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, 18 insertions, 61 deletions

diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
index 48f1fcb3..a188298d 100644
--- a/src/libcamera/v4l2_subdevice.cpp
+++ b/src/libcamera/v4l2_subdevice.cpp
@@ -29,7 +29,7 @@
 
 namespace libcamera {
 
-LOG_DEFINE_CATEGORY(V4L2Subdev)
+LOG_DECLARE_CATEGORY(V4L2)
 
 /**
  * \struct V4L2SubdeviceFormat
@@ -102,7 +102,7 @@ const std::string V4L2SubdeviceFormat::toString() const
  * path
  */
 V4L2Subdevice::V4L2Subdevice(const MediaEntity *entity)
-	: entity_(entity), fd_(-1)
+	: V4L2Device(entity->deviceNode()), entity_(entity)
 {
 }
 
@@ -117,45 +117,7 @@ V4L2Subdevice::~V4L2Subdevice()
  */
 int V4L2Subdevice::open()
 {
-	int ret;
-
-	if (isOpen()) {
-		LOG(V4L2Subdev, Error) << "Device already open";
-		return -EBUSY;
-	}
-
-	ret = ::open(entity_->deviceNode().c_str(), O_RDWR);
-	if (ret < 0) {
-		ret = -errno;
-		LOG(V4L2Subdev, Error)
-			<< "Failed to open V4L2 subdevice '"
-			<< entity_->deviceNode() << "': " << strerror(-ret);
-		return ret;
-	}
-	fd_ = ret;
-
-	return 0;
-}
-
-/**
- * \brief Check if the subdevice is open
- * \return True if the subdevice is open, false otherwise
- */
-bool V4L2Subdevice::isOpen() const
-{
-	return fd_ != -1;
-}
-
-/**
- * \brief Close the subdevice, releasing any resources acquired by open()
- */
-void V4L2Subdevice::close()
-{
-	if (!isOpen())
-		return;
-
-	::close(fd_);
-	fd_ = -1;
+	return V4L2Device::open(O_RDWR);
 }
 
 /**
@@ -200,7 +162,7 @@ ImageFormats V4L2Subdevice::formats(unsigned int pad)
 	ImageFormats formats;
 
 	if (pad >= entity_->pads().size()) {
-		LOG(V4L2Subdev, Error) << "Invalid pad: " << pad;
+		LOG(V4L2, Error) << "Invalid pad: " << pad;
 		return {};
 	}
 
@@ -210,7 +172,7 @@ ImageFormats V4L2Subdevice::formats(unsigned int pad)
 			return {};
 
 		if (formats.addFormat(code, sizes)) {
-			LOG(V4L2Subdev, Error)
+			LOG(V4L2, Error)
 				<< "Could not add sizes for media bus code "
 				<< code << " on pad " << pad;
 			return {};
@@ -232,10 +194,9 @@ int V4L2Subdevice::getFormat(unsigned int pad, V4L2SubdeviceFormat *format)
 	subdevFmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 	subdevFmt.pad = pad;
 
-	int ret = ioctl(fd_, VIDIOC_SUBDEV_G_FMT, &subdevFmt);
+	int ret = ioctl(VIDIOC_SUBDEV_G_FMT, &subdevFmt);
 	if (ret) {
-		ret = -errno;
-		LOG(V4L2Subdev, Error)
+		LOG(V4L2, Error)
 			<< "Unable to get format on pad " << pad
 			<< ": " << strerror(-ret);
 		return ret;
@@ -268,10 +229,9 @@ int V4L2Subdevice::setFormat(unsigned int pad, V4L2SubdeviceFormat *format)
 	subdevFmt.format.height = format->size.height;
 	subdevFmt.format.code = format->mbus_code;
 
-	int ret = ioctl(fd_, VIDIOC_SUBDEV_S_FMT, &subdevFmt);
+	int ret = ioctl(VIDIOC_SUBDEV_S_FMT, &subdevFmt);
 	if (ret) {
-		ret = -errno;
-		LOG(V4L2Subdev, Error)
+		LOG(V4L2, Error)
 			<< "Unable to set format on pad " << pad
 			<< ": " << strerror(-ret);
 		return ret;
@@ -321,18 +281,17 @@ std::vector<unsigned int> V4L2Subdevice::enumPadCodes(unsigned int pad)
 		mbusEnum.index = index;
 		mbusEnum.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 
-		ret = ioctl(fd_, VIDIOC_SUBDEV_ENUM_MBUS_CODE, &mbusEnum);
+		ret = ioctl(VIDIOC_SUBDEV_ENUM_MBUS_CODE, &mbusEnum);
 		if (ret)
 			break;
 
 		codes.push_back(mbusEnum.code);
 	}
 
-	if (ret && errno != EINVAL) {
-		ret = errno;
-		LOG(V4L2Subdev, Error)
+	if (ret < 0 && ret != -EINVAL) {
+		LOG(V4L2, Error)
 			<< "Unable to enumerate formats on pad " << pad
-			<< ": " << strerror(ret);
+			<< ": " << strerror(-ret);
 		return {};
 	}
 
@@ -352,7 +311,7 @@ std::vector<SizeRange> V4L2Subdevice::enumPadSizes(unsigned int pad,
 		sizeEnum.code = code;
 		sizeEnum.which = V4L2_SUBDEV_FORMAT_ACTIVE;
 
-		ret = ioctl(fd_, VIDIOC_SUBDEV_ENUM_FRAME_SIZE, &sizeEnum);
+		ret = ioctl(VIDIOC_SUBDEV_ENUM_FRAME_SIZE, &sizeEnum);
 		if (ret)
 			break;
 
@@ -360,9 +319,8 @@ std::vector<SizeRange> V4L2Subdevice::enumPadSizes(unsigned int pad,
 				   sizeEnum.max_width, sizeEnum.max_height);
 	}
 
-	if (ret && (errno != EINVAL && errno != ENOTTY)) {
-		ret = -errno;
-		LOG(V4L2Subdev, Error)
+	if (ret < 0 && ret != -EINVAL && ret != -ENOTTY) {
+		LOG(V4L2, Error)
 			<< "Unable to enumerate sizes on pad " << pad
 			<< ": " << strerror(-ret);
 		return {};
@@ -386,10 +344,9 @@ int V4L2Subdevice::setSelection(unsigned int pad, unsigned int target,
 	sel.r.width = rect->w;
 	sel.r.height = rect->h;
 
-	int ret = ioctl(fd_, VIDIOC_SUBDEV_S_SELECTION, &sel);
+	int ret = ioctl(VIDIOC_SUBDEV_S_SELECTION, &sel);
 	if (ret < 0) {
-		ret = -errno;
-		LOG(V4L2Subdev, Error)
+		LOG(V4L2, Error)
 			<< "Unable to set rectangle " << target << " on pad "
 			<< pad << ": " << strerror(-ret);
 		return ret;