I have an ACR122U NFC smartcard reader that I use with Linux Mint 17.1 and Kubuntu 15.04. This is a quick guide on how to get the reader working from a clean install of Mint or Kubuntu.

Ensure that pcscd and pcsc-tools are installed.

$ apt-get install pcscd pcsc-tools

We will use pcsc_scan to test if the reader has been detected. If I run this now, I get the following output which picks up the smartcard reader built into my laptop (Alcor Micro AU9540):

PC/SC device scanner
V 1.4.22 (c) 2001-2011, Ludovic Rousseau <ludovic.rousseau@free.fr>
Compiled with PC/SC lite version: 1.8.10
Using reader plug'n play mechanism
Scanning present readers...
0: Alcor Micro AU9540 00 00

Wed Apr 29 22:33:30 2015
Reader 0: Alcor Micro AU9540 00 00
  Card state: Card removed,

Currently, the ACR122U will not be picked up by pcsc_scan. In order for the OS to detect this we need to disable the kernel NFC drivers from loading, to do this add the following to /etc/modprobe.d/blacklist.conf.

install nfc /bin/false
install pn533 /bin/false

The drivers for the ACR122U reader can now be downloaded and installed from the ACR122U product page (Linux PC/SC Driver). Naturally for both Linux Mint and Kubuntu I used the driver provided in the Ubuntu folder of the driver download.

Restart your computer for the above changes to take affect.

You should now find that if you run pcsc_scan that there is an entry for ACS ACR122U.

PC/SC device scanner
V 1.4.22 (c) 2001-2011, Ludovic Rousseau <ludovic.rousseau@free.fr>
Compiled with PC/SC lite version: 1.8.10
Using reader plug'n play mechanism
Scanning present readers...
0: ACS ACR122U 00 00
1: Alcor Micro AU9540 00 00

Wed Apr 29 22:57:10 2015
Reader 0: ACS ACR122U 00 00
  Card state: Card removed, 
Reader 1: Alcor Micro AU9540 00 00
  Card state: Card removed, 

That's it! Your ACR122U reader is now ready to use!