Using external i/o expander line as a chip select in the device tree?

[charlieschultz]

I have a few I2C i/o expanders (PCA953x) in my device tree. I would like to use one of the lines from one of those i/o expanders as a chip select for another device in the device tree and I'm uncertain how to do it (or even if it can be done).

Any help would be appreciated, thanks. Specifically this is for an imx6ul-based board.

[weidong_sun]

Hello Charlie,

    About your question, I can only give some advice, because we don't have ready-made example code for you!

    In theory, your solution is feasible, Low Level expander output can be used for chip select. But this controlling method is much more complex than using GPIOs of CPU directly. Because you need to synchronize Chip Select and data transmission in software, you should consider how to realize it.

Have a great day,
Wedong

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