diff --git a/bluetooth/async/Android.bp b/bluetooth/async/Android.bp
new file mode 100644
index 0000000..bd7d7b8
--- /dev/null
+++ b/bluetooth/async/Android.bp
@@ -0,0 +1,41 @@
+package {
+    default_applicable_licenses: ["hardware_interfaces_license"],
+}
+
+cc_library_static {
+    name: "android.hardware.bluetooth.async",
+    vendor_available: true,
+    host_supported: true,
+    srcs: [
+        "async_fd_watcher.cc",
+    ],
+    export_include_dirs: ["."],
+    shared_libs: [
+        "liblog",
+    ],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
+}
+
+cc_test {
+    name: "bluetooth-vendor-interface-async-test",
+    host_supported: true,
+    srcs: [
+        "test/async_fd_watcher_unittest.cc",
+    ],
+    shared_libs: [
+        "liblog",
+        "libutils",
+    ],
+    static_libs: [
+        "android.hardware.bluetooth.async",
+        "libgmock",
+    ],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
+    test_suites: ["general-tests"],
+}
diff --git a/bluetooth/async/async_fd_watcher.cc b/bluetooth/async/async_fd_watcher.cc
new file mode 100644
index 0000000..fb634ff
--- /dev/null
+++ b/bluetooth/async/async_fd_watcher.cc
@@ -0,0 +1,176 @@
+/*
+ * Copyright 2022 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.
+ */
+
+#include "async_fd_watcher.h"
+
+#include <string.h>
+
+#include <algorithm>
+#include <atomic>
+#include <condition_variable>
+#include <map>
+#include <mutex>
+#include <thread>
+#include <vector>
+
+#include "fcntl.h"
+#include "log/log.h"
+#include "sys/select.h"
+#include "unistd.h"
+
+static const int INVALID_FD = -1;
+
+namespace android::hardware::bluetooth::async {
+
+int AsyncFdWatcher::WatchFdForNonBlockingReads(
+    int file_descriptor, const ReadCallback& on_read_fd_ready_callback) {
+  // Add file descriptor and callback
+  {
+    std::unique_lock<std::mutex> guard(internal_mutex_);
+    watched_fds_[file_descriptor] = on_read_fd_ready_callback;
+  }
+
+  // Start the thread if not started yet
+  return tryStartThread();
+}
+
+int AsyncFdWatcher::ConfigureTimeout(
+    const std::chrono::milliseconds timeout,
+    const TimeoutCallback& on_timeout_callback) {
+  // Add timeout and callback
+  {
+    std::unique_lock<std::mutex> guard(timeout_mutex_);
+    timeout_cb_ = on_timeout_callback;
+    timeout_ms_ = timeout;
+  }
+
+  notifyThread();
+  return 0;
+}
+
+void AsyncFdWatcher::StopWatchingFileDescriptors() { stopThread(); }
+
+AsyncFdWatcher::~AsyncFdWatcher() {}
+
+// Make sure to call this with at least one file descriptor ready to be
+// watched upon or the thread routine will return immediately
+int AsyncFdWatcher::tryStartThread() {
+  if (std::atomic_exchange(&running_, true)) return 0;
+
+  // Set up the communication channel
+  int pipe_fds[2];
+  if (pipe2(pipe_fds, O_NONBLOCK)) return -1;
+
+  notification_listen_fd_ = pipe_fds[0];
+  notification_write_fd_ = pipe_fds[1];
+
+  thread_ = std::thread([this]() { ThreadRoutine(); });
+  if (!thread_.joinable()) return -1;
+
+  return 0;
+}
+
+int AsyncFdWatcher::stopThread() {
+  if (!std::atomic_exchange(&running_, false)) return 0;
+
+  notifyThread();
+  if (std::this_thread::get_id() != thread_.get_id()) {
+    thread_.join();
+  }
+
+  {
+    std::unique_lock<std::mutex> guard(internal_mutex_);
+    watched_fds_.clear();
+  }
+
+  {
+    std::unique_lock<std::mutex> guard(timeout_mutex_);
+    timeout_cb_ = nullptr;
+  }
+
+  close(notification_listen_fd_);
+  close(notification_write_fd_);
+
+  return 0;
+}
+
+int AsyncFdWatcher::notifyThread() {
+  uint8_t buffer[] = {0};
+  if (TEMP_FAILURE_RETRY(write(notification_write_fd_, &buffer, 1)) < 0) {
+    return -1;
+  }
+  return 0;
+}
+
+void AsyncFdWatcher::ThreadRoutine() {
+  while (running_) {
+    fd_set read_fds;
+    FD_ZERO(&read_fds);
+    FD_SET(notification_listen_fd_, &read_fds);
+    int max_read_fd = INVALID_FD;
+    for (auto& it : watched_fds_) {
+      FD_SET(it.first, &read_fds);
+      max_read_fd = std::max(max_read_fd, it.first);
+    }
+
+    struct timeval timeout;
+    struct timeval* timeout_ptr = NULL;
+    if (timeout_ms_ > std::chrono::milliseconds(0)) {
+      timeout.tv_sec = timeout_ms_.count() / 1000;
+      timeout.tv_usec = (timeout_ms_.count() % 1000) * 1000;
+      timeout_ptr = &timeout;
+    }
+
+    // Wait until there is data available to read on some FD.
