https://www.raspberrypi.org/documentation/configuration/device-tree.md https://www.raspberrypi.org/documentation/configuration/pin-configuration.md https://github.com/systemd-mailing-devs/systemd-mailing-list/commit/405e116f57b1cf33d4ca0294ab045a9f709bbc96 http://www.wiki.xilinx.com/Linux+GPIO+Driver http://derekmolloy.ie/gpios-on-the-beaglebone-black-using-device-tree-overlays/#
https://www.kernel.org/doc/Documentation/devicetree/bindings/input/ https://github.com/notro/fbtft_tools/wiki/gpio_keys_device http://blog.thestateofme.com/2012/08/10/raspberry-pi-gpio-joystick/ http://www.wiki.xilinx.com/Linux+GPIO+Driver https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/gpio https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/input.h file:///boot/overlays/tinylcd35-overlay.dtb https://github.com/raspberrypi/linux/blob/c8baa9702cc99de9614367d0b96de560944e7ccd/arch/arm/boot/dts/overlays/tinylcd35-overlay.dts