BeagleBone-black GPIO pins use on FreeBSD

[Warner Losh]

On May 21, 2014, at 10:32 PM, Rui Paulo <rpaulo at felyko.com> wrote:

> On May 21, 2014, at 20:45, Luiz Otavio O Souza <loos.br at gmail.com> wrote:
> 
>> Hi,
>> 
>> I've updated the BeagleBone-black Wiki page
>> (https://wiki.freebsd.org/FreeBSD/arm/BeagleBoneBlack) with the
>> default settings for the GPIO expansion headers on FreeBSD.
>> 
>> It has all the pins used for ADC (AIN), I2C, PWMs and MMC1.
>> 
>> Please let me know if i have missed something.
>> 
>> I hope this saves some time for people who is going to work with GPIO.
> 
> This is good, but I always wished some information was present on dmesg.  This could be added to the FDT and printed automatically, e.g.:
> 
> i2c1 { 
> 	location = "SDA header P9 pin 18, SCL header P9 pin 17";
> };
> 
> That would print:
> 
> ti_i2c1: SDA header P9 pin 18, SCL header P9 pin 17
> 
> If we don't want to put this in the kernel, we could at least put it in a man page.  However, a lot of embedded systems don't even have man pages...

This information can be derived mostly from the pinmux stuff that (should be) in our .dts files. However, there’s no standard way to communicate these things. So the strongest we could do for this non-standard property is “freebsd,location”, even though it is a strong candidate for having it without since that describes hardware.  I’d squirrel this away in the dev sysctl tree though, since otherwise the boot will get rather uncomfortably chatty.

Warner
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