+    int nfds = std::max(notification_listen_fd_, max_read_fd);
+    int retval = select(nfds + 1, &read_fds, NULL, NULL, timeout_ptr);
+
+    // There was some error.
+    if (retval < 0) continue;
+
+    // Timeout.
+    if (retval == 0) {
+      // Allow the timeout callback to modify the timeout.
+      TimeoutCallback saved_cb;
+      {
+        std::unique_lock<std::mutex> guard(timeout_mutex_);
+        if (timeout_ms_ > std::chrono::milliseconds(0)) saved_cb = timeout_cb_;
+      }
+      if (saved_cb != nullptr) saved_cb();
+      continue;
+    }
+
+    // Read data from the notification FD.
+    if (FD_ISSET(notification_listen_fd_, &read_fds)) {
+      char buffer[] = {0};
+      TEMP_FAILURE_RETRY(read(notification_listen_fd_, buffer, 1));
+      continue;
+    }
+
+    // Invoke the data ready callbacks if appropriate.
+    {
+      // Hold the mutex to make sure that the callbacks are still valid.
+      std::unique_lock<std::mutex> guard(internal_mutex_);
+      for (auto& it : watched_fds_) {
+        if (FD_ISSET(it.first, &read_fds)) {
+          it.second(it.first);
+        }
+      }
+    }
+  }
+}
+
+}  // namespace android::hardware::bluetooth::async
diff --git a/bluetooth/async/async_fd_watcher.h b/bluetooth/async/async_fd_watcher.h
new file mode 100644
index 0000000..b50a7a0
--- /dev/null
+++ b/bluetooth/async/async_fd_watcher.h
@@ -0,0 +1,60 @@
+/*
+ * Copyright 2022 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 <map>
+#include <mutex>
+#include <thread>
+
+namespace android::hardware::bluetooth::async {
+
+using ReadCallback = std::function<void(int)>;
+using TimeoutCallback = std::function<void(void)>;
+
+class AsyncFdWatcher {
+ public:
+  AsyncFdWatcher() = default;
+  ~AsyncFdWatcher();
+
+  int WatchFdForNonBlockingReads(int file_descriptor,
+                                 const ReadCallback& on_read_fd_ready_callback);
+  int ConfigureTimeout(const std::chrono::milliseconds timeout,
+                       const TimeoutCallback& on_timeout_callback);
+  void StopWatchingFileDescriptors();
+
+ private:
+  AsyncFdWatcher(const AsyncFdWatcher&) = delete;
+  AsyncFdWatcher& operator=(const AsyncFdWatcher&) = delete;
+
+  int tryStartThread();
+  int stopThread();
+  int notifyThread();
+  void ThreadRoutine();
+
+  std::atomic_bool running_{false};
+  std::thread thread_;
+  std::mutex internal_mutex_;
+  std::mutex timeout_mutex_;
+
+  std::map<int, ReadCallback> watched_fds_;
+  int notification_listen_fd_;
+  int notification_write_fd_;
+  TimeoutCallback timeout_cb_;
+  std::chrono::milliseconds timeout_ms_;
+};
+
+}  // namespace android::hardware::bluetooth::async
diff --git a/bluetooth/async/test/async_fd_watcher_unittest.cc b/bluetooth/async/test/async_fd_watcher_unittest.cc
new file mode 100644
index 0000000..6d75f10
--- /dev/null
+++ b/bluetooth/async/test/async_fd_watcher_unittest.cc
