libcamera: Add MediaDevice class

The MediaDevice object implements handling and configuration of the media
graph associated with a media device.

The class allows enumeration of all pads, links and entities registered in
the media graph.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/libcamera/include/media_device.h

@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2018, Google Inc.
+ *
+ * media_device.h - Media device handler
+ */
+#ifndef __LIBCAMERA_MEDIA_DEVICE_H__
+#define __LIBCAMERA_MEDIA_DEVICE_H__
+
+#include <map>
+#include <sstream>
+#include <string>
+#include <vector>
+
+#include <linux/media.h>
+
+#include "media_object.h"
+
+namespace libcamera {
+
+class MediaDevice
+{
+public:
+	MediaDevice(const std::string &devnode);
+	~MediaDevice();
+
+	int open();
+	void close();
+
+	int populate();
+
+	const std::string driver() const { return driver_; }
+	const std::string devnode() const { return devnode_; }
+	const std::vector<MediaEntity *> &entities() const { return entities_; }
+
+private:
+	std::string driver_;
+	std::string devnode_;
+	int fd_;
+
+	std::map<unsigned int, MediaObject *> objects_;
+	MediaObject *object(unsigned int id);
+	int addObject(MediaObject *obj);
+	void clear();
+
+	std::vector<MediaEntity *> entities_;
+	MediaEntity *getEntityByName(const std::string &name);
+
+	void populateEntities(const struct media_v2_topology &topology);
+	int populatePads(const struct media_v2_topology &topology);
+	int populateLinks(const struct media_v2_topology &topology);
+};
+
+} /* namespace libcamera */
+
+#endif /* __LIBCAMERA_MEDIA_DEVICE_H__ */