modules/camera/3_4/V4L2CameraHAL.cpp

/*
 * Copyright 2016 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.
 */

// Modified from hardware/libhardware/modules/camera/CameraHAL.cpp

#include "V4L2CameraHAL.h"

#include <dirent.h>
#include <fcntl.h>
#include <linux/videodev2.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>

#include <algorithm>
#include <cstdlib>
#include <unordered_set>

#include "Common.h"
#include "V4L2Camera.h"

/*
 * This file serves as the entry point to the HAL. It is modified from the
 * example default HAL available in hardware/libhardware/modules/camera.
 * It contains the module structure and functions used by the framework
 * to load and interface to this HAL, as well as the handles to the individual
 * camera devices.
 */

namespace v4l2_camera_hal {

// Default global camera hal.
static V4L2CameraHAL gCameraHAL;

// Helper function for converting and validating string name to int id.
// Returns either a non-negative camera id, or a negative error code.
static int id_from_name(const char* name) {
  if (name == NULL || *name == '\0') {
    HAL_LOGE("Invalid camera id name is NULL");
    return -EINVAL;
  }
  char* nameEnd;
  int id = strtol(name, &nameEnd, 10);
  if (*nameEnd != '\0' || id < 0) {
    HAL_LOGE("Invalid camera id name %s", name);
    return -EINVAL;
  }
  return id;
}

V4L2CameraHAL::V4L2CameraHAL() : mCameras(), mCallbacks(NULL) {
  HAL_LOG_ENTER();
  // Adds all available V4L2 devices.
  // List /dev nodes.
  DIR* dir = opendir("/dev");
  if (dir == NULL) {
    HAL_LOGE("Failed to open /dev");
    return;
  }
  // Find /dev/video* nodes.
  dirent* ent;
  std::vector<std::string> nodes;
  while ((ent = readdir(dir))) {
    std::string desired = "video";
    size_t len = desired.size();
    if (strncmp(desired.c_str(), ent->d_name, len) == 0) {
      if (strlen(ent->d_name) > len && isdigit(ent->d_name[len])) {
        // ent is a numbered video node.
        nodes.push_back(std::string("/dev/") + ent->d_name);
        HAL_LOGV("Found video node %s.", nodes.back().c_str());
      }
    }
  }
  // Test each for V4L2 support and uniqueness.
  std::unordered_set<std::string> buses;
  std::string bus;
  v4l2_capability cap;
  int fd;
  int id = 0;
  for (const auto& node : nodes) {
    // Open the node.
    fd = TEMP_FAILURE_RETRY(open(node.c_str(), O_RDWR));
    if (fd < 0) {
      HAL_LOGE("failed to open %s (%s).", node.c_str(), strerror(errno));
      continue;
    }
    // Read V4L2 capabilities.
    if (TEMP_FAILURE_RETRY(ioctl(fd, VIDIOC_QUERYCAP, &cap)) != 0) {
      HAL_LOGE("VIDIOC_QUERYCAP on %s fail: %s.", node.c_str(),
               strerror(errno));
    } else if (!(cap.capabilities & V4L2_CAP_VIDEO_CAPTURE)) {
      HAL_LOGE("%s is not a V4L2 video capture device.", node.c_str());
    } else {
      // If the node is unique, add a camera for it.
      bus = reinterpret_cast<char*>(cap.bus_info);
      if (buses.insert(bus).second) {
        HAL_LOGV("Found unique bus at %s.", node.c_str());
        std::unique_ptr<V4L2Camera> cam(new V4L2Camera(id++, node));
        mCameras.push_back(std::move(cam));
      }
    }
    TEMP_FAILURE_RETRY(close(fd));
  }
}

