Sensor Objects

This includes all the sensor objects including a few
implementations, including dbus and sysfs sensors.

Change-Id: I9897c79f9fd463f00f0e02aeb6c32ffa89635dbe
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/dbus/util.cpp b/dbus/util.cpp
new file mode 100644
index 0000000..692e9c5
--- /dev/null
+++ b/dbus/util.cpp
@@ -0,0 +1,109 @@
+#include <iostream>
+
+#include "dbus/util.hpp"
+
+using Property = std::string;
+using Value = sdbusplus::message::variant<int64_t, std::string>;
+using PropertyMap = std::map<Property, Value>;
+
+/* TODO(venture): Basically all phosphor apps need this, maybe it should be a
+ * part of sdbusplus.  There is an old version in libmapper.
+ */
+std::string GetService(sdbusplus::bus::bus& bus,
+                       const std::string& intf,
+                       const std::string& path)
+{
+    auto mapper = bus.new_method_call(
+                      "xyz.openbmc_project.ObjectMapper",
+                      "/xyz/openbmc_project/object_mapper",
+                      "xyz.openbmc_project.ObjectMapper",
+                      "GetObject");
+
+    mapper.append(path);
+    mapper.append(std::vector<std::string>({intf}));
+
+    auto responseMsg = bus.call(mapper);
+    if (responseMsg.is_method_error())
+    {
+        throw std::runtime_error("ObjectMapper Call Failure");
+    }
+
+    std::map<std::string, std::vector<std::string>> response;
+    responseMsg.read(response);
+
+    if (response.begin() == response.end())
+    {
+        throw std::runtime_error("Unable to find Object: " + path);
+    }
+
+    return response.begin()->first;
+}
+
+void GetProperties(sdbusplus::bus::bus& bus,
+                   const std::string& service,
+                   const std::string& path,
+                   struct SensorProperties* prop)
+{
+
+    auto pimMsg = bus.new_method_call(service.c_str(),
+                                      path.c_str(),
+                                      propertiesintf.c_str(),
+                                      "GetAll");
+
+    pimMsg.append(sensorintf);
+    auto valueResponseMsg = bus.call(pimMsg);
+
+    if (valueResponseMsg.is_method_error())
+    {
+        std::cerr << "Error in value call\n";
+        throw std::runtime_error("ERROR in value call.");
+    }
+
+    // The PropertyMap returned will look like this because it's always
+    // reading a Sensor.Value interface.
+    // a{sv} 3:
+    // "Value" x 24875
+    // "Unit" s "xyz.openbmc_project.Sensor.Value.Unit.DegreesC"
+    // "Scale" x -3
+    PropertyMap propMap;
+    valueResponseMsg.read(propMap);
+
+    if (propMap.size() != 3)
+    {
+        throw std::runtime_error("ERROR in results, expected three properties");
+    }
+
+    prop->unit = sdbusplus::message::variant_ns::get<std::string>(propMap["Unit"]);
+    prop->scale = sdbusplus::message::variant_ns::get<int64_t>(propMap["Scale"]);
+    prop->value = sdbusplus::message::variant_ns::get<int64_t>(propMap["Value"]);
+
+    return;
+}
+
+std::string GetSensorPath(const std::string& type, const std::string& id)
+{
+    std::string layer = type;
+    if (type == "fan")
+    {
+        layer = "fan_tach";
+    }
+    else if (type == "temp")
+    {
+        layer = "temperature";
+    }
+    else
+    {
+        layer = "unknown"; // TODO(venture): Need to handle.
+    }
+
+    return std::string("/xyz/openbmc_project/sensors/" + layer + "/" + id);
+}
+
+std::string GetMatch(const std::string& type, const std::string& id)
+{
+    return std::string("type='signal',"
+                       "interface='org.freedesktop.DBus.Properties',"
+                       "member='PropertiesChanged',"
+                       "path='" + GetSensorPath(type, id) + "'");
+}
+