New ADC Interface for Continuous Sampling

[pdietl]

@anangl @erwango @henrikbrixandersen @yonsch

See this issue #39640
See this branch https://github.com/worldcoin/zephyr/tree/stm32_adc_dma

I would like to see a change to the public API of ADC to include some way to do continuous sampling. I intend this to be implemented with IRQs (if slow continuous sampling is what you want) or with DMA. I see this interface taking a buffer and calling some callback function when the provided buffer is 1/2 full.

I see three ways to go about this.

1. Create a new function for this purpose. This is what I went with here main...worldcoin:zephyr:stm32_adc_dma#diff-0fb1cb925599ca94ff475e7ac8f4a8bf67fca7d4b8760f9a398a03188af07556R6
2. Make an addition to adc_sequence_options to accept a callback function, which means that one wants to use continuous mode.
3. Something else entirely, maybe using the RTIO API?

Please give your thoughts here. Thanks!

[pdietl]

Pinging @anangl again.

[erwango]

Not sure if people get notifications from in discussions. You can try to ping him in discord

[pdietl]

@erwango what is his Discord handle?

[erwango]

not sure, but I guess he should be monitoring ADC channel

[erwango]

^^@anangl Did you reach to a conclusion on that matter ?