xref: /aosp_15_r20/hardware/interfaces/bluetooth/1.0/default/h4_protocol.cc (revision 4d7e907c777eeecc4c5bd7cf640a754fac206ff7)

//
// Copyright 2017 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 "h4_protocol.h"

#define LOG_TAG "android.hardware.bluetooth-hci-h4"

#include <errno.h>
#include <fcntl.h>
#include <log/log.h>
#include <sys/uio.h>
#include <unistd.h>

namespace android {
namespace hardware {
namespace bluetooth {
namespace hci {

size_t H4Protocol::Send(uint8_t type, const uint8_t* data, size_t length) {
  struct iovec iov_array[] = {{&type, sizeof(type)},
                              {const_cast<uint8_t*>(data), length}};
  struct iovec* iov = iov_array;
  int iovcnt = sizeof(iov_array) / sizeof(iov_array[0]);
  size_t total_bytes = 0;
  for (int i = 0; i < iovcnt; i++) {
    total_bytes += iov_array[i].iov_len;
  }
  size_t bytes_written = 0;
  size_t remaining_bytes = total_bytes;

  while (remaining_bytes > 0) {
    ssize_t ret = TEMP_FAILURE_RETRY(writev(uart_fd_, iov, iovcnt));
    if (ret == -1) {
      if (errno == EAGAIN) continue;
      ALOGE("%s error writing to UART (%s)", __func__, strerror(errno));
      break;
    } else if (ret == 0) {
      // Nothing written
      ALOGE("%s zero bytes written - something went wrong...", __func__);
      break;
    } else if (ret == remaining_bytes) {
      // Everything written
      bytes_written += ret;
      break;
    }

    bytes_written += ret;
    remaining_bytes -= ret;
    ALOGW("%s: %d/%d bytes written - retrying remaining %d bytes", __func__,
          static_cast<int>(bytes_written), static_cast<int>(total_bytes),
          static_cast<int>(remaining_bytes));

    // Remove iovs which are written from the list
    while (ret >= iov->iov_len) {
      ret -= iov->iov_len;
      ++iov;
      --iovcnt;
    }
    // Adjust the iov to point to the remaining data which needs to be written
    if (ret) {
      iov->iov_base = static_cast<uint8_t*>(iov->iov_base) + ret;
      iov->iov_len -= ret;
    }
  }
  return bytes_written;
}

void H4Protocol::OnPacketReady() {
  switch (hci_packet_type_) {
    case HCI_PACKET_TYPE_EVENT:
      event_cb_(hci_packetizer_.GetPacket());
      break;
    case HCI_PACKET_TYPE_ACL_DATA:
      acl_cb_(hci_packetizer_.GetPacket());
      break;
    case HCI_PACKET_TYPE_SCO_DATA:
      sco_cb_(hci_packetizer_.GetPacket());
      break;
    case HCI_PACKET_TYPE_ISO_DATA:
      iso_cb_(hci_packetizer_.GetPacket());
      break;
    default:
      LOG_ALWAYS_FATAL("%s: Unimplemented packet type %d", __func__,
                       static_cast<int>(hci_packet_type_));
  }
  // Get ready for the next type byte.
  hci_packet_type_ = HCI_PACKET_TYPE_UNKNOWN;
}

void H4Protocol::OnDataReady(int fd) {
  if (hci_packet_type_ == HCI_PACKET_TYPE_UNKNOWN) {
    uint8_t buffer[1] = {0};
    ssize_t bytes_read = TEMP_FAILURE_RETRY(read(fd, buffer, 1));
    if (bytes_read != 1) {
      if (bytes_read == 0) {
        // This is only expected if the UART got closed when shutting down.
        ALOGE("%s: Unexpected EOF reading the packet type!", __func__);
        sleep(5);  // Expect to be shut down within 5 seconds.
        return;
      } else if (bytes_read < 0) {
        LOG_ALWAYS_FATAL("%s: Read packet type error: %s", __func__,
                         strerror(errno));
      } else {
        LOG_ALWAYS_FATAL("%s: More bytes read than expected (%u)!", __func__,
                         static_cast<unsigned int>(bytes_read));
      }
    }
    hci_packet_type_ = static_cast<HciPacketType>(buffer[0]);
    if (hci_packet_type_ != HCI_PACKET_TYPE_ACL_DATA &&
        hci_packet_type_ != HCI_PACKET_TYPE_SCO_DATA &&
        hci_packet_type_ != HCI_PACKET_TYPE_ISO_DATA &&
        hci_packet_type_ != HCI_PACKET_TYPE_EVENT) {
      LOG_ALWAYS_FATAL("%s: Unimplemented packet type %d", __func__,
                       static_cast<int>(hci_packet_type_));
    }
  } else {
    hci_packetizer_.OnDataReady(fd, hci_packet_type_);
  }
}

}  // namespace hci
}  // namespace bluetooth
}  // namespace hardware
}  // namespace android