nixos/tuxedo-control-center: warn if tuxedo-keyboard is too old

Tuxedo Control Center has a minimum version requirement on the version
of the "tuxedo_io" kernel module (at runtime).

nix/module.nix

@@ -4,6 +4,7 @@ with lib;
 
 let
   cfg = config.hardware.tuxedo-control-center;
+  tuxedo-keyboard = config.boot.kernelPackages.tuxedo-keyboard;
 
   tuxedo-control-center = pkgs.callPackage ./tuxedo-control-center {};
 in
@@ -30,7 +31,20 @@ in
 
   config = mkIf cfg.enable {
     hardware.tuxedo-keyboard.enable = true;
-    boot.kernelModules = [ "tuxedo_io" ];
+    boot.kernelModules = [
+      # Tuxedo Control Center has a requirement on the minimum version
+      # of "tuxedo_io" kernel module.
+      # The exact requirement is currently in the 
+      # "src/native-lib/tuxedo_io_lib/tuxedo_io_ioctl.h" file of tuxedo-control-center
+      # (i.e. the #define of MOD_API_MIN_VERSION).
+      # The respective version of the module itself is in the 
+      # "src/tuxedo_io/tuxedo_io.c" file of tuxedo-keyboard
+      # (i.e. the #define of MODULE_VERSION).
+      (warnIf
+        ((builtins.compareVersions tuxedo-keyboard.version "3.1.0") < 0)
+        "Tuxedo Control Center requires at least version 3.1.0 of tuxedo-keyboard (0.2.6 tuxedo_io kernel module); current version is ${tuxedo-keyboard.version}"
+        "tuxedo_io")
+    ];
 
     environment.systemPackages = [ cfg.package ];
     services.dbus.packages = [ cfg.package ];

nix/tuxedo-control-center/README.md

@@ -2,4 +2,5 @@
 
 1. Run `update.sh` and pass the version you want to update to as a parameter. For example: `./update.sh 1.0.9`
 1. Bump the version and SHA-256 of `tuxedo-control-center` in [default.nix](./default.nix).
+1. Adjust the version check of `tuxedo-keyboard` in [module.nix](../module.nix).
 1. Build and test.

nix/tuxedo-control-center/default.nix

@@ -6,10 +6,7 @@
 let
   ## Update Instructions
   #
-  # 1. Run `./update.sh` and pass the version you want to update to as
-  #    a parameter. For example: `./update.sh 1.1.1`
-  # 2. Bump the version attribute and src SHA-256 here.
-  # 3. Build and test.
+  # see ./README.md
   version = "1.2.2";
 
   # keep in sync with update.sh!