1 #include "DeviceMgmt.hpp" 2 3 #include "Utils.hpp" 4 5 #include <cstdint> 6 #include <filesystem> 7 #include <fstream> 8 #include <iomanip> 9 #include <ios> 10 #include <iostream> 11 #include <optional> 12 #include <sstream> 13 #include <stdexcept> 14 #include <string> 15 #include <system_error> 16 #include <variant> 17 18 namespace fs = std::filesystem; 19 20 std::optional<I2CDeviceParams> getI2CDeviceParams( 21 const I2CDeviceTypeMap& dtmap, const SensorBaseConfigMap& cfg) 22 { 23 auto findType = cfg.find("Type"); 24 auto findBus = cfg.find("Bus"); 25 auto findAddr = cfg.find("Address"); 26 27 if (findType == cfg.end() || findBus == cfg.end() || findAddr == cfg.end()) 28 { 29 return std::nullopt; 30 } 31 32 const std::string* type = std::get_if<std::string>(&findType->second); 33 const uint64_t* bus = std::get_if<uint64_t>(&findBus->second); 34 const uint64_t* addr = std::get_if<uint64_t>(&findAddr->second); 35 36 if (type == nullptr || bus == nullptr || addr == nullptr) 37 { 38 return std::nullopt; 39 } 40 41 auto findDevType = dtmap.find(type->c_str()); 42 if (findDevType == dtmap.end()) 43 { 44 return std::nullopt; 45 } 46 47 return I2CDeviceParams(findDevType->second, *bus, *addr); 48 } 49 50 static fs::path i2cBusPath(uint64_t bus) 51 { 52 return {"/sys/bus/i2c/devices/i2c-" + std::to_string(bus)}; 53 } 54 55 static std::string deviceDirName(uint64_t bus, uint64_t address) 56 { 57 std::ostringstream name; 58 name << bus << "-" << std::hex << std::setw(4) << std::setfill('0') 59 << address; 60 return name.str(); 61 } 62 63 bool I2CDeviceParams::devicePresent() const 64 { 65 fs::path path = i2cBusPath(bus) / deviceDirName(bus, address); 66 67 if (type->createsHWMon) 68 { 69 path /= "hwmon"; 70 } 71 72 // Ignore errors; anything but a clean 'true' is fine as 'false' 73 std::error_code ec; 74 return fs::exists(path, ec); 75 } 76 77 bool I2CDeviceParams::deviceStatic() const 78 { 79 if (!devicePresent()) 80 { 81 return false; 82 } 83 84 fs::path ofNode = i2cBusPath(bus) / deviceDirName(bus, address) / "of_node"; 85 86 // Ignore errors -- if of_node is present the device is a static DT node; 87 // otherwise we can assume we created it from userspace. 88 std::error_code ec; 89 return fs::exists(ofNode, ec); 90 } 91 92 I2CDevice::I2CDevice(I2CDeviceParams params) : params(params) 93 { 94 if (create() != 0) 95 { 96 throw std::runtime_error("failed to instantiate i2c device"); 97 } 98 } 99 100 I2CDevice::~I2CDevice() 101 { 102 destroy(); 103 } 104 105 int I2CDevice::create() const 106 { 107 // If it's already instantiated, there's nothing we need to do. 108 if (params.devicePresent()) 109 { 110 return 0; 111 } 112 113 // Try to create it: 'echo $devtype $addr > .../i2c-$bus/new_device' 114 fs::path ctorPath = i2cBusPath(params.bus) / "new_device"; 115 std::ofstream ctor(ctorPath); 116 if (!ctor.good()) 117 { 118 std::cerr << "Failed to open " << ctorPath << "\n"; 119 return -1; 120 } 121 122 ctor << params.type->name << " " << params.address << "\n"; 123 ctor.flush(); 124 if (!ctor.good()) 125 { 126 std::cerr << "Failed to write to " << ctorPath << "\n"; 127 return -1; 128 } 129 130 // Check if that created the requisite sysfs directory 131 if (!params.devicePresent()) 132 { 133 destroy(); 134 return -1; 135 } 136 137 return 0; 138 } 139 140 int I2CDevice::destroy() const 141 { 142 // No params.devicePresent() check on this like in create(), since it 143 // might be used to clean up after a device instantiation that was only 144 // partially successful (i.e. when params.devicePresent() would return 145 // false but there's still a dummy i2c client device to remove) 146 147 fs::path dtorPath = i2cBusPath(params.bus) / "delete_device"; 148 std::ofstream dtor(dtorPath); 149 if (!dtor.good()) 150 { 151 std::cerr << "Failed to open " << dtorPath << "\n"; 152 return -1; 153 } 154 155 dtor << params.address << "\n"; 156 dtor.flush(); 157 if (!dtor.good()) 158 { 159 std::cerr << "Failed to write to " << dtorPath << "\n"; 160 return -1; 161 } 162 163 return 0; 164 } 165