device-tree on BeagleBone Black (enabling UART)

[Daniel O'Connor]

> On 12 Feb 2021, at 10:30, Kristoff <kristoff at skypro.be> wrote:
> 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?

They are a hang over from the old days of dial in/out modems, I don't think it makes a practical difference which one you use in this case - FWIW I use the cua one.

>> 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

This sounds like the kernel you have does not match the modules you have.

How did you upgrade the kernel?
A standard buildkernel/installkernel run would have installed both (unless.. say.. you ran out of space).

--
Daniel O'Connor
"The nice thing about standards is that there
are so many of them to choose from."
 -- Andrew Tanenbaum