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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 "libcamera/internal/v4l2_device.h"
#include <fcntl.h>
#include <iomanip>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/syscall.h>
#include <unistd.h>
#include "libcamera/internal/event_notifier.h"
#include "libcamera/internal/log.h"
#include "libcamera/internal/sysfs.h"
#include "libcamera/internal/utils.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 with 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), fdEventNotifier_(nullptr),
frameStartEnabled_(false)
{
}
/**
* \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 = syscall(SYS_openat, AT_FDCWD, deviceNode_.c_str(), flags);
if (ret < 0) {
ret = -errno;
LOG(V4L2, Error) << "Failed to open V4L2 device: "
<< strerror(-ret);
return ret;
}
setFd(ret);
listControls();
return 0;
}
/**
* \brief Set the file descriptor of a V4L2 device
* \param[in] fd The file descriptor handle
*
* This method allows a device to provide an already opened file descriptor
* referring to the V4L2 device node, instead of opening it with open(). This
* can be used for V4L2 M2M devices where a single video device node is used for
* both the output and capture devices, or when receiving an open file
* descriptor in a context that doesn't have permission to open the device node
* itself.
*
* This method and the open() method are mutually exclusive, only one of the two
* shall be used for a V4L2Device instance.
*
* \return 0 on success or a negative error code otherwise
*/
int V4L2Device::setFd(int fd)
{
if (isOpen())
return -EBUSY;
fd_ = fd;
fdEventNotifier_ = new EventNotifier(fd_, EventNotifier::Exception);
fdEventNotifier_->activated.connect(this, &V4L2Device::eventAvailable);
fdEventNotifier_->setEnabled(false);
return 0;
}
/**
* \brief Close the device node
*
* Reset the file descriptor to -1
*/
void V4L2Device::close()
{
if (!isOpen())
return;
delete fdEventNotifier_;
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[in] ids The list of controls to read, specified by their ID
*
* This method reads the value of all controls contained in \a ids, and returns
* their values as a ControlList.
*
* If any control in \a ids is not supported by the device, is disabled (i.e.
* has the V4L2_CTRL_FLAG_DISABLED flag set), or if any other error occurs
* during validation of the requested controls, no control is read and this
* method returns an empty control list.
*
* \return The control values in a ControlList on success, or an empty list on
* error
*/
ControlList V4L2Device::getControls(const std::vector<uint32_t> &ids)
{
if (ids.empty())
return {};
ControlList ctrls{ controls_ };
for (uint32_t id : ids) {
const auto iter = controls_.find(id);
if (iter == controls_.end()) {
LOG(V4L2, Error)
<< "Control " << utils::hex(id) << " not found";
return {};
}
ctrls.set(id, {});
}
std::vector<v4l2_ext_control> v4l2Ctrls(ids.size());
memset(v4l2Ctrls.data(), 0, sizeof(v4l2_ext_control) * ctrls.size());
unsigned int i = 0;
for (auto &ctrl : ctrls) {
unsigned int id = ctrl.first;
const struct v4l2_query_ext_ctrl &info = controlInfo_[id];
v4l2_ext_control &v4l2Ctrl = v4l2Ctrls[i++];
v4l2Ctrl.id = id;
if (info.flags & V4L2_CTRL_FLAG_HAS_PAYLOAD) {
ControlType type;
switch (info.type) {
case V4L2_CTRL_TYPE_U8:
type = ControlTypeByte;
break;
default:
LOG(V4L2, Error)
<< "Unsupported payload control type "
<< info.type;
return {};
}
ControlValue &value = ctrl.second;
value.reserve(type, true, info.elems);
Span<uint8_t> data = value.data();
v4l2Ctrl.p_u8 = data.data();
v4l2Ctrl.size = data.size();
}
}
struct v4l2_ext_controls v4l2ExtCtrls = {};
v4l2ExtCtrls.which = V4L2_CTRL_WHICH_CUR_VAL;
v4l2ExtCtrls.controls = v4l2Ctrls.data();
