i2c on RPi Zero?

[Per Hedeland]

On 2019-01-05 20:58, Oleksandr Tymoshenko wrote:
> Per Hedeland (per at hedeland.org) wrote:
>> I did a bit more testing on the Zero to see if the FreeBSD version
>> mattered:
>>
>> FreeBSD-12.0-STABLE-arm-armv6-RPI-B-20190103-r342709.img - still no
>> luck.
>>
>> FreeBSD-11.2-STABLE-arm-armv6-RPI-B-20190103-r342709.img - works!
>> (I.e. dmesg reports as below and /dev/iic{0,1} get created - I haven't
>> tested actual usage beyond having 'i2c -s' report "no devices found".)
>>
>> I guess that the i2c support hasn't been removed intentionally,
>> i.e. this seems to be a regression - or is there some additional
>> config etc required to enable it with FreeBSD-12? The iic and iicbus
>> drivers appear to be built into the kernel in both 11 and 12.
>>
>> (I haven't tested FreeBSD-12 on the Pi B, but I would guess that the
>> result will be the same as on the Zero, since it seems the hardware is
>> the same.)
> 
> There was a transition in device tree files between 11 and 12.
> bcm2708-rpi-0-w.dtb has i2c nodes but they're disabled by default.
> Try editing config.txt on FAT partition and adding following line:
> 
> dtparam=i2c
> 
> This should make boot firmware to enable device nodes in the device
> tree blob during the boot.

Thanks a lot! I can confirm that this makes i2c "work" on Zero with
12-RELEASE (almost) to the extent described above for 11.2-STABLE (it
detects/creates only iic0, not iic1, but as far as I understand from
other sources, iic0 is all that is needed for "plain B" and thus also
for Zero).

Should I file a PR for this? I assume that the i2c nodes being
disabled is not intentional...

--Per Hedeland