree hooks to enable them?

Have you tried something like this in your DTS:

#include <dt-bindings/gpio/gpio.h>
(...)
gpios = <&gpio 4 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;

Yours,
Linus Walleij