dmesg
...
[  556.580000] usb 1-1.1: new full-speed USB device number 6 using ehci-platform
[  556.710000] usb 1-1.1: New USB device found, idVendor=0403, idProduct=6001
[  556.710000] usb 1-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[  556.710000] usb 1-1.1: Product: USB <-> Serial
[  556.710000] usb 1-1.1: Manufacturer: FTDI
[  556.720000] ftdi_sio 1-1.1:1.0: FTDI USB Serial Device converter detected
[  556.720000] usb 1-1.1: Detected FT232BM
...

USB serial adapters

kmod-usb-serial-ftdi
 
0403  Future Technology Devices International, Ltd
    0232  Serial Converter
    6001  FT232 USB-Serial (UART) IC
...
opkg update
opkg install kmod-usb-serial kmod-usb-serial-ftdi