samv7/adc: fix handling of ANIOC_TRIGGER ioctl

[michallenc]

Summary

ADC peripheral can be configured also for PWM trigger, so the ifdef should depend only on CONFIG_SAMV7_AFEC_SWTRIG. Also handle the situation when ANIOC_TRIGGER is called and the peripheral is not configured for SW trigger (but the other one may be, so config option is set).

Trigger values saved to the private structure are also changed to enums for better code clarity.

Impact

Handling of ANIOC_TRIGGER ioctl is now fixed.

Testing

Tested on SAMv7 board, CI passes for different trigger combinations.

[nuttxpr]

[Experimental Bot, please feedback here]

Yes, this PR appears to meet the NuttX requirements, although some sections could be more detailed. Here's a breakdown:

Strengths:

• Clear Summary: The summary explains the "why," "what," and "how" of the change. The reference to code clarity with enums is a good addition.
• Impact Addresses Key Areas: The impact section covers most relevant areas. The explicit mention of the ANIOC_TRIGGER fix is helpful.
• Testing Mentions Platform and CI: Referencing the SAMv7 board and CI passing is positive.

Areas for Improvement (While Concise, More Detail Would Be Helpful):

• Summary - Missing Issue References: If this relates to any existing NuttX issues, those should be linked. Even if there isn't a directly related issue, mentioning that ("No related issue") is good practice.
• Impact - Be More Specific: While "Handling of ANIOC_TRIGGER ioctl is now fixed" is good, elaborating on the previous incorrect behavior and how this change fixes it would improve clarity. For other "NO" impact items, consider briefly stating why there's no impact (e.g., "Impact on build: NO (This change only affects driver code, not the build system)").
• Testing - Insufficient Logs: Providing actual test logs (even if abbreviated) is crucial for reviewers. "CI passes" is useful, but seeing specific before/after output helps validate the claims. Describe the tests performed. What was the expected behavior before? What is the expected behavior after? Did the logs demonstrate that change? Also, be more specific about the "different trigger combinations" tested in CI.

Example Improvements for Testing:

Testing Host: Linux, x86_64, GCC 12.2
Target: SAMV71-Xplained-Ultra, CONFIG_SAMV7_AFEC0_ADC=y, CONFIG_SAMV7_AFEC0_SWTRIG=y, CONFIG_SAMV7_AFEC0_PWMT=n 

Testing logs before change:

ioctl(fd, ANIOC_TRIGGER, 0) returned -EINVAL (Invalid Argument) <- This demonstrates the bug

Testing logs after change:

ioctl(fd, ANIOC_TRIGGER, 0) returned OK
ADC conversion completed successfully (verified via reading ADC data register)

CI tests included the following trigger combinations:
* SW Trigger only
* PWM Trigger Only
* Both SW and PWM Triggers
* No Triggers


By adding these details, the PR becomes much stronger and easier for reviewers to assess.  Even with the need for these improvements, the PR seems to generally meet the NuttX requirements in terms of structure and content areas covered.