On 29.03.21 12:33, Smith li wrote:
> jailhouse-images  is  a good demo.
> It can run very good in  rpi4.
> But how to  use GPIO  in non-root cell .
> Can some one  help me ?  Thanks very much!

I didn't look into the details of the rpi4 yet but the general approach
is first of all to organize the GPIO usage in a way that you can at
least isolate register accesses per cell. That means, you should assign
all GPIO pins managed by one separately accessible register to one
inmate only. A register (can be 32-bit wide, can be smaller - depends on
the hardware) can then be exclusively assigned to one cell via sub-page
memory regions.

You can find an example of such a split-up in the
configs/arm/orangepi0*.c file. The configuration relies on the root cell
not using the GPIO port assigned to a non-root cell anymore and the
non-root cell knowing the address of that assigned port already. If you
also need to reflect the change in device trees, things may become more
tricky, depending on the DT binding of the given GPIO hardware.

Jan

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