The Wii U GamePad communicates with other devices via the use of a slightly obfuscated version of Wi-Fi 802.11n and WPA2 AES-CCMP. Luckily, the required modifications for support of this obfuscated Wi-Fi protocol can be applied in userland without any kernel modification.
Using libdrc to communicate with a Wii U GamePad however also requires the host computer to get some information from its Wi-Fi interface which is not exported by default on Linux. For this purpose, a kernel module needs to be built and loaded on the machine to provide the required information.
Connecting a Wii U GamePad to a computer requires compatible Wi-Fi hardware. Any Wi-Fi NIC that can create access points on 5GHz 802.11 channels could potentially work. In practice, the following drivers/NICs were tested:
rt2800usb: works with Linux >= 3.12
ath9k/carl9170: works with some caveats (communication might desync more often because of a TSF drifting issue)
A very simple Linux kernel patch is required to export the Wi-Fi NIC Time
Synchronization Function (TSF) to userland. A patched version of the
mac80211 Linux module can be found on the memahaxx/drc-mac80211
repository. It is based on Linux 3.12.3 but the patch should apply cleanly to
most recent Linux versions (e.g. Ubuntu > 13.10).
To check if the patched module is being used, try:
test -f /sys/class/net/$WLANIFACE/tsf && echo ok
There are two methods to pair a GamePad with a computer:
Use a GamePad that has previously paired with a Wii U console. Connect the computer in client mode to the Wii U console to do the WPS negotiation and obtain the same details.
Download and build memahaxx/drc-hostap. Make sure CONFIG_WPS and
CONFIG_TENDONIN are enabled for both hostapd and wpa_supplicant.
Ensure that no other program (e.g. a system wpa_supplicant or
NetworkManager is currently managing the target interface wlanX).
Make a new config get_psk.conf file consisting of these two lines:
ctrl_interface=/var/run/wpa_supplicant_drc
update_config=1
In a terminal, execute:
sudo ./wpa_supplicant -Dnl80211 -i wlanX -c get_psk.conf
Replace wlanX with the correct network interface.
In a separate terminal, execute:
sudo ./wpa_cli -p /var/run/wpa_supplicant_drc
Press the sync button twice on your Wii U console.
In wpa_cli, type:
scan
Once you see <3>CTRL-EVENT-SCAN-RESULTS type:
scan_results
On the returned list, you should see an entry with an SSID along the lines
of WiiUAABBCCDDEEFF_STA1. Take a note of the BSSID for this access
point.
In wpa_cli, type:
wps_pin BSSID PIN
where BSSID is the BSSID you noted in the previous step, and PIN
is the PIN you calculated from the Pairing information.
You should see some output, including <3>WPS-CRED-RECEIVED followed
by <3>WPS-SUCCESS.
Ctrl+C wpa_supplicant.
To see your PSK, type:
cat get_psk.conf
Have a computer host WPS and sync a GamePad directly with it. TODO: write instructions for this method.
First of all, build the patched hostapd version available from
memahaxx/drc-hostap:
git clone https://bitbucket.org/memahaxx/drc-hostap
cd drc-hostap
cp conf/hostapd.config hostapd/.config
cd hostapd
make -j4
Adapt the example configuration file from conf/wiiu_ap_normal.conf:
Change the network interface name
Change the network SSID
Change the PSK used for the network WPA2 security
Stop anything that might conflict with hostapd (for example, NetworkManager is a known offender unless configured specifically to avoid this). Then start the access point:
sudo ./hostapd -dd ../conf/wiiu_ap_normal.conf
If everything worked well, hostapd should be waiting for devices to connect instead of exiting immediately.
Make sure that no network interface is using the 192.168.1.0/24 network (it is used for communication with the GamePad), then configure the interface:
sudo ip a a 192.168.1.10/24 dev $IFACE
sudo ip l set mtu 1800 dev $IFACE
The GamePad uses DHCP to get an IP address from the Wii U or the PC it is connected to. This IP address should always be 192.168.1.11. Any simple DHCP server should work, but we recommend using netboot, a very simple, self-contained DHCP server.
Using netboot, the following command line should work (with the propre MAC address of the GamePad):
./netboot 192.168.1.255 192.168.1.10 192.168.1.11 aa-bb-cc-dd-ee-ff
From there, when powering on the GamePad, it should get an IP from netboot and start sending packets to the computer. Using libdrc demos should work.