feat(gpu): add cardwire integration and gpu widget

2026-09-19 10:39:04 +05:30 · 2026-08-25 00:38:14 +05:30
parent 4453c280bf
commit c9310e802b
10 changed files with 709 additions and 24 deletions
--- a/.gitignore
+++ b/.gitignore
@@ -0,0 +1,4 @@
+result
+result-bin
+plugin/build/
+plugin/dist/
--- a/assets/icons/nvidia.svg
+++ b/assets/icons/nvidia.svg
@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Uploaded to: SVG Repo, www.svgrepo.com, Generator: SVG Repo Mixer Tools -->
+<svg xmlns:dc="http://purl.org/dc/elements/1.1/"
+     xmlns:cc="http://creativecommons.org/ns#"
+     xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+     xmlns:svg="http://www.w3.org/2000/svg"
+     xmlns="http://www.w3.org/2000/svg"
+     xmlns:xlink="http://www.w3.org/1999/xlink"
+     width="128" height="128" version="1.1">
+    <title>Nvidia Logo</title>
+    <desc>This is shape (source) for Clarity vector icon theme for gtk</desc>
+    <metadata>
+        <rdf:RDF>
+            <cc:Work rdf:about="">
+                <dc:title>Nvidia Logo</dc:title>
+                <dc:description>This is shape (source) for Clarity vector icon theme for gtk</dc:description>
+                <dc:creator>
+                    <cc:Agent>
+                        <dc:title>Jakub Jankiewicz</dc:title>
+                    </cc:Agent>
+                </dc:creator>
+                <dc:rights>
+                    <cc:Agent>
+                        <dc:title>Jakub Jankiewicz</dc:title>
+                    </cc:Agent>
+                </dc:rights>
+                <dc:date>2010</dc:date>
+                <dc:format>image/svg+xml</dc:format>
+                <dc:type rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+                <cc:license rdf:resource="http://creativecommons.org/licenses/by-sa/3.0/" />
+             </cc:Work>
+        </rdf:RDF>
+    </metadata>
+    <path d="m 19.777894,58.887563 c 0,0 10.05027,-14.828437 30.117316,-16.362058 l 0,-5.380182 c -22.2268,1.785057 -41.4742019,20.61011 -41.4742019,20.61011 0,0 10.9013539,31.514726 41.4742019,34.400204 l 0,-5.718258 C 27.458955,83.614426 19.777894,58.887563 19.777894,58.887563 z m 30.117316,16.177165 0,5.236824 C 32.938729,77.278522 28.232018,59.651693 28.232018,59.651693 c 0,0 8.141505,-9.019072 21.663192,-10.481238 l 0,5.746393 c -0.01032,0 -0.01741,-0.0031 -0.0259,-0.0031 -7.09691,-0.851665 -12.640994,5.777655 -12.640994,5.777655 0,0 3.106991,11.16141 12.666896,14.373351 m 0,-47.841948 0,9.922543 c 0.652482,-0.05047 1.304964,-0.09245 1.961018,-0.114779 25.269481,-0.851665 41.734256,20.724887 41.734256,20.724887 0,0 -18.910353,22.994504 -38.611635,22.994504 -1.805601,0 -3.495979,-0.167475 -5.083639,-0.448385 l 0,6.135827 c 1.357662,0.172387 2.765343,0.273767 4.234208,0.273767 18.333347,0 31.59154,-9.362955 44.429483,-20.444422 2.128489,1.704667 10.842539,5.851342 12.633849,7.667216 -12.206453,10.219531 -40.654381,18.457501 -56.782421,18.457501 -1.554612,0 -3.047594,-0.09424 -4.515119,-0.235803 l 0,8.6216 69.68378,0 0,-73.554458 z m 0,21.947675 0,-6.64495 c 0.645782,-0.04511 1.296477,-0.07995 1.961018,-0.100929 18.171232,-0.570753 30.0932,15.615345 30.0932,15.615345 0,0 -12.876351,17.883175 -26.682522,17.883175 -1.98692,0 -3.768404,-0.319318 -5.371696,-0.858364 l 0,-20.147881 c 7.074133,0.854792 8.497892,3.979647 12.750856,11.06941 l 9.458973,-7.976263 c 0,0 -6.904871,-9.055693 -18.544589,-9.055693 -1.266109,0 -2.476839,0.08888 -3.66524,0.216154"/>
