Find hwmon instances from OF device paths
Provide a method that scans the hwmon subtree for a matching
open firmware device path.
Change-Id: Ic71dea90113c6894d9d2b61e03bd02f6b550e1e6
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/sysfs.cpp b/sysfs.cpp
new file mode 100644
index 0000000..f1f46db
--- /dev/null
+++ b/sysfs.cpp
@@ -0,0 +1,54 @@
+/**
+ * Copyright © 2016 IBM Corporation
+ *
+ * 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 <cstdlib>
+#include <memory>
+#include "sysfs.hpp"
+#include "util.hpp"
+#include "directory.hpp"
+
+std::string findHwmon(const std::string& ofNode)
+{
+ static constexpr auto hwmonRoot = "/sys/class/hwmon";
+
+ std::string fullOfPath{"/sys/firmware/devicetree/base"};
+ fullOfPath.append(ofNode);
+
+ std::string hwmonInst;
+ Directory d(hwmonRoot);
+
+ while (d.next(hwmonInst))
+ {
+ std::string hwmonPath{hwmonRoot};
+ hwmonPath.append(1, '/');
+ hwmonPath.append(hwmonInst);
+ std::string path{hwmonPath};
+ path.append(1, '/');
+ path.append("of_node");
+
+ auto real = std::unique_ptr<char, phosphor::utility::Free<char>>(realpath(
+ path.c_str(), nullptr));
+ if (!real || real.get() != fullOfPath)
+ {
+ continue;
+ }
+
+ return hwmonPath;
+ }
+
+ return std::string();
+}
+
+// vim: tabstop=8 expandtab shiftwidth=4 softtabstop=4