Add TimeManager daemon to openbmc

Time Manager daemon supporting NTP and MANUAL modes and below policy

  *) BMC owns the time
  *) HOST owns the time
  *) SPLIT clock and HOST's time is maintained as an offset to BMC
  *) BOTH the BMC and HOST own the clock

Change-Id: I81701b67731aa4b37d6926d5b93d397fea96e086
Signed-off-by: Vishwanatha Subbanna <vishwa@linux.vnet.ibm.com>

9 files changed, 2212 insertions, 0 deletions

diff --git a/Makefile.am b/Makefile.am
new file mode 100644
index 0000000..090ee2c
--- /dev/null
+++ b/Makefile.am
@@ -0,0 +1,11 @@
+AM_DEFAULT_SOURCE_EXT = .cpp
+
+sbin_PROGRAMS = \
+	timemanager
+
+timemanager_SOURCES = \
+	time-register.c \
+	time-config.cpp \
+	time-manager.cpp
+
+timemanager_LDFLAGS = $(SYSTEMD_LIBS) $(libmapper_LIBS)
diff --git a/bootstrap.sh b/bootstrap.sh
new file mode 100755
index 0000000..412550f
--- /dev/null
+++ b/bootstrap.sh
@@ -0,0 +1,16 @@
+#!/bin/sh
+
+AUTOCONF_FILES="Makefile.in aclocal.m4 ar-lib autom4te.cache compile config.* \
+        configure depcomp install-sh ltmain.sh missing *libtool"
+
+case $1 in
+    clean)
+        test -f Makefile && make maintainer-clean
+        rm -rf ${AUTOCONF_FILES}
+
+        exit 0
+        ;;
+esac
+
+autoreconf -i
+echo 'Run "./configure ${CONFIGURE_FLAGS} && make"'
diff --git a/configure.ac b/configure.ac
new file mode 100644
index 0000000..f3f119b
--- /dev/null
+++ b/configure.ac
@@ -0,0 +1,25 @@
+# Initialization
+AC_PREREQ([2.69])
+AC_INIT([phosphor-time-manager], [1.0], [https://github.com/openbmc/phosphor-time-manager/issues])
+AC_CONFIG_HEADERS([config.h])
+AM_INIT_AUTOMAKE([subdir-objects -Wall -Werror foreign dist-xz])
+
+# Checks for programs.
+AC_PROG_CXX
+AX_CXX_COMPILE_STDCXX_14([noext])
+AC_PROG_CC
+AM_PROG_AR
+AC_PROG_INSTALL
+AC_PROG_MAKE_SET
+
+# Checks for libraries.
+AC_CHECK_LIB([mapper], [mapper_get_service])
+PKG_CHECK_MODULES([SYSTEMD], [libsystemd >= 221])
+
+# Checks for header files.
+AC_CHECK_HEADER(systemd/sd-bus.h, ,[AC_MSG_ERROR([Could not find systemd/sd-bus.h...systemd developement package required])])
+
+# Checks for typedefs, structures, and compiler characteristics.
+
+AC_CONFIG_FILES([Makefile])
+AC_OUTPUT
diff --git a/time-config.cpp b/time-config.cpp
new file mode 100644
index 0000000..ff62782
--- /dev/null
+++ b/time-config.cpp
@@ -0,0 +1,590 @@
+#include <cstdlib>
+#include <fstream>
+#include <iostream>
+#include <memory>
+#include <mapper.h>
+#include "time-manager.hpp"
+
+std::map<std::string, TimeConfig::FUNCTOR> TimeConfig::iv_TimeParams = {
+    {   "time_mode", std::make_tuple(&TimeConfig::getSystemSettings,
+        &TimeConfig::updateTimeMode)
+    },
+
+    {   "time_owner", std::make_tuple(&TimeConfig::getSystemSettings,
+        &TimeConfig::updateTimeOwner)
+    },
+
+    {   "use_dhcp_ntp", std::make_tuple(&TimeConfig::getSystemSettings,
+        &TimeConfig::updateNetworkSettings)
+    }
+};
+
+TimeConfig::TimeConfig() :
+    iv_CurrTimeMode(timeModes::NTP),
+    iv_RequestedTimeMode(timeModes::NTP),
+    iv_CurrTimeOwner(timeOwners::BMC),
+    iv_RequestedTimeOwner(timeOwners::BMC),
+    iv_CurrDhcpNtp("yes"),
+    iv_SettingChangeAllowed(false),
+    iv_SplitModeChanged(false),
+    iv_dbus(nullptr)
+{
+    // Not really having anything to do here.
+}
+
+// Given a mode string, returns it's equivalent mode enum
+TimeConfig::timeModes TimeConfig::getTimeMode(const char* timeMode)
+{
+    // We are forcing the values to be in specific case and range
+    if (!strcmp(timeMode,"NTP"))
+    {
+        return timeModes::NTP;
+    }
+    else
+    {
+        return timeModes::MANUAL;
+    }
+}
+
+// Accepts a timeMode enum and returns it's string value
+const char* TimeConfig::modeStr(const TimeConfig::timeModes timeMode)
+{
+    switch(timeMode)
+    {
+        case timeModes::NTP:
+        {
+            return "NTP";
+        }
+        case timeModes::MANUAL:
+        {
+            return "MANUAL";
+        }
+    }
+}
+
+// Given a owner string, returns it's equivalent owner enum
+TimeConfig::timeOwners TimeConfig::getTimeOwner(const char* timeOwner)
+{
+    if (!strcmp(timeOwner,"BMC"))
+    {
+        return timeOwners::BMC;
+    }
+    else if (!strcmp(timeOwner,"HOST"))
+    {
+        return timeOwners::HOST;
+    }
+    else if (!strcmp(timeOwner,"SPLIT"))
+    {
+        return timeOwners::SPLIT;
+    }
+    else
+    {
+        return timeOwners::BOTH;
+    }
+}
+
+// Accepts a timeOwner enum and returns it's string value
+const char* TimeConfig::ownerStr(const timeOwners timeOwner)
+{
+    switch(timeOwner)
+    {
+        case timeOwners::BMC:
+        {
+            return "BMC";
+        }
+        case timeOwners::HOST:
+        {
+            return "HOST";
+        }
+        case timeOwners::SPLIT:
+        {
+            return "SPLIT";
+        }
+        case timeOwners::BOTH:
+        {
+            return "BOTH";
+        }
+    }
+}
+
+// Returns the busname that hosts objPath
+std::unique_ptr<char> TimeConfig::getProvider(const char* objPath)
+{
+    char *provider = nullptr;
+    mapper_get_service(iv_dbus, objPath, &provider);
+    return std::unique_ptr<char>(provider);
+}
+
+// Accepts a settings name and returns its value.
