usbcamera: initial implementation of default usb camera HAL

* Basic skeleton of usb camera hal implementation
* Vendor tag is not supported yet
* Further usb camera hal implementation can be filled into UsbCamera.cpp
* Hot plug thread need to be implemented

Change-Id: Ida63b6d640e32192f5b60a280d9d5106d80e523f
diff --git a/modules/usbcamera/CameraHAL.cpp b/modules/usbcamera/CameraHAL.cpp
new file mode 100644
index 0000000..98111ef
--- /dev/null
+++ b/modules/usbcamera/CameraHAL.cpp
@@ -0,0 +1,154 @@
+/*
+ * Copyright (C) 2015 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_NDEBUG 0
+#define LOG_TAG "UsbCameraHAL"
+#include <cutils/log.h>
+
+#include <cstdlib>
+#include <hardware/camera_common.h>
+#include <hardware/hardware.h>
+#include "UsbCamera.h"
+#include "CameraHAL.h"
+
+/*
+ * This file serves as the entry point to the HAL.  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 usb_camera_hal {
+
+static CameraHAL gCameraHAL;
+
+CameraHAL::CameraHAL()
+  : mCallbacks(NULL) {
+    // Should not allocate the camera devices for now, as it is unclear if the device is plugged.
+
+    // Start hotplug thread
+    mHotplugThread = new HotplugThread(this);
+    mHotplugThread->run("usb-camera-hotplug");
+}
+
+CameraHAL::~CameraHAL() {
+    // Stop hotplug thread
+    {
+        android::Mutex::Autolock al(mModuleLock);
+        if (mHotplugThread != NULL) {
+            mHotplugThread->requestExit();
+        }
+
+        // Delete camera device from mCameras
+    }
+
+    // Joining done without holding mLock, otherwise deadlocks may ensue
+    // as the threads try to access parent states.
+    if (mHotplugThread != NULL) {
+        mHotplugThread->join();
+    }
+
+    delete mHotplugThread;
+}
+
+int CameraHAL::getNumberOfCameras() {
+    android::Mutex::Autolock al(mModuleLock);
+    ALOGV("%s: %d", __func__, mCameras.size());
+    return static_cast<int>(mCameras.size());
+}
+
+int CameraHAL::getCameraInfo(int id, struct camera_info* info) {
+    android::Mutex::Autolock al(mModuleLock);
+    ALOGV("%s: camera id %d: info=%p", __func__, id, info);
+    if (id < 0 || id >= static_cast<int>(mCameras.size())) {
+        ALOGE("%s: Invalid camera id %d", __func__, id);
+        return -ENODEV;
+    }
+
+    return mCameras[id]->getInfo(info);
+}
+
+int CameraHAL::setCallbacks(const camera_module_callbacks_t *callbacks) {
+    ALOGV("%s : callbacks=%p", __func__, callbacks);
+    mCallbacks = callbacks;
+    return 0;
+}
+
+int CameraHAL::open(const hw_module_t* mod, const char* name, hw_device_t** dev) {
+    int id;
+    char *nameEnd;
+
+    android::Mutex::Autolock al(mModuleLock);
+    ALOGV("%s: module=%p, name=%s, device=%p", __func__, mod, name, dev);
+    if (*name == '\0') {
+        ALOGE("%s: Invalid camera id name is NULL", __func__);
+        return -EINVAL;
+    }
+    id = strtol(name, &nameEnd, 10);
+    if (*nameEnd != '\0') {
+        ALOGE("%s: Invalid camera id name %s", __func__, name);
+        return -EINVAL;
+    } else if (id < 0 || id >= static_cast<int>(mCameras.size())) {
+        ALOGE("%s: Invalid camera id %d", __func__, id);
+        return -ENODEV;
+    }
+    return mCameras[id]->open(mod, dev);
+}
+
+extern "C" {
+
+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 int open_dev(const hw_module_t* mod, const char* name, hw_device_t** dev) {
+    return gCameraHAL.open(mod, name, dev);
+}
+
+static hw_module_methods_t gCameraModuleMethods = {
+    open : 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               : "Default USB Camera HAL",
+        author             : "The Android Open Source Project",
+        methods            : &gCameraModuleMethods,
+        dso                : NULL,
+        reserved           : {0},
+    },
+    get_number_of_cameras : get_number_of_cameras,
+    get_camera_info       : get_camera_info,
+    set_callbacks         : set_callbacks,
+    get_vendor_tag_ops    : NULL,
+    open_legacy           : NULL,
+    set_torch_mode        : NULL,
+    reserved              : {0},
+};
+} // extern "C"
+
+} // namespace usb_camera_hal