Hi, welcome to the PMMS (PinePhone Modem Mainline Suite)
It's a set of tools and scripts to make the development easier.
DO NOT use this if you you use your PinePhone as your main device. This MAY damage the modem PERMANENTLY. No warranties!
To get mainline going on your modem:
Unlock the modem (instructions adapted from xnux.eu):
# Open a console at the modem AT tty
picocom /dev/ttyUSB2 --baud 9600
# Get the ADB unlock key for your modem
# Save the output of this command.
AT+QADBKEY? [enter]
# Compile the tools/unlocker/unlocker.c
cc unlocker.c
# Generate the unlock key specific to your modem
./a.out <your key you just got>
# To unlock the modem, pass the first two commands from the unlocker [in the TTY]
AT+QADBKEY="<your unlock code>"
AT+QCFG="usbcfg",0x2C7C,0x125,1,1,1,1,1,1,0
# Reboot the modem to fastboot
adb reboot bootloader
# Flash a custom bootloader build
# You can either use the shipped prebuilt, or compile it from [1]
fastboot flash aboot prebuilts/emmc_appsboot.mbn
# Reboot your modem to make sure everything is fine
fastboot reboot
# The modem should now boot to its own OS and if it does, it's ready!
If you want to, replace dtb/qcom-mdm9607-quectel-eg25.dtb and zImage files with your own ones.
If you're running this for the first time, run ./firstrun.sh
If you're on a fresh Arch Linux ARM install, run ./scripts/setup_arch.sh
Now, simply run sudo ./qletsgo.sh (or ./q[tab][enter] ;))
Should the modem boot, running telnet 173.16.42.1 should drop you to an initrd shell.
Have fun!