[coreboot] GPIOs on CS5536 based boards

Daniel Mack daniel at caiaq.de
Wed Sep 23 06:03:38 CEST 2009

On Tue, Sep 22, 2009 at 01:56:53PM +0200, Peter Stuge wrote:
> Daniel Mack wrote:
> > I'm developing on a CS5536 based board (ALIX.2D) and I'm trying to
> > get access to the GPIO registers in order to set the LEDs on
> > bootup.
> Check out the 5536 data book on "Atomic Bit Programming" and/or look
> at the Linux LED driver for reference. To program the GPIOs you have
> to follow the algorithm outlined in 6.16.1.

Hmm. I followed that guideline, and did the same thing than the Linux
driver, but it still doesn't work. I only found one location from where
I could successfully write to the GPIO registers, and that is
hardware_stage1() in mainboard/pcengines/alix2c3/stage.c.

When moving the same code to southbridge_init() in
southbridge/amd/cs5536/cs5536.c, the register accesses fail.

Also, when booting Linux, the LED driver does not work with coreboot
for me. The register space mapping seems to be given up at some point
on the way, but I can't figure out where and why yet. As I don't know
coreboot's internals, I'd appreciate any pointer.


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