977cfbd526
A udev-based device enumerator is not sufficient, since libudev is an optional dependency, or udev might fail. In these cases, we should fall back to using sysfs to enumerate devices. Add a DeviceEnumeratorSysfs class which is a specialization of DeviceEnumerator that uses sysfs to enumerate media devices on the system. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
106 lines
2.0 KiB
C++
106 lines
2.0 KiB
C++
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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/*
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* Copyright (C) 2019, Google Inc.
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*
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* device_enumerator_sysfs.cpp - sysfs-based device enumerator
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*/
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#include "device_enumerator_sysfs.h"
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#include <dirent.h>
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#include <fcntl.h>
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#include <fstream>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include "log.h"
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namespace libcamera {
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LOG_DECLARE_CATEGORY(DeviceEnumerator)
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int DeviceEnumeratorSysfs::init()
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{
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return 0;
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}
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int DeviceEnumeratorSysfs::enumerate()
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{
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struct dirent *ent;
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DIR *dir;
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static const char * const sysfs_dirs[] = {
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"/sys/subsystem/media/devices",
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"/sys/bus/media/devices",
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"/sys/class/media/devices",
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};
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for (const char *dirname : sysfs_dirs) {
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dir = opendir(dirname);
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if (dir)
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break;
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}
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if (!dir) {
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LOG(DeviceEnumerator, Error)
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<< "No valid sysfs media device directory";
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return -ENODEV;
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}
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while ((ent = readdir(dir)) != nullptr) {
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if (strncmp(ent->d_name, "media", 5))
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continue;
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char *end;
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unsigned int idx = strtoul(ent->d_name + 5, &end, 10);
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if (*end != '\0')
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continue;
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std::string devnode = "/dev/media" + std::to_string(idx);
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/* Verify that the device node exists. */
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struct stat devstat;
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if (stat(devnode.c_str(), &devstat) < 0) {
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LOG(DeviceEnumerator, Warning)
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<< "Device node /dev/media" << idx
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<< " should exist but doesn't";
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continue;
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}
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addDevice(devnode);
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}
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closedir(dir);
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return 0;
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}
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std::string DeviceEnumeratorSysfs::lookupDeviceNode(int major, int minor)
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{
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std::string deviceNode;
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std::string line;
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std::ifstream ueventFile;
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ueventFile.open("/sys/dev/char/" + std::to_string(major) + ":" +
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std::to_string(minor) + "/uevent");
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if (!ueventFile)
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return std::string();
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while (ueventFile >> line) {
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if (line.find("DEVNAME=") == 0) {
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deviceNode = "/dev/" + line.substr(strlen("DEVNAME="));
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break;
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}
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}
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ueventFile.close();
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return deviceNode;
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}
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} /* namespace libcamera */
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