configure loading of bitstream at boot time

flake.nix

@@ -180,6 +180,22 @@
         '';
       };
 
+      fast-servo-config = { config, pkgs, lib, ... }: {
+        environment.systemPackages = [
+          linien-server
+        ];
+        boot.postBootCommands = lib.mkAfter ''
+
+          # Program the FPGA
+          set +x
+          echo Flashing bitstream...
+          echo 0 > /sys/class/fpga_manager/fpga0/flags
+          mkdir -p /lib/firmware
+          cp ${fast-servo-gateware}/gateware.bin /lib/firmware/
+          echo gateware.bin > /sys/class/fpga_manager/fpga0/firmware
+        '';
+      };
+
       mkbootimage = pkgs.stdenv.mkDerivation {
         pname = "mkbootimage";
         version = "2.3dev";
@@ -208,10 +224,7 @@
           inherit nixpkgs;
           extraModules = [
             "${patched-not-os}/zynq_image.nix"
-          ] ++ pkgs.lib.optionals (board == "fast-servo") [
-            ({ config, pkgs, ... }: {
-              environment.systemPackages = [ linien-server ];
-            })];
+          ] ++ pkgs.lib.optionals (board == "fast-servo") [ fast-servo-config ];
           system = "x86_64-linux";
           inherit crossSystem;
         });