android: camera_hal_manager: Support camera hotplug

Extend the support for camera hotplug from libcamera's CameraManager
to CameraHalManager. Use camera module callbacks to let the framework
know about the hotplug events and change the status of cameras being
hotplugged or unplugged via camera_device_status_change().

Introduce a map cameraIdsMap_ which book-keeps all cameras seen in the
past by the CameraHalManager. If the camera is seen for the first time,
a new id is assigned to it. If the camera has been seen before by the
manager, its old id is reused. IDs for internal cameras start with
'0' and for external cameras, they start with '1000'. Accesses to
cameraIdsMap_ and cameras_ are protected by a mutex.

Signed-off-by: Umang Jain <email@uajain.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

2 files changed, 163 insertions, 24 deletions

diff --git a/src/android/camera_hal_manager.cpp b/src/android/camera_hal_manager.cpp
index 3a744af5..a1805ebc 100644
--- a/src/android/camera_hal_manager.cpp
+++ b/src/android/camera_hal_manager.cpp
@@ -8,6 +8,7 @@
 #include "camera_hal_manager.h"
 
 #include <libcamera/camera.h>
+#include <libcamera/property_ids.h>
 
 #include "libcamera/internal/log.h"
 
@@ -28,7 +29,8 @@ LOG_DECLARE_CATEGORY(HAL);
  */
 
 CameraHalManager::CameraHalManager()
-	: cameraManager_(nullptr)
+	: cameraManager_(nullptr), numInternalCameras_(0),
+	  nextExternalCameraId_(firstExternalCameraId_)
 {
 }
 
@@ -47,6 +49,10 @@ int CameraHalManager::init()
 {
 	cameraManager_ = new CameraManager();
 
+	/* Support camera hotplug. */
+	cameraManager_->cameraAdded.connect(this, &CameraHalManager::cameraAdded);
+	cameraManager_->cameraRemoved.connect(this, &CameraHalManager::cameraRemoved);
+
 	int ret = cameraManager_->start();
 	if (ret) {
 		LOG(HAL, Error) << "Failed to start camera manager: "
@@ -56,35 +62,20 @@ int CameraHalManager::init()
 		return ret;
 	}
 
-	/*
-	 * For each Camera registered in the system, a CameraDevice
-	 * gets created here to wraps a libcamera Camera instance.
-	 *
-	 * \todo Support camera hotplug.
-	 */
-	unsigned int index = 0;
-	for (auto &cam : cameraManager_->cameras()) {
-		std::shared_ptr<CameraDevice> camera = CameraDevice::create(index, cam);
-		ret = camera->initialize();
-		if (ret)
-			continue;
-
-		cameras_.emplace_back(std::move(camera));
-		++index;
-	}
-
 	return 0;
 }
 
 CameraDevice *CameraHalManager::open(unsigned int id,
 				     const hw_module_t *hardwareModule)
 {
-	if (id >= numCameras()) {
+	MutexLocker locker(mutex_);
+
+	CameraDevice *camera = cameraDeviceFromHalId(id);
+	if (!camera) {
 		LOG(HAL, Error) << "Invalid camera id '" << id << "'";
 		return nullptr;
 	}
 
-	CameraDevice *camera = cameras_[id].get();
 	if (camera->open(hardwareModule))
 		return nullptr;
 
@@ -93,9 +84,120 @@ CameraDevice *CameraHalManager::open(unsigned int id,
 	return camera;
 }
 