+</svg>
--- a/config/BarLayout.qml
+++ b/config/BarLayout.qml
@@ -11,7 +11,7 @@ Singleton {
        return `${Quickshell.shellPath("modules/bar")}/${name}.qml`;
    }

-    property var left: [root.widget("LauncherButton"), root.widget("PowerProfileWidget"), root.widget("HomeWidget"), root.widget("MusicWidget")]
+    property var left: [root.widget("LauncherButton"), root.widget("PowerProfileWidget"), root.widget("GPUWidget"), root.widget("HomeWidget"), root.widget("MusicWidget")]

    property var center: [root.widget("CavaVisualizer"), root.widget("Workspaces"), root.widget("CavaVisualizer"),]

--- a/flake.nix
+++ b/flake.nix
@@ -39,6 +39,7 @@
        programs = {
          nixfmt.enable = true;
          qmlformat.enable = true;
+          clang-format.enable = true;
        };
      };
    in
@@ -57,7 +58,23 @@
          quickshellWithModules
          pkgs.cava
          pkgs.wallust
+          pkgs.dbus
+          pkgs.cmake
+          pkgs.ninja
+          pkgs.qt6.qtbase
+          pkgs.qt6.qtdeclarative
        ];
+
+        shellHook = ''
+          if [ -d "$PWD/plugin/dist/lib/qt-6/qml" ]; then
+            export NIXPKGS_QT6_QML_IMPORT_PATH="$PWD/plugin/dist/lib/qt-6/qml''${NIXPKGS_QT6_QML_IMPORT_PATH:+:$NIXPKGS_QT6_QML_IMPORT_PATH}"
+            export QML2_IMPORT_PATH="$PWD/plugin/dist/lib/qt-6/qml''${QML2_IMPORT_PATH:+:$QML2_IMPORT_PATH}"
+          else
+            echo "gpu plugin is not built; run from the repo root to enable 'import Tshell.Cardwire':"
+            echo "  cmake -S plugin -B plugin/dist -DCMAKE_INSTALL_PREFIX=\$PWD/plugin/dist"
+            echo "  cmake --build plugin/dist --target install"
+          fi
+        '';
      };
    };
 }
--- a/modules/bar/GPUWidget.qml
+++ b/modules/bar/GPUWidget.qml
@@ -0,0 +1,23 @@
+pragma ComponentBehavior: Bound
+
+import Quickshell
+import qs.config
+import qs.ui
+import qs.services
+
+BarButton {
+    id: root
+
+    hoverHighlight: false
+    pointerCursor: false
+    iconSource: GPU.icon
+
+    visible: GPU.connected && GPU.gpu !== null
+    opacity: GPU.gpu !== null && GPU.gpu.known ? 1 : 0
+
+    label: {
+        if (!GPU.gpu)
+            return "NA";
+        return GPU.gpu.blocked ? "Blocked" : "Active";
+    }
+}
--- a/package.nix
+++ b/package.nix
@@ -3,7 +3,10 @@
  stdenv,
  makeWrapper,
  makeFontsConf,
+  cmake,
+  ninja,
  quickshellWithModules,
+  qt6,
  cava,
  wallust,
  nerd-fonts,
@@ -21,41 +24,52 @@ let
  fontconfig = makeFontsConf {
    fontDirectories = [ nerd-fonts.fira-code ];
  };
+
+  # Unlike lib.fileset, this keeps untracked files (the flake only sees
+  # git-tracked paths) while dropping build artifacts.
