This is a very simple module that installs a single udev rule. The rule set the ownership of all /dev/i2c-* devices to a group, "i2c" by default but can be changed. The "uaccess" tag also makes systemd add an ACL for users with a seat[1]. Fix issue #91771 [1]: https://enotty.pipebreaker.pl/2012/05/23/linux-automatic-user-acl-management/
		
			
				
	
	
		
			44 lines
		
	
	
		
			932 B
		
	
	
	
		
			Nix
		
	
	
	
	
	
			
		
		
	
	
			44 lines
		
	
	
		
			932 B
		
	
	
	
		
			Nix
		
	
	
	
	
	
{ config, lib, ... }:
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with lib;
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let
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  cfg = config.hardware.i2c;
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in
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{
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  options.hardware.i2c = {
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    enable = mkEnableOption ''
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      i2c devices support. By default access is granted to users in the "i2c"
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      group (will be created if non-existent) and any user with a seat, meaning
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      logged on the computer locally.
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    '';
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    group = mkOption {
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      type = types.str;
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      default = "i2c";
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      description = ''
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        Grant access to i2c devices (/dev/i2c-*) to users in this group.
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      '';
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    };
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  };
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  config = mkIf cfg.enable {
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    boot.kernelModules = [ "i2c-dev" ];
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    users.groups = mkIf (cfg.group == "i2c") {
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      i2c = { };
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    };
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    services.udev.extraRules = ''
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      # allow group ${cfg.group} and users with a seat use of i2c devices
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      ACTION=="add", KERNEL=="i2c-[0-9]*", TAG+="uaccess", GROUP="${cfg.group}", MODE="660"
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    '';
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  };
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  meta.maintainers = [ maintainers.rnhmjoj ];
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}
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