@@ -0,0 +1,377 @@
+/*
+ * Copyright 2022 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 "async_fd_watcher_unittest"
+
+#include "async_fd_watcher.h"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <log/log.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <cstdint>
+#include <cstring>
+#include <vector>
+
+namespace android::hardware::bluetooth::async_test {
+
+using android::hardware::bluetooth::async::AsyncFdWatcher;
+
+class AsyncFdWatcherSocketTest : public ::testing::Test {
+ public:
+  static const uint16_t kPort = 6111;
+  static const size_t kBufferSize = 16;
+
+  bool CheckBufferEquals() {
+    return strcmp(server_buffer_, client_buffer_) == 0;
+  }
+
+ protected:
+  int StartServer() {
+    ALOGD("%s", __func__);
+    struct sockaddr_in serv_addr;
+    int fd = socket(AF_INET, SOCK_STREAM, 0);
+    EXPECT_FALSE(fd < 0);
+
+    memset(&serv_addr, 0, sizeof(serv_addr));
+    serv_addr.sin_family = AF_INET;
+    serv_addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+    serv_addr.sin_port = htons(kPort);
+    int reuse_flag = 1;
+    EXPECT_FALSE(setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &reuse_flag,
+                            sizeof(reuse_flag)) < 0);
+    EXPECT_FALSE(bind(fd, (sockaddr*)&serv_addr, sizeof(serv_addr)) < 0);
+
+    ALOGD("%s before listen", __func__);
+    listen(fd, 1);
+    return fd;
+  }
+
+  int AcceptConnection(int fd) {
+    ALOGD("%s", __func__);
+    struct sockaddr_in cli_addr;
+    memset(&cli_addr, 0, sizeof(cli_addr));
+    socklen_t clilen = sizeof(cli_addr);
+
+    int connection_fd = accept(fd, (struct sockaddr*)&cli_addr, &clilen);
+    EXPECT_FALSE(connection_fd < 0);
+
+    return connection_fd;
+  }
+
+  void ReadIncomingMessage(int fd) {
+    ALOGD("%s", __func__);
+    int n = TEMP_FAILURE_RETRY(read(fd, server_buffer_, kBufferSize - 1));
+    EXPECT_FALSE(n < 0);
+
+    if (n == 0) {  // got EOF
+      ALOGD("%s: EOF", __func__);
+    } else {
+      ALOGD("%s: Got something", __func__);
+      n = write(fd, "1", 1);
+    }
+  }
+
+  void SetUp() override {
+    ALOGD("%s", __func__);
+    memset(server_buffer_, 0, kBufferSize);
+    memset(client_buffer_, 0, kBufferSize);
+  }
+
+  void ConfigureServer() {
+    socket_fd_ = StartServer();
+
+    conn_watcher_.WatchFdForNonBlockingReads(socket_fd_, [this](int fd) {
+      int connection_fd = AcceptConnection(fd);
+      ALOGD("%s: Conn_watcher fd = %d", __func__, fd);
+
+      conn_watcher_.ConfigureTimeout(std::chrono::seconds(0), []() {
+        bool connection_timeout_cleared = false;
+        ASSERT_TRUE(connection_timeout_cleared);
+      });
+
+      ALOGD("%s: 3", __func__);
+      async_fd_watcher_.WatchFdForNonBlockingReads(
+          connection_fd, [this](int fd) { ReadIncomingMessage(fd); });
+
+      // Time out if it takes longer than a second.
