diff --git a/gnss/2.1/default/Gnss.cpp b/gnss/2.1/default/Gnss.cpp
new file mode 100644
index 0000000..2771f27
--- /dev/null
+++ b/gnss/2.1/default/Gnss.cpp
@@ -0,0 +1,301 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "Gnss"
+
+#include "Gnss.h"
+#include "GnssMeasurement.h"
+#include "Utils.h"
+
+#include <log/log.h>
+
+using ::android::hardware::gnss::common::Utils;
+
+namespace android {
+namespace hardware {
+namespace gnss {
+namespace V2_1 {
+namespace implementation {
+
+sp<V2_1::IGnssCallback> Gnss::sGnssCallback_2_1 = nullptr;
+
+Gnss::Gnss() : mMinIntervalMs(1000) {}
+
+Gnss::~Gnss() {
+    stop();
+}
+
+Return<bool> Gnss::start() {
+    ALOGD("start");
+    if (mIsActive) {
+        ALOGW("Gnss has started. Restarting...");
+        stop();
+    }
+
+    mIsActive = true;
+    mThread = std::thread([this]() {
+        while (mIsActive == true) {
+            auto svStatus = Utils::getMockSvInfoListV2_1();
+            this->reportSvStatus(svStatus);
+
+            const auto location = Utils::getMockLocationV2_0();
+            this->reportLocation(location);
+
+            std::this_thread::sleep_for(std::chrono::milliseconds(mMinIntervalMs));
+        }
+    });
+    return true;
+}
+
+Return<bool> Gnss::stop() {
+    ALOGD("stop");
+    mIsActive = false;
+    if (mThread.joinable()) {
+        mThread.join();
+    }
+    return true;
+}
+
+// Methods from V1_0::IGnss follow.
+Return<bool> Gnss::setCallback(const sp<V1_0::IGnssCallback>&) {
+    // TODO implement
+    return bool{};
+}
+
+Return<void> Gnss::cleanup() {
+    // TODO implement
+    return Void();
+}
+
+Return<bool> Gnss::injectTime(int64_t, int64_t, int32_t) {
+    // TODO implement
+    return bool{};
+}
+
+Return<bool> Gnss::injectLocation(double, double, float) {
+    // TODO implement
+    return bool{};
+}
+
+Return<void> Gnss::deleteAidingData(V1_0::IGnss::GnssAidingData) {
+    // TODO implement
+    return Void();
+}
+
+Return<bool> Gnss::setPositionMode(V1_0::IGnss::GnssPositionMode,
+                                   V1_0::IGnss::GnssPositionRecurrence, uint32_t, uint32_t,
+                                   uint32_t) {
+    // TODO implement
+    return bool{};
+}
+
+Return<sp<V1_0::IAGnssRil>> Gnss::getExtensionAGnssRil() {
+    // TODO implement
+    return ::android::sp<V1_0::IAGnssRil>{};
+}
+
+Return<sp<V1_0::IGnssGeofencing>> Gnss::getExtensionGnssGeofencing() {
+    // TODO implement
+    return ::android::sp<V1_0::IGnssGeofencing>{};
+}
+
+Return<sp<V1_0::IAGnss>> Gnss::getExtensionAGnss() {
+    // TODO implement
+    return ::android::sp<V1_0::IAGnss>{};
+}
+
+Return<sp<V1_0::IGnssNi>> Gnss::getExtensionGnssNi() {
+    // TODO implement
+    return ::android::sp<V1_0::IGnssNi>{};
+}
+
+Return<sp<V1_0::IGnssMeasurement>> Gnss::getExtensionGnssMeasurement() {
+    // TODO implement
+    return ::android::sp<V1_0::IGnssMeasurement>{};
+}
+
+Return<sp<V1_0::IGnssNavigationMessage>> Gnss::getExtensionGnssNavigationMessage() {
+    // TODO implement
+    return ::android::sp<V1_0::IGnssNavigationMessage>{};
+}
+
+Return<sp<V1_0::IGnssXtra>> Gnss::getExtensionXtra() {
+    // TODO implement
+    return ::android::sp<V1_0::IGnssXtra>{};
+}
+
+Return<sp<V1_0::IGnssConfiguration>> Gnss::getExtensionGnssConfiguration() {
+    // TODO implement
+    return ::android::sp<V1_0::IGnssConfiguration>{};
+}
+
+Return<sp<V1_0::IGnssDebug>> Gnss::getExtensionGnssDebug() {
+    // TODO implement
+    return ::android::sp<V1_0::IGnssDebug>{};
+}
+
+Return<sp<V1_0::IGnssBatching>> Gnss::getExtensionGnssBatching() {
+    // TODO implement
+    return ::android::sp<V1_0::IGnssBatching>{};
+}
+
+// Methods from V1_1::IGnss follow.
+Return<bool> Gnss::setCallback_1_1(const sp<V1_1::IGnssCallback>&) {
+    // TODO implement
+    return bool{};
+}
+
+Return<bool> Gnss::setPositionMode_1_1(V1_0::IGnss::GnssPositionMode,
+                                       V1_0::IGnss::GnssPositionRecurrence, uint32_t, uint32_t,
+                                       uint32_t, bool) {
+    return true;
+}
+
+Return<sp<V1_1::IGnssConfiguration>> Gnss::getExtensionGnssConfiguration_1_1() {
+    // TODO implement
+    return ::android::sp<V1_1::IGnssConfiguration>{};
+}
+
+Return<sp<V1_1::IGnssMeasurement>> Gnss::getExtensionGnssMeasurement_1_1() {
+    // TODO implement
+    return ::android::sp<V1_1::IGnssMeasurement>{};
+}
+
+Return<bool> Gnss::injectBestLocation(const V1_0::GnssLocation&) {
+    // TODO implement
+    return bool{};
+}
+
+// Methods from V2_0::IGnss follow.
