dmesg
...
[  103.970000] usb 1-1.1: USB disconnect, device number 3
[  132.110000] usb 1-1.1: new full-speed USB device number 5 using ehci-platform
[  132.240000] usb 1-1.1: New USB device found, idVendor=10c4, idProduct=ea60
[  132.240000] usb 1-1.1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  132.240000] usb 1-1.1: Product: CP2102 USB to UART Bridge Controller
[  132.250000] usb 1-1.1: Manufacturer: Silicon Labs
[  132.250000] usb 1-1.1: SerialNumber: 0001
...

USB serial adapters

kmod-usb-serial-cp210x
 
10c4  Cygnal Integrated Products, Inc. (Silicon Labs)
    80a9  CP210x to UART Bridge Controller
    ea60  CP210x UART Bridge / myAVR mySmartUSB light
...
opkg update
opkg install kmod-usb-serial kmod-usb-serial-cp210x