Compiling AXI DMA linux drivers in SDK.

Question

Hi guys,
I think I'm doing something wrong and It's making me crazy. I've got:
Vivado 2015.2 w/ SDK.
Zynq zc702.
Tested in Linux 14.04 and Windows 7.
And I want to use the axi dma drivers in a Linux application so that I downloaded the axidma_test.c example. At first most of the linux libraries threw an error until I linked somehow the libraries I found in the git repository "linux-xlnx/include".
Then all of the "linux/*.h" libraries are recognized, but a new error appears: fatal error: asm/linkage.h not found. I tried to include this last one but I just made it worse. I cut down the code so that I only have a small snippet, having the same error:
#include <linux/dma-mapping.h>
int main() {
    printf("Hello World\n");
    return 0;
I'm starting to think that I'm making it more difficult than it should be.
Could anyone give me some advise how to successfully compile that small snippet? I would really appreciate it.
Regards,
Leroy
 

Answer 1

Hello Leroy,
Hmmm okay I found the one that I was thinking of:
http://forums.xilinx.com/t5/Embedded-Linux/AXI-DMA-with-Zynq-Running-Linux/m-p/523105#M10658
There's a presentation there with some code. About halfway down the pdf is an explanation of the software architecture for the AXI DMA linux driver and an explanation of where you need to add your application-specific layers and an example of doing so.
As far as compiling, you really need two pieces still (bear in mind, I'm a little out of my area of expertise talking about the linux software side, so someone with more knowledge may correct the finer details. This is based on what I've gathered...):
1) Kernel module to interface from the driver to userspace (for simplicity, you might use UIO for this like the second pdf that linnj posted in that link)
2) Some application that runs in userspace that communicates with 1 above.
For 1, you don't use SDK. You build a cross compile environment dependent on your kernel configuration and follow build steps:
http://www.tldp.org/LDP/lkmpg/2.6/html/x181.html
For 2, you'd use SDK as you are to build a Linux 'Application' (the word seems to have the connotation of running in userspace).