GPMC configuration

claudiug

Hi Jonathan, Mike,

How is GPMC_CONFIGX_1 configured? It is not done in the kernel driver and it gets done even if the driver does not load upon boot (some settings are not at CPU reset values). Is this something that you preconfigured in the kernel?

I'm trying to use wishbone interface using Verilog. A simple port of just the 0xdeadbeef registers did not work. I would also like to extend the address space to allow AAD mode (32 bit addresses, needed if the device is viewable as 256 MB device).

Thanks,
Claudiu

jpiat

Hi Caludiug,

if you want to play with the GPMC configuration, you'll have to compile your own kernel as flatten device-tree will require to embed device tree configuration into your kernel (at least if you want the device tree configuration to be loaded based on the EEPROM ID).

To build you own kernel just clone the repository using the following command :

git clone -b am33x-v3.8 https://github.com/fpga-logi-dev/linux-dev.git

then in this directory modify the version.sh to match the bonexx version of your kernel (you can get it by doing a uname -a on the beaglebone black). Then build the kernel by running build_kernel.sh (takes some time on the first build).
After first build you will have a kernel configured for the logi-bone. You can then play with the GPMC configuration by editing the file :

KERNEL/firmware/capes/BB-BONE-LOGIBONE-00R1.dts

all the GPMC config is sumed up here and applied by the kernel on boot. I never tried 32bit adressing (and never found an example of device-tree for that) so you may have to dig deeper in device tree and gpmc config.

The dev branch of the kernel for the logibone is a bit ahead of the current image so you will need to load the new eeprom configuration (logi-kernel/beaglebone-black/cape_eeprom/data.eeprom) and use the new user-space loading tool (logi-tools/logibone_loader/user_space).

I can generate an image with the new configuration and tools if needed.

Keep us updated with your work !

Regards,

Jonathan Piat