+// for the variant of type 'string' now.
+std::string TimeConfig::getSystemSettings(const char* key)
+{
+    constexpr auto settingsObj = "/org/openbmc/settings/host0";
+    constexpr auto propertyIntf = "org.freedesktop.DBus.Properties";
+    constexpr auto hostIntf = "org.openbmc.settings.Host";
+
+    const char* value = nullptr;
+    std::string settingsVal {};
+    sd_bus_message* reply = nullptr;
+
+    std::cout <<"Getting System Settings: " << key << std::endl;
+
+    // Get the provider from object mapper
+    auto settingsProvider = getProvider(settingsObj);
+    if (!settingsProvider)
+    {
+        std::cerr << "Error Getting service for Settings" << std::endl;
+        return value;
+    }
+
+    auto r = sd_bus_call_method(iv_dbus,
+                                settingsProvider.get(),
+                                settingsObj,
+                                propertyIntf,
+                                "Get",
+                                nullptr,
+                                &reply,
+                                "ss",
+                                hostIntf,
+                                key);
+    if (r < 0)
+    {
+        std::cerr <<"Error" << strerror(-r)
+                  <<" reading system settings" << std::endl;
+        goto finish;
+    }
+
+    r = sd_bus_message_read(reply, "v", "s", &value);
+    if (r < 0)
+    {
+        std::cerr <<"Error " << strerror(-r)
+                  <<" parsing settings data" << std::endl;
+    }
+finish:
+    if (value)
+    {
+        settingsVal.assign(value);
+    }
+    reply = sd_bus_message_unref(reply);
+    return settingsVal;
+}
+
+// Reads value from /org/openbmc/control/power0
+// This signature on purpose to plug into time parameter map
+std::string TimeConfig::getPowerSetting(const char* key)
+{
+    constexpr auto powerObj = "/org/openbmc/control/power0";
+    constexpr auto powerIntf = "org.openbmc.control.Power";
+    constexpr auto propertyIntf = "org.freedesktop.DBus.Properties";
+
+    int value = -1;
+    std::string powerValue {};
+    sd_bus_message* reply = nullptr;
+
+    std::cout <<"Reading Power Control key: " << key << std::endl;
+
+    // Get the provider from object mapper
+    auto powerProvider = getProvider(powerObj);
+    if (!powerProvider)
+    {
+        std::cerr <<" Error getting provider for Power Settings" << std::endl;
+        return powerValue;
+    }
+
+    auto r = sd_bus_call_method(iv_dbus,
+                                powerProvider.get(),
+                                powerObj,
+                                propertyIntf,
+                                "Get",
+                                nullptr,
+                                &reply,
+                                "ss",
+                                powerIntf,
+                                key);
+    if (r < 0)
+    {
+        std::cerr <<"Error " << strerror(-r)
+                  << "reading: " << key << std::endl;
+        goto finish;
+    }
+
+    r = sd_bus_message_read(reply, "v", "i", &value);
+    if (r < 0)
+    {
+        std::cerr <<"Error " << strerror(-r)
+                  <<" parsing " << key << "value" << std::endl;
+        // For maintenance
+        goto finish;
+    }
+finish:
+    if (value != -1)
+    {
+        powerValue = std::to_string(value);
+    }
+    reply = sd_bus_message_unref(reply);
+    return powerValue;
+}
+
+// Updates .network file with UseNtp=
+int TimeConfig::updateNetworkSettings(const std::string& useDhcpNtp)
+{
+    constexpr auto networkObj = "/org/openbmc/NetworkManager/Interface";
+    constexpr auto networkIntf = "org.openbmc.NetworkManager";
+
+    std::cout << "use_dhcp_ntp = " << useDhcpNtp.c_str() << std::endl;
+
+    // If what we have already is what it is, then just return.
+    if (iv_CurrDhcpNtp == useDhcpNtp)
+    {
+        return 0;
+    }
+
+    // Get the provider from object mapper
+    auto networkProvider = getProvider(networkObj);
+    if (!networkProvider)
+    {
+        return -1;
+    }
+
+    auto r = sd_bus_call_method(iv_dbus,
+                                networkProvider.get(),
+                                networkObj,
+                                networkIntf,
+                                "UpdateUseNtpField",
+                                nullptr,
+                                nullptr,
+                                "s",
+                                useDhcpNtp.c_str());
+    if (r < 0)
+    {
+        std::cerr <<"Error " << strerror(-r)
+                  << " updating UseNtp" << std::endl;
+    }
+    else
+    {
+        std::cout <<"Successfully updated UseNtp=["
+                  << useDhcpNtp << "]" << std::endl;
+
+        r = writeData<decltype(useDhcpNtp)>(cv_DhcpNtpFile, useDhcpNtp);
+    }
+
+    return 0;
+}
+
+// Reads the values from 'settingsd' and applies:
+// 1) Time Mode
+// 2) time Owner
+// 3) UseNTP setting
+// 4) Pgood
+int TimeConfig::processInitialSettings(sd_bus* dbus)
+{
+    // First call from TimeManager to config manager
+    iv_dbus = dbus;
+
+    // Read saved info like Who was the owner , what was the mode,
+    // what was the use_dhcp_ntp setting before etc..
+    auto r = readPersistentData();
+    if (r < 0)
+    {
+        std::cerr << "Error reading the data saved in flash."
+                  << std::endl;
+        return r;
+    }
+
+    // Now read whats in settings and apply if allowed.
+    for (auto& iter : iv_TimeParams)
+    {
+        // Get the settings value for various keys.