+  src = lib.cleanSourceWith {
+    src = lib.cleanSource ./.;
+    filter =
+      path: _:
+      let
+        name = baseNameOf path;
+      in
+      !(name == "dist" || name == "result" || name == "result-bin" || lib.hasPrefix "build" name);
+  };
 in
 stdenv.mkDerivation {
-  inherit version;
+  inherit version src;
  pname = "tshell";
-  src = lib.fileset.toSource {
-    root = ./.;
-    fileset = lib.fileset.unions [
-      ./shell.qml
-      ./assets
-      ./config
-      ./modules
-      ./services
-      ./ui
-      ./windows
-    ];
-  };

-  nativeBuildInputs = [ makeWrapper ];
-  buildInputs = [ quickshellWithModules ];
+  dontWrapQtApps = true;
+
+  preConfigure = ''
+    cd plugin
+  '';
+
+  nativeBuildInputs = [
+    cmake
+    ninja
+    makeWrapper
+  ];
+  buildInputs = [
+    qt6.qtbase
+    qt6.qtdeclarative
+  ];
  propagatedBuildInputs = runtimeDeps;

-  dontBuild = true;
-
-  installPhase = ''
-    runHook preInstall
-
+  postInstall = ''
    mkdir -p $out/bin $out/share/tshell
-    cp -r . $out/share/tshell
+
+    for entry in shell.qml assets config modules services ui windows; do
+      cp -r "$src/$entry" $out/share/tshell/
+    done

    makeWrapper ${quickshellWithModules}/bin/qs $out/bin/tshell \
      --prefix PATH : "${lib.makeBinPath runtimeDeps}" \
      --set FONTCONFIG_FILE "${fontconfig}" \
+      --suffix NIXPKGS_QT6_QML_IMPORT_PATH : "$out/lib/qt-6/qml" \
      --add-flags "-p $out/share/tshell"
-
-    runHook postInstall
  '';

  meta = {
--- a/plugin/CMakeLists.txt
+++ b/plugin/CMakeLists.txt
@@ -0,0 +1,46 @@
+cmake_minimum_required(VERSION 3.20)
+project(tshell-cardwire LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_AUTOMOC ON)
+
+find_package(Qt6 REQUIRED COMPONENTS Core Qml DBus)
+
+qt_add_library(tshellcardwire SHARED src/cardwire.cpp src/cardwire.hpp)
+target_include_directories(tshellcardwire PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/src")
+
+qt_add_qml_module(tshellcardwire
+	URI Tshell.Cardwire
+	VERSION 0.1
+	DEPENDENCIES QtQml
+	OUTPUT_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/Tshell/Cardwire"
+)
+
+target_link_libraries(tshellcardwire PRIVATE Qt6::Core Qt6::Qml Qt6::DBus)
+
+# Keep the backing library next to the plugin so "$ORIGIN" rpaths resolve both
+# in the build tree and after install.
+set(module_build_dir "${CMAKE_CURRENT_BINARY_DIR}/Tshell/Cardwire")
+set_target_properties(tshellcardwire tshellcardwireplugin PROPERTIES
+	LIBRARY_OUTPUT_DIRECTORY "${module_build_dir}"
+	RUNTIME_OUTPUT_DIRECTORY "${module_build_dir}"
+	ARCHIVE_OUTPUT_DIRECTORY "${module_build_dir}"
+	BUILD_RPATH "$ORIGIN"
+	INSTALL_RPATH "$ORIGIN"
+)
+
+qt_query_qml_module(tshellcardwire
+	PLUGIN_TARGET module_plugin_target
+	TARGET_PATH module_target_path
+	QMLDIR module_qmldir
+	TYPEINFO module_typeinfo
+)
+
+set(module_dir "${CMAKE_INSTALL_PREFIX}/lib/qt-6/qml/${module_target_path}")
+
+install(TARGETS tshellcardwire "${module_plugin_target}"
+	LIBRARY DESTINATION "${module_dir}"
+	RUNTIME DESTINATION "${module_dir}"
+)
+install(FILES "${module_qmldir}" "${module_typeinfo}" DESTINATION "${module_dir}")
--- a/plugin/src/cardwire.cpp
+++ b/plugin/src/cardwire.cpp
@@ -0,0 +1,405 @@
+#include "cardwire.hpp"
+
+#include <qdbusargument.h>
+#include <qdbusconnection.h>
+#include <qdbusextratypes.h>
+#include <qdbusmessage.h>
+#include <qdbusmetatype.h>
+#include <qdbuspendingcall.h>
+#include <qdbusservicewatcher.h>
+#include <qloggingcategory.h>
+#include <qqmlengine.h>
+#include <qvariant.h>
+
+// a{oa{sa{sv}}} as returned by GetManagedObjects
+using InterfacesMap = QMap<QString, QVariantMap>;
+using ManagedObjects = QMap<QDBusObjectPath, InterfacesMap>;
+
