audio: Introduce read PCM from FMQ session functionality

This is required for audio input direction HAL session support.

Bug:
Tag: #feature
Test: vts-tradefed run vts -m VtsHalBluetoothAudioV2_1TargetTest
Sponsor: jpawlowski@
Change-Id: I3cd25f4af0c5c16074b17dd128de95dd53978379
diff --git a/bluetooth/audio/utils/session/BluetoothAudioSession.cpp b/bluetooth/audio/utils/session/BluetoothAudioSession.cpp
index 50119bf..2f3ddaf 100644
--- a/bluetooth/audio/utils/session/BluetoothAudioSession.cpp
+++ b/bluetooth/audio/utils/session/BluetoothAudioSession.cpp
@@ -43,7 +43,10 @@
 AudioConfiguration BluetoothAudioSession::invalidOffloadAudioConfiguration = {};
 
 static constexpr int kFmqSendTimeoutMs = 1000;  // 1000 ms timeout for sending
+static constexpr int kFmqReceiveTimeoutMs =
+    1000;                                       // 1000 ms timeout for receiving
 static constexpr int kWritePollMs = 1;          // polled non-blocking interval
+static constexpr int kReadPollMs = 1;           // polled non-blocking interval
 
 static inline timespec timespec_convert_from_hal(const TimeSpec& TS) {
   return {.tv_sec = static_cast<long>(TS.tvSec),
@@ -402,6 +405,39 @@
   return totalWritten;
 }
 
+// The control function reads stream from FMQ
+size_t BluetoothAudioSession::InReadPcmData(void* buffer, size_t bytes) {
+  if (buffer == nullptr || !bytes) return 0;
+  size_t totalRead = 0;
+  int ms_timeout = kFmqReceiveTimeoutMs;
+  do {
+    std::unique_lock<std::recursive_mutex> lock(mutex_);
+    if (!IsSessionReady()) break;
+    size_t availableToRead = mDataMQ->availableToRead();
+    if (availableToRead) {
+      if (availableToRead > (bytes - totalRead)) {
+        availableToRead = bytes - totalRead;
+      }
+      if (!mDataMQ->read(static_cast<uint8_t*>(buffer) + totalRead,
+                         availableToRead)) {
+        ALOGE("FMQ datapath reading %zu/%zu failed", totalRead, bytes);
+        return totalRead;
+      }
+      totalRead += availableToRead;
+    } else if (ms_timeout >= kReadPollMs) {
+      lock.unlock();
+      usleep(kReadPollMs * 1000);
+      ms_timeout -= kReadPollMs;
+      continue;
+    } else {
+      ALOGD("in data %zu/%zu overflow %d ms", totalRead, bytes,
+            (kFmqReceiveTimeoutMs - ms_timeout));
+      return totalRead;
+    }
+  } while (totalRead < bytes);
+  return totalRead;
+}
+
 std::unique_ptr<BluetoothAudioSessionInstance>
     BluetoothAudioSessionInstance::instance_ptr =
         std::unique_ptr<BluetoothAudioSessionInstance>(
diff --git a/bluetooth/audio/utils/session/BluetoothAudioSession.h b/bluetooth/audio/utils/session/BluetoothAudioSession.h
index 838d1cc..8d02387 100644
--- a/bluetooth/audio/utils/session/BluetoothAudioSession.h
+++ b/bluetooth/audio/utils/session/BluetoothAudioSession.h
@@ -153,6 +153,8 @@
 
   // The control function writes stream to FMQ
   size_t OutWritePcmData(const void* buffer, size_t bytes);
+  // The control function read stream from FMQ
+  size_t InReadPcmData(void* buffer, size_t bytes);
 
   static constexpr PcmParameters kInvalidPcmParameters = {
       .sampleRate = SampleRate::RATE_UNKNOWN,
diff --git a/bluetooth/audio/utils/session/BluetoothAudioSessionControl_2_1.h b/bluetooth/audio/utils/session/BluetoothAudioSessionControl_2_1.h
index 86af468..168de48 100644
--- a/bluetooth/audio/utils/session/BluetoothAudioSessionControl_2_1.h
+++ b/bluetooth/audio/utils/session/BluetoothAudioSessionControl_2_1.h
@@ -141,6 +141,17 @@
     }
     return 0;
   }
+
+  // The control API reads stream from FMQ
+  static size_t InReadPcmData(const SessionType_2_1& session_type, void* buffer,
+                              size_t bytes) {
+    std::shared_ptr<BluetoothAudioSession_2_1> session_ptr =
+        BluetoothAudioSessionInstance_2_1::GetSessionInstance(session_type);
+    if (session_ptr != nullptr) {
+      return session_ptr->GetAudioSession()->InReadPcmData(buffer, bytes);
+    }
+    return 0;
+  }
 };
 
 }  // namespace audio