Chosen a major number: WS2812_MAJOR=152 it is free to the best of my knowledge.
Automated creation of /dev/ws2812 -- with the horribly complex device and class concept of udev.
The old devfs_mk_char() was so much cleaner. I could even leave the device node around so that
programs could see it. Now I have to remove the node in device_release or sysfs remains in an unfixable borken state. You are not permitted to cleanup the mess in /sys/class/ws2812 manually.

Please do not hesitate to remove the device creation code, if it fails on you.
Until then: no more mknod needed. Yeah!