Description

A Qemu+SystemC Cosim enviornment for a cnn accelerator processor model based on distributed statically timed descriptor based address generators

Environment

This project needs the enviornment built from: https://github.com/Sparkles-Qemu/qemu_vp_builder

Minimal current steps/documentation

Enabling Cosim irqs

• Add debugdev to top level device tree so that linux kernel can see it

  • /home/peta/xilinx-zcu102-2019.2/project-spec/meta-user/recipes-bsp/device-tree/files/system-user.dtsi
  • add the new device directly under the amba bus
  • &amba{ your_device: device0 { .... ... }; };
  • this device tree gets compiled by petalinux-build cli

• Add uio support to kernel -petalinux-config -c kernel

  • Device Drivers -> Userspace I/O drivers

    • Userspace I/O platform driver with generic IRQ handling
    • Userspace platform driver with generic irq and dynamic memory
    • Xilinx AI Engine driver

  • Make sure that you use M instead of *

• Use uio module to probe our device -debugdevice should contain compability string that uio is looking for

  • added directly in device tree with chosen { bootargs = "earlycon clk_ignore_unused uio_pdrv_genirq.of_id=generic-uio"; stdout-path = "serial0:115200n8"; };
  • or through petalinux-config and changing the boot args there
  • **use petalinux-config tool instead. I have found that adding bootargs directly on device tree does not work b/c. It gets over written **

• debugdev entry is in /proc/device-tree

  • /proc/device-tree/debugdev@0xa0000000
  • catting interrupts prints Y
  • catting /proc/interrupts shows debugdev which contains a GIC V2 interrupt number of +32 from what is specified on the device tree

UIO Driver performed pre-reqs

• Created a seperate .dtsi file

  • this file contains the debugdev information

• This file in included on system-user.dtsi

• Visually confirm that the debugdevice has been added to the compiled device tree that QEMU uses.

  • decompiled commmand: dtc -I dtb -O dts -o decompiled.dts system.dtb

• Added bootargs through petalinux-config

  • uio_pdrv_genirq.of_id=debuginc,generic-uio,ui_pdrv

• Debugdev still not visible from QEMU side

• Debugdev is not visible and recieving irqs from the PL side

  • the main problem I was having was the bootargs were getting overwritten when I directly changed it on the system-user.dtsi file
  • use the petalinux-config tool for this to work correctly

Simulated Architecture

Resources

• https://forums.xilinx.com/t5/Embedded-Linux/Does-anyone-have-or-know-of-an-example-using-UIO-with-a-private/td-p/1083861

  • could be a problem with petalinux 2019.1

• https://www.kernel.org/doc/html/v4.17/driver-api/uio-howto.html#using-uio-pdrv-genirq-for-platform-devices

  • how the uio framework works

• https://harmoninstruments.com/posts/uio.html

  • uio user level example