+Q_DECLARE_METATYPE(InterfacesMap)
+Q_DECLARE_METATYPE(ManagedObjects)
+
+namespace {
+
+Q_LOGGING_CATEGORY(logCardwire, "tshell.cardwire", QtWarningMsg);
+
+const QString SERVICE = "org.opengamingcollective.cardwire";
+const QString ROOT_PATH = "/org/opengamingcollective/cardwire";
+const QString GPU_PREFIX = "/org/opengamingcollective/cardwire/Gpu/";
+const QString GPU_IFACE = "org.opengamingcollective.cardwire.Gpu";
+const QString PROPS_IFACE = "org.freedesktop.DBus.Properties";
+const QString OBJMGR_IFACE = "org.freedesktop.DBus.ObjectManager";
+
+void registerMetaTypes() {
+  qDBusRegisterMetaType<InterfacesMap>();
+  qDBusRegisterMetaType<ManagedObjects>();
+}
+
+QDBusMessage methodCall(const QString &path, const QString &iface,
+                        const QString &member) {
+  return QDBusMessage::createMethodCall(SERVICE, path, iface, member);
+}
+
+QDBusPendingCallWatcher *asyncCall(QObject *parent,
+                                   const QDBusMessage &message) {
+  return new QDBusPendingCallWatcher(
+      QDBusConnection::systemBus().asyncCall(message), parent);
+}
+
+void logError(const QString &what, const QDBusMessage &reply) {
+  if (reply.type() == QDBusMessage::ErrorMessage) {
+    qCWarning(logCardwire).nospace()
+        << what << ": " << reply.errorName() << " " << reply.errorMessage();
+  }
+}
+
+} // namespace
+
+CardwireGpu::CardwireGpu(QString objectPath, QObject *parent)
+    : QObject(parent), mObjectPath(std::move(objectPath)) {
+  auto bus = QDBusConnection::systemBus();
+  bus.connect(SERVICE, this->mObjectPath, PROPS_IFACE, "PropertiesChanged",
+              this, SLOT(onPropertiesChanged(QDBusMessage)));
+  bus.connect(SERVICE, this->mObjectPath, GPU_IFACE, "PowerStateChanged", this,
+              SLOT(onPowerStateChanged(QString)));
+
+  this->refreshDevice();
+  this->refreshProperties();
+}
+
+void CardwireGpu::refreshDevice() {
+  QObject::connect(
+      asyncCall(this, methodCall(this->mObjectPath, GPU_IFACE, "GetDevice")),
+      &QDBusPendingCallWatcher::finished, this,
+      &CardwireGpu::onGetDeviceFinished);
+}
+
+void CardwireGpu::onGetDeviceFinished() {
+  auto *watcher = qobject_cast<QDBusPendingCallWatcher *>(this->sender());
+  if (watcher == nullptr)
+    return;
+  watcher->deleteLater();
+
+  const QDBusMessage reply = watcher->reply();
+  logError("GetDevice failed for " + this->mObjectPath, reply);
+  if (reply.type() == QDBusMessage::ErrorMessage)
+    return;
+
+  // (ssuubbbbssbs): name pci render card default discrete virtual available
+  // vendor driver nvidia nvidia_minor
+  QString pci;
+  QString vendor;
+  QString driver;
+  QString nvidiaMinor;
+  uint render = 0;
+  uint card = 0;
+  bool virtualGpu = false;
+
+  const auto arguments = reply.arguments();
+  if (arguments.first().userType() != qMetaTypeId<QDBusArgument>()) {
+    // The daemon actually sends the fields as separate out arguments.
+    if (arguments.size() < 12) {
+      qCWarning(logCardwire)
+          << "GetDevice returned" << arguments.size() << "arguments";
+      return;
+    }
+    this->mName = arguments.at(0).toString();
+    pci = arguments.at(1).toString();
+    render = arguments.at(2).toUInt();
+    card = arguments.at(3).toUInt();
+    this->mDefault = arguments.at(4).toBool();
+    this->mDiscrete = arguments.at(5).toBool();
+    virtualGpu = arguments.at(6).toBool();
+    this->mAvailable = arguments.at(7).toBool();
+    vendor = arguments.at(8).toString();
+    driver = arguments.at(9).toString();
+    this->mNvidia = arguments.at(10).toBool();
+    nvidiaMinor = arguments.at(11).toString();
+  } else {
+    // Documented shape: all fields packed into a single struct.
