USB Serial adapters on TAS-x68

[mattq]

Hi all, I'm starting to develop small apps on a TAS-168 (current QNAP firmware 4.2.0) and want to add 1 or more COM/tty serial port adapters on the USB ports to give me RS-232 or RS-485. However, there doesn't seem to be any driver module anywhere on the system, at least nothing like is mentioned in several threads here:
http://forum.qnap.com/viewtopic.php?f=182&t=100368
http://forum.qnap.com/viewtopic.php?f=182&t=117253

Does anyone have or know where to get compatible driver modules? I have FTDI and PL2303 adapters so both would be nice.

I've connected an FTDI based USB-RS232 adapter and can see it detected in dmesg, and lsusb shows it. See output of a few commands below:

# uname -a
Linux NASxxxxxx 3.10.20-al-2.5.3 #3 SMP PREEMPT Wed Feb 3 08:21:06 CST 2016 armv7l unknown

# lsusb
Bus 001 Device 002: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 003: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC
Bus 003 Device 002: ID 174c:2074 ASMedia Technology Inc.
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 002: ID 174c:3074 ASMedia Technology Inc.
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 004 Device 003: ID 174c:55aa ASMedia Technology Inc.
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

# lsmod
Module Size Used by Tainted: P
fbdisk 17647 0 - Live 0x7f210000 (O)
bridge 78761 0 - Live 0x7f1f2000
stp 1395 1 bridge, Live 0x7f1ee000
fnotify 26101 0 - Live 0x7f1e3000 (PO)
ufsd 683098 0 - Live 0x7f053000 (PO)
jnl 42392 1 ufsd, Live 0x7f043000 (O)
rtksd_mod 20422 0 - Live 0x7f039000
flashcache 3610 1 - Live 0x7f035000 (O)
dm_thin_pool 51891 0 - Live 0x7f021000
dm_bio_prison 3779 1 dm_thin_pool, Live 0x7f01c000
dm_persistent_data 44864 1 dm_thin_pool, Live 0x7f009000
hal_netlink 4430 0 - Live 0x7f004000 (O)
raid_class 3169 0 - Live 0x7f000000

# dmesg
[ 23.716927] md13: bitmap initialized from disk: read 1 pages, set 6 of 8 bits
[ 23.750986] md13: detected capacity change from 0 to 469893120
[ 34.022327] md: bind<sda2>
... lots more startup lines ...
[7697.532134] hub 1-1:1.0: port 3, status 0101, change 0000, 12 Mb/s
[7697.611421] usb 1-1.3: new full-speed USB device number 3 using rtk-ehci
...

Any info appreciated!