I have been trying to build a working kernel from the sources. I get somewhat of a success but the bluetooth driver doesn't work. I am using the udooboard/linux_kernel repo and I've used the defconfig for the neo. I am a kickstarter backer with the full Wifi/BT4/1G. I want to use Bluez 5 because of DBUS integration and that's offered by the Jessie Armbian distro but the bluetooth driver doesn't work on that either. I went to the wiki to check for specs etc. but that is still "Coming soon" If there's a working 4.x based kernel, I'll take that too.
Kernel sources, as you found, are on https://github.com/UDOOboard/linux_kernel Kernel is one thing, bluetooth firmware is provided by the udooneo-bluetooth package (which is installed by default). What do you mean by "bluetooth driver does not work"? Bluez 5 cannot be used un Ubuntu 14.04. We are working on a way to provide Bluez 5, but for the moment only Bluez 4 can be used on UDOObuntu.
Firmware, of course. Yes the reason I moved to the community Armbian is because it has Bluez 5 which I want for the DBus based Bluetooth access since pygattlib is buggy or badly documented and my mission for the Udoo is to provide a bridge to Bluetooth LE lights. And I don't want to have to write that in C.
