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Altera_Forum's avatar
Altera_Forum
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10 years ago

Unable to access fpga regs from arm

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

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    10 years ago

    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's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    10 years ago

    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.