[libcamera-devel] [PATCH v4 3/6] libcamera: v4l2_device: Implement get and set controls

[Jacopo Mondi]

Implement getControls() and setControls() operations in V4L2Device class.

Both operations take a V4L2Controls instance and read or write the V4L2
controls on the V4L2 device.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 src/libcamera/include/v4l2_device.h |   6 +
 src/libcamera/v4l2_device.cpp       | 189 ++++++++++++++++++++++++++++
 2 files changed, 195 insertions(+)

diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
index 563be151c257..e66cc7ebe737 100644
--- a/src/libcamera/include/v4l2_device.h
+++ b/src/libcamera/include/v4l2_device.h
@@ -15,6 +15,7 @@
 namespace libcamera {
 
 class V4L2ControlInfo;
+class V4L2Controls;
 
 class V4L2Device : protected Loggable
 {
@@ -23,6 +24,10 @@ public:
 	bool isOpen() const { return fd_ != -1; }
 	const std::string &deviceNode() const { return deviceNode_; }
 
+	V4L2ControlInfo *getControlInfo(unsigned int id);
+	int getControls(V4L2Controls *ctrls);
+	int setControls(V4L2Controls *ctrls);
+
 protected:
 	V4L2Device(const std::string &deviceNode, const std::string &logTag);
 	~V4L2Device();
@@ -37,6 +42,7 @@ protected:
 
 private:
 	void listControls();
+	int validateControlType(V4L2ControlInfo *info);
 
 	std::map<unsigned int, V4L2ControlInfo *> controls_;
 	std::string deviceNode_;
diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
index 58dd94836686..5af0ddc468fe 100644
--- a/src/libcamera/v4l2_device.cpp
+++ b/src/libcamera/v4l2_device.cpp
@@ -66,6 +66,170 @@ void V4L2Device::close()
  * \return The device node path
  */
 
