I'm posting here what I did to run Armbian on a 4G LTE EM90 box. The image I'm using is armbian_5.37_S9xx_Debian_stretch_3.14.29_icewm_20171226. I extracted the dtb.img from the rooted android, I had to remove the beginning of the file to make it work. If you don't cut the file until you reach 0xD0 0D FE ED, you will get a magic number error when decompiling and Armbian will not boot with your fresh DTB.
WIFI :
The wifi is not well initialized at startup. You must precise to modprobe the firmware to load to AP6330 WIFI + BT4.0 chip
Create the file /etc/modprobe.d/options.conf and add the following line :
options dhd firmware_path=/lib/firmware/brcm/brcmfmac4330-sdio.bin nvram_path=/lib/firmware/brcm/nvram_ap6330.txt
then open the file /etc/modules and add the following lines :
cfg80211
dhd
I always have issues with DNS with Armbian, to solve this, i'm running these commands (with root privileges)
echo "nameserver 8.8.8.8" > /etc/resolvconf/resolv.conf.d/base
resolvconf -u
Bluetooth :
With the DTB, the device shows up with hciconfig but scanning and connecting doesn't work. One more time it's a firmware issue, loading the correct one using patchram solves this problem.
Edit /etc/rc.local with the these lines :
brcm_patchram_plus --patchram /lib/firmware/brcm/BCM40183B2.hcd --enable_hci --bd_addr 11:22:33:44:55:66 --no2bytes --tosleep 1000 /dev/ttyS1
su -c 'hciattach /dev/ttyS1 any'
exit 0
I haven't found the way to retrieve factory Bluetooth mac address, running the patchram command without the bd_addr option assign a different mac address witch is not the factory one. I would be interested if you know how to retrieve this address.
4G LTE modem :
The cellular modem works out of the box, you just have to put a sim card, install wvdial. I'm pasting a copy of my configuration file /etc/wvdial.conf for reference :
[Dialer Defaults]
Init1 = ATZ
Init2 = ATQ0 V1 E1 S0=0
Init3 = AT+CGDCONT=1,"IP","yourapnhere"
Stupid Mode = true
ISDN = 0
Modem Type = Analog Modem
Password = " "
New PPPD = yes
Username = " "
Phone = *99#
Modem = /dev/ttyUSB0
Baud = 9600
The DTB and the configuration files can be found on my github repo.