service: device-tree node vpd to d-bus hw id data
A daemon for transferring Viable Product Data (VPD) from device-tree
nodes to D-Bus as described in the design doc @
https://gerrit.openbmc.org/c/openbmc/docs/+/66369
and discussed in this Technical Oversight Forum topic @
https://github.com/openbmc/technical-oversight-forum/issues/38
Tested:
Ensure 'model' and/or 'serial-number' nodes are populated in
/proc/device-tree. Can be hardcoded into platform DTS via
linux-kernel recipe if needed.
'''
After OBMC boot, calling
> busctl introspect xyz.openbmc_project.MachineContext /xyz/openbmc_project/MachineContext
produces the following output:
NAME TYPE SIGNATURE RESULT/VALUE FLAGS
...
xyz.openbmc_project.Inventory.Decorator.Asset interface - - -
.BuildDate property s "" emits-change writable
.Manufacturer property s "" emits-change writable
.Model property s "hpe,dl360" emits-change writable
.PartNumber property s "" emits-change writable
.SerialNumber property s "t5texpl" emits-change writable
...
Note: Writing to one of these properties will update the property on D-Bus without affecting the
underlying device-tree node. An 'updated' event will be fired, so Entity-Manager probes monitoring
a given property would recognize the new value and key off it.
'''
Change-Id: Id52d1fc3b26010c864c7e64d3dfdf0a2b5de9294
Signed-off-by: Chris Sides <Christopher.Sides@hpe.com>
diff --git a/src/machine_context.cpp b/src/machine_context.cpp
new file mode 100644
index 0000000..6f2c956
--- /dev/null
+++ b/src/machine_context.cpp
@@ -0,0 +1,45 @@
+/*
+// Copyright (c) 2024 Hewlett Packard Enterprise
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+*/
+
+#include "machine_context.hpp"
+
+#include <filesystem>
+#include <fstream>
+
+void MachineContext::populateFromDeviceTree()
+{
+ std::string nodeVal;
+ std::ifstream vpdStream(nodeBasePath + std::string("model"));
+ if (vpdStream && std::getline(vpdStream, nodeVal))
+ {
+ MachineContext::Asset::model(nodeVal);
+ vpdStream.close();
+ }
+
+ vpdStream.open(nodeBasePath + std::string("serial-number"));
+ if (vpdStream && std::getline(vpdStream, nodeVal))
+ {
+ MachineContext::Asset::serial_number(nodeVal);
+ vpdStream.close();
+ }
+};
+
+bool MachineContext::keyNodeExists()
+{
+ std::filesystem::path nodePath{nodeBasePath + std::string("model")};
+
+ return std::filesystem::exists(nodePath);
+};