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12435 Discussions

Unable to access fpga regs from arm

Altera_Forum
Honored Contributor II
1,777 Views

Hi, i Compiled my own Linux Kernel using the Tutorial from the eekwiki ( https://eewiki.net/display/linuxonarm/de0-nano-soc+kit ). 

 

However when I try to access the fpga space i get a bus error. Also i don't have the /sys/class/fpga-bridge/*/enable option so I think the Bridges are not enabled. 

 

Any idea what could be my Problem? 

 

Cheers
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3 Replies
Altera_Forum
Honored Contributor II
131 Views

The first question is whether or not you included the FPGA bridge modules/drivers in your kernel. There are quite a few Altera drivers hidden in different places in the kernel make config process that can be turned on. Other then that, I can't think of what might be going on. This really just sounds like a missing driver. 

 

Did you pull from the main-line kernel or from Altera's linux-socfpga git repository?
Altera_Forum
Honored Contributor II
131 Views

You may want to try to mmap space from 0xFF200000 through /dev/mem. That gives you a neatly mapped address in user space that allows you to write to a peripheral through a pointer dereference. Try connecting a PIO to the hps lw-bridge in Qsys and assign some leds to it's output. That's the easiest way of testing I think.

Altera_Forum
Honored Contributor II
131 Views

Did you release the bridges from reset in uboot-stage?

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