Problem with L4Linux accessing ethernet clocks

Adam Lackorzynski adam at
Mon Oct 16 00:39:56 CEST 2017


On Wed Oct 11, 2017 at 16:33:58 +0300, Manolis Ragkousis wrote:
> On 10/05/2017 01:25 AM, Adam Lackorzynski wrote:
> > Those clocks are part of a clock device that has mmio registers just as
> > the network device. So you need to give access to those so that it can
> > set the clocks as needed. Another trick might be to let u-boot
> > initialize the network, and thus the clocks, so that they still work
> > when L4 has been booted. Do you boot other network in u-boot?
> > 
> I followed you advice and managed to fix everything and l4linux now has
> access to both the network and the sd cards.
> What took me time to understand is that access to all the clocks in zynq
> is controlled from the zynq-slcr. I first needed to add that mmio
> registers to the l4linux vbus. Next I ported the driver from the normal
> arm linux arch to the l4 arch and made sure it was properly initialized.
> Then I just needed to modify the clkc driver to work under l4linux and
> only enable the clocks for the peripherals I needed. With all this done
> the drivers for each device work as is.
> All my work can be found in
> and
> Everything I changed is specific to L4_PLATFORM_ZYNQ, the new config
> option I created. In the future I will move the whole Zynq slcr
> initialization out of l4linux and in l4, so the l4linux kernel will not
> control devices it shouldn't.
> If anyone has any question on the how and why please ask :).

Ok, great it works.

> Finally I have a question, Are you accepting patches for L4 and L4Linux?
> I could make my git patches more presentable and send them here if you
> want, to be added to your upstream repo.

Principally yes but obviously that also requires work, time and being
stringent on my/our side. This might not be pleasent and I also might
not find the proper time. We'd also require a CLA to be signed.

The Zynq is a popular SoC, so support for it is good. Which parts of
your work would you like to see in?


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