+        auto reader = std::get<READER>(iter.second);
+        auto value = (this->*reader)(iter.first.c_str());
+        if (!value.empty())
+        {
+            // Get the value for the key and validate.
+            auto updater = std::get<UPDATER>(iter.second);
+            auto r = (this->*updater)(value);
+            if (r < 0)
+            {
+                std::cerr << "Error setting up initial keys" << std::endl;
+                return r;
+            }
+        }
+        else
+        {
+            std::cerr << "key " << iter.first
+                      <<" has no value: " << std::endl;
+            return -1;
+        }
+    }
+
+    // Now that we have taken care of consuming, push this as well
+    // so that we can use the same map for handling pgood change too.
+    auto readerUpdater = std::make_tuple(&TimeConfig::getPowerSetting,
+                                         &TimeConfig::processPgoodChange);
+    iv_TimeParams.emplace("pgood", readerUpdater);
+
+    return 0;
+}
+
+// This is called by Property Change handler on the event of
+// receiving notification on property value change.
+int TimeConfig::updatePropertyVal(const char* key, const std::string& value)
+{
+    auto iter = iv_TimeParams.find(key);
+    if (iter != iv_TimeParams.end())
+    {
+        auto updater = std::get<UPDATER>(iter->second);
+        return (this->*updater)(value);
+    }
+    // Coming here indicates that we never had a matching key.
+    return -1;
+}
+
+// Called by sd_event when Properties are changed in Control/power0
+// Interested in change to 'pgood'
+int TimeConfig::processPgoodChange(const std::string& newPgood)
+{
+    // Indicating that we are safe to apply any changes
+    if (!newPgood.compare("0"))
+    {
+        iv_SettingChangeAllowed = true;
+        std::cout <<"Changing time settings allowed now" << std::endl;
+    }
+    else
+    {
+        iv_SettingChangeAllowed = false;
+        std::cout <<"Changing time settings is *deferred* now" << std::endl;
+    }
+
+    // if we have had users that changed the time settings
+    // when we were not ready yet, do it now.
+    if (iv_RequestedTimeOwner != iv_CurrTimeOwner)
+    {
+        auto r = updateTimeOwner(ownerStr(iv_RequestedTimeOwner));
+        if (r < 0)
+        {
+            std::cerr << "Error updating new time owner" << std::endl;
+            return r;
+        }
+        std::cout << "New Owner is : "
+                  << ownerStr(iv_RequestedTimeOwner) << std::endl;
+    }
+
+    if (iv_RequestedTimeMode != iv_CurrTimeMode)
+    {
+        auto r = updateTimeMode(modeStr(iv_RequestedTimeMode));
+        if (r < 0)
+        {
+            std::cerr << "Error updating new time mode" << std::endl;
+            return r;
+        }
+        std::cout <<"New Mode is : "
+                  << modeStr(iv_RequestedTimeMode) << std::endl;
+    }
+    return 0;
+}
+
+// Manipulates time owner if the system setting allows it
+int TimeConfig::updateTimeMode(const std::string& newModeStr)
+{
+    auto r = 0;
+    iv_RequestedTimeMode = getTimeMode(newModeStr.c_str());
+
+    std::cout <<"Requested_Mode: " << newModeStr
+              << " Current_Mode: " << modeStr(iv_CurrTimeMode)
+              << std::endl;
+
+    if (iv_RequestedTimeMode == iv_CurrTimeMode)
+    {
+        std::cout << "Mode is already set to : "
+                  << newModeStr << std::endl;
+        return 0;
+    }
+
+    // Also, if the time owner is HOST, then we should not allow NTP.
+    // However, it may so happen that there are 2 pending requests, one for
+    // changing to NTP and other for changing owner to something not HOST.
+    // So check if there is a pending timeOwner change and if so, allow NTP
+    // if the current is HOST and requested is non HOST.
+    if (iv_CurrTimeOwner == timeOwners::HOST &&
+            iv_RequestedTimeOwner == timeOwners::HOST &&
+            iv_RequestedTimeMode == timeModes::NTP)
+    {
+        std::cout <<"Can not set mode to NTP with HOST as owner"
+                  << std::endl;
+        return 0;
+    }
+
+    if (iv_SettingChangeAllowed)
+    {
+        r = modifyNtpSettings(iv_RequestedTimeMode);
+        if (r < 0)
+        {
+            std::cerr << "Error changing TimeMode settings"
+                      << std::endl;
+        }
+        else
+        {
+            iv_CurrTimeMode = iv_RequestedTimeMode;
+        }
+        std::cout << "Current_Mode changed to: "
+                  << newModeStr << " :: " << modeStr(iv_CurrTimeMode) << std::endl;
+
+        // Need this when we either restart or come back from reset
+        r = writeData(cv_TimeModeFile, modeStr(iv_CurrTimeMode));
+    }
+    else
+    {
+        std::cout <<"Deferring update until system state allows it"
+                  << std::endl;
+    }
+    return r;
+}
+
+// Manipulates time owner if the system setting allows it
+int TimeConfig::updateTimeOwner(const std::string& newOwnerStr)
+{
+    int r = 0;
+    iv_RequestedTimeOwner = getTimeOwner(newOwnerStr.c_str());
+
+    // Needed when owner changes to HOST
+    std::string manualMode = "Manual";
+
+    // Needed by time manager to do some house keeping
+    iv_SplitModeChanged = false;
+
+    if (iv_RequestedTimeOwner == iv_CurrTimeOwner)
+    {
+        std::cout <<"Owner is already set to : "
+                  << newOwnerStr << std::endl;
+        return 0;
+    }
+
+    std::cout <<"Requested_Owner: " << newOwnerStr
+              << " Current_Owner: " << ownerStr(iv_CurrTimeOwner)
+              << std::endl;
+
+    if (iv_SettingChangeAllowed)
+    {
+        // If we are transitioning from SPLIT to something else,
+        // reset the host offset.
