libcamera: Introduce V4L2Device base class

The V4L2 devices and subdevices share a few common operations,like
opening and closing a device node, and perform IOCTLs on the device.

With the forthcoming introduction of support for V4L2 controls, the
quantity of shared code will increase, as the control support
implementation is identical for the two derived classes.

To maximize code re-use and avoid duplications, provide a V4L2Device
base class which groups the common operations and members.

The newly introduced base class provides methods to open/close a device
node, access the file descriptor, and perform IOCTLs on the device.

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

1 files changed, 29 insertions, 71 deletions

diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
index 0e70498c..2de3751f 100644
--- a/src/libcamera/v4l2_videodevice.cpp
+++ b/src/libcamera/v4l2_videodevice.cpp
@@ -30,7 +30,7 @@
  */
 namespace libcamera {
 
-LOG_DEFINE_CATEGORY(V4L2)
+LOG_DECLARE_CATEGORY(V4L2)
 
 /**
  * \struct V4L2Capability
@@ -270,7 +270,7 @@ const std::string V4L2DeviceFormat::toString() const
  * \param[in] deviceNode The file-system path to the video device node
  */
 V4L2VideoDevice::V4L2VideoDevice(const std::string &deviceNode)
-	: deviceNode_(deviceNode), fd_(-1), bufferPool_(nullptr),
+	: V4L2Device(deviceNode), bufferPool_(nullptr),
 	  queuedBuffersCount_(0), fdEvent_(nullptr)
 {
 	/*
@@ -305,23 +305,12 @@ int V4L2VideoDevice::open()
 {
 	int ret;
 
-	if (isOpen()) {
-		LOG(V4L2, Error) << "Device already open";
-		return -EBUSY;
-	}
-
-	ret = ::open(deviceNode_.c_str(), O_RDWR | O_NONBLOCK);
-	if (ret < 0) {
-		ret = -errno;
-		LOG(V4L2, Error)
-			<< "Failed to open V4L2 device: " << strerror(-ret);
+	ret = V4L2Device::open(O_RDWR | O_NONBLOCK);
+	if (ret < 0)
 		return ret;
-	}
-	fd_ = ret;
 
-	ret = ioctl(fd_, VIDIOC_QUERYCAP, &caps_);
+	ret = ioctl(VIDIOC_QUERYCAP, &caps_);
 	if (ret < 0) {
-		ret = -errno;
 		LOG(V4L2, Error)
 			<< "Failed to query device capabilities: "
 			<< strerror(-ret);
@@ -342,20 +331,20 @@ int V4L2VideoDevice::open()
 	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
 	 */
 	if (caps_.isVideoCapture()) {
-		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
+		fdEvent_ = new EventNotifier(fd(), EventNotifier::Read);
 		bufferType_ = caps_.isMultiplanar()
 			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
 			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
 	} else if (caps_.isVideoOutput()) {
-		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
+		fdEvent_ = new EventNotifier(fd(), EventNotifier::Write);
 		bufferType_ = caps_.isMultiplanar()
 			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
 			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
 	} else if (caps_.isMetaCapture()) {
-		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
+		fdEvent_ = new EventNotifier(fd(), EventNotifier::Read);
 		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
 	} else if (caps_.isMetaOutput()) {
-		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
+		fdEvent_ = new EventNotifier(fd(), EventNotifier::Write);
 		bufferType_ = V4L2_BUF_TYPE_META_OUTPUT;
 	} else {
 		LOG(V4L2, Error) << "Device is not a supported type";
@@ -369,27 +358,17 @@ int V4L2VideoDevice::open()
 }
 
 /**
- * \brief Check if device is successfully opened
- * \return True if the device is open, false otherwise
- */
-bool V4L2VideoDevice::isOpen() const
-{
-	return fd_ != -1;
-}
-
-/**
  * \brief Close the device, releasing any resources acquired by open()
  */
 void V4L2VideoDevice::close()
 {
-	if (fd_ < 0)
+	if (!isOpen())
 		return;
 
 	releaseBuffers();
 	delete fdEvent_;
 
-	::close(fd_);
-	fd_ = -1;
+	V4L2Device::close();
 }
 
 /**
@@ -410,15 +389,9 @@ void V4L2VideoDevice::close()
  * \return The string containing the device location
  */
 
-/**
- * \fn V4L2VideoDevice::deviceNode()
- * \brief Retrieve the video device node path
- * \return The video device device node path
- */
-
 std::string V4L2VideoDevice::logPrefix() const
 {
-	return deviceNode_ + (V4L2_TYPE_IS_OUTPUT(bufferType_) ? "[out]" : "[cap]");
+	return deviceNode() + (V4L2_TYPE_IS_OUTPUT(bufferType_) ? "[out]" : "[cap]");
 }
 
 /**
@@ -462,9 +435,8 @@ int V4L2VideoDevice::getFormatMeta(V4L2DeviceFormat *format)
 	int ret;
 
 	v4l2Format.type = bufferType_;
-	ret = ioctl(fd_, VIDIOC_G_FMT, &v4l2Format);
+	ret = ioctl(VIDIOC_G_FMT, &v4l2Format);
 	if (ret) {
-		ret = -errno;
 		LOG(V4L2, Error) << "Unable to get format: " << strerror(-ret);
 		return ret;
 	}
@@ -488,9 +460,8 @@ int V4L2VideoDevice::setFormatMeta(V4L2DeviceFormat *format)
 	v4l2Format.type = bufferType_;
 	pix->dataformat = format->fourcc;
 	pix->buffersize = format->planes[0].size;
-	ret = ioctl(fd_, VIDIOC_S_FMT, &v4l2Format);
+	ret = ioctl(VIDIOC_S_FMT, &v4l2Format);
 	if (ret) {
-		ret = -errno;
 		LOG(V4L2, Error) << "Unable to set format: " << strerror(-ret);
 		return ret;
 	}
@@ -516,9 +487,8 @@ int V4L2VideoDevice::getFormatMultiplane(V4L2DeviceFormat *format)
 	int ret;
 
 	v4l2Format.type = bufferType_;
-	ret = ioctl(fd_, VIDIOC_G_FMT, &v4l2Format);
+	ret = ioctl(VIDIOC_G_FMT, &v4l2Format);
 	if (ret) {
-		ret = -errno;
 		LOG(V4L2, Error) << "Unable to get format: " << strerror(-ret);
 		return ret;
 	}
@@ -554,9 +524,8 @@ int V4L2VideoDevice::setFormatMultiplane(V4L2DeviceFormat *format)
 		pix->plane_fmt[i].sizeimage = format->planes[i].size;
 	}
 
-	ret = ioctl(fd_, VIDIOC_S_FMT, &v4l2Format);
+	ret = ioctl(VIDIOC_S_FMT, &v4l2Format);
 	if (ret) {
-		ret = -errno;
 		LOG(V4L2, Error) << "Unable to set format: " << strerror(-ret);
 		return ret;
 	}
@@ -584,9 +553,8 @@ int V4L2VideoDevice::getFormatSingleplane(V4L2DeviceFormat *format)
 	int ret;
 
 	v4l2Format.type = bufferType_;
-	ret = ioctl(fd_, VIDIOC_G_FMT, &v4l2Format);
+	ret = ioctl(VIDIOC_G_FMT, &v4l2Format);
 	if (ret) {
-		ret = -errno;
 		LOG(V4L2, Error) << "Unable to get format: " << strerror(-ret);
 		return ret;
 	}
@@ -613,9 +581,8 @@ int V4L2VideoDevice::setFormatSingleplane(V4L2DeviceFormat *format)
 	pix->pixelformat = format->fourcc;
 	pix->bytesperline = format->planes[0].bpl;
 	pix->field = V4L2_FIELD_NONE;
-	ret = ioctl(fd_, VIDIOC_S_FMT, &v4l2Format);
+	ret = ioctl(VIDIOC_S_FMT, &v4l2Format);
 	if (ret) {
-		ret = -errno;
 		LOG(V4L2, Error) << "Unable to set format: " << strerror(-ret);
 		return ret;
 	}
@@ -670,9 +637,8 @@ int V4L2VideoDevice::requestBuffers(unsigned int count)
 	rb.type = bufferType_;
 	rb.memory = memoryType_;
 
-	ret = ioctl(fd_, VIDIOC_REQBUFS, &rb);
+	ret = ioctl(VIDIOC_REQBUFS, &rb);
 	if (ret < 0) {
-		ret = -errno;
 		LOG(V4L2, Error)
 			<< "Unable to request " << count << " buffers: "
 			<< strerror(-ret);
@@ -722,9 +688,8 @@ int V4L2VideoDevice::exportBuffers(BufferPool *pool)
 		buf.length = VIDEO_MAX_PLANES;
 		buf.m.planes = planes;
 
-		ret = ioctl(fd_, VIDIOC_QUERYBUF, &buf);
+		ret = ioctl(VIDIOC_QUERYBUF, &buf);
 		if (ret < 0) {
-			ret = -errno;
 			LOG(V4L2, Error)
 				<< "Unable to query buffer " << i << ": "
 				<< strerror(-ret);
@@ -775,9 +740,8 @@ int V4L2VideoDevice::createPlane(Buffer *buffer, unsigned int planeIndex,
 	expbuf.plane = planeIndex;
 	expbuf.flags = O_RDWR;
 
-	ret = ioctl(fd_, VIDIOC_EXPBUF, &expbuf);
+	ret = ioctl(VIDIOC_EXPBUF, &expbuf);
 	if (ret < 0) {
-		ret = -errno;
 		LOG(V4L2, Error)
 			<< "Failed to export buffer: " << strerror(-ret);
 		return ret;
@@ -801,15 +765,14 @@ std::vector<unsigned int> V4L2VideoDevice::enumPixelformats()
 		pixelformatEnum.index = index;
 		pixelformatEnum.type = bufferType_;
 
-		ret = ioctl(fd_, VIDIOC_ENUM_FMT, &pixelformatEnum);
+		ret = ioctl(VIDIOC_ENUM_FMT, &pixelformatEnum);
 		if (ret)
 			break;
 
 		formats.push_back(pixelformatEnum.pixelformat);
 	}
 
-	if (ret && errno != EINVAL) {
-		ret = -errno;
+	if (ret && ret != -EINVAL) {
 		LOG(V4L2, Error)
 			<< "Unable to enumerate pixel formats: "
 			<< strerror(-ret);
@@ -829,7 +792,7 @@ std::vector<SizeRange> V4L2VideoDevice::enumSizes(unsigned int pixelFormat)
 		frameSize.index = index;
 		frameSize.pixel_format = pixelFormat;
 
-		ret = ioctl(fd_, VIDIOC_ENUM_FRAMESIZES, &frameSize);
+		ret = ioctl(VIDIOC_ENUM_FRAMESIZES, &frameSize);
 		if (ret)
 			break;
 
@@ -867,8 +830,7 @@ std::vector<SizeRange> V4L2VideoDevice::enumSizes(unsigned int pixelFormat)
 		}
 	}
 
-	if (ret && errno != EINVAL) {
-		ret = -errno;
+	if (ret && ret != -EINVAL) {
 		LOG(V4L2, Error)
 			<< "Unable to enumerate frame sizes: "
 			<< strerror(-ret);
@@ -969,9 +931,8 @@ int V4L2VideoDevice::queueBuffer(Buffer *buffer)
 
 	LOG(V4L2, Debug) << "Queueing buffer " << buf.index;
 
-	ret = ioctl(fd_, VIDIOC_QBUF, &buf);
+	ret = ioctl(VIDIOC_QBUF, &buf);
 	if (ret < 0) {
-		ret = -errno;
 		LOG(V4L2, Error)
 			<< "Failed to queue buffer " << buf.index << ": "
 			<< strerror(-ret);
@@ -1006,9 +967,8 @@ Buffer *V4L2VideoDevice::dequeueBuffer()
 		buf.m.planes = planes;
 	}
 
-	ret = ioctl(fd_, VIDIOC_DQBUF, &buf);
+	ret = ioctl(VIDIOC_DQBUF, &buf);
 	if (ret < 0) {
-		ret = -errno;
 		LOG(V4L2, Error)
 			<< "Failed to dequeue buffer: " << strerror(-ret);
 		return nullptr;
@@ -1066,9 +1026,8 @@ int V4L2VideoDevice::streamOn()
 {
 	int ret;
 
-	ret = ioctl(fd_, VIDIOC_STREAMON, &bufferType_);
+	ret = ioctl(VIDIOC_STREAMON, &bufferType_);
 	if (ret < 0) {
-		ret = -errno;
 		LOG(V4L2, Error)
 			<< "Failed to start streaming: " << strerror(-ret);
 		return ret;
@@ -1089,9 +1048,8 @@ int V4L2VideoDevice::streamOff()
 {
 	int ret;
 
-	ret = ioctl(fd_, VIDIOC_STREAMOFF, &bufferType_);
+	ret = ioctl(VIDIOC_STREAMOFF, &bufferType_);
 	if (ret < 0) {
-		ret = -errno;
 		LOG(V4L2, Error)
 			<< "Failed to stop streaming: " << strerror(-ret);
 		return ret;