USB-gLINK

Connecting

Install packages:

 sudo apt install libqmi-utils udhcpc

Create new file /etc/qmi-network.conf.

 sudo vi /etc/qmi-network.conf

Inside type your APN settings:

 APN=internet.xxx.xxx
 APN_USER=xxxxx APN_PASS=xxxxx

Start network and check status

 sudo qmi-network /dev/cdc-wdm0 start
 sudo qmi-network /dev/cdc-wdm0 status
 ......
 Status: connected

Check interface name

 dmesg | grep "wwan0"
 ....
 qmi_wwan 3-1:1.4 wwp8s0u1i4: renamed from wwan0

Obtain ip address:

 sudo udhcpc -q -f -n -i wwp8s0u1i4

Check interface

 ifconfig wwp8s0u1i4
 wwp8s0u1i4: flags=4305<UP,POINTOPOINT,RUNNING,NOARP,MULTICAST>  mtu 1500
       inet 10.167.84.92  netmask 255.255.255.248  destination 10.167.84.92
       unspec 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  txqueuelen 1000  (UNSPEC)
       RX packets 47  bytes 16255 (16.2 KB)
       RX errors 0  dropped 0  overruns 0  frame 0
       TX packets 163  bytes 16212 (16.2 KB)
       TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
 

Enabling serial port

By default when you connect the USB-gLINK to PC, qmi_wwan module is used. This is because the VID/PIN is not listed in drivers/usb/serial/option.c.

Login as root user

 su -

Probe usbserial module

 modprobe usbserial

Bind device VID/PID to usbserial

 echo 2c7c 0125 > /sys/bus/usb-serial/drivers/generic/new_id

Check result

 dmesg
 .....
 usb 3-1: new high-speed USB device number 36 using xhci_hcd
 usb 3-1: New USB device found, idVendor=2c7c, idProduct=0125
 usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
 usb 3-1: Product: EG25-G
 usb 3-1: Manufacturer: Quectel
 usbserial_generic 3-1:1.0: The "generic" usb-serial driver is only for testing and one-off prototypes.
 usbserial_generic 3-1:1.0: Tell linux-usb@vger.kernel.org to add your device to a proper driver.
 usbserial_generic 3-1:1.0: generic converter detected
 usb 3-1: generic converter now attached to ttyUSB0
 usbserial_generic 3-1:1.1: The "generic" usb-serial driver is only for testing and one-off prototypes.
 usbserial_generic 3-1:1.1: Tell linux-usb@vger.kernel.org to add your device to a proper driver.
 usbserial_generic 3-1:1.1: generic converter detected
 usb 3-1: generic converter now attached to ttyUSB1
 usbserial_generic 3-1:1.2: The "generic" usb-serial driver is only for testing and one-off prototypes.
 usbserial_generic 3-1:1.2: Tell linux-usb@vger.kernel.org to add your device to a proper driver.
 usbserial_generic 3-1:1.2: generic converter detected
 usb 3-1: generic converter now attached to ttyUSB2
 usbserial_generic 3-1:1.3: The "generic" usb-serial driver is only for testing and one-off prototypes.
 usbserial_generic 3-1:1.3: Tell linux-usb@vger.kernel.org to add your device to a proper driver.
 usbserial_generic 3-1:1.3: generic converter detected
 usb 3-1: generic converter now attached to ttyUSB3