+        if (iv_CurrTimeOwner == timeOwners::SPLIT &&
+                iv_RequestedTimeOwner != timeOwners::SPLIT)
+        {
+            // Needed by time manager to do some house keeping
+            iv_SplitModeChanged = true;
+        }
+        iv_CurrTimeOwner = iv_RequestedTimeOwner;
+        std::cout << "Current_Owner is now: "
+                  << newOwnerStr << std::endl;
+
+        // HOST and NTP are exclusive
+        if (iv_CurrTimeOwner == timeOwners::HOST)
+        {
+            std::cout <<"Forcing the mode to MANUAL" << std::endl;
+            r = updateTimeMode(manualMode);
+            if (r < 0)
+            {
+                std::cerr << "Error forcing the mode to MANUAL" << std::endl;
+                return r;
+            }
+        }
+        // Need this when we either restart or come back from reset
+        r = writeData(cv_TimeOwnerFile, ownerStr(iv_CurrTimeOwner));
+    }
+    else
+    {
+        std::cout <<"Deferring update until system state allows it"
+                  << std::endl;
+    }
+
+    return r;
+}
+
+// Accepts the time mode and makes necessary changes to timedate1
+int TimeConfig::modifyNtpSettings(const timeModes& newTimeMode)
+{
+    auto ntpChangeOp = 0;
+
+    // Pass '1' -or- '0' to SetNTP method indicating Enable/Disable
+    ntpChangeOp = (newTimeMode == timeModes::NTP) ? 1 : 0;
+
+    std::cout <<"Applying NTP setting..." << std::endl;
+
+    auto r = sd_bus_call_method(iv_dbus,
+                                "org.freedesktop.timedate1",
+                                "/org/freedesktop/timedate1",
+                                "org.freedesktop.timedate1",
+                                "SetNTP",
+                                nullptr,
+                                nullptr,    // timedate1 does not return response
+                                "bb",
+                                ntpChangeOp,       // '1' means Enable
+                                0);              // '0' meaning no policy-kit
+    if (r < 0)
+    {
+        std::cerr <<"Error: " << strerror(-r)
+                  << "changing time Mode" << std::endl;
+    }
+    else
+    {
+        std::cout << "SUCCESS. NTP setting is now: " <<
+                  (ntpChangeOp) ? "Enabled" : "Disabled";
+
+        // TODO : https://github.com/openbmc/phosphor-time-manager/issues/1
+        if (ntpChangeOp)
+        {
+            system("systemctl restart systemd-timesyncd &");
+        }
+        else
+        {
+            system("systemctl stop systemd-timesyncd &");
+        }
+    }
+    return r;
+}
+
+// Reads all the saved data from the last run
+int TimeConfig::readPersistentData()
+{
+    // If we are coming back from a reset reload, then need to
+    // read what was the last successful Mode and Owner.
+    auto savedTimeMode = readData<std::string>(cv_TimeModeFile);
+    if (!savedTimeMode.empty())
+    {
+        iv_CurrTimeMode = getTimeMode(savedTimeMode.c_str());
+        std::cout <<"Last known time_mode: "
+                  << savedTimeMode.c_str() << std::endl;
+    }
+
+    auto savedTimeOwner = readData<std::string>(cv_TimeOwnerFile);
+    if (!savedTimeOwner.empty())
+    {
+        iv_CurrTimeOwner = getTimeOwner(savedTimeOwner.c_str());
+        std::cout <<"Last known time_owner: "
+                  << savedTimeOwner.c_str() << std::endl;
+    }
+
+    auto savedDhcpNtp = readData<std::string>(cv_DhcpNtpFile);
+    if (!savedDhcpNtp.empty())
+    {
+        iv_CurrDhcpNtp = savedDhcpNtp;
+        std::cout <<"Last known use_dhcp_ntp: "
+                  << iv_CurrDhcpNtp.c_str() << std::endl;
+    }
+    else
+    {
+        // This seems to be the first time.
+        std::cerr <<"Empty DhcpNtp string" << std::endl;
+        iv_CurrDhcpNtp = "yes";
+    }
+
+    // Doing this here to make sure 'pgood' is read and handled
+    // first before anything.
+    auto pgood = getPowerSetting("pgood");
+    if (!pgood.compare("0"))
+    {
+        std::cout << "Changing settings *allowed* now" << std::endl;
+        iv_SettingChangeAllowed = true;
+    }
+    return 0;
+}
diff --git a/time-config.hpp b/time-config.hpp
new file mode 100644
index 0000000..0f08641
--- /dev/null
+++ b/time-config.hpp
@@ -0,0 +1,313 @@
+#include <map>
+#include <systemd/sd-bus.h>
+
+/** @class TimeConfig
+ *  @brief Maintains various time modes and time owners.
+ */
+class TimeConfig
+{
+public:
+    /** @brief Supported time modes
+     *  NTP     Time sourced by Network Time Server
+     *  MANUAL  User of the system need to set the time
+     */
+    enum class timeModes
+    {
+        NTP,
+        MANUAL
+    };
+
+    /** @brief Supported time owners
+     *  BMC     Time source may be NTP or MANUAL but it has to be set natively
+     *          on the BMC. Meaning, host can not set the time. What it also
+     *          means is that when BMC gets IPMI_SET_SEL_TIME, then its ignored.
+     *          similarly, when BMC gets IPMI_GET_SEL_TIME, then the BMC's time
+     *          is returned.
+     *
+     *  HOST    Its only IPMI_SEL_SEL_TIME that will set the time on BMC.
+     *          Meaning, IPMI_GET_SEL_TIME and request to get BMC time will
+     *          result in same value.
+     *
+     *  SPLIT   Both BMC and HOST will maintain their individual clocks but then
+     *          the time information is stored in BMC. BMC can have either NTP
+     *          or MANUAL as it's source of time and will set the time directly
+     *          on the BMC. When IPMI_SET_SEL_TIME is received, then the delta
+     *          between that and BMC's time is calculated and is stored.
+     *          When BMC reads the time, the current time is returned.
+     *          When IPMI_GET_SEL_TIME is received, BMC's time is retrieved and
+     *          then the delta offset is factored in prior to returning.
+     *
+     *  BOTH:   BMC's time is set with whoever that sets the time. Similarly,
+     *          BMC's time is returned to whoever that asks the time.