+    // Must be const: demarshalling uses the const (read) overloads.
+    const QDBusArgument arg = arguments.first().value<QDBusArgument>();
+    arg.beginStructure();
+    arg >> this->mName >> pci >> render >> card >> this->mDefault >>
+        this->mDiscrete >> virtualGpu >> this->mAvailable >> vendor >> driver >>
+        this->mNvidia >> nvidiaMinor;
+    arg.endStructure();
+  }
+
+  if (!this->mKnown) {
+    this->mKnown = true;
+    qCInfo(logCardwire).nospace() << "found gpu \"" << this->mName << "\" at "
+                                  << this->mObjectPath << " (" << pci << ")";
+  }
+
+  emit this->deviceChanged();
+}
+
+void CardwireGpu::refreshProperties() {
+  QDBusMessage call = methodCall(this->mObjectPath, PROPS_IFACE, "GetAll");
+  call << GPU_IFACE;
+
+  QObject::connect(asyncCall(this, call), &QDBusPendingCallWatcher::finished,
+                   this, &CardwireGpu::onGetAllFinished);
+}
+
+void CardwireGpu::onGetAllFinished() {
+  auto *watcher = qobject_cast<QDBusPendingCallWatcher *>(this->sender());
+  if (watcher == nullptr)
+    return;
+  watcher->deleteLater();
+
+  const QDBusMessage reply = watcher->reply();
+  logError("GetAll failed for " + this->mObjectPath, reply);
+  if (reply.type() == QDBusMessage::ErrorMessage)
+    return;
+
+  const auto properties = qdbus_cast<QVariantMap>(reply.arguments().at(0));
+  for (auto it = properties.constBegin(); it != properties.constEnd(); ++it) {
+    if (it.key() == "Block")
+      this->setBlockedValue(it.value().toBool());
+    else if (it.key() == "Launchable")
+      this->setLaunchableValue(it.value().toBool());
+  }
+}
+
+void CardwireGpu::setBlocked(bool blocked) {
+  QDBusMessage call = methodCall(this->mObjectPath, PROPS_IFACE, "Set");
+  call << GPU_IFACE << QStringLiteral("Block")
+       << QVariant::fromValue(QDBusVariant(blocked));
+
+  // The resulting state is confirmed asynchronously via PropertiesChanged.
+  asyncCall(this, call);
+}
+
+void CardwireGpu::onPropertiesChanged(const QDBusMessage &message) {
+  const auto arguments = message.arguments();
+  if (arguments.isEmpty() || arguments.first().toString() != GPU_IFACE)
+    return;
+
+  if (arguments.size() > 1) {
+    const auto properties = qdbus_cast<QVariantMap>(arguments.at(1));
+    for (auto it = properties.constBegin(); it != properties.constEnd(); ++it) {
+      if (it.key() == "Block")
+        this->setBlockedValue(it.value().toBool());
+      else if (it.key() == "Launchable")
+        this->setLaunchableValue(it.value().toBool());
+    }
+  }
+
+  if (arguments.size() > 2) { // invalidated properties: refetch everything
+    const auto invalidated = qdbus_cast<QStringList>(arguments.at(2));
+    if (invalidated.contains("Block") || invalidated.contains("Launchable")) {
+      this->refreshProperties();
+    }
+  }
+}
+
+void CardwireGpu::onPowerStateChanged(const QString &state) {
+  emit this->powerStateChanged(state);
+}
+
+void CardwireGpu::setBlockedValue(bool blocked) {
+  if (blocked == this->mBlocked)
+    return;
+  this->mBlocked = blocked;
+  qCDebug(logCardwire).nospace()
+      << this->mObjectPath << ": block = " << blocked;
+  emit this->blockedChanged();
+}
+
+void CardwireGpu::setLaunchableValue(bool launchable) {
+  if (launchable == this->mLaunchable)
+    return;
+  this->mLaunchable = launchable;
+  emit this->launchableChanged();
+}
+
+Cardwire::Cardwire(QObject *parent) : QObject(parent), mWatcher(this) {}
+
+Cardwire *Cardwire::instance() {
+  static Cardwire *instance =
+      nullptr; // NOLINT(cppcoreguidelines-avoid-non-const-global-variables)
+  if (instance == nullptr) {
+    registerMetaTypes();
+    instance = new Cardwire();
+    instance->connectSignals();
+  }
+  return instance;
+}
+
+Cardwire *Cardwire::create(QQmlEngine * /*qmlEngine*/,
+                           QJSEngine * /*jsEngine*/) {
+  auto *instance = Cardwire::instance();
+  QQmlEngine::setObjectOwnership(instance, QQmlEngine::CppOwnership);
+  return instance;
+}
+
+CardwireGpu *Cardwire::nvidiaGpu() const {
+  for (auto *gpu : this->mGpus) {
+    if (gpu->isNvidia())
+      return gpu;
+  }
+  return nullptr;
+}
+
+void Cardwire::connectSignals() {
+  // cardwired runs as a system service, so its API is on the system bus.
