Enable dynamic presence detect of FRUs

This commit enables presence detect of FRUs at runtime.
Anytime any FRU can get attached or de-attached,
this code will detect it and will enable/disable the corresponding
output I2C pin respectively.
Right now we have only one FRU- op-panel, which is attachable or
de-attachable at runtime.

Test- Tested on Simics:
>> 2timers keep running, as part of vpd-manager-
./vpd-manager

keep checking for event occurance...
hasEventOccurred ?
keep checking for event occurance...
hasEventOccurred ?

>> changed signal at presence-pin of FRU2
keep checking for event occurance...
hasEventOccurred ?
keep checking for event occurance...
hasEventOccurred ?
Yes, togggle the gpio            <---------------------event on 2nd timer

>> Again, changed signal at presence-pin of FRU2
keep checking for event occurance...
hasEventOccurred ?
keep checking for event occurance...
hasEventOccurred ?
Yes, togggle the gpio             <---------------------event on 2nd timer

>> changed signal at presence-pin of FRU1
keep checking for event occurance...
hasEventOccurred ?
Yes, togggle the gpio             <---------------------event on 1st timer
keep checking for event occurance...
hasEventOccurred ?

>> Again changed signal at presence-pin of FRU1
keep checking for event occurance...
hasEventOccurred ?
Yes, togggle the gpio             <---------------------event on 1st timer
keep checking for event occurance...
hasEventOccurred ?

>> Noticed change on output gpio after every signal change.
   As of now for testing, output gpio is same for both of these FRUs-

>> Effects on i2c-
 i2cdetect -y 7
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: 20 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- --
50: UU UU UU -- -- -- -- -- -- -- 5a -- -- -- -- --
60: UU UU UU -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- UU --

 i2cdetect -y 7
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: 20 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- UU -- -- -- -- -- -- --
50: UU 51 UU -- -- -- -- -- -- -- 5a -- -- -- -- --
60: UU UU UU -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- UU --

Also tested for write functionality, shouldn't be affected due to this change
It looks fine.
root@p10bmc:~# busctl introspect  xyz.openbmc_project.Inventory.Manager /xyz/openbmc_project/inventory/system/chassis/motherboard |grep PN
.PN                                                  property  ay        7 48 50 87 71 54 55 56                   emits-change writable

root@p10bmc:~# busctl call com.ibm.VPD.Manager /com/ibm/VPD/Manager com.ibm.VPD.Manager WriteKeyword ossay  "/system/chassis/motherboard" "VINI" "PN" 1 80

root@p10bmc:~# busctl introspect  xyz.openbmc_project.Inventory.Manager /xyz/openbmc_project/inventory/system/chassis/motherboard |grep PN
.PN                                                  property  ay        7 80 50 87 71 54 55 56                   emits-change writable

root@p10bmc:~# busctl call com.ibm.VPD.Manager /com/ibm/VPD/Manager com.ibm.VPD.Manager WriteKeyword ossay  "/system/chassis/motherboard" "VINI" "PN" 1 48

root@p10bmc:~# busctl introspect  xyz.openbmc_project.Inventory.Manager /xyz/openbmc_project/inventory/system/chassis/motherboard |grep PN
.PN                                                  property  ay        7 48 50 87 71 54 55 56                   emits-change writable

Change-Id: If7d311d36bf56ece751afe393a9ba2d83be5df11
Signed-off-by: Alpana Kumari <alpankum@in.ibm.com>
diff --git a/vpd-manager/manager.cpp b/vpd-manager/manager.cpp
index 829dce8..edef56b 100644
--- a/vpd-manager/manager.cpp
+++ b/vpd-manager/manager.cpp
@@ -3,6 +3,7 @@
 #include "manager.hpp"
 
 #include "editor_impl.hpp"
+#include "gpioMonitor.hpp"
 #include "ibm_vpd_utils.hpp"
 #include "ipz_parser.hpp"
 #include "reader_impl.hpp"
@@ -10,6 +11,7 @@
 
 #include <phosphor-logging/elog-errors.hpp>
 
+using namespace openpower::vpd::manager;
 using namespace openpower::vpd::constants;
 using namespace openpower::vpd::inventory;
 using namespace openpower::vpd::manager::editor;
@@ -38,19 +40,18 @@
     try
     {
         processJSON();
+
+        auto event = sdeventplus::Event::get_default();
+        GpioMonitor gpioMon1(jsonFile, event);
+
+        _bus.attach_event(event.get(), SD_EVENT_PRIORITY_IMPORTANT);
+        cout << "VPD manager event loop started\n";
+        event.loop();
     }
     catch (const std::exception& e)
     {
         std::cerr << e.what() << "\n";
     }
-
-    while (true)
-    {
-        _bus.process_discard();
-
-        // wait for event
-        _bus.wait();
-    }
 }
 
 void Manager::processJSON()
@@ -233,15 +234,14 @@
         }
         else
         {
-            string cmd = str + deviceAddress + " > /sys/bus/" + busType +
-                         "/drivers/" + driverType;
-
-            executeCmd(cmd + "/unbind");
-            executeCmd(cmd + "/bind");
+            executeCmd(createBindUnbindDriverCmnd(deviceAddress, busType,
+                                                  driverType, "/unbind"));
+            executeCmd(createBindUnbindDriverCmnd(deviceAddress, busType,
+                                                  driverType, "/bind"));
         }
     }
 }
 
 } // namespace manager
 } // namespace vpd
-} // namespace openpower
+} // namespace openpower
\ No newline at end of file