+     */
+    enum class timeOwners
+    {
+        BMC,
+        HOST,
+        SPLIT,
+        BOTH
+    };
+
+    // Do not have a usecase of copying this object so disable
+    TimeConfig();
+    ~TimeConfig() = default;
+    TimeConfig(const TimeConfig&) = delete;
+    TimeConfig& operator=(const TimeConfig&) = delete;
+    TimeConfig(TimeConfig&&) = delete;
+    TimeConfig& operator=(TimeConfig&&) = delete;
+
+    inline auto getCurrTimeMode() const
+    {
+        return iv_CurrTimeMode;
+    }
+
+    inline auto getCurrTimeOwner() const
+    {
+        return iv_CurrTimeOwner;
+    }
+
+    inline auto getRequestedTimeMode() const
+    {
+        return iv_RequestedTimeMode;
+    }
+
+    inline auto getRequestedTimeOwner() const
+    {
+        return iv_RequestedTimeOwner;
+    }
+
+    inline auto isSplitModeChanged() const
+    {
+        return iv_SplitModeChanged;
+    }
+
+    inline void updateSplitModeFlag(const bool& value)
+    {
+        iv_SplitModeChanged = value;
+    }
+
+    inline sd_bus* getDbus() const
+    {
+        return iv_dbus;
+    }
+
+    /** brief Generic file reader used to read time mode,
+     *  time owner, host time,  host offset and useDhcpNtp
+     *
+     *  @param[in] filename - Name of file where data is preserved.
+     *  @return             - File content
+     */
+    template <typename T>
+    T readData(const char* fileName)
+    {
+        T data = T();
+        if(std::ifstream(fileName))
+        {
+            std::ifstream file(fileName, std::ios::in);
+            file >> data;
+            file.close();
+        }
+        return data;
+    }
+
+    /** @brief Generic file writer used to write time mode,
+     *  time owner, host time,  host offset and useDhcpNtp
+     *
+     *  @param[in] filename - Name of file where data is preserved.
+     *  @param[in] data     - Data to be written to file
+     *  @return             - 0 for now. But will be changed to raising
+     *                      - Exception
+     */
+    template <typename T>
+    auto writeData(const char* fileName, const T&& data)
+    {
+        std::ofstream file(fileName, std::ios::out);
+        file << data;
+        file.close();
+        return 0;
+    }
+
+    /** @brief Reads saved data and populates below properties
+     *  - Current Time Mode
+     *  - Current Time Owner
+     *  - Whether to use NTP settings given by DHCP
+     *  - Last known host offset
+     *
+     *  @param[in] dbus -  Handler to sd_bus used by time manager
+     *
+     *  @return         -  < 0 for failure and others for success
+     */
+    int processInitialSettings(sd_bus* dbus);
+
+    /** @brief Accepts time mode string, returns the equivalent enum
+     *
+     *  @param[in] timeModeStr - Current Time Mode in string
+     *
+     *  @return                - Equivalent ENUM
+     *                         - Input : "NTP", Output: timeModes::NTP
+     */
+    static timeModes getTimeMode(const char* timeModeStr);
+
+    /** @brief Accepts timeMode enum and returns it's string equivalent
+     *
+     *  @param[in] timeMode - Current Time Mode Enum
+     *
+     *  @return             - Equivalent string
+     *                      - Input : timeModes::NTP, Output : "NTP"
+     */
+    static const char* modeStr(const timeModes timeMode);
+
+    /** @brief Accepts timeOwner string and returns it's equivalent enum
+     *
+     *  @param[in] timeOwnerStr - Current Time Owner in string
+     *
+     *  @return              - Equivalent ENUM
+     *                       - Input : "BMC", output : timeOwners::BMC
+     */
+    static timeOwners getTimeOwner(const char* timeOwnerStr);
+
+    /** @brief Accepts timeOwner enum and returns it's string equivalent
+     *
+     *  @param[in] timeOwner - Current Time Mode Enum
+     *
+     *  @return              - Equivalent string
+     *                       - Input : timeOwners::BMC, Output : "BMC"
+     */
+    static const char* ownerStr(const timeOwners timeOwner);
+
+    /** @brief Gets called when the settings property changes.
+     *  Walks the map and then applies the changes
+     *
+     *  @param[in] key   - Name of the property
+     *  @param[in] value - Value
+     *
+     *  @return              - < 0 on failure, success otherwise
+     */
+    int updatePropertyVal(const char* key, const std::string& value);
+
+    // Acts on the time property changes / reads initial property
+    using READER = std::string (TimeConfig::*) (const char*);
+    using UPDATER = int (TimeConfig::*) (const std::string&);
+    using FUNCTOR = std::tuple<READER, UPDATER>;
+
+    // Most of this is statically constructed and PGOOD is added later.
+    static std::map<std::string, FUNCTOR> iv_TimeParams;
+
+private:
+    // Bus initialised by manager on a call to process initial settings
+    sd_bus *iv_dbus;
+
+    /** @brief 'Requested' is what is asked by user in settings
+     * 'Current' is what the TimeManager is really using since its not
+     *  possible to apply the mode and owner as and when the user updates
+     *  Settings. They are only applied when the system power is off.
+     */
+    timeModes  iv_CurrTimeMode;
+    timeModes  iv_RequestedTimeMode;
+
+    timeOwners iv_CurrTimeOwner;
+    timeOwners iv_RequestedTimeOwner;
+
+    /** @brief One of the entry in .network file indicates whether the
+     *  systemd-timesyncd should use the NTP server list that are sent by DHCP
+     *  server or not. If the value is 'yes', then NTP server list sent by DHCP
+     *  are used. else entries that are configured statically with NTP= are used
+     */
+    std::string iv_CurrDhcpNtp;
+
+    /** @brief Dictated by state of pgood. When the pgood value is 'zero', then
+     *  its an indication that we are okay to apply any pending Mode / Owner
+     *  values. Meaning, Current will be updated with what is in Requested.
+     */
+    bool        iv_SettingChangeAllowed;
+
+    // Needed to nudge Time Manager to reset offset
+    bool        iv_SplitModeChanged;
+
+    static constexpr auto cv_TimeModeFile = "/var/lib/obmc/saved_timeMode";
+    static constexpr auto cv_TimeOwnerFile = "/var/lib/obmc/saved_timeOwner";
+    static constexpr auto cv_DhcpNtpFile = "/var/lib/obmc/saved_dhcpNtp";
+
+    /** @brief Wrapper that looks up in the mapper service for a given
+     *  object path and returns the service name
+     *
+     *  @param[in] objpath - dbus object path
+     *
+     *  @return            - unique_ptr holding service name.