+  this->mWatcher.setConnection(QDBusConnection::systemBus());
+  QObject::connect(&this->mWatcher, &QDBusServiceWatcher::serviceOwnerChanged,
+                   this, &Cardwire::onServiceOwnerChanged);
+  this->mWatcher.setWatchMode(QDBusServiceWatcher::WatchForOwnerChange);
+
+  auto bus = QDBusConnection::systemBus();
+  bus.connect(SERVICE, ROOT_PATH, OBJMGR_IFACE, "InterfacesAdded", this,
+              SLOT(onInterfacesAdded(QDBusMessage)));
+  bus.connect(SERVICE, ROOT_PATH, OBJMGR_IFACE, "InterfacesRemoved", this,
+              SLOT(onInterfacesRemoved(QDBusMessage)));
+
+  // Kick off the initial sync; if the daemon is not running yet the service
+  // watcher triggers another sync once it appears.
+  this->sync();
+}
+
+void Cardwire::onServiceOwnerChanged(const QString &serviceName,
+                                     const QString &oldOwner,
+                                     const QString &newOwner) {
+  if (serviceName != SERVICE)
+    return;
+  qCInfo(logCardwire).nospace()
+      << SERVICE << " owner: " << oldOwner << " -> " << newOwner;
+
+  this->sync();
+}
+
+void Cardwire::sync() {
+  const auto generation = ++this->mGeneration;
+  auto *watcher =
+      asyncCall(this, methodCall(ROOT_PATH, OBJMGR_IFACE, "GetManagedObjects"));
+  QObject::connect(watcher, &QDBusPendingCallWatcher::finished, this,
+                   [this, generation]() { this->handleSyncReply(generation); });
+}
+
+void Cardwire::handleSyncReply(quint32 generation) {
+  auto *watcher = qobject_cast<QDBusPendingCallWatcher *>(this->sender());
+  if (watcher == nullptr)
+    return;
+  watcher->deleteLater();
+
+  if (generation != this->mGeneration)
+    return; // a newer sync superseded this one
+
+  const QDBusMessage reply = watcher->reply();
+  logError("GetManagedObjects failed", reply);
+  if (reply.type() == QDBusMessage::ErrorMessage) {
+    if (this->mConnected) {
+      this->mConnected = false;
+      emit this->connectedChanged();
+    }
+
+    for (auto *gpu : this->mGpus)
+      gpu->deleteLater();
+    if (!this->mGpus.isEmpty()) {
+      this->mGpus.clear();
+      emit this->gpusChanged();
+    }
+    return;
+  }
+
+  QList<CardwireGpu *> seen;
+  const auto objects = qdbus_cast<ManagedObjects>(reply.arguments().at(0));
+  for (auto it = objects.constBegin(); it != objects.constEnd(); ++it) {
+    if (!it.value().contains(GPU_IFACE))
+      continue;
+
+    const QString &path = it.key().path();
+    if (!path.startsWith(GPU_PREFIX))
+      continue;
+
+    this->ensureGpu(path);
+    seen.append(this->findGpu(path));
+  }
+
+  // Remove GPUs that disappeared (hotplug).
+  for (auto *gpu : this->mGpus) {
+    if (!seen.contains(gpu))
+      gpu->deleteLater();
+  }
+
+  if (seen != this->mGpus) {
+    this->mGpus = seen;
+    emit this->gpusChanged();
+  }
+
+  if (!this->mConnected) {
+    this->mConnected = true;
+    qCInfo(logCardwire) << "connected to" << SERVICE;
+    emit this->connectedChanged();
+  }
+}
+
+void Cardwire::ensureGpu(const QString &path) {
+  if (this->findGpu(path) != nullptr)
+    return;
+
+  auto *gpu = new CardwireGpu(path, this);
+  // The nvidia flag only becomes known once GetDevice replies.