+/**
+ * \brief Get informations for control with \a id
+ * \param[in] id The control id to search info for
+ * \return The V4L2ControlInfo associated to the V4L2 control with \a id or
+ * nullptr if the control is not supported by the V4L2Device
+ */
+V4L2ControlInfo *V4L2Device::getControlInfo(unsigned int id)
+{
+	auto it = controls_.find(id);
+	if (it == controls_.end())
+		return nullptr;
+
+	return it->second;
+}
+
+/**
+ * \brief Read values of a list of controls from the device
+ * \param[inout] ctrls The list of controls to read
+ *
+ * Read the value of each V4L2Controls contained in \a ctrls, overwriting
+ * it's current value with the one returned by the device.
+ *
+ * Each V4L2Control instance in \a ctrls should be supported by the device.
+ *
+ * \return 0 on success or a negative error code otherwise
+ */
+int V4L2Device::getControls(V4L2Controls *ctrls)
+{
+	unsigned int count = ctrls->size();
+	if (count == 0)
+		return 0;
+
+	struct V4L2ControlInfo *controlInfo[count];
+	struct v4l2_ext_control v4l2Ctrls[count];
+	for (unsigned int i = 0; i < count; ++i) {
+		V4L2Control *ctrl = (*ctrls)[i];
+
+		/* Validate the control. */
+		V4L2ControlInfo *info = getControlInfo(ctrl->id());
+		if (!info) {
+			LOG(V4L2, Error) << "Control '" << ctrl->id()
+					 << "' not valid";
+			return -EINVAL;
+		}
+
+		if (validateControlType(info))
+			return -EINVAL;
+
+		controlInfo[i] = info;
+
+		/* Prepare the v4l2_ext_control entry for the read operation. */
+		struct v4l2_ext_control *v4l2Ctrl = &v4l2Ctrls[i];
+		v4l2Ctrl->id = info->id();
+		v4l2Ctrl->size = info->size();
+	}
+
+	struct v4l2_ext_controls v4l2ExtCtrls = {};
+	v4l2ExtCtrls.which = V4L2_CTRL_WHICH_CUR_VAL;
+	v4l2ExtCtrls.controls = v4l2Ctrls;
+	v4l2ExtCtrls.count = count;
+
+	int ret = ioctl(VIDIOC_G_EXT_CTRLS, &v4l2ExtCtrls);
+	if (ret) {
+		LOG(V4L2, Error) << "Unable to read controls: "
+				 << strerror(ret);
+		return ret;
+	}
+
+	/*
+	 * For each control read from the device, set the value in the
+	 * V4L2ControlValue provided by the caller.
+	 */
+	for (unsigned int i = 0; i < count; ++i) {
+		struct v4l2_ext_control *v4l2Ctrl = &v4l2Ctrls[i];
+		V4L2ControlInfo *info = controlInfo[i];
+		V4L2Control *ctrl = (*ctrls)[i];
+
+		switch (info->type()) {
+		case V4L2_CTRL_TYPE_INTEGER64:
+			ctrl->setValue(v4l2Ctrl->value64);
+			break;
+		case V4L2_CTRL_TYPE_INTEGER:
+		case V4L2_CTRL_TYPE_BOOLEAN:
+		case V4L2_CTRL_TYPE_BUTTON:
+		case V4L2_CTRL_TYPE_MENU:
+			ctrl->setValue(static_cast<long int>(v4l2Ctrl->value));
+			break;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * \brief Write a list of controls to the device
+ * \param[in] ctrls The list of controls to apply
+ *
+ * Write the value of each V4L2Control contained in \a ctrls. Each
+ * control should be initialized by the caller with a value, otherwise
+ * the result of the operation is undefined.
+ *
+ * The value of each control is not updated to reflect what has been
+ * actually applied on the device. To read the actual value of a control
+ * after a setControls(), users should read the control value back with
+ * getControls().
+ *
+ * Each V4L2Control instance in \a ctrls should be supported by the device.
+ *
+ * \return 0 on success or a negative error code otherwise
+ */
+int V4L2Device::setControls(V4L2Controls *ctrls)
+{
+	unsigned int count = ctrls->size();
+	if (count == 0)
+		return 0;
+
+	struct v4l2_ext_control v4l2Ctrls[count];
+	for (unsigned int i = 0; i < count; ++i) {
+		V4L2Control *ctrl = (*ctrls)[i];
+
+		/* Validate the control. */
+		V4L2ControlInfo *info = getControlInfo(ctrl->id());
+		if (!info) {
+			LOG(V4L2, Error) << "Control '" << ctrl->id()
+					 << "' not valid";
+			return -EINVAL;
+		}
+
+		if (validateControlType(info))
+			return -EINVAL;
+
+		/* Prepare the v4l2_ext_control entry for the write operation. */
+		struct v4l2_ext_control *v4l2Ctrl = &v4l2Ctrls[i];
+		v4l2Ctrl->id = info->id();
+		v4l2Ctrl->size = info->size();
+
+		switch (info->type()) {
+		case V4L2_CTRL_TYPE_INTEGER64:
+			v4l2Ctrl->value64 = ctrl->value();
+			break;
+		case V4L2_CTRL_TYPE_INTEGER:
+		case V4L2_CTRL_TYPE_BOOLEAN:
+		case V4L2_CTRL_TYPE_BUTTON:
+		case V4L2_CTRL_TYPE_MENU:
+			v4l2Ctrl->value = static_cast<int32_t>(ctrl->value());
+			break;
+		}
+	}
+
+	struct v4l2_ext_controls v4l2ExtCtrls = {};
+	v4l2ExtCtrls.which = V4L2_CTRL_WHICH_CUR_VAL;
+	v4l2ExtCtrls.controls = v4l2Ctrls;
+	v4l2ExtCtrls.count = count;
+
+	int ret = ioctl(VIDIOC_S_EXT_CTRLS, &v4l2ExtCtrls);
+	if (ret) {
+		LOG(V4L2, Error) << "Unable to write controls: "
+				 << strerror(ret);
+		return ret;
+	}
+
+	return 0;
+}
+
 /**
  * \brief Construct a V4L2Device
  * \param[in] deviceNode The device node filesystem path
@@ -171,4 +335,29 @@ void V4L2Device::listControls()
 	}
 }
 
+/*
+ * \brief Make sure the control type is supported
+ * \param[in] info The V4L2ControlInfo to inspect type of
+ * \return 0 on success or a negative error code otherwise
+ * \retval -EINVAL The control type is not supported
+ */
+int V4L2Device::validateControlType(V4L2ControlInfo *info)
+{
+	/* \todo support compound and menu controls. */
+	switch (info->type()) {
+	case V4L2_CTRL_TYPE_INTEGER64:
+	case V4L2_CTRL_TYPE_INTEGER:
+	case V4L2_CTRL_TYPE_BOOLEAN:
+	case V4L2_CTRL_TYPE_BUTTON:
+	case V4L2_CTRL_TYPE_MENU:
+		break;
+	default:
+		LOG(V4L2, Error) << "Control type '" << info->type()
+				 << "' not supported";
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 } /* namespace libcamera */
-- 
2.21.0