diff options
Diffstat (limited to 'src/libcamera/sysfs.cpp')
| -rw-r--r-- | src/libcamera/sysfs.cpp | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/src/libcamera/sysfs.cpp b/src/libcamera/sysfs.cpp index 398df2c2..6c8e9554 100644 --- a/src/libcamera/sysfs.cpp +++ b/src/libcamera/sysfs.cpp @@ -7,10 +7,12 @@ #include "libcamera/internal/sysfs.h" +#include <fstream> #include <sstream> #include <sys/stat.h> #include <sys/sysmacros.h> +#include "libcamera/internal/file.h" #include "libcamera/internal/log.h" /** @@ -47,6 +49,62 @@ std::string charDevPath(const std::string &deviceNode) return dev.str(); } +/** + * \brief Retrieve the path of the firmware node for a device + * \param[in] device Path in sysfs to search + * + * Physical devices in a system are described by the system firmware. Depending + * on the type of platform, devices are identified using different naming + * schemes. The Linux kernel abstract those differences with "firmware nodes". + * This function retrieves the firmware node path corresponding to the + * \a device. + * + * For DT-based systems, the path is the full name of the DT node that + * represents the device. For ACPI-based systems, the path is the absolute + * namespace path to the ACPI object that represents the device. In both cases, + * the path is guaranteed to be unique and persistent as long as the system + * firmware is not modified. + * + * \return The firmware node path on success or an empty string on failure + */ +std::string firmwareNodePath(const std::string &device) +{ + std::string fwPath, node; + + /* Lookup for DT-based systems */ + node = device + "/of_node"; + if (File::exists(node)) { + char *ofPath = realpath(node.c_str(), nullptr); + if (!ofPath) + return {}; + + static const char prefix[] = "/sys/firmware/devicetree"; + if (strncmp(ofPath, prefix, strlen(prefix)) == 0) + fwPath = ofPath + strlen(prefix); + else + fwPath = ofPath; + + free(ofPath); + + return fwPath; + } + + /* Lookup for ACPI-based systems */ + node = device + "/firmware_node/path"; + if (File::exists(node)) { + std::ifstream file(node); + if (!file.is_open()) + return {}; + + std::getline(file, fwPath); + file.close(); + + return fwPath; + } + + return {}; +} + } /* namespace sysfs */ } /* namespace libcamera */ |