moby: enable gpsd

hosts/by-name/moby/default.nix

@@ -14,6 +14,7 @@
   imports = [
     ./bootloader.nix
     ./fs.nix
+    ./gps.nix
     ./kernel.nix
     ./polyfill.nix
   ];

hosts/by-name/moby/gps.nix

@@ -0,0 +1,24 @@
+# pinephone GPS happens in EG25 modem
+# serial control interface to modem is /dev/ttyUSB2
+# after enabling GPS, readout is /dev/ttyUSB1
+#
+# minimal process to enable modem and GPS:
+# - `echo 1 > /sys/class/modem-power/modem-power/device/powered`
+# - `screen /dev/ttyUSB2 115200`
+#   - `AT+QGPSCFG="nmeasrc",1`
+#   - `AT+QGPS=1`
+#
+# now, something like `gpsd` can directly read from /dev/ttyUSB1.
+#
+# initial GPS fix can take 15+ minutes.
+# meanwhile, services like eg25-manager can speed this up by uploading assisted GPS data to the modem.
+#
+# geoclue somehow fits in here as a geospatial provider that leverages GPS and also other sources like radio towers
+
+{ ... }:
+{
+  services.gpsd.enable = true;
+  services.gpsd.devices = [ "/dev/ttyUSB1" ];
+
+  # TODO: enable eg25-manager, and bring online both the modem and GPS on boot
+}

hosts/common/programs/mepo.nix

@@ -9,12 +9,18 @@
     persist.private = [
       { type = "file"; path = ".cache/mepo/savestate"; }
     ];
+
+    # give mepo access to gpsd for location data, if that's enabled.
+    # same with geoclue2.
+    suggestedPrograms = lib.optional config.services.gpsd.enable "gpsd"
+      ++ lib.optional config.services.geoclue2.enable "geoclue2-with-demo-agent"
+    ;
   };
 
-  programs.mepo = lib.mkIf config.sane.programs.mepo.enabled {
-    # enable location services (via geoclue)
-    enable = true;
-    # more precise, via gpsd ("may require additional config")
-    # programs.mepo.gpsd.enable = true
-  };
+  # programs.mepo = lib.mkIf config.sane.programs.mepo.enabled {
+  #   # enable location services (via geoclue)
+  #   enable = true;
+  #   # more precise, via gpsd ("may require additional config")
+  #   # programs.mepo.gpsd.enable = true
+  # };
 }