+Return<bool> Gnss::setCallback_2_0(const sp<V2_0::IGnssCallback>&) {
+    // TODO implement
+    return bool{};
+}
+
+Return<sp<V2_0::IGnssConfiguration>> Gnss::getExtensionGnssConfiguration_2_0() {
+    // TODO implement
+    return ::android::sp<V2_0::IGnssConfiguration>{};
+}
+
+Return<sp<V2_0::IGnssDebug>> Gnss::getExtensionGnssDebug_2_0() {
+    // TODO implement
+    return ::android::sp<V2_0::IGnssDebug>{};
+}
+
+Return<sp<V2_0::IAGnss>> Gnss::getExtensionAGnss_2_0() {
+    // TODO implement
+    return ::android::sp<V2_0::IAGnss>{};
+}
+
+Return<sp<V2_0::IAGnssRil>> Gnss::getExtensionAGnssRil_2_0() {
+    // TODO implement
+    return ::android::sp<V2_0::IAGnssRil>{};
+}
+
+Return<sp<V2_0::IGnssMeasurement>> Gnss::getExtensionGnssMeasurement_2_0() {
+    // TODO implement
+    return ::android::sp<V2_0::IGnssMeasurement>{};
+}
+
+Return<sp<measurement_corrections::V1_0::IMeasurementCorrections>>
+Gnss::getExtensionMeasurementCorrections() {
+    // TODO implement
+    return ::android::sp<measurement_corrections::V1_0::IMeasurementCorrections>{};
+}
+
+Return<sp<visibility_control::V1_0::IGnssVisibilityControl>> Gnss::getExtensionVisibilityControl() {
+    // TODO implement
+    return ::android::sp<visibility_control::V1_0::IGnssVisibilityControl>{};
+}
+
+Return<sp<V2_0::IGnssBatching>> Gnss::getExtensionGnssBatching_2_0() {
+    // TODO implement
+    return ::android::sp<V2_0::IGnssBatching>{};
+}
+
+Return<bool> Gnss::injectBestLocation_2_0(const V2_0::GnssLocation&) {
+    // TODO implement
+    return bool{};
+}
+
+// Methods from V2_1::IGnss follow.
+Return<bool> Gnss::setCallback_2_1(const sp<V2_1::IGnssCallback>& callback) {
+    ALOGD("Gnss::setCallback_2_1");
+    if (callback == nullptr) {
+        ALOGE("%s: Null callback ignored", __func__);
+        return false;
+    }
+
+    sGnssCallback_2_1 = callback;
+
+    using Capabilities = V2_0::IGnssCallback::Capabilities;
+    const auto capabilities = Capabilities::MEASUREMENTS | Capabilities::MEASUREMENT_CORRECTIONS |
+                              Capabilities::LOW_POWER_MODE | Capabilities::SATELLITE_BLACKLIST;
+    auto ret = sGnssCallback_2_1->gnssSetCapabilitiesCb_2_0(capabilities);
+    if (!ret.isOk()) {
+        ALOGE("%s: Unable to invoke callback", __func__);
+    }
+
+    V1_1::IGnssCallback::GnssSystemInfo gnssInfo = {.yearOfHw = 2020};
+
+    ret = sGnssCallback_2_1->gnssSetSystemInfoCb(gnssInfo);
+    if (!ret.isOk()) {
+        ALOGE("%s: Unable to invoke callback", __func__);
+    }
+
+    auto gnssName = "Android Mock GNSS Implementation v2.1";
+    ret = sGnssCallback_2_1->gnssNameCb(gnssName);
+    if (!ret.isOk()) {
+        ALOGE("%s: Unable to invoke callback", __func__);
+    }
+
+    return true;
+}
+
+Return<sp<V2_1::IGnssMeasurement>> Gnss::getExtensionGnssMeasurement_2_1() {
+    ALOGD("Gnss::getExtensionGnssMeasurement_2_1");
+    return new GnssMeasurement();
+}
+
+void Gnss::reportSvStatus(const hidl_vec<GnssSvInfo>& svInfoList) const {
+    std::unique_lock<std::mutex> lock(mMutex);
+    if (sGnssCallback_2_1 == nullptr) {
+        ALOGE("%s: sGnssCallback v2.1 is null.", __func__);
+        return;
+    }
+    auto ret = sGnssCallback_2_1->gnssSvStatusCb_2_1(svInfoList);
+    if (!ret.isOk()) {
+        ALOGE("%s: Unable to invoke callback", __func__);
+    }
+}
+
+void Gnss::reportLocation(const V2_0::GnssLocation& location) const {
+    std::unique_lock<std::mutex> lock(mMutex);
+    if (sGnssCallback_2_1 == nullptr) {
+        ALOGE("%s: sGnssCallback v2.1 is null.", __func__);
+        return;
+    }
+    auto ret = sGnssCallback_2_1->gnssLocationCb_2_0(location);
+    if (!ret.isOk()) {
+        ALOGE("%s: Unable to invoke callback", __func__);
+    }
+}
+
+}  // namespace implementation
+}  // namespace V2_1
+}  // namespace gnss
+}  // namespace hardware
+}  // namespace android