Re: Porting eCos to Cogent CSB337

[Tue Brems Olesen <tue at cs dot auc dot dk>]

Hi again,

I'd like to share some thougts, and question, on the port of eCos to
Cogent's CSB337 board, which i'm preparing at the moment.


In the last few days, i have been looking through the code for the
"aaed2000" and "smdk2410" ports, as well as the "at91" tree (containing
four ports)

I realized that the Atmel AT91RM9200 chip on the CSB337 board is not as
equivalent to the chip aaed2000 and smdk2401 ports as i thought.
Basically, all three has ARM9 cores on them, but each has a different
set of peripherals (*).

This made me start looking at the "AT91" tree of ports. It contains
ports to four boards, all based on chips in the AT91 series from Atmel.
The chips have an ARM7TDMI core, but a slightly different set of
peripherals. The important thing is, many of these peripherals are
equivalent to those on the AT91RM9200 Chip.



Porting eCos to the CSB337 (AT91RM9200 based) board, seems to be
possible by combining the following:

* ARM9 Core support (from the ARM9 variant code, and/or the
  aaed2000/smdk2401 ports)

* AT91 Peripheral support (form the AT91  variant code, and possibly one
  or more of the AT91 ports.)

* Additional drivers for Ethernet and USB, present on the AT91RM9200
  Chip.


Now, a two overall questions are present:

- I assume that it's not possible to combine to *variants*, as both  
  defines functions with the same names, doing different things (e.g. 
  hal_hardware_init();). Then again, with my limited knowledge of eCos, i
  may be wrong?


- If the above is true, what would be the most feasible strategy, in
  terms of copying as  little code as possible: 

  (a) To include ARM9 core support in the AT91 tree, or 
  (b) to include AT91 peripheral support in the ARM9 tree. 

  My impression is that (a) is the most feasible way to combine the 
  worlds of ARM9 core support and AT91 peripheral support. Any opinions on
  this are very welcome!



Last, if anyone is interested in joining a cooperative effort to
establish an open, free CSB337 port of eCos, just speak up.


Best regards,
--Tue


(*) note that in the context of this mail, "peripherals" refer to
circuitry in the same chip as the core. Perhaps, the best description of
what is meant is "System on a Chip".)




-- 
Tue Brems Olesen          | phone: +45 6133 5015 / +45 9633 0865
Strubjerg 32, 3. th       | mail: tue  at  aye  dot  dk
9400 Nørresundby, Denmark | homepage: http://www.aye.dk