+void CameraHalManager::cameraAdded(std::shared_ptr<Camera> cam)
+{
+	unsigned int id;
+	bool isCameraExternal = false;
+	bool isCameraNew = false;
+
+	MutexLocker locker(mutex_);
+
+	/*
+	 * Each camera is assigned a unique integer ID when it is seen for the
+	 * first time. If the camera has been seen before, the previous ID is
+	 * re-used.
+	 *
+	 * IDs starts from '0' for internal cameras and '1000' for external
+	 * cameras.
+	 */
+	auto iter = cameraIdsMap_.find(cam->id());
+	if (iter != cameraIdsMap_.end()) {
+		id = iter->second;
+	} else {
+		isCameraNew = true;
+
+		/*
+		 * Now check if this is an external camera and assign
+		 * its id accordingly.
+		 */
+		if (cameraLocation(cam.get()) == properties::CameraLocationExternal) {
+			isCameraExternal = true;
+			id = nextExternalCameraId_;
+		} else {
+			id = numInternalCameras_;
+		}
+	}
+
+	/* Create a CameraDevice instance to wrap the libcamera Camera. */
+	std::shared_ptr<CameraDevice> camera = CameraDevice::create(id, std::move(cam));
+	int ret = camera->initialize();
+	if (ret) {
+		LOG(HAL, Error) << "Failed to initialize camera: " << cam->id();
+		return;
+	}
+
+	if (isCameraNew) {
+		cameraIdsMap_.emplace(cam->id(), id);
+
+		if (isCameraExternal)
+			nextExternalCameraId_++;
+		else
+			numInternalCameras_++;
+	}
+
+	cameras_.emplace_back(std::move(camera));
+
+	if (callbacks_)
+		callbacks_->camera_device_status_change(callbacks_, id,
+							CAMERA_DEVICE_STATUS_PRESENT);
+
+	LOG(HAL, Debug) << "Camera ID: " << id << " added successfully.";
+}
+
+void CameraHalManager::cameraRemoved(std::shared_ptr<Camera> cam)
+{
+	MutexLocker locker(mutex_);
+
+	auto iter = std::find_if(cameras_.begin(), cameras_.end(),
+				 [&cam](std::shared_ptr<CameraDevice> &camera) {
+					 return cam.get() == camera->camera();
+				 });
+	if (iter == cameras_.end())
+		return;
+
+	/*
+	 * CAMERA_DEVICE_STATUS_NOT_PRESENT should be set for external cameras
+	 * only.
+	 */
+	unsigned int id = (*iter)->id();
+	if (id >= firstExternalCameraId_)
+		callbacks_->camera_device_status_change(callbacks_, id,
+							CAMERA_DEVICE_STATUS_NOT_PRESENT);
+
+	/*
+	 * \todo Check if the camera is already open and running.
+	 * Inform the framework about its absence before deleting its
+	 * reference here.
+	 */
+	cameras_.erase(iter);
+
+	LOG(HAL, Debug) << "Camera ID: " << id << " removed successfully.";
+}
+
+int32_t CameraHalManager::cameraLocation(const Camera *cam)
+{
+	const ControlList &properties = cam->properties();
+	if (!properties.contains(properties::Location))
+		return -1;
+
+	return properties.get(properties::Location);
+}
+
+CameraDevice *CameraHalManager::cameraDeviceFromHalId(unsigned int id)
+{
+	auto iter = std::find_if(cameras_.begin(), cameras_.end(),
+				 [id](std::shared_ptr<CameraDevice> &camera) {
+					 return camera->id() == id;
+				 });
+	if (iter == cameras_.end())
+		return nullptr;
+
+	return iter->get();
+}
+
 unsigned int CameraHalManager::numCameras() const
 {
-	return cameraManager_->cameras().size();
+	return numInternalCameras_;
 }
 
 int CameraHalManager::getCameraInfo(unsigned int id, struct camera_info *info)
@@ -103,13 +205,14 @@ int CameraHalManager::getCameraInfo(unsigned int id, struct camera_info *info)
 	if (!info)
 		return -EINVAL;
 
-	if (id >= numCameras()) {
+	MutexLocker locker(mutex_);
+
+	CameraDevice *camera = cameraDeviceFromHalId(id);
+	if (!camera) {
 		LOG(HAL, Error) << "Invalid camera id '" << id << "'";
 		return -EINVAL;
 	}
 
-	CameraDevice *camera = cameras_[id].get();
-
 	info->facing = camera->facing();
 	info->orientation = camera->orientation();
 	info->device_version = CAMERA_DEVICE_API_VERSION_3_3;
@@ -124,4 +227,21 @@ int CameraHalManager::getCameraInfo(unsigned int id, struct camera_info *info)
 void CameraHalManager::setCallbacks(const camera_module_callbacks_t *callbacks)
 {
 	callbacks_ = callbacks;
+
+	MutexLocker locker(mutex_);
+
+	/*
+	 * Some external cameras may have been identified before the callbacks_
+	 * were set. Iterate all existing external cameras and mark them as
+	 * CAMERA_DEVICE_STATUS_PRESENT explicitly.
+	 *
+	 * Internal cameras are already assumed to be present at module load
+	 * time by the Android framework.
+	 */
+	for (std::shared_ptr<CameraDevice> &camera : cameras_) {
+		unsigned int id = camera->id();
+		if (id >= firstExternalCameraId_)
+			callbacks_->camera_device_status_change(callbacks_, id,
+								CAMERA_DEVICE_STATUS_PRESENT);
+	}
 }
diff --git a/src/android/camera_hal_manager.h b/src/android/camera_hal_manager.h
index 3e34d63f..a91decc7 100644
--- a/src/android/camera_hal_manager.h
+++ b/src/android/camera_hal_manager.h
@@ -7,6 +7,8 @@
 #ifndef __ANDROID_CAMERA_MANAGER_H__
 #define __ANDROID_CAMERA_MANAGER_H__
 
+#include <map>
+#include <mutex>
 #include <stddef.h>
 #include <vector>
 
@@ -33,10 +35,27 @@ public:
 	void setCallbacks(const camera_module_callbacks_t *callbacks);
 
 private:
+	using Mutex = std::mutex;
+	using MutexLocker = std::unique_lock<std::mutex>;
+
+	static constexpr unsigned int firstExternalCameraId_ = 1000;
+
+	static int32_t cameraLocation(const libcamera::Camera *cam);
+
+	void cameraAdded(std::shared_ptr<libcamera::Camera> cam);
+	void cameraRemoved(std::shared_ptr<libcamera::Camera> cam);
+
+	CameraDevice *cameraDeviceFromHalId(unsigned int id);
+
 	libcamera::CameraManager *cameraManager_;
 
 	const camera_module_callbacks_t *callbacks_;
 	std::vector<std::shared_ptr<CameraDevice>> cameras_;
+	std::map<std::string, unsigned int> cameraIdsMap_;
+	Mutex mutex_;
+
+	unsigned int numInternalCameras_;
+	unsigned int nextExternalCameraId_;
 };
 
 #endif /* __ANDROID_CAMERA_MANAGER_H__ */