GPIO Expander : How to Add TCA9539 GPIOs to Zephyr RTOS?

[loicgillioz]

Hi all,

I am quite new to Zephyr, did my first projects and I am now trying to write a custom DTS for one of my custom boards.

I am using the TI TCA9539 on this board.
I would like to use one of the existing PCA95XX or PCA953X driver for it.
I think the closest is the PCA953X, but the PCA953X/TCA9538 DTS binding in Zephyr RTOS has a constant amount of GPIOs fixed to 8.
However, the TCA9539 follows the same “953X” pattern and offers 16 GPIOs.

What’s the best approach to add support for the TCA9539 GPIOs in Zephyr?
Should I add a new binding, or can I create a PR for a non-const amount of GPIOs ?
I’d appreciate any insights or recommendations from the community.

@kieran-mackey or @henrikbrixandersen maybe you can help me on this one ?

Thanks a lot in advance !