commit 8951c87e8fca6ba57f78344119ab42866c190c80
author Harshit Aghera <haghera@nvidia.com> Wed Jun 25 15:25:33 2025 +0530
committer Ed Tanous <ed@tanous.net> Tue Jul 22 01:25:38 2025 +0000
tree 6c8fe6bcb22aeebd9bb63ee1d2228e497aafcfbf
parent a499a168f10d3913fbfd01a71ca7c0b207483b6c

nvidia-gpu: add SMA Temperature Sensor

Add support for device type SMA (System Management Agent) and its
temperature sensor. It is typically an MCU 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 -s -k -u 'root:0penBmc' https://10.137.203.193/redfish/v1/Chassis/NVIDIA_GB200_1/Sensors/temperature_NVIDIA_GB200_GPU_SMA_255_TEMP_0
{
  "@odata.id": "/redfish/v1/Chassis/NVIDIA_GB200_1/Sensors/temperature_NVIDIA_GB200_GPU_SMA_255_TEMP_0",
  "@odata.type": "#Sensor.v1_2_0.Sensor",
  "Id": "temperature_NVIDIA_GB200_GPU_SMA_255_TEMP_0",
  "Name": "NVIDIA GB200 GPU SMA 255 TEMP 0",
  "Reading": 34.0,
  "ReadingRangeMax": 127.0,
  "ReadingRangeMin": -128.0,
  "ReadingType": "Temperature",
  "ReadingUnits": "Cel",
  "Status": {
    "Health": "OK",
    "State": "Enabled"
  }
}%
```

Change-Id: I560864758036a5b6ea6c1745145736c7bfa0a1c5
Signed-off-by: Harshit Aghera <haghera@nvidia.com>

src/nvidia-gpu/NvidiaSmaDevice.cpp

diff --git a/src/nvidia-gpu/NvidiaSmaDevice.cpp b/src/nvidia-gpu/NvidiaSmaDevice.cpp
new file mode 100644
index 0000000..755e1f8
--- /dev/null
+++ b/src/nvidia-gpu/NvidiaSmaDevice.cpp
@@ -0,0 +1,66 @@
+/*
+ * SPDX-FileCopyrightText: Copyright (c) 2024-2025 NVIDIA CORPORATION &
+ * AFFILIATES. All rights reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include "NvidiaSmaDevice.hpp"
+
+#include "NvidiaDeviceDiscovery.hpp"
+#include "NvidiaGpuSensor.hpp"
+#include "Thresholds.hpp"
+#include "Utils.hpp"
+
+#include <bits/basic_string.h>
+
+#include <MctpRequester.hpp>
+#include <boost/asio/io_context.hpp>
+#include <phosphor-logging/lg2.hpp>
+#include <sdbusplus/asio/connection.hpp>
+#include <sdbusplus/asio/object_server.hpp>
+
+#include <chrono>
+#include <cstdint>
+#include <memory>
+#include <string>
+#include <vector>
+
+SmaDevice::SmaDevice(const SensorConfigs& configs, const std::string& name,
+                     const std::string& path,
+                     const std::shared_ptr<sdbusplus::asio::connection>& conn,
+                     uint8_t eid, boost::asio::io_context& io,
+                     mctp::MctpRequester& mctpRequester,
+                     sdbusplus::asio::object_server& objectServer) :
+    eid(eid), sensorPollMs(std::chrono::milliseconds{configs.pollRate}),
+    waitTimer(io, std::chrono::steady_clock::duration(0)),
+    mctpRequester(mctpRequester), conn(conn), objectServer(objectServer),
+    configs(configs), name(escapeName(name)), path(path)
+{
+    makeSensors();
+}
+
+void SmaDevice::makeSensors()
+{
+    tempSensor = std::make_shared<NvidiaGpuTempSensor>(
+        conn, mctpRequester, name + "_TEMP_0", path, eid, smaTempSensorId,
+        objectServer, std::vector<thresholds::Threshold>{});
+
+    lg2::info("Added MCA {NAME} Sensors with chassis path: {PATH}.", "NAME",
+              name, "PATH", path);
+
+    read();
+}
+
+void SmaDevice::read()
+{
+    tempSensor->update();
+
+    waitTimer.expires_after(std::chrono::milliseconds(sensorPollMs));
+    waitTimer.async_wait([this](const boost::system::error_code& ec) {
+        if (ec)
+        {
+            return;
+        }
+        read();
+    });
+}