+     *                     - Caller needs to validate if its populated
+     */
+    std::unique_ptr<char> getProvider(const char* objPath);
+
+    /** @brief Helper function for processInitialSettings.
+     *  Reads saved data and populates below properties. Only the values are
+     *  read from the file system. but it will not take the action on those.
+     *  Actions on these are taken by processInitialSettings
+     *
+     *  - Current Time Mode
+     *  - Current Time Owner
+     *  - Whether to use NTP settings given by DHCP
+     *  - Current Pgood state
+     *
+     *  @return         -  < 0 for failure and success on others
+     */
+    int readPersistentData();
+
+    /** @brief Updates the 'ntp' field in systemd/timedate1,
+     *  which enables / disables NTP syncing
+     *
+     *  @param[in] newTimeMode - Time Mode Enum
+     *
+     *  @return                - < 0 on failure and success on others
+     */
+    int modifyNtpSettings(const timeModes& newTimeMode);
+
+    /** @brief Accepts system setting parameter and returns its value
+     *
+     *  @param[in] key - Name of the property
+     *
+     *  @return        - Value as string
+     */
+    std::string getSystemSettings(const char* key);
+
+    /** @brief Reads the data hosted by /org/openbmc/control/power0
+     *
+     *  @param[in] key - Name of the property
+     *
+     *  @return        - Value as string
+     */
+    std::string getPowerSetting(const char* key);
+
+    /** @brief Accepts Mode string and applies only if conditions allow it.
+     *
+     *  @param[in] newModeStr - Requested Time Mode
+     *
+     *  @return               - < 0 on failure, success otherwise
+     */
+    int updateTimeMode(const std::string& newModeStr);
+
+    /** @brief Accepts Ownere string and applies only if conditions allow it.
+     *
+     *  @param[in] newOwnerStr - Requested Time Owner
+     *
+     *  @return               - < 0 on failure, success otherwise
+     */
+
+    int updateTimeOwner(const std::string& newownerStr);
+
+    /** @brief Updates .network file with UseNtp= provided by NetworkManager
+     *
+     *  @param[in] useDhcpNtp - will be 'yes' or 'no'
+     *
+     *  @return               - < 0 on failure, success otherwise
+     */
+    int updateNetworkSettings(const std::string& useDhcpNtp);
+
+    /** @brief Accepts current pgood value and then updates any pending mode
+     *  or owner requests
+     *
+     *  @param[in] useDhcpNtp - will be 'yes' or 'no'
+     *
+     *  @return               - < 0 on failure, success otherwise
+     */
+    int processPgoodChange(const std::string& newPgood);
+};
diff --git a/time-manager.cpp b/time-manager.cpp
new file mode 100644
index 0000000..bde2e0d
--- /dev/null
+++ b/time-manager.cpp
@@ -0,0 +1,912 @@
+#define _XOPEN_SOURCE
+#include <chrono>
+#include <sstream>
+#include <iostream>
+#include <iomanip>
+#include <array>
+#include <unistd.h>
+#include <assert.h>
+#include <sys/timerfd.h>
+#include <systemd/sd-event.h>
+#include <systemd/sd-bus.h>
+#include <systemd/sd-daemon.h>
+#include "time-register.hpp"
+#include "time-manager.hpp"
+
+// Neeed to do this since its not exported outside of the kernel.
+// Refer : https://gist.github.com/lethean/446cea944b7441228298
+#ifndef TFD_TIMER_CANCEL_ON_SET
+#define TFD_TIMER_CANCEL_ON_SET (1 << 1)
+#endif
+
+// Needed to make sure timerfd does not misfire eventhough we set CANCEL_ON_SET
+#define TIME_T_MAX (time_t)((1UL << ((sizeof(time_t) << 3) - 1)) - 1)
+
+// Used in time-register.c
+extern sd_bus_vtable timeServicesVtable[];
+
+Time::Time(const TimeConfig& timeConfig) : config(timeConfig)
+{
+    // Nothing to do here
+}
+
+BmcTime::BmcTime(const TimeConfig& timeConfig) : Time(timeConfig)
+{
+    // Nothing to do here
+}
+
+HostTime::HostTime(const TimeConfig& timeConfig,
+                   const std::chrono::microseconds& hostOffset)
+    : Time(timeConfig),
+      iv_Offset(hostOffset)
+{
+    // Nothing to do here
+}
+
+TimeManager::TimeManager() :
+    iv_HostOffset(std::chrono::microseconds(0)),
+    iv_UptimeUsec(std::chrono::microseconds(0)),
+    iv_EventSource(nullptr),
+    iv_Event(nullptr)
+{
+    assert(setupTimeManager() >= 0);
+}
+
+// Needed to be standalone extern "C" to register
+// as a callback routine with sd_bus_vtable
+int GetTime(sd_bus_message* m, void* userdata,
+            sd_bus_error* retError)
+{
+    auto tmgr = static_cast<TimeManager*>(userdata);
+    return tmgr->getTime(m, userdata, retError);
+}
+
+int SetTime(sd_bus_message* m, void* userdata,
+            sd_bus_error* retError)
+{
+    auto tmgr = static_cast<TimeManager*>(userdata);
+    return tmgr->setTime(m, userdata, retError);
+}
+
+// Property reader
+int getCurrTimeModeProperty(sd_bus* bus, const char* path,
+                            const char* interface, const char* property,
+                            sd_bus_message* m, void* userdata,
+                            sd_bus_error* error)
+{
+    auto tmgr = static_cast<TimeManager*>(userdata);
+    return sd_bus_message_append(m, "s",
+                                 TimeConfig::modeStr(tmgr->config.getCurrTimeMode()));
+}
+
+int getCurrTimeOwnerProperty(sd_bus* bus, const char* path,
+                             const char* interface, const char* property,
+                             sd_bus_message* m, void* userdata,
+                             sd_bus_error* error)
+{
+    auto tmgr = static_cast<TimeManager*>(userdata);
+    return sd_bus_message_append(m, "s",
+                                 TimeConfig::ownerStr(tmgr->config.getCurrTimeOwner()));
+}
+
+int getReqTimeModeProperty(sd_bus* bus, const char* path,