+  QObject::connect(gpu, &CardwireGpu::deviceChanged, this,
+                   &Cardwire::updateNvidiaGpu);
+  this->mGpus.append(gpu);
+  qCInfo(logCardwire) << "tracking" << path;
+  emit this->gpusChanged();
+}
+
+CardwireGpu *Cardwire::findGpu(const QString &path) const {
+  for (auto *gpu : this->mGpus) {
+    if (gpu->objectPath() == path)
+      return gpu;
+  }
+  return nullptr;
+}
+
+void Cardwire::removeGpu(const QString &path) {
+  auto *gpu = this->findGpu(path);
+  if (gpu == nullptr)
+    return;
+
+  gpu->deleteLater();
+  this->mGpus.removeOne(gpu);
+  qCInfo(logCardwire) << "stopped tracking" << path;
+  emit this->gpusChanged();
+}
+
+void Cardwire::onInterfacesAdded(const QDBusMessage &message) {
+  const auto arguments = message.arguments();
+  if (arguments.size() < 2)
+    return;
+
+  const auto path = arguments.first().toString();
+  if (!path.startsWith(GPU_PREFIX))
+    return;
+
+  if (qdbus_cast<InterfacesMap>(arguments.at(1)).contains(GPU_IFACE))
+    this->ensureGpu(path);
+}
+
+void Cardwire::onInterfacesRemoved(const QDBusMessage &message) {
+  const auto arguments = message.arguments();
+  if (arguments.size() < 2)
+    return;
+
+  const auto path = arguments.first().toString();
+  if (!path.startsWith(GPU_PREFIX))
+    return;
+
+  if (qdbus_cast<QStringList>(arguments.at(1)).contains(GPU_IFACE))
+    this->removeGpu(path);
+}
+
+void Cardwire::updateNvidiaGpu() {
+  auto *current = this->nvidiaGpu();
+  if (current == this->mCurrentNvidiaGpu)
+    return;
+
+  this->mCurrentNvidiaGpu = current;
+  emit this->nvidiaGpuChanged();
+}
--- a/plugin/src/cardwire.hpp
+++ b/plugin/src/cardwire.hpp
@@ -0,0 +1,129 @@
+#pragma once
+
+#include <qcontainerfwd.h>
+#include <qdbusmessage.h>
+#include <qdbusservicewatcher.h>
+#include <qlist.h>
+#include <qobject.h>
+#include <qqmlintegration.h>
+#include <qstring.h>
+
+class QDBusPendingCallWatcher;
+class QJSEngine;
+class QQmlEngine;
+
+/// A single GPU exposed by cardwire at
+/// /org/opengamingcollective/cardwire/Gpu/{id}.
+///
+/// Mirrors org.opengamingcollective.cardwire.Gpu: device details are fetched
+/// once via GetDevice, while Block/Launchable are kept in sync through
+/// org.freedesktop.DBus.Properties.PropertiesChanged.
+class CardwireGpu : public QObject {
+  Q_OBJECT
+  QML_ELEMENT
+  QML_UNCREATABLE("Gpu objects are managed by the Cardwire singleton")
+
+  Q_PROPERTY(QString objectPath READ objectPath CONSTANT)
+  Q_PROPERTY(bool known READ known NOTIFY deviceChanged)
+  Q_PROPERTY(QString name READ name NOTIFY deviceChanged)
+  Q_PROPERTY(bool nvidia READ isNvidia NOTIFY deviceChanged)
+  Q_PROPERTY(bool defaultGpu READ isDefault NOTIFY deviceChanged)
+  Q_PROPERTY(bool discrete READ isDiscrete NOTIFY deviceChanged)
+  Q_PROPERTY(bool available READ isAvailable NOTIFY deviceChanged)
+  Q_PROPERTY(bool blocked READ isBlocked NOTIFY blockedChanged)
+  Q_PROPERTY(bool launchable READ isLaunchable NOTIFY launchableChanged)
+
+public:
+  explicit CardwireGpu(QString objectPath, QObject *parent = nullptr);
+
+  [[nodiscard]] const QString &objectPath() const { return this->mObjectPath; }
+  [[nodiscard]] bool known() const { return this->mKnown; }
+  [[nodiscard]] const QString &name() const { return this->mName; }
+  [[nodiscard]] bool isNvidia() const { return this->mNvidia; }
+  [[nodiscard]] bool isDefault() const { return this->mDefault; }
+  [[nodiscard]] bool isDiscrete() const { return this->mDiscrete; }
+  [[nodiscard]] bool isAvailable() const { return this->mAvailable; }
+  [[nodiscard]] bool isBlocked() const { return this->mBlocked; }
+  [[nodiscard]] bool isLaunchable() const { return this->mLaunchable; }
+
+  // Writes the Block property. Only succeeds when the daemon mode allows it
+  // (the daemon rejects the write otherwise and the state stays unchanged).