v4l2ExtCtrls.count = v4l2Ctrls.size();
int ret = ioctl(VIDIOC_G_EXT_CTRLS, &v4l2ExtCtrls);
if (ret) {
unsigned int errorIdx = v4l2ExtCtrls.error_idx;
/* Generic validation error. */
if (errorIdx == 0 || errorIdx >= v4l2Ctrls.size()) {
LOG(V4L2, Error) << "Unable to read controls: "
<< strerror(-ret);
return {};
}
/* A specific control failed. */
LOG(V4L2, Error) << "Unable to read control " << errorIdx
<< ": " << strerror(-ret);
v4l2Ctrls.resize(errorIdx);
}
updateControls(&ctrls, v4l2Ctrls);
return ctrls;
}
/**
* \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, 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(ControlList *ctrls)
{
if (ctrls->empty())
return 0;
std::vector<v4l2_ext_control> v4l2Ctrls(ctrls->size());
memset(v4l2Ctrls.data(), 0, sizeof(v4l2_ext_control) * ctrls->size());
for (auto [ctrl, i] = std::pair(ctrls->begin(), 0u); i < ctrls->size(); ctrl++, i++) {
const unsigned int id = ctrl->first;
const auto iter = controls_.find(id);
if (iter == controls_.end()) {
LOG(V4L2, Error)
<< "Control " << utils::hex(id) << " not found";
return -EINVAL;
}
v4l2_ext_control &v4l2Ctrl = v4l2Ctrls[i];
v4l2Ctrl.id = id;
/* Set the v4l2_ext_control value for the write operation. */
ControlValue &value = ctrl->second;
switch (iter->first->type()) {
case ControlTypeInteger64:
v4l2Ctrl.value64 = value.get<int64_t>();
break;
case ControlTypeByte: {
if (!value.isArray()) {
LOG(V4L2, Error)
<< "Control " << utils::hex(id)
<< " requires an array value";
return -EINVAL;
}
Span<uint8_t> data = value.data();
v4l2Ctrl.p_u8 = data.data();
v4l2Ctrl.size = data.size();
break;
}
default:
/* \todo To be changed to support strings. */
v4l2Ctrl.value = value.get<int32_t>();
break;
}
}
struct v4l2_ext_controls v4l2ExtCtrls = {};
v4l2ExtCtrls.which = V4L2_CTRL_WHICH_CUR_VAL;
v4l2ExtCtrls.controls = v4l2Ctrls.data();
v4l2ExtCtrls.count = v4l2Ctrls.size();
int ret = ioctl(VIDIOC_S_EXT_CTRLS, &v4l2ExtCtrls);
if (ret) {
unsigned int errorIdx = v4l2ExtCtrls.error_idx;
/* Generic validation error. */
if (errorIdx == 0 || errorIdx >= v4l2Ctrls.size()) {
LOG(V4L2, Error) << "Unable to set controls: "
<< strerror(-ret);
return -EINVAL;
}
/* A specific control failed. */
LOG(V4L2, Error) << "Unable to set control " << errorIdx
<< ": " << strerror(-ret);
v4l2Ctrls.resize(errorIdx);
ret = errorIdx;
}
updateControls(ctrls, v4l2Ctrls);
return ret;
}
/**
* \brief Retrieve the v4l2_query_ext_ctrl information for the given control
* \param[in] id The V4L2 control id
* \return A pointer to the v4l2_query_ext_ctrl structure for the given
* control, or a null pointer if not found
*/
const struct v4l2_query_ext_ctrl *V4L2Device::controlInfo(uint32_t id) const
{
const auto it = controlInfo_.find(id);
if (it == controlInfo_.end())
return nullptr;
return &it->second;
}
/**
* \brief Retrieve the device path in sysfs
*
* This function returns the sysfs path to the physical device backing the V4L2
* device. The path is guaranteed to be an absolute path, without any symbolic
* link.
*
* It includes the sysfs mount point prefix
*
* \return The device path in sysfs
*/
std::string V4L2Device::devicePath() const
{
std::string devicePath = sysfs::charDevPath(deviceNode_) + "/device";
char *realPath = realpath(devicePath.c_str(), nullptr);
if (!realPath) {
LOG(V4L2, Fatal)
<< "Can not resolve device path for " << devicePath;
return {};
}
std::string path{ realPath };
free(realPath);
return path;
}
/**
* \brief Enable or disable frame start event notification
* \param[in] enable True to enable frame start events, false to disable them
*
* This function enables or disables generation of frame start events. Once
* enabled, the events are signalled through the frameStart signal.
