Re: [Discuss OpenCPI] Zynq AXI Peripherals in Platform

From: Jerry Darko <jerry.darko_at_cnftech.com>
Date: Tue, 02 Mar 21 16:52:57 +0000

_at_James Kulp<mailto:jek_at_parera.com> Would this be something where he would touch the HdlDrivers code? Just like we did with the gpsd gps Daemon?
________________________________
From: discuss <discuss-bounces_at_lists.opencpi.org> on behalf of Brian Padalino <bpadalino_at_gmail.com>
Sent: Tuesday, March 2, 2021 10:44 AM
To: James Kulp <jek_at_parera.com>
Cc: discuss_at_lists.opencpi.org <discuss_at_lists.opencpi.org>
Subject: Re: [Discuss OpenCPI] Zynq AXI Peripherals in Platform

On Tue, Mar 2, 2021 at 10:17 AM James Kulp <jek_at_parera.com> wrote:

> On 3/2/21 10:04 AM, Brian Padalino wrote:
> > I have some AXI peripherals that I want to use on the PL side of things
> > along with OpenCPI. I want to use these in the form of a device tree
> > overlay to load once the FPGA image has been loaded.
>
> Are these AXI slaves, like the OpenCPI control plane?
>

These are slaves that are used in the platform by a daemon that control
other aspects of my system. I don't want to re-write the drivers/daemon or
maintain two separate systems. They utilize sysfs entries for opening and
interacting with the devices. I figured it is easier to make a daemon
interface in OpenCPI than bring all the PL IP into it.


>
> One way to do this is to use the other AXI slave port (AXI_GP1).
> That keeps everything separate.
> Then attach your "other" logic to that AXI PS->PL port, in the platform
> worker.
>

Is there an example of this somewhere in the OpenCPI code?


>
> But that has nothing to do with device trees and overlays - which can
> get into some pretty complicated scenarios, depending on how much you
> want to deal with dynamic loading and probing of other linux device
> drivers. Not to mention that the whole DTO system only works on pretty
> recent Linux kernels.
>

Understandable about the recent nature of this feature. I am worried about
keeping the drivers instantiated when the FPGA image is being reprogrammed
underneath it all, hence the overlays.


>
> Are you thinking of partial reconfiguration in this case?
>

No.

Brian


Received on Tue Mar 02 2021 - 16:52:57 CST