Add tach sensors to each fan enclosure

Create a tach sensor instance for each sensor listed within a fan
enclosure that uses 'tach' based presence detection. Each tach sensor
has a pointer to the fan it's associated with and is added to the list
of sensors for that fan enclosure.

Change-Id: I9a83ec52d1a5d01e39702e185336a09edeb4d158
Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
diff --git a/tach_sensor.hpp b/tach_sensor.hpp
index 0ef2b0a..24ee453 100644
--- a/tach_sensor.hpp
+++ b/tach_sensor.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <sdbusplus/bus.hpp>
 #include "sensor_base.hpp"
 
 
@@ -20,9 +21,19 @@
         TachSensor& operator=(TachSensor&&) = delete;
         ~TachSensor() = default;
 
+        TachSensor(sdbusplus::bus::bus& bus,
+                   const std::string& id,
+                   FanEnclosure& fanEnc) : Sensor(id, fanEnc),
+                       bus(bus)
+        {
+            // Nothing to do here
+        }
+
         bool isPresent();
 
     private:
+        sdbusplus::bus::bus& bus;
+        int64_t tach = 0;
 
 };