*
* \return 0 on success, a negative error code otherwise
*/
int V4L2Device::setFrameStartEnabled(bool enable)
{
if (frameStartEnabled_ == enable)
return 0;
struct v4l2_event_subscription event{};
event.type = V4L2_EVENT_FRAME_SYNC;
unsigned long request = enable ? VIDIOC_SUBSCRIBE_EVENT
: VIDIOC_UNSUBSCRIBE_EVENT;
int ret = ioctl(request, &event);
if (enable && ret)
return ret;
fdEventNotifier_->setEnabled(enable);
frameStartEnabled_ = enable;
return ret;
}
/**
* \var V4L2Device::frameStart
* \brief A Signal emitted when capture of a frame has started
*/
/**
* \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 Retrieve the libcamera control type associated with the V4L2 control
* \param[in] ctrlType The V4L2 control type
* \return The ControlType associated to \a ctrlType
*/
ControlType V4L2Device::v4l2CtrlType(uint32_t ctrlType)
{
switch (ctrlType) {
case V4L2_CTRL_TYPE_U8:
return ControlTypeByte;
case V4L2_CTRL_TYPE_BOOLEAN:
return ControlTypeBool;
case V4L2_CTRL_TYPE_INTEGER:
return ControlTypeInteger32;
case V4L2_CTRL_TYPE_INTEGER64:
return ControlTypeInteger64;
case V4L2_CTRL_TYPE_MENU:
case V4L2_CTRL_TYPE_BUTTON:
case V4L2_CTRL_TYPE_BITMASK:
case V4L2_CTRL_TYPE_INTEGER_MENU:
/*
* More precise types may be needed, for now use a 32-bit
* integer type.
*/
return ControlTypeInteger32;
default:
return ControlTypeNone;
}
}
/**
* \brief Create a ControlId for a V4L2 control
* \param[in] ctrl The v4l2_query_ext_ctrl that represents a V4L2 control
* \return A ControlId associated to \a ctrl
*/
std::unique_ptr<ControlId> V4L2Device::v4l2ControlId(const v4l2_query_ext_ctrl &ctrl)
{
const size_t len = strnlen(ctrl.name, sizeof(ctrl.name));
const std::string name(static_cast<const char *>(ctrl.name), len);
const ControlType type = v4l2CtrlType(ctrl.type);
return std::make_unique<ControlId>(ctrl.id, name, type);
}
/**
* \brief Create a ControlInfo for a V4L2 control
* \param[in] ctrl The v4l2_query_ext_ctrl that represents a V4L2 control
* \return A ControlInfo that represents \a ctrl
*/
ControlInfo V4L2Device::v4l2ControlInfo(const v4l2_query_ext_ctrl &ctrl)
{
switch (ctrl.type) {
case V4L2_CTRL_TYPE_U8:
return ControlInfo(static_cast<uint8_t>(ctrl.minimum),
static_cast<uint8_t>(ctrl.maximum),
static_cast<uint8_t>(ctrl.default_value));
case V4L2_CTRL_TYPE_BOOLEAN:
return ControlInfo(static_cast<bool>(ctrl.minimum),
static_cast<bool>(ctrl.maximum),
static_cast<bool>(ctrl.default_value));
case V4L2_CTRL_TYPE_INTEGER64:
return ControlInfo(static_cast<int64_t>(ctrl.minimum),
static_cast<int64_t>(ctrl.maximum),
static_cast<int64_t>(ctrl.default_value));
case V4L2_CTRL_TYPE_INTEGER_MENU:
case V4L2_CTRL_TYPE_MENU:
return v4l2MenuControlInfo(ctrl);
default:
return ControlInfo(static_cast<int32_t>(ctrl.minimum),
static_cast<int32_t>(ctrl.maximum),
static_cast<int32_t>(ctrl.default_value));
}
}
/**
* \brief Create ControlInfo for a V4L2 menu control
* \param[in] ctrl The v4l2_query_ext_ctrl that represents a V4L2 menu control
*
* The created ControlInfo contains indices acquired by VIDIOC_QUERYMENU.
