microsoft/surface: remove repos.nix file and update README

Author: 8bitbuddhist

microsoft/surface/README.md

@@ -1,8 +1,3 @@
-# NOTE: Structure changes from 2023-01-10
-
-Please read the [Deprecated Behaviour README](./OLD-BEHAVIOUR-DEPRECATION.md) to understand how some structural changes to
-the code might affect you!
-
 # Derivations for Microsoft Surface notebooks
 
 These derivatives use the patches from the [linux-surface repo](https://github.com/linux-surface/linux-surface/tree/master/patches).
@@ -32,13 +27,24 @@ Not all hardware is fully supported, but the
 [linux-surface feature matrix](https://github.com/linux-surface/linux-surface/wiki/Supported-Devices-and-Features#feature-matrix)
 provides details on which devices are supported on which types of machine.
 
-The kernel-specific derivations are under the [`common/kernel/`](./common/kernel/) sub-directory.
-In order to simplify maintenance of the Nix code, only the most-recent kernel patch-set is expected
-to be maintained in this repo.
+The kernel-specific derivations are under the [`common/kernel/`](./common/kernel/) sub-directory. This directory defines patch sets for each supported kernel release (see Kernel versions below for more information).
 
 _*NOTE:*_ Some built-in Kernel config items need to be set, that aren't set by default:
 - https://github.com/linux-surface/surface-aggregator-module/wiki/Testing-and-Installing
 
+#### Kernel versions
+
+There are multiple versions of the Surface kernel available:
+
+- `lts`, which tracks the latest LTS release.
+- `latest`, which tracks the most recent release.
+
+This repo uses `lts` by default, but you can switch it to `latest` by adding this to your configuration file:
+
+```nix
+microsoft-surface.kernelVersion = "latest";
+```
+
 ### Support Tools
 
 ### IPTS
@@ -120,3 +126,7 @@ References:
 - https://github.com/thebitstick/surfacego-wifi
 - https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/tree/ath10k
 - https://wireless.wiki.kernel.org/en/users/drivers/ath10k/firmware
+
+## Structural changes from earlier versions (2023-01-10 and earlier)
+
+If you're upgrading from an older version of nixos-hardware, please read the [Deprecated Behaviour README](./OLD-BEHAVIOUR-DEPRECATION.md) to understand how some structural changes to the code might affect you!

microsoft/surface/common/default.nix

@@ -1,19 +1,19 @@
 { config, lib, pkgs, ... }:
 
 let
-  inherit (lib) mkDefault mkOption types;
+  inherit (lib) fetchFromGitHub mkDefault mkOption types versions;
 
-  shortVersion = config.microsoft-surface.kernelVersion;
-  version = if shortVersion == "6.12" then
+  # Set the full kernel version and hashes
+  version =
+    if config.microsoft-surface.kernelVersion == "lts" then
       "6.12.19"
-    else if shortVersion == "6.13" then
+    else if config.microsoft-surface.kernelVersion == "latest" then
       "6.13.6"
     else
-      abort "Invalid kernel version: ${shortVersion}";
-
-  rev = "arch-${version}-1";
+      abort "Invalid kernel version: ${config.microsoft-surface.kernelVersion}";
 
-  hash =
+  shortVersion = versions.majorMinor version;
+  packageHash =
     if shortVersion == "6.12" then
       "sha256-Pv7O8D8ma+MPLhYP3HSGQki+Yczp8b7d63qMb6l4+mY="
     else if shortVersion == "6.13" then
@@ -29,40 +29,51 @@ let
     else
       abort "Invalid kernel version: ${shortVersion}";
 
-  inherit (pkgs.callPackage ./kernel/linux-package.nix { repos = pkgs.callPackage ./kernel/repos.nix { rev = rev; hash = hash; }; }) linuxPackage surfacePatches;
+  # Fetch the release from the linux-surface project
+  rev = "arch-${version}-1";
+  repos = pkgs.callPackage ({ fetchFromGitHub, rev, packageHash }: {
+    linux-surface = fetchFromGitHub {
+      owner = "linux-surface";
+      repo = "linux-surface";
+      rev = rev;
+      hash = packageHash;
+    };
+  }) { inherit rev packageHash; };
 
+  # Build the kernel package
+  inherit (pkgs.callPackage ./kernel/linux-package.nix { inherit repos; }) linuxPackage surfacePatches;
   kernelPatches = surfacePatches {
     inherit version;
     patchFn = ./kernel/${shortVersion}/patches.nix;
   };
   kernelPackages = linuxPackage {
     inherit version kernelPatches;
-    sha256 = srcHash;
+    hash = srcHash;
     ignoreConfigErrors=true;
   };
 
 in {
   options.microsoft-surface.kernelVersion = mkOption {
     description = "Kernel Version to use (patched for MS Surface)";
     type = types.enum [
-      "6.12"
-      "6.13"
+      "lts"
+      "latest"
     ];
-    default = "6.12";
+    default = "lts";
   };
 
   config = {
     boot = {
       inherit kernelPackages;
 
-      kernelParams = mkDefault [ "mem_sleep_default=deep" ];
       # Seems to be required to properly enable S0ix "Modern Standby":
+      kernelParams = mkDefault [ "mem_sleep_default=deep" ];
     };
 
     # NOTE: Check the README before enabling TLP:
     services.tlp.enable = mkDefault false;
 
-    # i.e. needed for wifi firmware, see https://github.com/NixOS/nixos-hardware/issues/364
+    # Needed for wifi firmware, see https://github.com/NixOS/nixos-hardware/issues/364
     hardware = {
       enableRedistributableFirmware = mkDefault true;
       sensor.iio.enable = mkDefault true;