Add a Nix derivation for working with tmk_keyboard

shell.nix

@@ -0,0 +1,49 @@
+# A Nix shell for tmk_keyboard.
+# Based on the shell for qmk/qmk_firmware:
+# https://github.com/qmk/qmk_firmware/blob/master/shell.nix
+
+with import <nixpkgs> {
+  config = {
+    allowUnsupportedSystem = true;
+  };
+}; 
+
+let
+  avrbinutils = pkgsCross.avr.buildPackages.binutils;
+  avrlibc = pkgsCross.avr.libcCross;
+
+  avr_incflags = [
+    "-isystem ${avrlibc}/avr/include"
+    "-B${avrlibc}/avr/lib/avr5"
+    "-L${avrlibc}/avr/lib/avr5"
+    "-B${avrlibc}/avr/lib/avr35"
+    "-L${avrlibc}/avr/lib/avr35"
+    "-B${avrlibc}/avr/lib/avr51"
+    "-L${avrlibc}/avr/lib/avr51"
+  ];
+
+  avrgcc = pkgsCross.avr.buildPackages.gcc.overrideAttrs (oldAttrs: rec {
+    name = "avr-gcc-8.1.0";
+    src = fetchurl {
+      url = "mirror://gcc/releases/gcc-8.1.0/gcc-8.1.0.tar.xz";
+      sha256 = "0lxil8x0jjx7zbf90cy1rli650akaa6hpk8wk8s62vk2jbwnc60x";
+    };
+  });
+in 
+
+stdenv.mkDerivation {
+  name = "tmk_keyboard";
+
+  buildInputs = [
+    diffutils
+    dfu-programmer
+    dfu-util
+    avrbinutils
+    avrgcc
+    avrlibc
+    avrdude
+  ];
+
+  CFLAGS = avr_incflags;
+  ASFLAGS = avr_incflags;
+}

tmk_core/doc/build.md

@@ -14,6 +14,7 @@ Download and Install
 
 If you use PJRC Teensy you don't need step 2 and 3 above, just get [Teensy loader][teensy-loader].
 
+If you use NixOS or the Nix package manager, just run `nix-shell`.
 
 ### 2. Download source
 You can find firmware source at github: