control: Zone configuration framework and basic attrs

The zone class contains the configuration attributes for each zone
within a system. Each zone is a logical grouping of fans as configured
within the `fans.json` file.

Tested:
    Parsed each basic attribute from `zones.json` file
    Zone objects created per profile configured

Change-Id: I85f52661831ec201a1b0ee1358c239dbc22c8e49
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/control/json/zone.cpp b/control/json/zone.cpp
new file mode 100644
index 0000000..24dceee
--- /dev/null
+++ b/control/json/zone.cpp
@@ -0,0 +1,81 @@
+/**
+ * Copyright © 2020 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 "zone.hpp"
+
+#include <nlohmann/json.hpp>
+#include <phosphor-logging/log.hpp>
+#include <sdbusplus/bus.hpp>
+
+namespace phosphor::fan::control::json
+{
+
+using json = nlohmann::json;
+using namespace phosphor::logging;
+
+Zone::Zone(sdbusplus::bus::bus& bus, const json& jsonObj) :
+    ConfigBase(jsonObj), _incDelay(0)
+{
+    if (jsonObj.contains("profiles"))
+    {
+        for (const auto& profile : jsonObj["profiles"])
+        {
+            _profiles.emplace_back(profile.get<std::string>());
+        }
+    }
+    // Speed increase delay is optional, defaults to 0
+    if (jsonObj.contains("increase_delay"))
+    {
+        _incDelay = jsonObj["increase_delay"].get<uint64_t>();
+    }
+    setFullSpeed(jsonObj);
+    setDefaultFloor(jsonObj);
+    setDecInterval(jsonObj);
+}
+
+void Zone::setFullSpeed(const json& jsonObj)
+{
+    if (!jsonObj.contains("full_speed"))
+    {
+        log<level::ERR>("Missing required zone's full speed",
+                        entry("JSON=%s", jsonObj.dump().c_str()));
+        throw std::runtime_error("Missing required zone's full speed");
+    }
+    _fullSpeed = jsonObj["full_speed"].get<uint64_t>();
+}
+
+void Zone::setDefaultFloor(const json& jsonObj)
+{
+    if (!jsonObj.contains("default_floor"))
+    {
+        log<level::ERR>("Missing required zone's default floor speed",
+                        entry("JSON=%s", jsonObj.dump().c_str()));
+        throw std::runtime_error("Missing required zone's default floor speed");
+    }
+    _defaultFloor = jsonObj["default_floor"].get<uint64_t>();
+}
+
+void Zone::setDecInterval(const json& jsonObj)
+{
+    if (!jsonObj.contains("decrease_interval"))
+    {
+        log<level::ERR>("Missing required zone's decrease interval",
+                        entry("JSON=%s", jsonObj.dump().c_str()));
+        throw std::runtime_error("Missing required zone's decrease interval");
+    }
+    _decInterval = jsonObj["decrease_interval"].get<uint64_t>();
+}
+
+} // namespace phosphor::fan::control::json