Default implementation for CAN bus HAL

This implementation supports SocketCAN interfaces.

Bug: 135918744
Test: VTS (separate new change)
Change-Id: I12b93e37fa64e341bee2c64eaf130b39977fcef5
diff --git a/automotive/can/1.0/default/CanBus.h b/automotive/can/1.0/default/CanBus.h
new file mode 100644
index 0000000..81a83c8
--- /dev/null
+++ b/automotive/can/1.0/default/CanBus.h
@@ -0,0 +1,97 @@
+/*
+ * 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.
+ */
+
+#pragma once
+
+#include "CanSocket.h"
+
+#include <android-base/unique_fd.h>
+#include <android/hardware/automotive/can/1.0/ICanBus.h>
+#include <android/hardware/automotive/can/1.0/ICanController.h>
+#include <utils/Mutex.h>
+
+#include <atomic>
+#include <thread>
+
+namespace android {
+namespace hardware {
+namespace automotive {
+namespace can {
+namespace V1_0 {
+namespace implementation {
+
+struct CanBus : public ICanBus {
+    virtual ~CanBus();
+
+    Return<Result> send(const CanMessage& message) override;
+    Return<void> listen(const hidl_vec<CanMessageFilter>& filter,
+                        const sp<ICanMessageListener>& listener, listen_cb _hidl_cb) override;
+
+    ICanController::Result up();
+    bool down();
+
+  protected:
+    CanBus(const std::string& ifname);
+
+    /**
+     * Prepare the SocketCAN interface.
+     *
+     * After calling this method, mIfname network interface is available and ready to be brought up.
+     */
+    virtual ICanController::Result preUp();
+
+    /**
+     * Cleanup after bringing the interface down.
+     *
+     * This is a counterpart to preUp().
+     */
+    virtual bool postDown();
+
+    /** Network interface name. */
+    const std::string mIfname;
+
+  private:
+    struct CanMessageListener {
+        sp<ICanMessageListener> callback;
+        hidl_vec<CanMessageFilter> filter;
+        wp<ICloseHandle> closeHandle;
+    };
+    void clearListeners();
+
+    void onRead(const struct canfd_frame& frame, std::chrono::nanoseconds timestamp);
+    void onError();
+
+    std::mutex mListenersGuard;
+    std::vector<CanMessageListener> mListeners GUARDED_BY(mListenersGuard);
+
+    std::unique_ptr<CanSocket> mSocket;
+    bool mWasUpInitially;
+
+    /**
+     * Guard for up flag is required to be held for entire time when the interface is being used
+     * (i.e. message being sent), because we don't want the interface to be torn down while
+     * executing that operation.
+     */
+    std::mutex mIsUpGuard;
+    bool mIsUp GUARDED_BY(mIsUpGuard) = false;
+};
+
+}  // namespace implementation
+}  // namespace V1_0
+}  // namespace can
+}  // namespace automotive
+}  // namespace hardware
+}  // namespace android