Add support for System76 hardware, specifically the Darter Pro 6.

This relies on new `system76`, `system76-acpi`, and `system76-io`
packages in `linuxPackages` in Nixpkgs.

CODEOWNERS

@@ -5,3 +5,4 @@ lenovo/thinkpad/x230 @makefu @yegortimoshenko
 lenovo/thinkpad/x250 @Mic92
 pcengines/apu @yegortimoshenko
 purism/librem/13v3 @yegortimoshenko
+system76/darp6 @khumba

README.md

@@ -126,6 +126,8 @@ See code for all available configurations.
 | [Purism Librem 15v3][]            | `<nixos-hardware/purism/librem/15v3>`              |
 | Supermicro A1SRi-2758F            | `<nixos-hardware/supermicro/a1sri-2758f>`          |
 | Supermicro X10SLL-F               | `<nixos-hardware/supermicro/x10sll-f>`             |
+| [System76 (generic)][]            | `<nixos-hardware/system76>`                        |
+| [System76 Darter Pro 6][]         | `<nixos-hardware/system76/darp6>`                  |
 | [Toshiba Chromebook 2 `swanky`][] | `<nixos-hardware/toshiba/swanky>`                  |
 | [Tuxedo InfinityBook v4][]        | `<nixos-hardware/tuxedo/infinitybook/v4>`          |
 
@@ -151,6 +153,8 @@ See code for all available configurations.
 [Microsoft Surface Pro 3]: microsoft/surface-pro/3
 [Raspberry Pi 2]: raspberry-pi/2
 [Samsung Series 9 NP900X3C]: samsung/np900x3c
+[System76 (generic)]: system76
+[System76 Darter Pro 6]: system76/darp6
 [Purism Librem 13v3]: purism/librem/13v3
 [Purism Librem 15v5]: purism/librem/15v5
 [Toshiba Chromebook 2 `swanky`]: toshiba/swanky

flake.nix

@@ -56,6 +56,8 @@
       pcengines-apu = import ./pcengines/apu;
       raspberry-pi-2 = import ./raspberry-pi/2;
       samsung-np900x3c = import ./samsung/np900x3c;
+      system76 = import ./system76;
+      system76-darp6 = import ./system76/darp6;
       purism-librem-13v3 = import ./purism/librem/13v3;
       purism-librem-15v3 = import ./purism/librem/15v3;
       supermicro-a1sri-2758f = import ./supermicro/a1sri-2758f;

system76/darp6/default.nix

@@ -0,0 +1,27 @@
+# Hardware profile for the Darter Pro 6 laptop by System76.
+#
+# https://system76.com/laptops/darter
+
+{ config, ... }:
+let
+  # darp6 needs system76-acpi-dkms, not system76-dkms:
+  #
+  # [1] https://github.com/pop-os/system76-dkms/issues/39
+  # jackpot51> system76-acpi-dkms is the correct driver to use on the darp6
+  #
+  # system76-io-dkms also appears to be loaded on darp6 with Pop!_OS, and
+  # system76-dkms does not, and in fact refuses to load.
+  packages = with config.boot.kernelPackages; [ system76-acpi system76-io ];
+in
+{
+  imports = [
+    ../../common/pc/laptop
+    ../../common/pc/laptop/ssd
+  ];
+
+  boot.extraModulePackages = packages;
+
+  # system76_acpi automatically loads on darp6, but system76_io does not.
+  # Explicitly list all modules to be loaded, for consistency.
+  boot.kernelModules = map (drv: drv.moduleName) packages;
+}

system76/default.nix

@@ -0,0 +1,22 @@
+# Implementation of support for general System76 hardware.
+#
+# https://system76.com/
+
+{ config, ... }:
+let
+  # Try loading all system76 modules.  The ones not relevant to specific
+  # hardware won't be loaded.
+  packages = with config.boot.kernelPackages; [ system76 system76-acpi system76-io ];
+in
+{
+  imports = [ ../common/pc ];
+
+  # This seems to be required for system76-driver.
+  boot.kernelParams = [ "ec_sys.write_support=1" ];
+
+  boot.extraModulePackages = packages;
+
+  # Explicitly attempt to load all available system76 modules.  Some do
+  # (system76-acpi), some don't (system76-io).
+  boot.kernelModules = map (drv: drv.moduleName) packages;
+}