+      SetTimeout(std::chrono::seconds(1));
+    });
+    conn_watcher_.ConfigureTimeout(std::chrono::seconds(1), []() {
+      bool connection_timeout = true;
+      ASSERT_FALSE(connection_timeout);
+    });
+  }
+
+  void CleanUpServer() {
+    async_fd_watcher_.StopWatchingFileDescriptors();
+    conn_watcher_.StopWatchingFileDescriptors();
+    close(socket_fd_);
+  }
+
+  void TearDown() override {
+    ALOGD("%s 3", __func__);
+    EXPECT_TRUE(CheckBufferEquals());
+  }
+
+  void OnTimeout() {
+    ALOGD("%s", __func__);
+    timed_out_ = true;
+  }
+
+  void ClearTimeout() {
+    ALOGD("%s", __func__);
+    timed_out_ = false;
+  }
+
+  bool TimedOut() {
+    ALOGD("%s %d", __func__, timed_out_ ? 1 : 0);
+    return timed_out_;
+  }
+
+  void SetTimeout(std::chrono::milliseconds timeout_ms) {
+    ALOGD("%s", __func__);
+    async_fd_watcher_.ConfigureTimeout(timeout_ms, [this]() { OnTimeout(); });
+    ClearTimeout();
+  }
+
+  int ConnectClient() {
+    ALOGD("%s", __func__);
+    int socket_cli_fd = socket(AF_INET, SOCK_STREAM, 0);
+    EXPECT_FALSE(socket_cli_fd < 0);
+
+    struct sockaddr_in serv_addr;
+    memset((void*)&serv_addr, 0, sizeof(serv_addr));
+    serv_addr.sin_family = AF_INET;
+    serv_addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+    serv_addr.sin_port = htons(kPort);
+
+    int result =
+        connect(socket_cli_fd, (struct sockaddr*)&serv_addr, sizeof(serv_addr));
+    EXPECT_FALSE(result < 0);
+
+    return socket_cli_fd;
+  }
+
+  void WriteFromClient(int socket_cli_fd) {
+    ALOGD("%s", __func__);
+    strcpy(client_buffer_, "1");
+    int n = write(socket_cli_fd, client_buffer_, strlen(client_buffer_));
+    EXPECT_TRUE(n > 0);
+  }
+
+  void AwaitServerResponse(int socket_cli_fd) {
+    ALOGD("%s", __func__);
+    int n = read(socket_cli_fd, client_buffer_, 1);
+    ALOGD("%s done", __func__);
+    EXPECT_TRUE(n > 0);
+  }
+
+ private:
+  AsyncFdWatcher async_fd_watcher_;
+  AsyncFdWatcher conn_watcher_;
+  int socket_fd_;
+  char server_buffer_[kBufferSize];
+  char client_buffer_[kBufferSize];
+  bool timed_out_;
+};
+
+// Use a single AsyncFdWatcher to signal a connection to the server socket.
+TEST_F(AsyncFdWatcherSocketTest, Connect) {
+  int socket_fd = StartServer();
+
+  AsyncFdWatcher conn_watcher;
+  conn_watcher.WatchFdForNonBlockingReads(socket_fd, [this](int fd) {
+    int connection_fd = AcceptConnection(fd);
+    close(connection_fd);
+  });
+
+  // Fail if the client doesn't connect within 1 second.
+  conn_watcher.ConfigureTimeout(std::chrono::seconds(1), []() {
+    bool connection_timeout = true;
+    ASSERT_FALSE(connection_timeout);
+  });
+
+  int socket_cli_fd = ConnectClient();
+  conn_watcher.StopWatchingFileDescriptors();
+  close(socket_fd);
+  close(socket_cli_fd);
+}
+
+// Use a single AsyncFdWatcher to signal a connection to the server socket.
+TEST_F(AsyncFdWatcherSocketTest, TimedOutConnect) {
+  int socket_fd = StartServer();
+  bool timed_out = false;
+  bool* timeout_ptr = &timed_out;
+
+  AsyncFdWatcher conn_watcher;
+  conn_watcher.WatchFdForNonBlockingReads(socket_fd, [this](int fd) {
+    int connection_fd = AcceptConnection(fd);
+    close(connection_fd);
+  });
+
+  // Set the timeout flag after 100ms.
+  conn_watcher.ConfigureTimeout(std::chrono::milliseconds(100),
+                                [timeout_ptr]() { *timeout_ptr = true; });
+  EXPECT_FALSE(timed_out);
+  sleep(1);
+  EXPECT_TRUE(timed_out);
+  conn_watcher.StopWatchingFileDescriptors();
+  close(socket_fd);
+}
+
+// Modify the timeout in a timeout callback.
+TEST_F(AsyncFdWatcherSocketTest, TimedOutSchedulesTimeout) {
+  int socket_fd = StartServer();
+  bool timed_out = false;
+  bool timed_out2 = false;
+
+  AsyncFdWatcher conn_watcher;
+  conn_watcher.WatchFdForNonBlockingReads(socket_fd, [this](int fd) {
+    int connection_fd = AcceptConnection(fd);
+    close(connection_fd);
+  });
+
+  // Set a timeout flag in each callback.
