> Date: Thu, 8 May 2025 08:38:31 -0500
> From: joshua stein <j...@jcs.org>
>
> On Thu, 08 May 2025 at 11:52:51 +0200, Mark Kettenis wrote:
> > > From: joshua stein <j...@jcs.org>
> > > Date: Wed, 7 May 2025 21:52:22 -0500
> > >
> > > This is found on the XPI-3128
> >
> > I'm fairly confident this is the same chip that is already supported
> > by abcrtc(4). The registers match and the datasheet for the Abracon
> > AB18X5 RTC that I can find has a disclaimer that says:
> >
> > AB18X5 series of devices are based on innovative SPOT technology,
> > proprietary to Ambiq Micro.
> >
> > The compatible string you're using ("geniatech,rtc_am1805") isn't
> > documented anywhere in the Linux. The fact that it uses "geniatech"
> > as the vendor prefix makes me suspect that you're using a vendor
> > device tree. We try to stick to proper upstream Linux device trees as
> > much as possible as vendors put all sorts of crap in their device
> > trees. That said, adding a non-standard compatible string to a driver
> > isn't a big issue, as long as we annotate as such.
> >
> > Can you try whether the abcrtc(4) driver works for you once you add
> > the appropriate compatible string?
>
> Yes, abcrtc seems to work here without the trickle charger stuff.
> The upstream XPI-3128 device tree has no mention of the RTC (I don't
> think it was submitted by the vendor) but the one I extracted from
> the device before erasing it did. It ships with a very old
> Rockchip-specific U-Boot and Linux kernel.
>
> So I copied the geniatech,rtc_am1805 block to the device tree I'm
> using on my unit. I'm not sure what to use as the actual compatible
> string in the device tree.
The device tree bindings are in:
https://github.com/torvalds/linux/blob/master/Documentation/devicetree/bindings/rtc/abracon%2Cabx80x.yaml
If you're sure this is an AM1805 part, "abracon,ab1805" is probably
the right choice.
The trickle charging stuff is probably best left alone (disabled) if
you're not sure how the chip is wired up.
So in conclusion, I think this diff can be dropped. I'll look at the
other diffs soon.
