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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2019, Google Inc.
*
* v4l2_device.cpp - Common base for V4L2 video devices and subdevices
*/
#include "v4l2_device.h"
#include <fcntl.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include "log.h"
#include "v4l2_controls.h"
/**
* \file v4l2_device.h
* \brief Common base for V4L2 devices and subdevices
*/
namespace libcamera {
LOG_DEFINE_CATEGORY(V4L2)
/**
* \class V4L2Device
* \brief Base class for V4L2VideoDevice and V4L2Subdevice
*
* The V4L2Device class groups together the methods and fields common to
* both the V4L2VideoDevice and V4L2Subdevice classes, and provides a base
* class whith methods to open and close the device node associated with the
* device and to perform IOCTL system calls on it.
*
* The V4L2Device class cannot be instantiated directly, as its constructor
* is protected. Users should instead create instances of one the derived
* classes to model either a V4L2 video device or a V4L2 subdevice.
*/
/**
* \brief Construct a V4L2Device
* \param[in] deviceNode The device node filesystem path
*
* Initialize the file descriptor to -1 and store the \a deviceNode to be used
* at open() time, and the \a logTag to prefix log messages with.
*/
V4L2Device::V4L2Device(const std::string &deviceNode)
: deviceNode_(deviceNode), fd_(-1)
{
}
/**
* \brief Destroy a V4L2Device
*/
V4L2Device::~V4L2Device()
{
}
/**
* \brief Open a V4L2 device node
* \param[in] flags Access mode flags
*
* Open the device node path with the provided access mode \a flags and
* initialize the file descriptor, which was initially set to -1.
*
* \return 0 on success or a negative error code otherwise
*/
int V4L2Device::open(unsigned int flags)
{
if (isOpen()) {
LOG(V4L2, Error) << "Device already open";
return -EBUSY;
}
int ret = ::open(deviceNode_.c_str(), flags);
if (ret < 0) {
ret = -errno;
LOG(V4L2, Error) << "Failed to open V4L2 device: "
<< strerror(-ret);
return ret;
}
fd_ = ret;
listControls();
return 0;
}
/**
* \brief Close the device node
*
* Reset the file descriptor to -1
*/
void V4L2Device::close()
{
if (!isOpen())
return;
if (::close(fd_) < 0)
LOG(V4L2, Error) << "Failed to close V4L2 device: "
<< strerror(errno);
fd_ = -1;
}
/**
* \fn V4L2Device::isOpen()
* \brief Check if the V4L2 device node is open
* \return True if the V4L2 device node is open, false otherwise
*/
/**
* \fn V4L2Device::controls()
* \brief Retrieve the supported V4L2 controls and their information
* \return A map of the V4L2 controls supported by the device
*/
/**
* \brief Read controls from the device
* \param[inout] ctrls The list of controls to read
*
* This method reads the value of all controls contained in \a ctrls, and stores
* their values in the corresponding \a ctrls entry.
*
* If any control in \a ctrls is not supported by the device, is disabled (i.e.
* has the V4L2_CTRL_FLAG_DISABLED flag set), is a compound control, or if any
* other error occurs during validation of the requested controls, no control is
* read and this method returns -EINVAL.
*
* If an error occurs while reading the controls, the index of the first control
* that couldn't be read is returned. The value of all controls below that index
* are updated in \a ctrls, while the value of all the other controls are not
* changed.
*
* \return 0 on success or an error code otherwise
* \retval -EINVAL One of the control is not supported or not accessible
* \retval i The index of the control that failed
*/
int V4L2Device::getControls(V4L2ControlList *ctrls)
{
unsigned int count = ctrls->size();
if (count == 0)
return 0;
const V4L2ControlInfo *controlInfo[count];
struct v4l2_ext_control v4l2Ctrls[count];
memset(v4l2Ctrls, 0, sizeof(v4l2Ctrls));
for (unsigned int i = 0; i < count; ++i) {
const V4L2Control *ctrl = ctrls->getByIndex(i);
const auto iter = controls_.find(ctrl->id());
if (iter == controls_.end()) {
LOG(V4L2, Error)
<< "Control '" << ctrl->id() << "' not found";
return -EINVAL;
}
const V4L2ControlInfo *info = &iter->second;
controlInfo[i] = info;
v4l2Ctrls[i].id = info->id();
}
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) {
unsigned int errorIdx = v4l2ExtCtrls.error_idx;
/* Generic validation error. */
if (errorIdx == 0 || errorIdx >= count) {
LOG(V4L2, Error) << "Unable to read controls: "
<< strerror(ret);
return -EINVAL;
}
/* A specific control failed. */
LOG(V4L2, Error) << "Unable to read control " << errorIdx
<< ": " << strerror(ret);
count = errorIdx - 1;
ret = errorIdx;
}
updateControls(ctrls, controlInfo, v4l2Ctrls, count);
return ret;
}
/**
* \brief Write controls to the device
* \param[in] ctrls The list of controls to write
*
* This method writes the value of all controls contained in \a ctrls, and
* stores the values actually applied to the device in the corresponding
* \a ctrls entry.
*
* If any control in \a ctrls is not supported by the device, is disabled (i.e.
* has the V4L2_CTRL_FLAG_DISABLED flag set), is read-only, is a
* compound control, or if any other error occurs during validation of
* the requested controls, no control is written and this method returns
* -EINVAL.
