Logitech keyboard

hi all, and thx for reading and answering this post if you can.

I use a logitech S520 USB keyboard + mouse on my linux box. It works but quite a few extra keys are not available. Nevertheless it exists 2 projects for tackling this issue:
Solaar, that doesn’t work with my keyboard, and
hidpoint, a proprietary driver but 32 bits only.

the hid-logitech-dj module doesn’t seem to change anything to the issue.

Does it exist somewhere a opensource driver or tool for that typew of kbd ? X11 can only acknowledges some extra keys, and /dev/input/by-id/usb-Logitech_USB_Receiver-event-kbd is mute when I press an extra key.