[coreboot] GPIOs on CS5536 based boards

Daniel Mack daniel at caiaq.de
Wed Sep 23 09:03:17 CEST 2009

On Wed, Sep 23, 2009 at 06:03:38AM +0200, Daniel Mack wrote:
> On Tue, Sep 22, 2009 at 01:56:53PM +0200, Peter Stuge wrote:
> > 
> > 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.

I traced a little further and implemented a cs5536_set_resources() which
simply wraps the call to pci_set_resources(). GPIO registers are
accessed ok before pci_set_resources() but fail after.

This is the output of print_resource_tree() of the device used:

(CB)  PCI: 00:0f.0 links 0 child on link 0 NULL
(CB)  PCI: 00:0f.0 resource base 0 size 1000 align 0 gran 0 limit 0 flags e0000100 index 0
(CB)  PCI: 00:0f.0 resource base 20b0 size 8 align 3 gran 3 limit ffff flags 40000100 index 10
(CB)  PCI: 00:0f.0 resource base 1800 size 100 align 8 gran 8 limit ffff flags 40000100 index 14
(CB)  PCI: 00:0f.0 resource base 2000 size 40 align 6 gran 6 limit ffff flags 40000100 index 18
(CB)  PCI: 00:0f.0 resource base 2080 size 20 align 5 gran 5 limit ffff flags 40000100 index 1c
(CB)  PCI: 00:0f.0 resource base 1c00 size 80 align 7 gran 7 limit ffff flags 40000100 index 20
(CB)  PCI: 00:0f.0 resource base 2040 size 40 align 6 gran 6 limit ffff flags 40000100 index 24

Any ideas?


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