QMK Kernel Module

This system is an experiment on Linux - specifically the Raspberry Pi - to have the Pi do all gpio/matrix scanning, and sending keycodes directly to the OS. There are many exciting possibilities with a system like this, and this repo is only scratching the surface.

It's separated into a Loadable Kernel Module, libqmk (a proof-of-concept for a abstracted version of qmk_firmware), and a Device Tree Overlay configuration (which is also loadable). Both can be installed and loaded at boot, or they can be loaded at runtime to aid in development.

These are the options exposed for doing everything all together:

make KEYBOARD=planck load-all   # builds the kernel module and planck overlay, and loads both
make clean-all                  # cleans up all the files

Kernel Module

This is a QMK-inspired kernel module based on matrix_keypad, which includes instructions for layers, and can serve as a learning tool for how things work in QMK, via sysfs - writing to the platform device in the filesystem (more documentation will come once this is built-out more).

Building

You'll need the Raspberry Pi kernel headers installed, along with the basic tools for building, and some tools for testing:

sudo apt install raspberrypi-kernel-headers git bc bison flex libssl-dev evtest input-utils

make                 # builds the kernel module
sudo make load       # builds and loads the kernel module
sudo make unload     # unloads the kernel module
sudo make install    # builds and installs the kernel module
sudo make remove     # removes the kernel module
make clean           # cleans up the build files

Installing

Sometimes the depmod fails - I'm not entirely sure if that's normal, or how the configuration could be changed. The module is dependent on libcomposite and input_polldev - these modules may need to be added to your etc/modules in addition to qmk, depending on if you're installing it or not.

Device Tree Overlays

For planck, the Planck PCB wired up to a Raspberry Pi like this:

COL 0: BCM 20
    1: BCM 21
    2: BCM 6
    3: BCM 24
    4: BCM 23
    5: BCM 22
ROW 0: BCM 12
    1: BCM 13
    2: BCM 16
    3: BCM 19
    4: BCM 25
    5: BCM 10
    6: BCM 9
    7: BCM 11

List of event codes can be found here.

The installation was based on this guide.

Building

make KEYBOARD=planck                 # builds the "planck" overlay
sudo make KEYBOARD=planck load       # builds and loads the overlay
sudo make KEYBOARD=planck unload     # unloads the overlay
sudo make KEYBOARD=planck install    # builds and installs the overlay
sudo make KEYBOARD=planck remove     # removes the overlay
make KEYBOARD=planck clean           # cleans up the build files

Other info

sudo apt install xserver-xorg-input-libinput xserver-xorg-input-kbd may be required to get things working in X (if you've installed the lite version of Raspbian).

/boot/config.txt additions

dtoverlay=dwc2
dtoverlay=planck

/etc/modules additions

libcomposite
input-polldev
qmk

QMK Helper

This passes keycodes onto a computer for the Pi Zero & Zero W and displays other useful info. libusbgx is required for the passthrough. It requires there packages to build:

sudo apt install autoconf libtool libconfig-dev

You can build it like this:

cd lib/libusbgx
autoreconf -i
./configure --prefix=build
make
make install 

Once that is done, make -C helper from the root folder. qmk_helper is the console program, and takes these arguments:

-o open gadget
-c close gadget
-t test
-d daemon mode, open and pass through keycodes

qmk_ghelper is the gui version - make -C helper qmk_ghelper to build. Both need sudo privegdes to run.

Git helper

You can run git config --local include.path ../.gitconfig in the main repo to have a libqmk alias for submodules. Run this from the lib/libqmk directory to be able to push easier with git libqmk push: git config url."ssh://git@".insteadOf https://