libcamera: v4l2_device: Implement get and set controls

Implement getControls() and setControls() operations in V4L2Device class.

Both operations take a V4L2Controls instance and read or write the V4L2
controls on the V4L2 device.

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

src/libcamera/include/v4l2_device.h

@@ -10,11 +10,14 @@
 #include <map>
 #include <string>
 
+#include <linux/videodev2.h>
+
 #include "log.h"
 
 namespace libcamera {
 
 class V4L2ControlInfo;
+class V4L2ControlList;
 
 class V4L2Device : protected Loggable
 {
@@ -23,6 +26,8 @@ public:
 	bool isOpen() const { return fd_ != -1; }
 
 	const V4L2ControlInfo *getControlInfo(unsigned int id) const;
+	int getControls(V4L2ControlList *ctrls);
+	int setControls(V4L2ControlList *ctrls);
 
 	const std::string &deviceNode() const { return deviceNode_; }
 
@@ -38,6 +43,10 @@ protected:
 
 private:
 	void listControls();
+	void updateControls(V4L2ControlList *ctrls,
+			    const V4L2ControlInfo **controlInfo,
+			    const struct v4l2_ext_control *v4l2Ctrls,
+			    unsigned int count);
 
 	std::map<unsigned int, V4L2ControlInfo> controls_;
 	std::string deviceNode_;