bootcount support for AM62 RTCSS

[Thom Nichols]

Hi Bryan - I realized what I think you were trying to say - the bootcount_davinci driver uses the davinci_rtc​ struct which is a completely different register layout between the AM33 and AM62 RTCSS.  I imagine I could make an alternate davinci_rtc struct in my new header file just to remap the kick and scratch registers but that feels icky.  Of course I could just make a bootcount_am62x driver instead of trying to reuse bootcount_davinci.  Or change bootcount_davinci so that it uses offsets instead of the davinci_rtc struct.  Do you have any suggestion for which would be the preferred approach?

Thanks again.

-Thom


From: Bryan Brattlof <bb at ti.com>
Date: Tuesday, April 8, 2025 at 3:05 PM
To: Thom Nichols <thom.nichols at voltserver.com>
Cc: u-boot at lists.denx.de <u-boot at lists.denx.de>
Subject: Re: bootcount support for AM62 RTCSS

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Hi Thorm!

On April  8, 2025 thus sayeth Thom Nichols:
> I’d like to get bootcount support for the AM62 RTCSS.  The RTCSS on
> the AM62 is very similar to the AM33.  In fact, I’m pretty sure the
> bootcount_davinci driver would work for AM62, with just the register
> address/ offset and KICK_WE constants redefined for the correct AM62
> values.  A while back I tested the AM62 scratch register from
> userspace [1] and confirmed it works the same as the AM33.
>

Wonderful! It is a different IP from the AM335 but not completely
different however I think your approach should work.

> I’ve never contributed to u-boot but I believe I could get a working
> PR that modifies the davinci_bootcount driver, if this would be
> acceptable.
>

You should feel free to start if you want! U-Boot is very welcoming in
this regard. The more devs we have in U-Boot the better :)

> Alternately I don’t know if there’s any near-term plan for any of the
> AM62 maintainers to port the rtc driver so that bootcount/rtc could be
> used.  I think doing this would be beyond my capabilities.
>

So we do have some plans to improve RTC support in both in Linux and in
U-Boot to extend some features needed for the latest Sitara class SoC
but I'm unsure about timelines. I've added a ticket internally to track
this if we get to it before you do though :)

~Bryan

> Thanks in advance.
>
> Thom Nichols
>
> 1. https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2FVoltServer%2Fuboot-bootcount%2Fpull%2F15%2Ffiles&data=05%7C02%7Cthom.nichols%40voltserver.com%7Cbf306542d0ce48c4bc4308dd76d056ec%7C9d9544062c0145a39cc8be64a19fb626%7C0%7C0%7C638797359401626648%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C60000%7C%7C%7C&sdata=MgIfiZ5MnTaFkOfpH9kVXXxwarhhj1d73qoX76TYTuo%3D&reserved=0<https://github.com/VoltServer/uboot-bootcount/pull/15/files>

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