init: experimental yosys-{bluespec, ghdl} plugins

These plugins can be included in a closure, along with the `yosys`
derivation, and they will be automatically picked up for use. For
example, this allows you to include 'yosys-bluespec' in your
`buildInputs`, and then immediately run:

    $ nix-shell -p yosys yosys-bluespec yosys-ghdl
    $ yosys -m bluespec -p 'help read_bluespec'
    $ yosys -m ghdl -p 'help ghdl'

These two plugins are a bit experimental, admittedly, but they are good,
clean examples of how to write and use the yosys plugin infrastructure,
and make it easy to test updates, etc.

Signed-off-by: Austin Seipp <aseipp@pobox.com>

pkgs/development/compilers/yosys/plugins/bluespec.nix

@@ -0,0 +1,32 @@
+{ stdenv, lib, fetchFromGitHub, pkg-config
+, yosys, readline, zlib, bluespec
+}:
+
+stdenv.mkDerivation {
+  pname = "yosys-bluespec";
+  version = "2021.01.14";
+
+  src = fetchFromGitHub {
+    owner  = "thoughtpolice";
+    repo   = "yosys-bluespec";
+    rev    = "7a0c609e9b601560067c34b8ce41e89ea4a397d4";
+    sha256 = "0xj9j5dwvq0dwqzfjd4ikmxkd28amj6d9m6ava7pwcrpjhyjnd0c";
+  };
+
+  buildInputs = [ yosys readline zlib bluespec ];
+  nativeBuildInputs = [ pkg-config ];
+
+  doCheck = true;
+  makeFlags = [
+    "PREFIX=$(out)/share/yosys/plugins"
+    "STATIC_BSC_PATH=${bluespec}/bin/bsc"
+    "STATIC_BSC_LIBDIR=${bluespec}/lib"
+  ];
+
+  meta = with lib; {
+    description = "Bluespec plugin for Yosys";
+    license     = licenses.isc;
+    platforms   = platforms.all;
+    maintainers = with maintainers; [ thoughtpolice ];
+  };
+}

pkgs/development/compilers/yosys/plugins/ghdl.nix

@@ -0,0 +1,31 @@
+{ stdenv, lib, fetchFromGitHub, pkg-config
+, yosys, readline, zlib, ghdl
+}:
+
+stdenv.mkDerivation {
+  pname = "yosys-ghdl";
+  version = "2021.01.01";
+
+  src = fetchFromGitHub {
+    owner  = "ghdl";
+    repo   = "ghdl-yosys-plugin";
+    rev    = "8b3e740fef9a653a20a838f1ade475960e1d379b";
+    sha256 = "13kpcp37r11xgqd8aksddi40a5vpzqi7p8qgyjbs99lyscyli75x";
+  };
+
+  buildInputs = [ yosys readline zlib ghdl ];
+  nativeBuildInputs = [ pkg-config ];
+
+  doCheck = true;
+  installPhase = ''
+    mkdir -p $out/share/yosys/plugins
+    cp ghdl.so $out/share/yosys/plugins/ghdl.so
+  '';
+
+  meta = with lib; {
+    description = "GHDL plugin for Yosys";
+    license     = licenses.isc;
+    platforms   = platforms.all;
+    maintainers = with maintainers; [ thoughtpolice ];
+  };
+}

pkgs/top-level/all-packages.nix

@@ -10832,6 +10832,8 @@ in
   yasm = callPackage ../development/compilers/yasm { };
 
   yosys = callPackage ../development/compilers/yosys { };
+  yosys-bluespec = callPackage ../development/compilers/yosys/plugins/bluespec.nix { };
+  yosys-ghdl = callPackage ../development/compilers/yosys/plugins/ghdl.nix { };
 
   z88dk = callPackage ../development/compilers/z88dk { };