[libcamera-devel] [PATCH] libcamera: v4l2_device: Group base operations in V4L2Base

[Jacopo Mondi]

Group operations commont to V4L2Device and the forthcoming V4L2Subdevice
in a common V4L2Base class.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
As I started implementing V4L2Subdevice support, I realized I was going to
re-implement what is now part of V4L2Base.

I would like to develop V4L2Subdevice on top of this.
Patch to be applied on top of my latest:
[PATCH v2 0/2] Add mplane support to V4L2 device

Thanks
   j
---
 src/libcamera/include/v4l2_device.h |  38 ++++++---
 src/libcamera/v4l2_device.cpp       | 127 ++++++++++++++++++----------
 2 files changed, 112 insertions(+), 53 deletions(-)

diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
index 2da30d1..08bfe9f 100644
--- a/src/libcamera/include/v4l2_device.h
+++ b/src/libcamera/include/v4l2_device.h
@@ -54,30 +54,48 @@ struct V4L2Capability final : v4l2_capability {
 };

 class MediaEntity;
-class V4L2Device
+class V4L2Base
 {
 public:
-	explicit V4L2Device(const std::string &deviceNode);
-	explicit V4L2Device(const MediaEntity &entity);
+	virtual ~V4L2Base() { close(); }
+
+	virtual int open();
+	bool isOpen() const { return fd_ != -1; }
+	virtual void close();
+
+protected:
+	V4L2Base(const std::string &deviceNode);
+	V4L2Base(const MediaEntity &entity);
+	V4L2Base(const V4L2Base &) = delete;
+	bool operator=(const V4L2Base &) = delete;
+
+	std::string deviceNode_;
+	int fd_;
+};
+
+class V4L2Device : public V4L2Base
+{
+public:
+	explicit V4L2Device(const std::string &deviceNode)
+		: V4L2Base(deviceNode) {}
+	explicit V4L2Device(const MediaEntity &entity)
+		: V4L2Base(entity) {}
 	V4L2Device(const V4L2Device &) = delete;
-	~V4L2Device();

-	void operator=(const V4L2Device &) = delete;
+	~V4L2Device() {}

-	int open();
-	bool isOpen() const;
-	void close();
+	void operator=(const V4L2Device &) = delete;

 	const char *driverName() const { return caps_.driver(); }
 	const char *deviceName() const { return caps_.card(); }
 	const char *busName() const { return caps_.bus_info(); }

+	int open();
+
 	int format();
 	int setFormat();

 private:
-	std::string deviceNode_;
-	int fd_;
 	V4L2Capability caps_;

 	int getFormatSingleplane();
diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
index 2ddb800..f505240 100644
--- a/src/libcamera/v4l2_device.cpp
+++ b/src/libcamera/v4l2_device.cpp
@@ -81,16 +81,15 @@ LOG_DEFINE_CATEGORY(V4L2)
  */

 /**
- * \class V4L2Device
- * \brief V4L2Device object and API
+ * \class V4L2Base
+ * \brief Group methods and field common to V4L2 devices and subdevices
  *
- * The V4L2 Device API class models an instance of a V4L2 device node.
- * It is constructed with the path to a V4L2 video device node. The device node
- * is only opened upon a call to open() which must be checked for success.
+ * Represents the base class for V4L2 devices and sub-devices.
+ * It is constructed with the path to a V4L2 video (sub-)device node or
+ * with a MediaEntity, provided its deviceNode() path has been set.
  *
- * The device capabilities are validated when the device is opened and the
- * device is rejected if it is not a suitable V4L2 capture or output device, or
- * if the device does not support streaming I/O.
+ * The device node is only opened upon a call to open() which must be
+ * checked for success.
  *
  * No API call other than open(), isOpen() and close() shall be called on an
  * unopened device instance.
@@ -100,35 +99,32 @@ LOG_DEFINE_CATEGORY(V4L2)
  */

