nvidia-gpu: introduce notion of a device

Perform device discovery tasks only once per device to prepare for
introducing additional gpu sensors.

In the current implementation, sensor updates and device discovery via
MCTP are managed within a single class for simplicity. However, since a
GPU device typically includes multiple sensors, performing device
discovery for each individual sensor is inefficient. Instead, it would
be more effective to execute device discovery once per device.

Tested: Build an image for gb200nvl-obmc machine with the following
patches cherry picked. This patches are needed to enable the mctp stack.
https://gerrit.openbmc.org/c/openbmc/openbmc/+/79422

```
$ curl -k -u 'root:0penBmc' https://10.137.203.137/redfish/v1/Chassis/NVIDIA_GB200_1/Sensors/temperature_NVIDIA_GB200_GPU_0_TEMP_0
{
  "@odata.id": "/redfish/v1/Chassis/NVIDIA_GB200_1/Sensors/temperature_NVIDIA_GB200_GPU_0_TEMP_0",
  "@odata.type": "#Sensor.v1_2_0.Sensor",
  "Id": "temperature_NVIDIA_GB200_GPU_0_TEMP_0",
  "Name": "NVIDIA GB200 GPU 0 TEMP 0",
  "Reading": 37.6875,
  "ReadingRangeMax": 127.0,
  "ReadingRangeMin": -128.0,
  "ReadingType": "Temperature",
  "ReadingUnits": "Cel",
  "Status": {
    "Health": "OK",
    "State": "Enabled"
  }
}%
```

Change-Id: Ie3dcd43caa031b4aaa61d8be3f5d71aefd53bc9a
Signed-off-by: Harshit Aghera <haghera@nvidia.com>
diff --git a/src/nvidia-gpu/NvidiaGpuSensorMain.cpp b/src/nvidia-gpu/NvidiaGpuSensorMain.cpp
index cf764d3..6ccbb05 100644
--- a/src/nvidia-gpu/NvidiaGpuSensorMain.cpp
+++ b/src/nvidia-gpu/NvidiaGpuSensorMain.cpp
@@ -5,15 +5,14 @@
  */
 
 #include "MctpRequester.hpp"
-#include "NvidiaGpuSensor.hpp"
 #include "Utils.hpp"
 
+#include <NvidiaDeviceDiscovery.hpp>
 #include <boost/asio/error.hpp>
 #include <boost/asio/io_context.hpp>
 #include <boost/asio/post.hpp>
 #include <boost/asio/steady_timer.hpp>
 #include <boost/container/flat_map.hpp>
-#include <phosphor-logging/lg2.hpp>
 #include <sdbusplus/asio/connection.hpp>
 #include <sdbusplus/asio/object_server.hpp>
 #include <sdbusplus/bus.hpp>
@@ -27,7 +26,7 @@
 #include <string>
 #include <vector>
 
-boost::container::flat_map<std::string, std::shared_ptr<GpuTempSensor>> sensors;
+boost::container::flat_map<std::string, std::shared_ptr<GpuDevice>> gpuDevices;
 
 void configTimerExpiryCallback(
     boost::asio::io_context& io, sdbusplus::asio::object_server& objectServer,
@@ -38,11 +37,7 @@
     {
         return; // we're being canceled
     }
-    createSensors(io, objectServer, sensors, dbusConnection, mctpRequester);
-    if (sensors.empty())
-    {
-        lg2::info("Configuration not detected");
-    }
+    createSensors(io, objectServer, gpuDevices, dbusConnection, mctpRequester);
 }
 
 int main()
@@ -56,7 +51,7 @@
     mctp::MctpRequester mctpRequester(io);
 
     boost::asio::post(io, [&]() {
-        createSensors(io, objectServer, sensors, systemBus, mctpRequester);
+        createSensors(io, objectServer, gpuDevices, systemBus, mctpRequester);
     });
 
     boost::asio::steady_timer configTimer(io);
@@ -73,7 +68,7 @@
 
     std::vector<std::unique_ptr<sdbusplus::bus::match_t>> matches =
         setupPropertiesChangedMatches(
-            *systemBus, std::to_array<const char*>({sensorType}), eventHandler);
+            *systemBus, std::to_array<const char*>({deviceType}), eventHandler);
 
     // Watch for entity-manager to remove configuration interfaces
     // so the corresponding sensors can be removed.
@@ -81,7 +76,7 @@
         static_cast<sdbusplus::bus_t&>(*systemBus),
         sdbusplus::bus::match::rules::interfacesRemovedAtPath(
             std::string(inventoryPath)),
-        [](sdbusplus::message_t& msg) { interfaceRemoved(msg, sensors); });
+        [](sdbusplus::message_t& msg) { interfaceRemoved(msg, gpuDevices); });
 
     io.run();
     return 0;