Hello Peter, thanks for the response.
On Thursday 12 of June 2025 17:50:20 Peter Maydell wrote: > On Wed, 28 May 2025 at 12:50, Pavel Pisa <p...@cmp.felk.cvut.cz> wrote: > > The system/platform bus mapping alternative to PCI/PCIe mapping. > > In this case, the platform bus is used to match FPGA design > > for Xilinx Zynq MZ_APO education kit with four CTU CAN FD > > cores on branch mz_apo-2x-xcan-4x-ctu of repo > > > > https://gitlab.fel.cvut.cz/canbus/zynq/zynq-can-sja1000-top > > > > The system is started by command > > > > qemu-system-arm -m 1G -M xilinx-zynq-a9 \ > > -kernel kernel-zynq \ > > -dtb zynq-microzed-uart1-2x-xcan-4x-ctu-axi.dtb \ > > -initrd ramdisk.cpio \ > > -serial null -serial mon:stdio \ > > -nographic \ > > -object can-bus,id=canbus0-bus \ > > -object > > can-host-socketcan,if=can0,canbus=canbus0-bus,id=canbus0-socketcan \ > > -device > > ctucan_mm,iobase=0x43c30000,irqnum=29,irqctrl=/machine/unattached/device[ > >3],canbus=canbus0-bus \ -device > > ctucan_mm,iobase=0x43c70000,irqnum=30,irqctrl=/machine/unattached/device[ > >3],canbus=canbus0-bus \ -device > > ctucan_mm,iobase=0x43bf0000,irqnum=31,irqctrl=/machine/unattached/device[ > >3],canbus=canbus0-bus \ -device > > ctucan_mm,iobase=0x43bb0000,irqnum=32,irqctrl=/machine/unattached/device[ > >3],canbus=canbus0-bus > > Please don't use the platform bus for this. Command line > created devices should not have properties like "iobase" > and should not be mapping their own MMIO regions in their > realize methods. > > If we have a board that does or should have a memory-mapped > CAN device, then that board should create it at the appropriate > address and wire up the interrupt lines. That is easy when SoC has integrated IP on the silicon, in our case ESP32-C5. So if Espressif's chips are emulated by mainline QEMU one day are, then it would be easy to add CTU CAN FD support into appropriate chips. My student has defended thesis documenting his FlexCAN for iMX6 emulation last week https://dspace.cvut.cz/bitstream/handle/10467/122654/F3-BP-2025-Bobek-Matyas-BP_Bobek_FlexCAN_final_4.pdf https://gitlab.fel.cvut.cz/bobekmat/qemu-flexcan The code will need review and there could be problems but there are no doubts how to integrate it into QEMU supported SoC. But CTU CAN FD as FPGA IP component is another case. > We don't have infrastructure currently for users to create > custom "frankenstein" setups on the command line, and I don't > want us to add small disconnected portions of it ad-hoc. > > I'll let the Zynq board maintainers make the call about whether > they want to add a CAN bus controller to it. I do not expect that they want it as the standard component of the SoC support. The CTU CAN FD is an IP core which can be synthesized from our VHDL sources https://canbus.pages.fel.cvut.cz/ into one of AXI processor system (PS) to programmable logic (PL/FPGA) regions. The Xilinx QEMU fork adds support for that with some mechanism based on device-tree and dynamic mapping of designed IP cores functional emulation into address space. But that is part of their fork. I would like to support, contribute and provide mainline QEMU to Linux, RTEMS and NuttX communities and proposed solution seems to me as the least intrusive option. The QEMU use is for CAN subsystem maintenance, development and CI tests for these systems as well as the option for application developers to test whole system including CAN communication. We want to use it even for RTEMS, Linux and NuttX CAN testing on PolarFife, where we plan to work even on design example for FPGA soon. Is there some other alternative how to add support of FPGA AXI mapped IP cores to QEMU mainline? If not, is there chance that something else emerges and is acceptable in some foreseen future? Best wishes, Pavel -- Pavel Pisa phone: +420 603531357 e-mail: p...@cmp.felk.cvut.cz Department of Control Engineering FEE CVUT Karlovo namesti 13, 121 35, Prague 2 university: http://control.fel.cvut.cz/ personal: http://cmp.felk.cvut.cz/~pisa social: https://social.kernel.org/ppisa projects: https://www.openhub.net/accounts/ppisa CAN related:http://canbus.pages.fel.cvut.cz/ RISC-V education: https://comparch.edu.cvut.cz/ Open Technologies Research Education and Exchange Services https://gitlab.fel.cvut.cz/otrees/org/-/wikis/home
