Beaglebone Serial Ports

[Warner Losh]

On Feb 2, 2013, at 8:13 AM, Ian Lepore wrote:

> On Sat, 2013-02-02 at 10:22 +0000, Iain Young wrote:
>> Hi Folks,
>> 
>> Just a quick question with regards to some clarification serial ports
>> on the Beaglbone and FreeBSD. Am I correct in deducing that FreeBSD
>> lacks support for UARTS1 thru 5 at the moment ?
>> 
>> I can see what I believe to be UART0 (which is attached to the USB) as
>> /dev/cuau0, but not the others. A few finds and greps through the
>> kernel source didn't show up anything obvious either.
>> 
>> Is any one working on them ? Or is there a kernel module or option
>> that I need to enable for them to build ?
>> 
> 
> According to the datasheet all the onboard uarts should be supported by
> our standard uart driver (but only uart1 has all the modem-control lines
> wired).  Two things need to be done to enable them: add entries to
> the .dts file (easy), and configure the multipurpose pins for them at
> runtime.  I have no idea how we handle the latter in the FDT world.  In
> the pre-FDT world it was pretty much ad-hoc and board-support routines
> that ran at startup configured pins for that board.

For Linux, there's a number of pin-mask registers that one just frobs to select the active peripherals per pin. I don't think we have this pinmux functionality yet. We should, since that's the right way to do it.

Warner