+                           const char* interface, const char* property,
+                           sd_bus_message* m, void* userdata,
+                           sd_bus_error* error)
+{
+    auto tmgr = static_cast<TimeManager*>(userdata);
+    return sd_bus_message_append(m, "s",
+                                 TimeConfig::modeStr(tmgr->config.getRequestedTimeMode()));
+}
+
+int getReqTimeOwnerProperty(sd_bus* bus, const char* path,
+                            const char* interface, const char* property,
+                            sd_bus_message* m, void* userdata,
+                            sd_bus_error* error)
+{
+    auto tmgr = static_cast<TimeManager*>(userdata);
+    return sd_bus_message_append(m, "s",
+                                 TimeConfig::ownerStr(tmgr->config.getRequestedTimeOwner()));
+}
+
+int TimeManager::getTime(sd_bus_message* m, void* userdata,
+                         sd_bus_error* retError)
+{
+    const char* target = nullptr;
+
+    // Extract the target and call respective GetTime
+    auto r = sd_bus_message_read(m, "s", &target);
+    if (r < 0)
+    {
+        std::cerr << "Error:" << strerror(-r)
+                  <<" reading user time" << std::endl;
+        *retError = SD_BUS_ERROR_MAKE_CONST(
+                        SD_BUS_ERROR_IO_ERROR, "Error reading input");
+
+        return sd_bus_reply_method_error(m, retError);
+    }
+
+    if (!strcasecmp(target, "bmc"))
+    {
+        auto time = BmcTime(config);
+        return time.getTime(m, retError);
+    }
+    else if (!strcasecmp(target, "host"))
+    {
+        auto time = HostTime(config, iv_HostOffset);
+        return time.getTime(m, retError);
+    }
+    else
+    {
+        std::cerr << "Error:" << strerror(-r)
+                  <<" Invalid Target" << std::endl;
+        *retError = SD_BUS_ERROR_MAKE_CONST(
+                        SD_BUS_ERROR_IO_ERROR, "Valid targets are BMC or HOST");
+
+        return sd_bus_reply_method_error(m, retError);
+    }
+}
+
+int TimeManager::setTime(sd_bus_message* m, void* userdata,
+                         sd_bus_error* retError)
+{
+    long long int timeInUsec {};
+
+    const char* target = nullptr;
+    auto r = sd_bus_message_read(m, "s", &target);
+    if (r < 0)
+    {
+        std::cerr << "Error:" << strerror(-r)
+                  <<" reading user time" << std::endl;
+        *retError = SD_BUS_ERROR_MAKE_CONST(
+                        SD_BUS_ERROR_IO_ERROR, "Error reading input");
+
+        return sd_bus_reply_method_error(m, retError);
+    }
+
+    if (!strcasecmp(target, "bmc"))
+    {
+        auto time = BmcTime(config);
+        auto r = time.setTime(m, retError);
+        if (r < 0)
+        {
+            // This would have the error populated
+            return sd_bus_reply_method_error(m, retError);
+        }
+    }
+    else if (!strcasecmp(target, "host"))
+    {
+        auto time = HostTime(config, iv_HostOffset);
+
+        auto r = time.setTime(m, retError);
+        if (r < 0)
+        {
+            // This would have the error populated
+            return sd_bus_reply_method_error(m, retError);
+        }
+
+        if (config.getCurrTimeOwner() == TimeConfig::timeOwners::SPLIT)
+        {
+            iv_HostOffset = time.getChangedOffset();
+            r = config.writeData<decltype(iv_HostOffset.count())>
+                (cv_HostOffsetFile,
+                 iv_HostOffset.count());
+            if (r < 0)
+            {
+                // probably does not make sense to crash on these..
+                // The next NTP sync will set things right.
+                std::cerr << "Error saving host_offset: "
+                          << iv_HostOffset.count() << std::endl;
+            }
+        }
+    }
+    return sd_bus_reply_method_return(m, "i", 0);
+}
+
+int Time::setTimeOfDay(const std::chrono::microseconds& timeOfDayUsec)
+{
+    // These 2 are for bypassing some policy
+    // checking in the timedate1 service
+    auto relative = false;
+    auto interactive = false;
+
+    return sd_bus_call_method(config.getDbus(),
+                              "org.freedesktop.timedate1",
+                              "/org/freedesktop/timedate1",
+                              "org.freedesktop.timedate1",
+                              "SetTime",
+                              nullptr,
+                              nullptr,            // timedate1 does not return response
+                              "xbb",
+                              (int64_t)timeOfDayUsec.count(), //newTimeUsec,
+                              relative,        // Time in absolute seconds since epoch
+                              interactive);    // bypass polkit checks
+}
+
+// Common routine for BMC and HOST Get Time operations
+std::chrono::microseconds Time::getBaseTime()
+{
+    auto currBmcTime = std::chrono::system_clock::now();
+    return std::chrono::duration_cast<std::chrono::microseconds>
+           (currBmcTime.time_since_epoch());
+}
+
+// Accepts the time in microseconds and converts to Human readable format.
+std::string Time::convertToStr(const std::chrono::microseconds& timeInUsec)
+{
+    using namespace std::chrono;
+
+    // Convert this to number of seconds;
+    auto timeInSec = duration_cast<seconds>(microseconds(timeInUsec));
+    auto time_T = static_cast<std::time_t>(timeInSec.count());
+
+    std::ostringstream timeFormat {};
+    timeFormat << std::put_time(std::gmtime(&time_T), "%c %Z");
+
+    auto timeStr = timeFormat.str();
+    std::cout << timeStr.c_str() << std::endl;
+    return timeStr;
+}
+
+// Reads timeofday and returns time string
+// and also number of microseconds.
