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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* Copyright (C) 2019, Google Inc.
*
* device_enumerator_sysfs.cpp - sysfs-based device enumerator
*/
#include "libcamera/internal/device_enumerator_sysfs.h"
#include <dirent.h>
#include <fcntl.h>
#include <fstream>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <libcamera/base/log.h>
#include "libcamera/internal/media_device.h"
namespace libcamera {
LOG_DECLARE_CATEGORY(DeviceEnumerator)
int DeviceEnumeratorSysfs::init()
{
return 0;
}
int DeviceEnumeratorSysfs::enumerate()
{
struct dirent *ent;
DIR *dir;
static const char * const sysfs_dirs[] = {
"/sys/subsystem/media/devices",
"/sys/bus/media/devices",
"/sys/class/media/devices",
};
for (const char *dirname : sysfs_dirs) {
dir = opendir(dirname);
if (dir)
break;
}
if (!dir) {
LOG(DeviceEnumerator, Error)
<< "No valid sysfs media device directory";
return -ENODEV;
}
while ((ent = readdir(dir)) != nullptr) {
if (strncmp(ent->d_name, "media", 5))
continue;
char *end;
unsigned int idx = strtoul(ent->d_name + 5, &end, 10);
if (*end != '\0')
continue;
std::string devnode = "/dev/media" + std::to_string(idx);
/* Verify that the device node exists. */
struct stat devstat;
if (stat(devnode.c_str(), &devstat) < 0) {
LOG(DeviceEnumerator, Warning)
<< "Device node /dev/media" << idx
<< " should exist but doesn't";
continue;
}
std::unique_ptr<MediaDevice> media = createDevice(devnode);
if (!media)
continue;
if (populateMediaDevice(media.get()) < 0) {
LOG(DeviceEnumerator, Warning)
<< "Failed to populate media device "
<< media->deviceNode()
<< " (" << media->driver() << "), skipping";
continue;
}
addDevice(std::move(media));
}
closedir(dir);
return 0;
}
int DeviceEnumeratorSysfs::populateMediaDevice(MediaDevice *media)
{
/* Associate entities to device node paths. */
for (MediaEntity *entity : media->entities()) {
if (entity->deviceMajor() == 0 && entity->deviceMinor() == 0)
continue;
std::string deviceNode = lookupDeviceNode(entity->deviceMajor(),
entity->deviceMinor());
if (deviceNode.empty())
return -EINVAL;
int ret = entity->setDeviceNode(deviceNode);
if (ret)
return ret;
}
return 0;
}
/**
* \brief Lookup device node path from device number
* \param[in] major The device major number
* \param[in] minor The device minor number
*
* Translate a device number given as \a major and \a minor to a device node
* path.
*
* \return The device node path on success, or an empty string if the lookup
* fails
*/
std::string DeviceEnumeratorSysfs::lookupDeviceNode(int major, int minor)
{
std::string deviceNode;
std::string line;
std::ifstream ueventFile;
ueventFile.open("/sys/dev/char/" + std::to_string(major) + ":" +
std::to_string(minor) + "/uevent");
if (!ueventFile)
return std::string();
while (ueventFile >> line) {
if (line.find("DEVNAME=") == 0) {
deviceNode = "/dev/" + line.substr(strlen("DEVNAME="));
break;
}
}
ueventFile.close();
return deviceNode;
}
} /* namespace libcamera */
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