[ECOS] Getting serial buffer status: patch attached

[Grant Edwards]

>   In order to avoid re-designing the application completely, I
>   need to provide non-blocking serial I/O.
> 
>   Additionally, one of the requirements for the application is
>   that it be able to find out how much space is available in
>   the tx buffer [there's a lot of existing stuff that depends
>   on this ability, and not having it would require ton's of
>   application code to be scrapped.]

I've attached a patch that adds a config key and corresponding
codeto get the current rx/tx buffer info for a serial device.
This only returns status on the buffer implimented in the
mid-level serial driver, and doesn't take into account any FIFO
that the UART may have.

(It also fixes the typo in the 230400 baud rate constant.)

The diff was done against the CVS snapshot of 16 Feb or so.

-- 
Grant Edwards
grante@visi.com