*
* \return A ControlInfo that represents \a ctrl
*/
ControlInfo V4L2Device::v4l2MenuControlInfo(const struct v4l2_query_ext_ctrl &ctrl)
{
std::vector<ControlValue> indices;
struct v4l2_querymenu menu = {};
menu.id = ctrl.id;
if (ctrl.minimum < 0)
return ControlInfo();
for (int32_t index = ctrl.minimum; index <= ctrl.maximum; ++index) {
menu.index = index;
if (ioctl(VIDIOC_QUERYMENU, &menu) != 0)
continue;
indices.push_back(index);
}
return ControlInfo(indices,
ControlValue(static_cast<int32_t>(ctrl.default_value)));
}
/*
* \brief List and store information about all controls supported by the
* V4L2 device
*/
void V4L2Device::listControls()
{
ControlInfoMap::Map ctrls;
struct v4l2_query_ext_ctrl ctrl = {};
while (1) {
ctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL |
V4L2_CTRL_FLAG_NEXT_COMPOUND;
if (ioctl(VIDIOC_QUERY_EXT_CTRL, &ctrl))
break;
if (ctrl.type == V4L2_CTRL_TYPE_CTRL_CLASS ||
ctrl.flags & V4L2_CTRL_FLAG_DISABLED)
continue;
switch (ctrl.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:
case V4L2_CTRL_TYPE_U8:
break;
/* \todo Support other control types. */
default:
LOG(V4L2, Debug)
<< "Control " << utils::hex(ctrl.id)
<< " has unsupported type " << ctrl.type;
continue;
}
LOG(V4L2, Debug) << "Control: " << ctrl.name
<< " (" << utils::hex(ctrl.id) << ")";
controlIds_.emplace_back(v4l2ControlId(ctrl));
controlInfo_.emplace(ctrl.id, ctrl);
ctrls.emplace(controlIds_.back().get(), v4l2ControlInfo(ctrl));
}
controls_ = std::move(ctrls);
}
/**
* \brief Update the information for all device controls
*
* The V4L2Device class caches information about all controls supported by the
* device and exposes it through the controls() and controlInfo() functions.
* Control information may change at runtime, for instance when formats on a
* subdev are modified. When this occurs, this function can be used to refresh
* control information. The information is refreshed in-place, all pointers to
* v4l2_query_ext_ctrl instances previously returned by controlInfo() and
* iterators to the ControlInfoMap returned by controls() remain valid.
*
* Note that control information isn't refreshed automatically is it may be an
* expensive operation. The V4L2Device users are responsible for calling this
* function when required, based on their usage pattern of the class.
*/
void V4L2Device::updateControlInfo()
{
for (auto &[controlId, info] : controls_) {
unsigned int id = controlId->id();
/*
* Assume controlInfo_ has a corresponding entry, as it has been
* generated by listControls().
*/
struct v4l2_query_ext_ctrl &ctrl = controlInfo_[id];
if (ioctl(VIDIOC_QUERY_EXT_CTRL, &ctrl)) {
LOG(V4L2, Debug)
<< "Could not refresh control "
<< utils::hex(id);
continue;
}
info = v4l2ControlInfo(ctrl);
}
}
/*
* \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] v4l2Ctrls List of V4L2 extended controls as returned by the driver
*/
void V4L2Device::updateControls(ControlList *ctrls,
Span<const v4l2_ext_control> v4l2Ctrls)
{
for (const v4l2_ext_control &v4l2Ctrl : v4l2Ctrls) {
const unsigned int id = v4l2Ctrl.id;
ControlValue value = ctrls->get(id);
const auto iter = controls_.find(id);
ASSERT(iter != controls_.end());
switch (iter->first->type()) {
case ControlTypeInteger64:
value.set<int64_t>(v4l2Ctrl.value64);
break;
case ControlTypeInteger32:
value.set<int32_t>(v4l2Ctrl.value);
break;
case ControlTypeByte:
/*
* No action required, the VIDIOC_[GS]_EXT_CTRLS ioctl
* accessed the ControlValue storage directly.
*/
break;
default:
/*
* \todo To be changed when support for string controls
* will be added.
*/
value.set<int32_t>(v4l2Ctrl.value);
break;
}
ctrls->set(id, value);
}
}
/**
* \brief Slot to handle V4L2 events from the V4L2 device
* \param[in] notifier The event notifier
*
* When this slot is called, a V4L2 event is available to be dequeued from the
* device.
*/
void V4L2Device::eventAvailable([[maybe_unused]] EventNotifier *notifier)
{
struct v4l2_event event{};
int ret = ioctl(VIDIOC_DQEVENT, &event);
if (ret < 0) {
LOG(V4L2, Error)
<< "Failed to dequeue event, disabling event notifier";
fdEventNotifier_->setEnabled(false);
return;
}
if (event.type != V4L2_EVENT_FRAME_SYNC) {
LOG(V4L2, Error)
<< "Spurious event (" << event.type
<< "), disabling event notifier";
fdEventNotifier_->setEnabled(false);
return;
}
frameStart.emit(event.u.frame_sync.frame_sequence);
}
} /* namespace libcamera */
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