add STM32 firmware build files (WIP)

stm32/default.nix

@@ -0,0 +1,60 @@
+{ # Use master branch of the overlay by default
+  mozillaOverlay ? import (builtins.fetchTarball https://github.com/mozilla/nixpkgs-mozilla/archive/master.tar.gz),
+  rustManifest ? builtins.fetchurl "https://static.rust-lang.org/dist/channel-rust-nightly.toml"
+}:
+
+let
+  pkgs = import <nixpkgs> { overlays = [ mozillaOverlay ]; };
+  rustPlatform = pkgs.recurseIntoAttrs (pkgs.callPackage ./rustPlatform.nix {
+    inherit rustManifest;
+  });
+  fetchcargo = import ./fetchcargo.nix {
+    inherit (pkgs) stdenv cacert git cargo-vendor;
+    inherit (rustPlatform.rust) cargo;
+  };
+  buildStm32Firmware = { name, src, cargoSha256 }:
+    let
+      firmwareDeps = fetchcargo { inherit name src; sha256 = cargoSha256; };
+    in
+      rustPlatform.buildRustPackage rec {
+        inherit name;
+        version = "0.0.0";
+
+        inherit src cargoSha256;
+
+        buildInputs = [ firmwareDeps ];
+        patchPhase = ''
+          cat >> .cargo/config <<EOF
+          [source.crates-io]
+          replace-with = "vendored-sources"
+
+          [source.vendored-sources]
+          directory = "${firmwareDeps}"
+          EOF
+        '';
+
+        buildPhase = ''
+          export CARGO_HOME=$(mktemp -d cargo-home.XXX)
+          cargo build --release
+        '';
+
+        doCheck = false;
+        installPhase = ''
+          mkdir -p $out $out/nix-support
+          cp target/thumbv7em-none-eabihf/release/${name} $out/${name}.elf
+          echo file binary-dist ${name}.elf >> $out/nix-support/hydra-build-products
+        '';
+      };
+in
+  {
+    stabilizer = buildStm32Firmware {
+      name = "stabilizer";
+      src = /home/sb/stabilizer;
+      cargoSha256 = "1m4cxf6c4lh28xv4iagp20ni97cya1f12yg58q0m733qahk8gncb";
+    };
+    thermostat = buildStm32Firmware {
+      name = "thermostat";
+      src = /home/sb/thermostat;
+      cargoSha256 = "1i9p5d5n01ajbp8lmavyway6vr1mmy107qnccff9glvr91rqx352";
+    };
+  }

stm32/fetchcargo.nix

@@ -0,0 +1,49 @@
+{ stdenv, cacert, git, cargo, cargo-vendor }:
+{ name, src, sha256 }:
+let
+  # `src` restricted to the two files that define dependencies
+  cargoOnlySrc = stdenv.mkDerivation {
+    name = "${name}-cargo";
+    inherit src;
+    phases = "installPhase";
+    installPhase = ''
+      mkdir $out
+      cp ${src}/Cargo.{toml,lock} $out/
+      mkdir $out/src
+      touch $out/src/main.rs
+    '';
+  };
+in
+stdenv.mkDerivation {
+  name = "${name}-vendor";
+  nativeBuildInputs = [ cacert git cargo cargo-vendor ];
+  src = cargoOnlySrc;
+
+  phases = "unpackPhase patchPhase installPhase";
+
+  installPhase = ''
+    if [[ ! -f Cargo.lock ]]; then
+        echo
+        echo "ERROR: The Cargo.lock file doesn't exist"
+        echo
+        echo "Cargo.lock is needed to make sure that cargoSha256 doesn't change"
+        echo "when the registry is updated."
+        echo
+
+        exit 1
+    fi
+
+    export CARGO_HOME=$(mktemp -d cargo-home.XXX)
+
+    cargo vendor
+
+    cp -ar vendor $out
+  '';
+
+  outputHashAlgo = "sha256";
+  outputHashMode = "recursive";
+  outputHash = sha256;
+
+  impureEnvVars = stdenv.lib.fetchers.proxyImpureEnvVars;
+  preferLocalBuild = true;
+}

stm32/release.nix

@@ -0,0 +1,12 @@
+# For running on Hydra
+{ pkgs ? import <nixpkgs> {},
+  rustManifest ? ./channel-rust-nightly.toml
+}:
+
+let
+  jobs = callPackage ./default.nix {
+    inherit rustManifest;
+    mozillaOverlay = import <mozillaOverlay>;
+  };
+in
+  builtins.mapAttrs (key: value: pkgs.lib.hydraJob value) jobs

stm32/result

@@ -0,0 +1 @@
+/nix/store/nk713fs4q784pdz7wdr5x8m2zfqhls6v-stabilizer

stm32/rustPlatform.nix

@@ -0,0 +1,23 @@
+{ recurseIntoAttrs, stdenv, lib,
+  makeRustPlatform,
+  fetchurl, patchelf,
+  rustManifest ? ./channel-rust-nightly.toml
+}:
+
+let
+  targets = [
+    "thumbv7em-none-eabihf"
+  ];
+  rustChannel =
+    lib.rustLib.fromManifestFile rustManifest {
+      inherit stdenv fetchurl patchelf;
+    };
+  rust =
+    rustChannel.rust.override {
+      inherit targets;
+    };
+in
+makeRustPlatform {
+  rustc = rust;
+  cargo = rust;
+}