diff --git a/health/aidl/default/include/health-impl/HalHealthLoop.h b/health/aidl/default/include/health-impl/HalHealthLoop.h
new file mode 100644
index 0000000..c46aaa4
--- /dev/null
+++ b/health/aidl/default/include/health-impl/HalHealthLoop.h
@@ -0,0 +1,77 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+#pragma once
+
+#include <memory>
+#include <optional>
+
+#include <aidl/android/hardware/health/IHealth.h>
+#include <health/HealthLoop.h>
+
+namespace aidl::android::hardware::health {
+
+class HalHealthLoop;
+
+class HalHealthLoopCallback {
+  public:
+    virtual ~HalHealthLoopCallback() = default;
+
+    // Called by HalHealthLoop::Init
+    virtual void OnInit(HalHealthLoop* hal_health_loop, struct healthd_config* config) = 0;
+    // Called by HalHealthLoop::Heartbeat
+    virtual void OnHeartbeat(){};
+    // Called by HalHealthLoop::PrepareToWait
+    virtual int OnPrepareToWait() { return -1; }
+    // Called by HalHealthLoop::ScheduleBatteryUpdate
+    virtual void OnHealthInfoChanged(const HealthInfo&) {}
+};
+
+// AIDL version of android::hardware::health::V2_1::implementation::HalHealthLoop.
+// An implementation of HealthLoop for using a given health HAL.
+class HalHealthLoop final : public ::android::hardware::health::HealthLoop {
+  public:
+    // Caller must ensure that the lifetime of service_ is not shorter than this object.
+    HalHealthLoop(std::shared_ptr<IHealth> service, std::shared_ptr<HalHealthLoopCallback> callback)
+        : service_(std::move(service)), callback_(std::move(callback)) {}
+
+    using HealthLoop::RegisterEvent;
+
+    bool charger_online() const { return charger_online_; }
+
+  protected:
+    virtual void Init(struct healthd_config* config) override;
+    virtual void Heartbeat() override;
+    virtual int PrepareToWait() override;
+    virtual void ScheduleBatteryUpdate() override;
+
+  private:
+    std::shared_ptr<IHealth> service_;
+    std::shared_ptr<HalHealthLoopCallback> callback_;
+    bool charger_online_ = false;
+
+    // Helpers of OnHealthInfoChanged.
+    void set_charger_online(const HealthInfo& health_info);
+
+    // HealthLoop periodically calls ScheduleBatteryUpdate, which calls
+    // OnHealthInfoChanged callback. A subclass of the callback can override
+    // HalHealthLoopCallback::OnHealthInfoChanged to
+    // broadcast the health_info to interested listeners.
+    // This adjust uevents / wakealarm periods.
+    void OnHealthInfoChanged(const HealthInfo& health_info);
+};
+
+}  // namespace aidl::android::hardware::health
diff --git a/health/aidl/default/include/health-impl/Health.h b/health/aidl/default/include/health-impl/Health.h
new file mode 100644
index 0000000..e49f44c
--- /dev/null
+++ b/health/aidl/default/include/health-impl/Health.h
@@ -0,0 +1,113 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+#pragma once
+
+#include <memory>
+#include <optional>
+
+#include <aidl/android/hardware/health/BnHealth.h>
+#include <aidl/android/hardware/health/IHealthInfoCallback.h>
+#include <android/binder_auto_utils.h>
+#include <health-impl/HalHealthLoop.h>
+#include <healthd/BatteryMonitor.h>
+#include <healthd/healthd.h>
+
+namespace aidl::android::hardware::health {
+
+class LinkedCallback;
+
+// AIDL version of android::hardware::health::V2_1::implementation::Health and BinderHealth.
+// There's no need to separate the two in AIDL because AIDL does not support passthrough transport.
+//
+// Instead of inheriting from HalHealthLoop directly, implements the callback interface to
+// HalHealthLoop instead.
+//
+// Sample implementation of health HAL.
+class Health : public BnHealth, public HalHealthLoopCallback {
+  public:
+    // Initialize with |config|.
+    // A subclass may modify |config| before passing it to the parent constructor.
+    // See implementation of Health for code samples.
+    Health(std::string_view instance_name, std::unique_ptr<struct healthd_config>&& config);
+
+    ndk::ScopedAStatus registerCallback(
+            const std::shared_ptr<IHealthInfoCallback>& callback) override;
+    ndk::ScopedAStatus unregisterCallback(
+            const std::shared_ptr<IHealthInfoCallback>& callback) override;
+    ndk::ScopedAStatus update() override;
+
+    // A subclass should not override this. Override UpdateHealthInfo instead.
+    ndk::ScopedAStatus getHealthInfo(HealthInfo* out) override final;
+
+    // A subclass is recommended to override the path in healthd_config in the constructor.
+    // Only override these if there are no suitable kernel interfaces to read these values.
+    ndk::ScopedAStatus getChargeCounterUah(int32_t* out) override;
+    ndk::ScopedAStatus getCurrentNowMicroamps(int32_t* out) override;
+    ndk::ScopedAStatus getCurrentAverageMicroamps(int32_t* out) override;
+    ndk::ScopedAStatus getCapacity(int32_t* out) override;
+    ndk::ScopedAStatus getChargeStatus(BatteryStatus* out) override;
+
+    // A subclass may either override these or provide function pointers in
+    // in healthd_config in the constructor.
+    // Prefer overriding these for efficiency.
+    ndk::ScopedAStatus getEnergyCounterNwh(int64_t* out) override;
+
+    // A subclass may override these for a specific device.
+    // The default implementations return nothing in |out|.
+    ndk::ScopedAStatus getDiskStats(std::vector<DiskStats>* out) override;
+    ndk::ScopedAStatus getStorageInfo(std::vector<StorageInfo>* out) override;
+
+    // A subclass may override these to provide a different implementation.
+    binder_status_t dump(int fd, const char** args, uint32_t num_args) override;
+
+    // HalHealthLoopCallback implementation.
+    void OnInit(HalHealthLoop* hal_health_loop, struct healthd_config* config) override;
+    void OnHealthInfoChanged(const HealthInfo& health_info) override;
+
+    // A subclass may override this if it wants to handle binder events differently.
+    virtual void BinderEvent(uint32_t epevents);
+
+    // A subclass may override this to determine whether screen should be kept on in charger mode.
+    // Default is to invoke healthd_config->screen_on() on the BatteryProperties converted
+    // from getHealthInfo.
+    // Prefer overriding these to providing screen_on in healthd_config in the constructor
+    // for efficiency.
+    virtual std::optional<bool> ShouldKeepScreenOn();
+
+  protected:
+    // A subclass can override this to modify any health info object before
+    // returning to clients. This is similar to healthd_board_battery_update().
+    // By default, it does nothing.
+    // See implementation of Health for code samples.
+    virtual void UpdateHealthInfo(HealthInfo* health_info);
+
+  private:
+    friend LinkedCallback;  // for exposing death_recipient_
+
+    bool unregisterCallbackInternal(std::shared_ptr<IHealthInfoCallback> callback);
+
+    std::string instance_name_;
+    ::android::BatteryMonitor battery_monitor_;
+    std::unique_ptr<struct healthd_config> healthd_config_;
+
+    ndk::ScopedAIBinder_DeathRecipient death_recipient_;
+    int binder_fd_ = -1;
+    std::mutex callbacks_lock_;
+    std::vector<std::unique_ptr<LinkedCallback>> callbacks_;
+};
+
+}  // namespace aidl::android::hardware::health