1QEMU CAN bus emulation support 2============================== 3 4The CAN bus emulation provides mechanism to connect multiple 5emulated CAN controller chips together by one or multiple CAN busses 6(the controller device "canbus" parameter). The individual busses 7can be connected to host system CAN API (at this time only Linux 8SocketCAN is supported). 9 10The concept of busses is generic and different CAN controllers 11can be implemented. 12 13The initial submission implemented SJA1000 controller which 14is common and well supported by by drivers for the most operating 15systems. 16 17The PCI addon card hardware has been selected as the first CAN 18interface to implement because such device can be easily connected 19to systems with different CPU architectures (x86, PowerPC, Arm, etc.). 20 21In 2020, CTU CAN FD controller model has been added as part 22of the bachelor thesis of Jan Charvat. This controller is complete 23open-source/design/hardware solution. The core designer 24of the project is Ondrej Ille, the financial support has been 25provided by CTU, and more companies including Volkswagen subsidiaries. 26 27The project has been initially started in frame of RTEMS GSoC 2013 28slot by Jin Yang under our mentoring The initial idea was to provide generic 29CAN subsystem for RTEMS. But lack of common environment for code and RTEMS 30testing lead to goal change to provide environment which provides complete 31emulated environment for testing and RTEMS GSoC slot has been donated 32to work on CAN hardware emulation on QEMU. 33 34Examples how to use CAN emulation for SJA1000 based boards 35========================================================== 36 37When QEMU with CAN PCI support is compiled then one of the next 38CAN boards can be selected 39 40 (1) CAN bus Kvaser PCI CAN-S (single SJA1000 channel) boad. QEMU startup options 41 -object can-bus,id=canbus0 42 -device kvaser_pci,canbus=canbus0 43 Add "can-host-socketcan" object to connect device to host system CAN bus 44 -object can-host-socketcan,id=canhost0,if=can0,canbus=canbus0 45 46 (2) CAN bus PCM-3680I PCI (dual SJA1000 channel) emulation 47 -object can-bus,id=canbus0 48 -device pcm3680_pci,canbus0=canbus0,canbus1=canbus0 49 50 another example: 51 -object can-bus,id=canbus0 52 -object can-bus,id=canbus1 53 -device pcm3680_pci,canbus0=canbus0,canbus1=canbus1 54 55 (3) CAN bus MIOe-3680 PCI (dual SJA1000 channel) emulation 56 -device mioe3680_pci,canbus0=canbus0 57 58 59The ''kvaser_pci'' board/device model is compatible with and has been tested with 60''kvaser_pci'' driver included in mainline Linux kernel. 61The tested setup was Linux 4.9 kernel on the host and guest side. 62Example for qemu-system-x86_64: 63 64 qemu-system-x86_64 -accel kvm -kernel /boot/vmlinuz-4.9.0-4-amd64 \ 65 -initrd ramdisk.cpio \ 66 -virtfs local,path=shareddir,security_model=none,mount_tag=shareddir \ 67 -object can-bus,id=canbus0 \ 68 -object can-host-socketcan,id=canhost0,if=can0,canbus=canbus0 \ 69 -device kvaser_pci,canbus=canbus0 \ 70 -nographic -append "console=ttyS0" 71 72Example for qemu-system-arm: 73 74 qemu-system-arm -cpu arm1176 -m 256 -M versatilepb \ 75 -kernel kernel-qemu-arm1176-versatilepb \ 76 -hda rpi-wheezy-overlay \ 77 -append "console=ttyAMA0 root=/dev/sda2 ro init=/sbin/init-overlay" \ 78 -nographic \ 79 -virtfs local,path=shareddir,security_model=none,mount_tag=shareddir \ 80 -object can-bus,id=canbus0 \ 81 -object can-host-socketcan,id=canhost0,if=can0,canbus=canbus0 \ 82 -device kvaser_pci,canbus=canbus0,host=can0 \ 83 84The CAN interface of the host system has to be configured for proper 85bitrate and set up. Configuration is not propagated from emulated 86devices through bus to the physical host device. Example configuration 87for 1 Mbit/s 88 89 ip link set can0 type can bitrate 1000000 90 ip link set can0 up 91 92Virtual (host local only) can interface can be used on the host 93side instead of physical interface 94 95 ip link add dev can0 type vcan 96 97The CAN interface on the host side can be used to analyze CAN 98traffic with "candump" command which is included in "can-utils". 