+  Q_INVOKABLE void setBlocked(bool blocked);
+
+signals:
+  void deviceChanged();
+  void blockedChanged();
+  void launchableChanged();
+  void powerStateChanged(const QString &state);
+
+private slots:
+  void onPropertiesChanged(const QDBusMessage &message);
+  void onPowerStateChanged(const QString &state);
+  void onGetDeviceFinished();
+  void onGetAllFinished();
+
+private:
+  void refreshDevice();
+  void refreshProperties();
+  void setBlockedValue(bool blocked);
+  void setLaunchableValue(bool launchable);
+
+  QString mObjectPath;
+  bool mKnown = false;
+  QString mName;
+  bool mNvidia = false;
+  bool mDefault = false;
+  bool mDiscrete = false;
+  bool mAvailable = false;
+  bool mBlocked = false;
+  bool mLaunchable = false;
+};
+
+/// Exposes the GPUs tracked by the cardwire daemon over D-Bus.
+class Cardwire : public QObject {
+  Q_OBJECT
+  QML_ELEMENT
+  QML_SINGLETON
+
+  Q_PROPERTY(bool connected READ isConnected NOTIFY connectedChanged)
+  Q_PROPERTY(QList<CardwireGpu *> gpus READ gpus NOTIFY gpusChanged)
+  Q_PROPERTY(CardwireGpu *nvidiaGpu READ nvidiaGpu NOTIFY nvidiaGpuChanged)
+
+public:
+  static Cardwire *create(QQmlEngine *qmlEngine, QJSEngine *jsEngine);
+  static Cardwire *instance();
+
+  [[nodiscard]] bool isConnected() const { return this->mConnected; }
+  [[nodiscard]] QList<CardwireGpu *> gpus() const { return this->mGpus; }
+
+  /// The first NVIDIA GPU found by the daemon, or nullptr if there is none.
+  [[nodiscard]] CardwireGpu *nvidiaGpu() const;
+
+signals:
+  void connectedChanged();
+  void gpusChanged();
+  void nvidiaGpuChanged();
+
+private slots:
+  void onServiceOwnerChanged(const QString &serviceName,
+                             const QString &oldOwner, const QString &newOwner);
+  void onInterfacesAdded(const QDBusMessage &message);
+  void onInterfacesRemoved(const QDBusMessage &message);
+
+private:
+  explicit Cardwire(QObject *parent = nullptr);
+
+  void connectSignals();
+  void sync();
+  void handleSyncReply(quint32 generation);
+  void ensureGpu(const QString &path);
+  [[nodiscard]] CardwireGpu *findGpu(const QString &path) const;
+  void removeGpu(const QString &path);
+  void updateNvidiaGpu();
+
+  QDBusServiceWatcher mWatcher;
+  QList<CardwireGpu *> mGpus;
+  CardwireGpu *mCurrentNvidiaGpu = nullptr;
+  bool mConnected = false;
+  quint32 mGeneration = 0;
+};
--- a/services/GPU.qml
+++ b/services/GPU.qml
@@ -0,0 +1,12 @@
+pragma Singleton
+
+import Quickshell
+import Tshell.Cardwire
+
+Singleton {
+    id: root
+
+    readonly property bool connected: Cardwire.connected
+    readonly property CardwireGpu gpu: Cardwire.nvidiaGpu
+    readonly property url icon: `${Quickshell.shellPath("assets")}/icons/nvidia.svg`
+}