Add Toshiba swanky along with documentation

toshiba/swanky/README.md

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+# Toshiba Chromebook (`swanky`)
+
+There might be a way to install NixOS without hardware modifications (via
+enabled developer mode and SeaBIOS boot on Ctrl+L), however I'd highly
+recommend replacing Google's Coreboot payload with Tianocore: that allows for
+proper virtualization, suspend, removes annoying developer mode screen, and
+generally just works much better.
+
+These instructions carry some risk of bricking your device, since you'll be
+reflashing BIOS. Risk is rather low, but please for the love of god make a BIOS
+backup and store it someplace safe. That's the only way to reinstall ChromeOS
+back after this procedure (BIOS image has licensing info), and it's the easiest
+way to unbrick (it's nice to be able to return to the last good state).
+
+If you ever get unlucky, you can unbrick your device using a makeshift programmer
+based on Raspberry Pi or BeagleBone Black, some cables and a SOIC clip, see:
+http://sicarul.com/how-to-un-brick-your-toshiba-chromebook-2-gandof-without-invoking-any-demons/
+
+## Enable developer mode
+
+This will wipe all user data and settings from the laptop.
+
+Power off, then hold ESC + Refresh (F3) and abruptly press power button. You
+should see "Chrome OS is missing or damaged" message, press Ctrl+D. Press enter
+at the next screen, then press Ctrl+D again. Wait until the laptop boots into
+ChromeOS, then power it off.
+
+## Disable hardware-backed BIOS write protection
+
+Follow guide at: https://github.com/brendenyule/NativeToshibaCB2Guide/wiki/Remove-Write-Protect
+
+Ignore 2.2, only follow the first part of the guide. I also placed some ductape
+over #5 to make sure that metallic motherboard shield would not re-enable write
+protection.
+
+## Flash Coreboot + Tianocore BIOS
+
+Go through installation dialogues until you have network access and are able to
+log into Guest session. Open Chrome, press Ctrl+Alt+T to open `crosh`, type in
+`shell` to get a real shell. Then, run:
+
+```
+$ cd ~
+$ curl -LO https://mrchromebox.tech/firmware-util.sh
+$ sudo bash firmware-util.sh
+```
+
+Choose option 3. Do not skip BIOS backup!
+
+Documentation: https://mrchromebox.tech/#fwscript
+
+## Enable hardware-backed BIOS write protection
+
+This is a cool security feature, so after flashing Coreboot + Tianocore BIOS
+and making sure new BIOS works, consider re-enabling BIOS protection. Just put
+in the missing screw #5.
+
+## Install NixOS
+
+`dd` an image on a flash drive, partition the drive, etc. On some later models,
+you can swap SSD with any other 2242 M.2 SATA SSD, but on `swanky`, you have
+to live with what you have (16GB eMMC). I recommend `256MB` for EFI partition,
+and the rest for `/`.

toshiba/swanky/default.nix

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+with pkgs;
+
+let
+  ucm = fetchzip {
+    url = "https://github.com/plbossart/UCM/archive/2050ca78a4d1a853d1ba050b591f42e6f97adfc0.tar.gz";
+    sha256 = "1rs4mpz3b965nmz0yhy6j4ga3fdz320qnpkd7d61nvpv9c3i6zwj";
+  };
+in
+
+{
+  imports = [
+    ../../common/cpu/intel
+    ../../common/pc/laptop
+  ];
+
+  # Sound only properly works out of the box on 4.18+ kernels.
+  boot.kernelPackages = lib.mkDefault pkgs.linuxPackages_latest;
+
+  # Required for screen brightness control:
+  boot.kernelParams = [ "acpi_backlight=vendor" ];
+
+  # Sound requires a custom UCM config:
+  system.replaceRuntimeDependencies = [{
+    original = pkgs.alsaLib;
+
+    replacement = pkgs.alsaLib.overrideAttrs (super: {
+      postFixup = "cp -r ${ucm}/chtmax98090 $out/share/alsa/ucm";
+    });
+  }];
+}