v4l2: camera: Handle memory mapping of buffers directly

In the upcoming FrameBuffer API the memory mapping of buffers will be
left to the user of the FrameBuffer objects. Prepare the V4L2
compatibility layer to this upcoming change to ease conversion to the
new API.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/v4l2/v4l2_camera_proxy.cpp

@@ -75,7 +75,8 @@ void V4L2CameraProxy::close()
 	vcam_->invokeMethod(&V4L2Camera::close, ConnectionTypeBlocking);
 }
 
-void *V4L2CameraProxy::mmap(size_t length, int prot, int flags, off_t offset)
+void *V4L2CameraProxy::mmap(void *addr, size_t length, int prot, int flags,
+			    off_t offset)
 {
 	LOG(V4L2Compat, Debug) << "Servicing mmap";
 
@@ -91,13 +92,22 @@ void *V4L2CameraProxy::mmap(size_t length, int prot, int flags, off_t offset)
 		return MAP_FAILED;
 	}
 
-	void *val = vcam_->invokeMethod(&V4L2Camera::mmap,
-					ConnectionTypeBlocking, index);
+	FileDescriptor fd = vcam_->invokeMethod(&V4L2Camera::getBufferFd,
+						ConnectionTypeBlocking, index);
+	if (!fd.isValid()) {
+		errno = EINVAL;
+		return MAP_FAILED;
+	}
+
+	void *map = V4L2CompatManager::instance()->fops().mmap(addr, length, prot,
+							       flags, fd.fd(), 0);
+	if (map == MAP_FAILED)
+		return map;
 
 	buffers_[index].flags |= V4L2_BUF_FLAG_MAPPED;
-	mmaps_[val] = index;
+	mmaps_[map] = index;
 
-	return val;
+	return map;
 }
 
 int V4L2CameraProxy::munmap(void *addr, size_t length)
@@ -110,6 +120,10 @@ int V4L2CameraProxy::munmap(void *addr, size_t length)
 		return -1;
 	}
 
+	if (V4L2CompatManager::instance()->fops().munmap(addr, length))
+		LOG(V4L2Compat, Error) << "Failed to unmap " << addr
+				       << " with length " << length;
+
 	buffers_[iter->second].flags &= ~V4L2_BUF_FLAG_MAPPED;
 	mmaps_.erase(iter);