 /**
- * \brief Construct a V4L2Device
- * \param deviceNode The file-system path to the video device node
+ * \fn V4L2Base::V4L2Base(const std::string &deviceNode)
+ * \brief Construct a V4L2 base instance
+ * \param deviceNode The file-system path to the video (sub-)device node
  */
-V4L2Device::V4L2Device(const std::string &deviceNode)
+V4L2Base::V4L2Base(const std::string &deviceNode)
 	: deviceNode_(deviceNode), fd_(-1)
 {
 }

 /**
- * \brief Construct a V4L2Device from a MediaEntity
+ * \fn V4L2Base::V4L2Base(const MediaEntity &entity)
+ * \brief Construct a V4L2 base instance from a MediaEntity
  * \param entity The MediaEntity to build the device from
  *
- * Construct a V4L2Device from a MediaEntity's device node path.
+ * Construct a V4L2 base instance from a MediaEntity's device node path.
  */
-V4L2Device::V4L2Device(const MediaEntity &entity)
-	: V4L2Device(entity.deviceNode())
-{
-}
-
-V4L2Device::~V4L2Device()
+V4L2Base::V4L2Base(const MediaEntity &entity)
+	: V4L2Base(entity.deviceNode())
 {
-	close();
 }

 /**
- * \brief Open a V4L2 device and query its capabilities
+ * \brief Open a device node associated with a V4L2 device or subdevice
  * \return 0 on success, or a negative error code otherwise
  */
-int V4L2Device::open()
+int V4L2Base::open()
 {
 	int ret;

@@ -147,6 +143,72 @@ int V4L2Device::open()
 	}
 	fd_ = ret;

+	return 0;
+}
+
+/**
+ * \fn V4L2Base::isOpen()
+ * \brief Check if device is successfully opened
+ * \return True if the device is open, false otherwise
+ */
+
+/**
+ * \brief Close the device node, releasing any resources acquired by open()
+ */
+void V4L2Base::close()
+{
+	if (fd_ < 0)
+		return;
+
+	::close(fd_);
+	fd_ = -1;
+}
+
+/**
+ * \var V4L2Base::deviceNode_
+ * \brief The device node path associated with the V4L2 instance.
+ */
+
+/**
+ * \var V4L2Base::fd_
+ * \brief The file descriptor associated with an open device node
+ */
+
+/**
+ * \class V4L2Device
+ * \brief V4L2Device object and API
+ *
+ * The V4L2 Device API class models an instance of a V4L2 device node.
+ *
+ * The device capabilities are validated when the device is opened and the
+ * device is rejected if it is not a suitable V4L2 capture or output device, or
+ * if the device does not support streaming I/O.
+ */
+
+/**
+ * \fn V4L2Device::V4L2Device(const std::string &deviceNode)
+ * \brief Construct a V4L2Device
+ * \param deviceNode The file-system path to the video (sub)device node
+ */
+
+/**
+ * \fn V4L2Device::V4L2Device(const MediaEntity &entity)
+ * \brief Construct a V4L2Device from a MediaEntity
+ * \param entity The MediaEntity to build the device from
+ *
+ * Construct a V4L2Device from a MediaEntity's device node path.
+ */
+
+/**
+ * \brief Open a V4L2 device and query its capabilities
+ * \return 0 on success, or a negative error code otherwise
+ */
+int V4L2Device::open()
+{
+	int ret = V4L2Base::open();
+	if (ret)
+		return ret;
+
 	ret = ioctl(fd_, VIDIOC_QUERYCAP, &caps_);
 	if (ret < 0) {
 		ret = -errno;
@@ -174,27 +236,6 @@ int V4L2Device::open()
 	return 0;
 }

-/**
- * \brief Check if device is successfully opened
- * \return True if the device is open, false otherwise
- */
-bool V4L2Device::isOpen() const
-{
-	return fd_ != -1;
-}
-
-/**
- * \brief Close the device, releasing any resources acquired by open()
- */
-void V4L2Device::close()
-{
-	if (fd_ < 0)
-		return;
-
-	::close(fd_);
-	fd_ = -1;
-}
-
 /**
  * \fn const char *V4L2Device::driverName()
  * \brief Retrieve the name of the V4L2 device driver
--
2.20.1