drivers: digipot: add generic interface and AD528x driver support

[jocelynmass]

This patch introduces a generic digital potentiometer (digipot) driver interface in Zephyr along with an implementation for the Analog Devices AD528x series.

Key changes:
• Added a digipot driver API to provide a unified interface for controlling digital potentiometers.
• Implemented support for AD5280 and AD5282 devices, including RDAC read/write operations over I2C.
• Added Kconfig and device tree bindings to configure and instantiate AD528x devices.
• Provides basic initialization, wiper position set/get functions, and integration with Zephyr’s device model.

This enables Zephyr applications to use digital potentiometers in a standardized way, making it easier to add support for additional digipot devices in the future.

Tested on:
• STM32 platform using I2C devices configured via device tree.

[github-actions]

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[carlescufi]

Hi @jocelynmass. Thanks for your contribution. Since this introduces a new API, it needs to go through the Architecture WG meeting. Agendas are emailed to the devel@ mailing list, and additional details can be found here:
https://github.com/zephyrproject-rtos/zephyr/wiki/Architecture-Working-Group

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[jocelynmass]

@carlescufi got it, thanks for your reply. At this point, is there anything I need to do on my side?

[carlescufi]

@carlescufi got it, thanks for your reply. At this point, is there anything I need to do on my side?

Not really, I will schedule your PR to be discussed (may take a couple of weeks depending on how busy the meeting is) and email the mailing list. If you could attend the corresponding meeting it'd be great.

[jocelynmass]

@carlescufi got it, thanks for your reply. At this point, is there anything I need to do on my side?

Not really, I will schedule your PR to be discussed (may take a couple of weeks depending on how busy the meeting is) and email the mailing list. If you could attend the corresponding meeting it'd be great.

Sounds good, I’ll do my best to join the meeting when this PR comes up

[matt-wood-ct]

First off, great to see this getting contributed, IMO definately worth doing.

One note, it may be worth including some consideration for retained/nv digipots e.g. MCP41U83. Perhaps an optional API for storing/recalling NV value? Some applications I have worked on before use both volatile and non-volatile APIs for different application contexts.

Best, Matt