device-tree on BeagleBone Black (enabling UART)

[Kristoff]

Hi Ian, Daniel,


I am sorry for the late reply.
(inline comments)


On 8/02/2021 9:41 p.m., Ian Lepore wrote:
>
>> I am running FreeBSD 12.1 on a beaglebone black. As I want to use it
>> for
>> a time-server (i.e. connect it to a GPS), I want to enable an
>> additional
>> UART (and also a pps gpio-pin, I guess).

Good news! I managed to get the uart working.
To get to the same configuration as Daniel, I upgraded to FreeBSD 13.0, 
and that seams to have done the trick.

Uart1 has been created with a device-tree overlay-file and I can use it 
on the device.


Question, what is the difference between /dev/cuau0 and /dev/ttyu0, and 
which one do I use for what?

> The beaglebone has a special pps driver that uses the am335x chip's
> timer hardware to measure the pps pulse time with better accuracy than
> the generic gpio-pps driver.  To use it, add
>
>    am335x_dmtpps_load=YES

At the same time I also wanted to try the pps driver you mention.

However, it does not seams to load.

I get this:

[root at black1 ~]# kldload am335x_dmtpps
kldload: can't load am335x_dmtpps: No such file or directory


The issue seams to be this:

# dmesg
(...)
KLD am335x_dmtpps.ko: depends on ti_sysc - not available or version mismatch

Looking on my system, I seems to have the source of 'to_sysc', but not 
the .ko.
[root at black1 ~]# locate ti_sysc
/usr/src/sys/arm/ti/ti_sysc.c
/usr/src/sys/arm/ti/ti_sysc.h


What is the procedure to compile one single kernel-module?
I tried "make ti_sysc", but that failed due to compilation errors



> -- Ian
Kristoff