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.cpp

@@ -121,12 +121,6 @@ int V4L2Camera::configure(StreamConfiguration *streamConfigOut,
 	return 0;
 }
 
-void *V4L2Camera::mmap(unsigned int index)
-{
-	Stream *stream = *camera_->streams().begin();
-	return stream->buffers()[index].planes()[0].mem();
-}
-
 int V4L2Camera::allocBuffers(unsigned int count)
 {
 	int ret = camera_->allocateBuffers();
@@ -138,6 +132,12 @@ void V4L2Camera::freeBuffers()
 	camera_->freeBuffers();
 }
 
+FileDescriptor V4L2Camera::getBufferFd(unsigned int index)
+{
+	Stream *stream = *camera_->streams().begin();
+	return FileDescriptor(stream->buffers()[index].planes()[0].dmabuf());
+}
+
 int V4L2Camera::streamOn()
 {
 	if (isRunning_)

src/v4l2/v4l2_camera.h

@@ -14,6 +14,7 @@
 
 #include <libcamera/buffer.h>
 #include <libcamera/camera.h>
+#include <libcamera/file_descriptor.h>
 
 #include "semaphore.h"
 
@@ -53,14 +54,14 @@ public:
 	void getStreamConfig(StreamConfiguration *streamConfig);
 	std::vector<V4L2FrameMetadata> completedBuffers();
 
-	void *mmap(unsigned int index);
-
 	int configure(StreamConfiguration *streamConfigOut,
 		      const Size &size, PixelFormat pixelformat,
 		      unsigned int bufferCount);
 
 	int allocBuffers(unsigned int count);
 	void freeBuffers();
+	FileDescriptor getBufferFd(unsigned int index);
+
 	int streamOn();
 	int streamOff();
 

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,
+	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);
 

src/v4l2/v4l2_camera_proxy.h

@@ -28,7 +28,7 @@ public:
 	int open(bool nonBlocking);
 	void dup();
 	void close();
-	void *mmap(size_t length, int prot, int flags, off_t offset);
+	void *mmap(void *addr, size_t length, int prot, int flags, off_t offset);
 	int munmap(void *addr, size_t length);
 
 	int ioctl(unsigned long request, void *arg);

src/v4l2/v4l2_compat_manager.cpp

@@ -223,7 +223,7 @@ void *V4L2CompatManager::mmap(void *addr, size_t length, int prot, int flags,
 	if (!proxy)
 		return fops_.mmap(addr, length, prot, flags, fd, offset);
 
-	void *map = proxy->mmap(length, prot, flags, offset);
+	void *map = proxy->mmap(addr, length, prot, flags, offset);
 	if (map == MAP_FAILED)
 		return map;