FreeBSD 12.0 RBPI3B+ and hardware clock support

[Ian Lepore]

On Wed, 2018-11-21 at 22:42 +0200, Stefan Parvu wrote:
> > 
> > Oddly enough, the ds1307 driver supports that chip. I think it's
> > because the register set on the two chips is identical (or close
> > enough
> > to work right).
> uauu. nice one. 
> 
> how on earth i can enable ds1307 - no need to rebuild anything
> right ? Can I load the driver , if yes how ? 
> 
> 
> Stefan

You can load it interactively with "kldload ds1307". Add
ds1307_load=YES to /boot/loader.conf to load it every time you boot.

But without modified FDT data, just loading the driver won't make it
attach to the hardware.

And this is where I can't help much more than that. In the old days the
thing to do would be to hack the standard rpi .dts file to enable the
i2c bus device and add the clock slave device, then rebuild that and
replace the standard .dtb file with the new one.

The new way to do all that is to code an overlay that enables the bus
and adds the device, then set a loader.conf variable to make that
overlay get loaded. But I don't know the details of how to do that,
hopefully one of the folks who does know more about overlays can reply
with that info.

-- Ian