*
* If an error occurs while writing the controls, the index of the first
* control that couldn't be written is returned. All controls below that index
* are written and their values are updated in \a ctrls, while all other
* controls are not written and their values are not changed.
*
* \return 0 on success or an error code otherwise
* \retval -EINVAL One of the control is not supported or not accessible
* \retval i The index of the control that failed
*/
int V4L2Device::setControls(V4L2ControlList *ctrls)
{
unsigned int count = ctrls->size();
if (count == 0)
return 0;
const V4L2ControlInfo *controlInfo[count];
struct v4l2_ext_control v4l2Ctrls[count];
memset(v4l2Ctrls, 0, sizeof(v4l2Ctrls));
for (unsigned int i = 0; i < count; ++i) {
const V4L2Control *ctrl = ctrls->getByIndex(i);
const auto iter = controls_.find(ctrl->id());
if (iter == controls_.end()) {
LOG(V4L2, Error)
<< "Control '" << ctrl->id() << "' not found";
return -EINVAL;
}
const V4L2ControlInfo *info = &iter->second;
controlInfo[i] = info;
v4l2Ctrls[i].id = info->id();
/* Set the v4l2_ext_control value for the write operation. */
switch (info->type()) {
case V4L2_CTRL_TYPE_INTEGER64:
v4l2Ctrls[i].value64 = ctrl->value();
break;
default:
/*
* \todo To be changed when support for string and
* compound controls will be added.
*/
v4l2Ctrls[i].value = 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) {
unsigned int errorIdx = v4l2ExtCtrls.error_idx;
/* Generic validation error. */
if (errorIdx == 0 || errorIdx >= count) {
LOG(V4L2, Error) << "Unable to read controls: "
<< strerror(ret);
return -EINVAL;
}
/* A specific control failed. */
LOG(V4L2, Error) << "Unable to read control " << errorIdx
<< ": " << strerror(ret);
count = errorIdx - 1;
ret = errorIdx;
}
updateControls(ctrls, controlInfo, v4l2Ctrls, count);
return ret;
}
/**
* \brief Perform an IOCTL system call on the device node
* \param[in] request The IOCTL request code
* \param[in] argp A pointer to the IOCTL argument
* \return 0 on success or a negative error code otherwise
*/
int V4L2Device::ioctl(unsigned long request, void *argp)
{
/*
* Printing out an error message is usually better performed
* in the caller, which can provide more context.
*/
if (::ioctl(fd_, request, argp) < 0)
return -errno;
return 0;
}
/**
* \fn V4L2Device::deviceNode()
* \brief Retrieve the device node path
* \return The device node path
*/
/**
* \fn V4L2Device::fd()
* \brief Retrieve the V4L2 device file descriptor
* \return The V4L2 device file descriptor, -1 if the device node is not open
*/
/*
* \brief List and store information about all controls supported by the
* V4L2 device
*/
void V4L2Device::listControls()
{
struct v4l2_query_ext_ctrl ctrl = {};
/* \todo Add support for menu and compound controls. */
while (1) {
ctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
if (ioctl(VIDIOC_QUERY_EXT_CTRL, &ctrl))
break;
if (ctrl.type == V4L2_CTRL_TYPE_CTRL_CLASS ||
ctrl.flags & V4L2_CTRL_FLAG_DISABLED)
continue;
V4L2ControlInfo info(ctrl);
switch (info.type()) {
case V4L2_CTRL_TYPE_INTEGER:
case V4L2_CTRL_TYPE_BOOLEAN:
case V4L2_CTRL_TYPE_MENU:
case V4L2_CTRL_TYPE_BUTTON:
case V4L2_CTRL_TYPE_INTEGER64:
case V4L2_CTRL_TYPE_BITMASK:
case V4L2_CTRL_TYPE_INTEGER_MENU:
break;
/* \todo Support compound controls. */
default:
LOG(V4L2, Debug) << "Control type '" << info.type()
<< "' not supported";
continue;
}
controls_.emplace(ctrl.id, info);
}
}
/*
* \brief Update the value of the first \a count V4L2 controls in \a ctrls using
* values in \a v4l2Ctrls
* \param[inout] ctrls List of V4L2 controls to update
* \param[in] controlInfo List of V4L2 control information
* \param[in] v4l2Ctrls List of V4L2 extended controls as returned by the driver
* \param[in] count The number of controls to update
*/
void V4L2Device::updateControls(V4L2ControlList *ctrls,
const V4L2ControlInfo **controlInfo,
const struct v4l2_ext_control *v4l2Ctrls,
unsigned int count)
{
for (unsigned int i = 0; i < count; ++i) {
const struct v4l2_ext_control *v4l2Ctrl = &v4l2Ctrls[i];
const V4L2ControlInfo *info = controlInfo[i];
V4L2Control *ctrl = ctrls->getByIndex(i);
switch (info->type()) {
case V4L2_CTRL_TYPE_INTEGER64:
ctrl->setValue(v4l2Ctrl->value64);
break;
default:
/*
* \todo To be changed when support for string and
* compound controls will be added.
*/
ctrl->setValue(v4l2Ctrl->value);
break;
}
}
}
} /* namespace libcamera */
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