Add device-management infrastructure
We're moving toward having dbus-sensors take over sensor device
lifecycle management from entity-manager; this code (loosely based on
entity-manager's include/devices.hpp and src/overlay.cpp) provides some
general-purpose utilities for instantiating and destroying devices.
This also includes a variant of setupPropertiesChangedMatches() taking
an I2CDeviceTypeMap instead of a span of C strings, so that we can
support both existing sensor daemons and ones that get converted to use
that instead of the simple string arrays they currently employ.
Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Change-Id: I39fcd0de2c70cd58b4d132cdcae5f82319732dbb
diff --git a/src/DeviceMgmt.cpp b/src/DeviceMgmt.cpp
new file mode 100644
index 0000000..ca52a3a
--- /dev/null
+++ b/src/DeviceMgmt.cpp
@@ -0,0 +1,124 @@
+#include <DeviceMgmt.hpp>
+
+#include <filesystem>
+#include <fstream>
+
+namespace fs = std::filesystem;
+
+std::optional<I2CDevice> getI2CDevice(const I2CDeviceTypeMap& dtmap,
+ const SensorBaseConfigMap& cfg)
+{
+ auto findType = cfg.find("Type");
+ auto findBus = cfg.find("Bus");
+ auto findAddr = cfg.find("Address");
+
+ if (findType == cfg.end() || findBus == cfg.end() || findAddr == cfg.end())
+ {
+ return std::nullopt;
+ }
+
+ const std::string* type = std::get_if<std::string>(&findType->second);
+ const uint64_t* bus = std::get_if<uint64_t>(&findBus->second);
+ const uint64_t* addr = std::get_if<uint64_t>(&findAddr->second);
+
+ if (type == nullptr || bus == nullptr || addr == nullptr)
+ {
+ return std::nullopt;
+ }
+
+ auto findDevType = dtmap.find(type->c_str());
+ if (findDevType == dtmap.end())
+ {
+ return std::nullopt;
+ }
+
+ return I2CDevice(findDevType->second, *bus, *addr);
+}
+
+static fs::path i2cBusPath(uint64_t bus)
+{
+ return {"/sys/bus/i2c/devices/i2c-" + std::to_string(bus)};
+}
+
+static std::string deviceDirName(uint64_t bus, uint64_t address)
+{
+ std::ostringstream name;
+ name << bus << "-" << std::hex << std::setw(4) << std::setfill('0')
+ << address;
+ return name.str();
+}
+
+bool I2CDevice::present(void) const
+{
+ fs::path path = i2cBusPath(bus) / deviceDirName(bus, address);
+
+ if (type->createsHWMon)
+ {
+ path /= "hwmon";
+ }
+
+ // Ignore errors; anything but a clean 'true' is fine as 'false'
+ std::error_code ec;
+ return fs::exists(path, ec);
+}
+
+int I2CDevice::create(void) const
+{
+ // If it's already instantiated, there's nothing we need to do.
+ if (present())
+ {
+ return 0;
+ }
+
+ // Try to create it: 'echo $devtype $addr > .../i2c-$bus/new_device'
+ fs::path ctorPath = i2cBusPath(bus) / "new_device";
+ std::ofstream ctor(ctorPath);
+ if (!ctor.good())
+ {
+ std::cerr << "Failed to open " << ctorPath << "\n";
+ return -1;
+ }
+
+ ctor << type->name << " " << address << "\n";
+ ctor.flush();
+ if (!ctor.good())
+ {
+ std::cerr << "Failed to write to " << ctorPath << "\n";
+ return -1;
+ }
+
+ // Check if that created the requisite sysfs directory
+ if (!present())
+ {
+ destroy();
+ return -1;
+ }
+
+ return 0;
+}
+
+int I2CDevice::destroy(void) const
+{
+ // No present() check on this like in create(), since it might be used to
+ // clean up after a device instantiation that was only partially
+ // successful (i.e. when present() would return false but there's still a
+ // dummy i2c client device to remove)
+
+ fs::path dtorPath = i2cBusPath(bus) / "delete_device";
+ std::ofstream dtor(dtorPath);
+ if (!dtor.good())
+ {
+ std::cerr << "Failed to open " << dtorPath << "\n";
+ return -1;
+ }
+
+ dtor << address << "\n";
+ dtor.flush();
+ if (!dtor.good())
+ {
+ std::cerr << "Failed to write to " << dtorPath << "\n";
+ return -1;
+ }
+
+ return 0;
+}
diff --git a/src/Utils.cpp b/src/Utils.cpp
index 7b33cb7..700b336 100644
--- a/src/Utils.cpp
+++ b/src/Utils.cpp
@@ -16,6 +16,7 @@
#include "dbus-sensor_config.h"
+#include <DeviceMgmt.hpp>
#include <Utils.hpp>
#include <boost/container/flat_map.hpp>
#include <sdbusplus/asio/connection.hpp>
@@ -713,3 +714,17 @@
}
return matches;
}
+
+std::vector<std::unique_ptr<sdbusplus::bus::match_t>>
+ setupPropertiesChangedMatches(
+ sdbusplus::asio::connection& bus, const I2CDeviceTypeMap& typeMap,
+ const std::function<void(sdbusplus::message_t&)>& handler)
+{
+ std::vector<const char*> types;
+ types.reserve(typeMap.size());
+ for (const auto& [type, dt] : typeMap)
+ {
+ types.push_back(type.data());
+ }
+ return setupPropertiesChangedMatches(bus, {types}, handler);
+}