99 100 candump can0 101 102CTU CAN FD support examples 103=========================== 104 105This open-source core provides CAN FD support. CAN FD drames are 106delivered even to the host systems when SocketCAN interface is found 107CAN FD capable. 108 109The PCIe board emulation is provided for now (the device identifier is 110ctucan_pci). The default build defines two CTU CAN FD cores 111on the board. 112 113Example how to connect the canbus0-bus (virtual wire) to the host 114Linux system (SocketCAN used) and to both CTU CAN FD cores emulated 115on the corresponding PCI card expects that host system CAN bus 116is setup according to the previous SJA1000 section. 117 118 qemu-system-x86_64 -enable-kvm -kernel /boot/vmlinuz-4.19.52+ \ 119 -initrd ramdisk.cpio \ 120 -virtfs local,path=shareddir,security_model=none,mount_tag=shareddir \ 121 -vga cirrus \ 122 -append "console=ttyS0" \ 123 -object can-bus,id=canbus0-bus \ 124 -object can-host-socketcan,if=can0,canbus=canbus0-bus,id=canbus0-socketcan \ 125 -device ctucan_pci,canbus0=canbus0-bus,canbus1=canbus0-bus \ 126 -nographic 127 128Setup of CTU CAN FD controller in a guest Linux system 129 130 insmod ctucanfd.ko || modprobe ctucanfd 131 insmod ctucanfd_pci.ko || modprobe ctucanfd_pci 132 133 for ifc in /sys/class/net/can* ; do 134 if [ -e $ifc/device/vendor ] ; then 135 if ! grep -q 0x1760 $ifc/device/vendor ; then 136 continue; 137 fi 138 else 139 continue; 140 fi 141 if [ -e $ifc/device/device ] ; then 142 if ! grep -q 0xff00 $ifc/device/device ; then 143 continue; 144 fi 145 else 146 continue; 147 fi 148 ifc=$(basename $ifc) 149 /bin/ip link set $ifc type can bitrate 1000000 dbitrate 10000000 fd on 150 /bin/ip link set $ifc up 151 done 152 153The test can run for example 154 155 candump can1 156 157in the guest system and next commands in the host system for basic CAN 158 159 cangen can0 160 161for CAN FD without bitrate switch 162 163 cangen can0 -f 164 165and with bitrate switch 166 167 cangen can0 -b 168 169The test can be run viceversa, generate messages in the guest system and capture them 170in the host one and much more combinations. 171 172Links to other resources 173======================== 174 175 (1) CAN related projects at Czech Technical University, Faculty of Electrical Engineering 176 http://canbus.pages.fel.cvut.cz/ 177 (2) Repository with development can-pci branch at Czech Technical University 178 https://gitlab.fel.cvut.cz/canbus/qemu-canbus 179 (3) RTEMS page describing project 180 https://devel.rtems.org/wiki/Developer/Simulators/QEMU/CANEmulation 181 (4) RTLWS 2015 article about the project and its use with CANopen emulation 182 http://cmp.felk.cvut.cz/~pisa/can/doc/rtlws-17-pisa-qemu-can.pdf 183 (5) GNU/Linux, CAN and CANopen in Real-time Control Applications 184 Slides from LinuxDays 2017 (include updated RTLWS 2015 content) 185 https://www.linuxdays.cz/2017/video/Pavel_Pisa-CAN_canopen.pdf 186 (6) Linux SocketCAN utilities 187 https://github.com/linux-can/can-utils/ 188 (7) CTU CAN FD project including core VHDL design, Linux driver, 189 test utilities etc. 190 https://gitlab.fel.cvut.cz/canbus/ctucanfd_ip_core 191 (8) CTU CAN FD Core Datasheet Documentation 192 http://canbus.pages.fel.cvut.cz/ctucanfd_ip_core/Progdokum.pdf 193 (9) CTU CAN FD Core System Architecture Documentation 194 http://canbus.pages.fel.cvut.cz/ctucanfd_ip_core/ctu_can_fd_architecture.pdf 195 (10) CTU CAN FD Driver Documentation 196 http://canbus.pages.fel.cvut.cz/ctucanfd_ip_core/driver_doc/ctucanfd-driver.html 197 (11) Integration with PCIe interfacing for Intel/Altera Cyclone IV based board 198 https://gitlab.fel.cvut.cz/canbus/pcie-ctu_can_fd 199