nixos: add try to make gpio work on rpi

Author: zahidkizmaz

nixos/hosts/pi4b/configuration.nix

@@ -1,6 +1,7 @@
-{ stateVersion, ... }:
+{ pkgs, stateVersion, ... }:
 {
   hardware = {
+    enableAllFirmware = true;
     bluetooth.enable = true;
     bluetooth.powerOnBoot = true;
   };
@@ -16,6 +17,11 @@
     ];
   };
 
+  environment.systemPackages = with pkgs; [
+    libraspberrypi
+    raspberrypi-eeprom
+  ];
+
   i18n.defaultLocale = "en_US.UTF-8";
   console = {
     keyMap = "us";

nixos/hosts/pi4b/fan-control.nix

@@ -2,6 +2,7 @@
 {
   environment.systemPackages = with pkgs; [
     haskellPackages.gpio
+    libgpiod
     libraspberrypi
   ];
 

nixos/hosts/pi4b/gpio.nix

@@ -0,0 +1,19 @@
+{ pkgs, user, ... }:
+{
+  # Create gpio group
+  users.groups.gpio = { };
+
+  # Change permissions gpio devices
+  services.udev.extraRules = ''
+    SUBSYSTEM=="bcm2835-gpiomem", KERNEL=="gpiomem", GROUP="gpio",MODE="0660"
+    SUBSYSTEM=="gpio", KERNEL=="gpiochip*", ACTION=="add", RUN+="${pkgs.bash}/bin/bash -c 'chown root:gpio /sys/class/gpio/export /sys/class/gpio/unexport ; chmod 220 /sys/class/gpio/export /sys/class/gpio/unexport'"
+    SUBSYSTEM=="gpio", KERNEL=="gpio*", ACTION=="add",RUN+="${pkgs.bash}/bin/bash -c 'chown root:gpio /sys%p/active_low /sys%p/direction /sys%p/edge /sys%p/value ; chmod 660 /sys%p/active_low /sys%p/direction /sys%p/edge /sys%p/value'"
+  '';
+
+  # Add user to group
+  users = {
+    users."${user}" = {
+      extraGroups = [ "gpio" ];
+    };
+  };
+}