drivers: rtc: Add RV3028 RTC driver

[jakubtopic]

This PR adds basic support for microcrystal RV3028 RTC connected to the I2C bus:

• It supports getting/setting time and time alarm/update callbacks.
• Backup switchover and trickle charger configuration using devicetree.
• I also added an API extension for accessing the user RAM registers and EEPROM.
  • Accessing the user RAM and EEPROM will be handled using the retained_mem API in a separate PR
• I didn't implement the device PM API because it wasn't clear to me how it should behave in terms of power switchover functionality.

I have tested the driver using the RTC API test suite. The Y2K test is skipped because this RTC only supports the final two digits of years.

Thanks

[github-actions]

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[jakubtopic]

Oh, I just realized my PR overlaps with #73385. I didn't see it at the time of submission. This is my first zephyr contribution, so I'd still appreciate any suggestions for the next time 🙂

[bjarki-andreasen]

Wild timing, only 1 hour after #73385 was pushed :) It would be great if you help review #73385 since you probably have quite a bit of knowledge of that specific RTC :)

[Kampi]

Hi @jakubtopic and @bjarki-trackunit,

I removed the RV-3028 stuff from my PR because the driver from @jakubtopic is more advanced than my driver. I will focus on RV-8263 because this RTC is more important to me. 👍

[bjarki-andreasen]

Regarding the Y2K test failing, it really shouldn't be, if the year can't be set to 1999, the RTC should return -EINVAL, and the test should be skipped, see

zephyr/tests/drivers/rtc/rtc_api/src/test_y2k.c

Lines 44 to 51 in 3570408

	int ret = rtc_set_time(rtc, &rtm[Y99]);
	if (ret == -EINVAL) {
	TC_PRINT("Rollover not supported\n");
	ztest_test_skip();
	} else {
	zassert_ok(ret, "RTC Set Time Failed");
	}

It may be a legitimate bug :)

[jakubtopic]

Hi @Kampi, I wouldn't say it is more advanced, but I appreciate your trust. I'll keep working on my driver then. Good luck with the other device!

[jakubtopic]

• I was actually running an older version of the Y2K test. It looks ok now
• removed the custom API for accessing retained registers. Looking forward to implement it using retained_mem API in the future
• replaced the dedicated thread with the system workqueue
• added time validation
• the EEPROM Backup register value is now determined directly in the device instance
  • may have introduced some preprocessor evil 😳
    https://github.com/zephyrproject-rtos/zephyr/blob/41112f1335e17da5da971d23b343ca0ed4e1188d/drivers/rtc/rtc_rv3028.c#L959-L965

[jakubtopic]

@Kampi, do you want me to implement the RTC calibration?

[jakubtopic]

I would suggest removing this test case dependency so we can test boards that have RTC connected externally (it already looks for the rtc alias in the DT) but do not list it in the supported features.

zephyr/tests/drivers/rtc/rtc_api/testcase.yaml

Line 11 in 3625880

depends_on: rtc

[Kampi]

@Kampi, do you want me to implement the RTC calibration?

The RTC doesn´t have a calibration function so you have to add it (somehow) in the driver. Not sure if this would make sense.

[jakubtopic]

By calibration I meant setting frequency offset correction using the rtc_set_calibration function. I noticed it in your driver for RV8263, so I wasn't sure if you needed it for RV3028 as well.

[Kampi]

By calibration I meant setting frequency offset correction using the rtc_set_calibration function. I noticed it in your driver for RV8263, so I wasn't sure if you needed it for RV3028 as well.

I added it because the RTC contains a register for a calibration value so it's done in hardware. You can do a software calibration for the RV3028 too and use this interface.

[jakubtopic]

I added it because the RTC contains a register for a calibration value so it's done in hardware. You can do a software calibration for the RV3028 too and use this interface.

I think both ICs support frequency offset compensations. It's not a feature I need, so I was wondering if you hadn't originally planned it for RV3028 as well 🙂

[Kampi]

I added it because the RTC contains a register for a calibration value so it's done in hardware. You can do a software calibration for the RV3028 too and use this interface.

I think both ICs support frequency offset compensations. It's not a feature I need, so I was wondering if you hadn't originally planned it for RV3028 as well 🙂

No I haven´t planed it for RV3028 because I haven´t found a calibration register or function during a quick check. 🙂

[jakubtopic]

Fixed formatting errors

[jakubtopic]

@bjarki-trackunit, @decsny Kindly asking for re-review :)

[bjarki-andreasen]

The driver looks really good, Minor nits and a request to use k_sem for locking to optimize size and speed compared to a mutex :)

[jakubtopic]

@bjarki-trackunit Thanks for all the feedback. I've addressed the requested changes.

[decsny]

binding seems fine

[bjarki-andreasen]

Great! I have one suggestion but it is just a minor nit IMO, great work!

[github-actions]

Hi @jakubtopic!
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