+  conn_watcher.ConfigureTimeout(std::chrono::milliseconds(500),
+                                [&conn_watcher, &timed_out, &timed_out2]() {
+                                  timed_out = true;
+                                  conn_watcher.ConfigureTimeout(
+                                      std::chrono::seconds(1),
+                                      [&timed_out2]() { timed_out2 = true; });
+                                });
+  EXPECT_FALSE(timed_out);
+  EXPECT_FALSE(timed_out2);
+  sleep(1);
+  EXPECT_TRUE(timed_out);
+  EXPECT_FALSE(timed_out2);
+  sleep(1);
+  EXPECT_TRUE(timed_out);
+  EXPECT_TRUE(timed_out2);
+  conn_watcher.StopWatchingFileDescriptors();
+  close(socket_fd);
+}
+
+MATCHER_P(ReadAndMatchSingleChar, byte,
+          "Reads a byte from the file descriptor and matches the value against "
+          "byte") {
+  char inbuf[1] = {0};
+
+  int n = TEMP_FAILURE_RETRY(read(arg, inbuf, 1));
+
+  TEMP_FAILURE_RETRY(write(arg, inbuf, 1));
+  if (n != 1) {
+    return false;
+  }
+  return inbuf[0] == byte;
+};
+
+// Use a single AsyncFdWatcher to watch two file descriptors.
+TEST_F(AsyncFdWatcherSocketTest, WatchTwoFileDescriptors) {
+  int sockfd1[2];
+  int sockfd2[2];
+  socketpair(AF_LOCAL, SOCK_STREAM, 0, sockfd1);
+  socketpair(AF_LOCAL, SOCK_STREAM, 0, sockfd2);
+
+  testing::MockFunction<void(int)> cb1;
+  testing::MockFunction<void(int)> cb2;
+
+  AsyncFdWatcher watcher;
+  watcher.WatchFdForNonBlockingReads(sockfd1[0], cb1.AsStdFunction());
+
+  watcher.WatchFdForNonBlockingReads(sockfd2[0], cb2.AsStdFunction());
+
+  EXPECT_CALL(cb1, Call(ReadAndMatchSingleChar('1')));
+  char one_buf[1] = {'1'};
+  TEMP_FAILURE_RETRY(write(sockfd1[1], one_buf, sizeof(one_buf)));
+
+  EXPECT_CALL(cb2, Call(ReadAndMatchSingleChar('2')));
+  char two_buf[1] = {'2'};
+  TEMP_FAILURE_RETRY(write(sockfd2[1], two_buf, sizeof(two_buf)));
+
+  // Blocking read instead of a flush.
+  TEMP_FAILURE_RETRY(read(sockfd1[1], one_buf, sizeof(one_buf)));
+  TEMP_FAILURE_RETRY(read(sockfd2[1], two_buf, sizeof(two_buf)));
+
+  watcher.StopWatchingFileDescriptors();
+}
+
+// Use two AsyncFdWatchers to set up a server socket.
+TEST_F(AsyncFdWatcherSocketTest, ClientServer) {
+  ConfigureServer();
+  int socket_cli_fd = ConnectClient();
+
+  WriteFromClient(socket_cli_fd);
+
+  AwaitServerResponse(socket_cli_fd);
+
+  close(socket_cli_fd);
+  CleanUpServer();
+}
+
+// Use two AsyncFdWatchers to set up a server socket, which times out.
+TEST_F(AsyncFdWatcherSocketTest, TimeOutTest) {
+  ConfigureServer();
+  int socket_cli_fd = ConnectClient();
+
+  while (!TimedOut()) sleep(1);
+
+  close(socket_cli_fd);
+  CleanUpServer();
+}
+
+// Use two AsyncFdWatchers to set up a server socket, which times out.
+TEST_F(AsyncFdWatcherSocketTest, RepeatedTimeOutTest) {
+  ConfigureServer();
+  int socket_cli_fd = ConnectClient();
+  ClearTimeout();
+
+  // Time out when there are no writes.
+  EXPECT_FALSE(TimedOut());
+  sleep(2);
+  EXPECT_TRUE(TimedOut());
+  ClearTimeout();
+
+  // Don't time out when there is a write.
+  WriteFromClient(socket_cli_fd);
+  AwaitServerResponse(socket_cli_fd);
+  EXPECT_FALSE(TimedOut());
+  ClearTimeout();
+
+  // Time out when the write is late.
+  sleep(2);
+  WriteFromClient(socket_cli_fd);
+  AwaitServerResponse(socket_cli_fd);
+  EXPECT_TRUE(TimedOut());
+  ClearTimeout();
+
+  // Time out when there is a pause after a write.
+  WriteFromClient(socket_cli_fd);
+  sleep(2);
+  AwaitServerResponse(socket_cli_fd);
+  EXPECT_TRUE(TimedOut());
+  ClearTimeout();
+
+  close(socket_cli_fd);
+  CleanUpServer();
+}
+
+}  // namespace android::hardware::bluetooth::async_test