PCI virtual gpio with interrupts support for using together with ivshmem qemu
See original articles for older versions:
- http://maquefel.me/en/qemu-ivshmem-introducing-interrupt-capable-virtual-gpio-concept/
- http://maquefel.me/en/using-gpio-generic-and-irq_chip_generic-subsystems-for-gpio-driver/
- linux kernel
- qemu
This version is done for usage with 5.12 linux kernel and 6.0 qemu
KDIR={$PATH_TO_KERNEL_SOURCE_DIRECTORY} QEMU_DIR={$PATH_TO_QEMU_SOURCES_DIRECTORY} make all
optional ARCH={$ARCH} optional CROSS_COMPILE={$CROSSCOMPILER_PREFIX}
Use https://github.com/maquefel/kernel-bisect-template/tree/virtual_gpio project for quickstart.
I have dropped non-irq based version and switched to MSI vector usage. The modules simply won't load with error (it can be fixed easily if you really require that).
See https://github.com/qemu/qemu/blob/master/docs/specs/ivshmem-spec.txt for additional info.
host machine: $ ./qemu/build/contrib/ivshmem-server/ivshmem-server -F -v -l 1M -n 1 $ qemu-system-x86_64 -cpu host -kernel build-linux/arch/x86/boot/bzImage -initrd initramfs.cpio.xz -nographic -append "nokaslr console=ttyS0 root=/dev/ram" -chardev socket,path=/tmp/ivshmem_socket,id=ivshmemid -device ivshmem-doorbell,chardev=ivshmemid,vectors=1 -enable-kvm guest # lsgpio ... GPIO chip: gpiochip4, "0000:00:04.0", 32 GPIO lines line 0: unnamed unused [input] line 1: unnamed unused [input] line 2: unnamed unused [input] line 3: unnamed unused [input] ... guest # /usr/bin/gpio-event-mon -n gpiochip4 -o 0 host $ ./vg_get_set -p 6 -i 0 # get -p (peer id) from ivshmem-client main:346:: write 0=1 main:349:: interrupt was enabled for 0 main:353:: interrupt was raised for 0 main:357:: rising edge interrupt was enabled for 0 and new value is high 1 guest: No flags specified, listening on both rising and falling edges Monitoring line 0 on gpiochip4 Initial line value: 0 GPIO EVENT at 33533945213 on line 0 (1|1) rising edge GPIO EVENT at 39910880760 on line 0 (2|2) falling edge GPIO EVENT at 44507121043 on line 0 (3|3) rising edge GPL Nikita Shubin nikita.shubin@maquefel.me