V4L2CameraHAL::~V4L2CameraHAL() {
  HAL_LOG_ENTER();
}

int V4L2CameraHAL::getNumberOfCameras() {
  HAL_LOGV("returns %d", mCameras.size());
  return mCameras.size();
}

int V4L2CameraHAL::getCameraInfo(int id, camera_info_t* info) {
  HAL_LOG_ENTER();
  if (id < 0 || id >= mCameras.size()) {
    return -EINVAL;
  }
  // TODO(b/29185945): Hotplugging: return -EINVAL if unplugged.
  return mCameras[id]->getInfo(info);
}

int V4L2CameraHAL::setCallbacks(const camera_module_callbacks_t* callbacks) {
  HAL_LOG_ENTER();
  mCallbacks = callbacks;
  return 0;
}

void V4L2CameraHAL::getVendorTagOps(vendor_tag_ops_t* ops) {
  HAL_LOG_ENTER();
  // No vendor ops for this HAL. From <hardware/camera_common.h>:
  // "leave ops unchanged if no vendor tags are defined."
}

int V4L2CameraHAL::openLegacy(const hw_module_t* module, const char* id,
                              uint32_t halVersion, hw_device_t** device) {
  HAL_LOG_ENTER();
  // Not supported.
  return -ENOSYS;
}

int V4L2CameraHAL::setTorchMode(const char* camera_id, bool enabled) {
  HAL_LOG_ENTER();
  // TODO(b/29158098): HAL is required to respond appropriately if
  // the desired camera actually does support flash.
  return -ENOSYS;
}

int V4L2CameraHAL::openDevice(const hw_module_t* module, const char* name,
                              hw_device_t** device) {
  HAL_LOG_ENTER();

  if (module != &HAL_MODULE_INFO_SYM.common) {
    HAL_LOGE("Invalid module %p expected %p", module,
             &HAL_MODULE_INFO_SYM.common);
    return -EINVAL;
  }

  int id = id_from_name(name);
  if (id < 0) {
    return id;
  } else if (id < 0 || id >= mCameras.size()) {
    return -EINVAL;
  }
  // TODO(b/29185945): Hotplugging: return -EINVAL if unplugged.
  return mCameras[id]->open(module, device);
}

/*
 * The framework calls the following wrappers, which in turn
 * call the corresponding methods of the global HAL object.
 */

static int get_number_of_cameras() {
  return gCameraHAL.getNumberOfCameras();
}

static int get_camera_info(int id, struct camera_info* info) {
  return gCameraHAL.getCameraInfo(id, info);
}

static int set_callbacks(const camera_module_callbacks_t *callbacks) {
  return gCameraHAL.setCallbacks(callbacks);
}

static void get_vendor_tag_ops(vendor_tag_ops_t* ops) {
  return gCameraHAL.getVendorTagOps(ops);
}

static int open_legacy(const hw_module_t* module, const char* id,
                       uint32_t halVersion, hw_device_t** device) {
  return gCameraHAL.openLegacy(module, id, halVersion, device);
}

static int set_torch_mode(const char* camera_id, bool enabled) {
  return gCameraHAL.setTorchMode(camera_id, enabled);
}

static int open_dev(const hw_module_t* module, const char* name,
                    hw_device_t** device) {
  return gCameraHAL.openDevice(module, name, device);
}

}  // namespace v4l2_camera_hal

static hw_module_methods_t v4l2_module_methods = {
  .open = v4l2_camera_hal::open_dev
};

camera_module_t HAL_MODULE_INFO_SYM __attribute__ ((visibility("default"))) = {
  .common = {
    .tag =                 HARDWARE_MODULE_TAG,
    .module_api_version =  CAMERA_MODULE_API_VERSION_2_4,
    .hal_api_version =     HARDWARE_HAL_API_VERSION,
    .id =                  CAMERA_HARDWARE_MODULE_ID,
    .name =                "V4L2 Camera HAL v3",
    .author =              "The Android Open Source Project",
    .methods =             &v4l2_module_methods,
    .dso =                 nullptr,
    .reserved =            {0},
  },
  .get_number_of_cameras =  v4l2_camera_hal::get_number_of_cameras,
  .get_camera_info =        v4l2_camera_hal::get_camera_info,
  .set_callbacks =          v4l2_camera_hal::set_callbacks,
  .get_vendor_tag_ops =     v4l2_camera_hal::get_vendor_tag_ops,
  .open_legacy =            v4l2_camera_hal::open_legacy,
  .set_torch_mode =         v4l2_camera_hal::set_torch_mode,
  .init =                   nullptr,
  .reserved =               {nullptr, nullptr, nullptr, nullptr, nullptr}
};