remoteproc over PCIe

[Simon Maurer <mail@maurer.systems>]

Hi,
I've got a "Zynq PCIe FMC Carrier Evaluation Board" with a x86 host. The 
Zynq 7000 is an FPGA with 2x Cortex-A9, on which ZephyrOS with the 
OpenAMP framework is running. The VirtIO ring and the buffer for the 
RPMSGs are located in the nocache memory section of the ZephyrOS. The 
card DDR-RAM and the CPU control registers are mapped into PCIe BARs. On 
the FPGA the "AXI Memory Mapped To PCI Express" IP core is used, so the 
kernel has mmio access to the card DDR-RAM.
Besides the kernel module, I had to do a few modifications elsewhere in 
the kernel. In remoteproc_virtio.c I implemented the get_shm_region 
function for the rproc_virtio_config_ops. This gives access to the rpmsg 
buffer, that is already mapped. In virtio_rpmsg_bus.c this function is 
used instead of allocating a new region. This is just a proof of 
concept, but it seems to be working, ttyRPMSG is created and I can send 
and receive messages.
But what would be the clean way to do this? I'm thinking about 
implementing dma_map_ops for the vdev, but maybe there is a better solution?

Best regards,
Simon