+// Ex : Tue Aug 16 22:49:43 2016
+int BmcTime::getTime(sd_bus_message *m, sd_bus_error *retError)
+{
+    std::cout << "Request to get BMC time: ";
+
+    // Get BMC time
+    auto timeInUsec = getBaseTime();
+    auto timeStr = convertToStr(timeInUsec);
+    return sd_bus_reply_method_return(
+               m, "sx", timeStr.c_str(), (uint64_t)timeInUsec.count());
+}
+
+// Designated to be called by IPMI_GET_SEL time from host
+int HostTime::getTime(sd_bus_message *m, sd_bus_error *retError)
+{
+    using namespace std::chrono;
+
+    std::cout << "Request to get HOST time" << std::endl;
+
+    // Get BMC time and add Host's offset
+    // Referencing the iv_hostOffset of TimeManager object
+    auto timeInUsec = getBaseTime();
+    auto hostTime = timeInUsec.count() + iv_Offset.count();
+
+    auto timeStr = convertToStr(duration_cast<microseconds>
+                                (microseconds(hostTime)));
+
+    std::cout << " Host_time_str: [ " << timeStr
+              << " ] host_time usec: [ " << hostTime
+              << " ] host_offset: [ " << iv_Offset.count()
+              << " ] " << std::endl;
+
+    return sd_bus_reply_method_return(m, "sx", timeStr.c_str(),
+                                      (uint64_t)hostTime);
+    return 0;
+}
+
+// Gets the time string and verifies if it conforms to format %Y-%m-%d %H:%M:%S
+// and then sets the BMC time. If the input time string does not conform to the
+// format, an error message is returned.
+int BmcTime::setTime(sd_bus_message *m, sd_bus_error *retError)
+{
+    tm userTm {};
+    const char* userTimeStr = nullptr;
+
+    std::cout << "Request to set BMC time" << std::endl;
+
+    std::cout << "Curr_Mode: " << TimeConfig::modeStr(config.getCurrTimeMode())
+              << " Curr_Owner: " << TimeConfig::ownerStr(config.getCurrTimeOwner())
+              << std::endl;
+
+    if (config.getCurrTimeMode() == TimeConfig::timeModes::NTP)
+    {
+        std::cerr << "Can not set time. Mode is NTP" << std::endl;
+        *retError = SD_BUS_ERROR_MAKE_CONST(
+                        SD_BUS_ERROR_FAILED, "Current Mode is NTP");
+
+        return -1;
+    }
+
+    if(config.getCurrTimeOwner() == TimeConfig::timeOwners::HOST)
+    {
+        std::cerr << "Can not set time. Owner is HOST" << std::endl;
+        *retError = SD_BUS_ERROR_MAKE_CONST(
+                        SD_BUS_ERROR_FAILED, "Current owner is HOST");
+
+        return -1;
+    }
+
+    auto r = sd_bus_message_read(m, "s", &userTimeStr);
+    if (r < 0)
+    {
+        std::cerr << "Error:" << strerror(-r)
+                  <<" reading user time" << std::endl;
+        *retError = SD_BUS_ERROR_MAKE_CONST(
+                        SD_BUS_ERROR_IO_ERROR, "Error reading input");
+        return r;
+    }
+
+    std::cout <<" BMC TIME : " << userTimeStr << std::endl;
+
+    // Convert the time string into tm structure
+    std::istringstream timeString {};
+    timeString.str(userTimeStr);
+    timeString >> std::get_time(&userTm, "%Y-%m-%d %H:%M:%S");
+    if (timeString.fail())
+    {
+        std::cerr << "Error: Incorrect time format" << std::endl;
+        *retError = SD_BUS_ERROR_MAKE_CONST(
+                        SD_BUS_ERROR_INVALID_ARGS, "Incorrect time format");
+        return -1;
+    }
+
+    // Convert the time structure into number of
+    // seconds maintained in GMT. Followed the same that is in
+    // systemd/timedate1
+    auto timeOfDay = timegm(&userTm);
+    if (timeOfDay < 0)
+    {
+        std::cerr <<"Error converting tm to seconds" << std::endl;
+        *retError = SD_BUS_ERROR_MAKE_CONST(
+                        SD_BUS_ERROR_FAILED, "Error converting tm to seconds");
+        return -1;
+    }
+
+    // Set REALTIME and also update hwclock
+    auto timeInUsec = std::chrono::microseconds(
+                          std::chrono::seconds(timeOfDay));
+    r = setTimeOfDay(timeInUsec);
+    if (r < 0)
+    {
+        std::cerr <<"Error: " << strerror(-r)
+                  << "setting time on BMC" << std::endl;
+        *retError = SD_BUS_ERROR_MAKE_CONST(
+                        SD_BUS_ERROR_FAILED, "Error setting time on BMC");
+    }
+    return r < 0 ? r : 0;
+}
+
+// Gets the time string from IPMI ( which is currently in seconds since epoch )
+// and then sets the BMC time / adjusts the offset depending on current owner
+// policy.
+int HostTime::setTime(sd_bus_message *m, sd_bus_error *retError)
+{
+    using namespace std::chrono;
+
+    std::cout << "Request to SET Host time" << std::endl;
+
+    std::cout << "Curr_Mode: " << TimeConfig::modeStr(config.getCurrTimeMode())
+              << "Curr_Owner: " << TimeConfig::ownerStr(config.getCurrTimeOwner())
+              << "host_offset: " << iv_Offset.count() << std::endl;
+
+    if (config.getCurrTimeOwner() == TimeConfig::timeOwners::BMC)
+    {
+        *retError = SD_BUS_ERROR_MAKE_CONST(
+                        SD_BUS_ERROR_FAILED, "Current Owner is BMC");
+        return -1;
+    }
+
+    const char* newHostTime = nullptr;
+    auto r = sd_bus_message_read(m, "s", &newHostTime);
+    if (r < 0)
+    {
+        std::cerr << "Error: " << strerror(-r)
+                  << "reading host time" << std::endl;
+        *retError = SD_BUS_ERROR_MAKE_CONST(
+                        SD_BUS_ERROR_IO_ERROR, "Error reading input");
+        return -1;
+    }
+
+    // We need to convert the string input to decimal.
+    auto hostTimeSec = std::stol(std::string(newHostTime));
+
+    // And then to microseconds
+    auto hostTimeUsec = duration_cast<microseconds>(seconds(hostTimeSec));
+    std::cout << "setHostTime: HostTimeInUSec: "
+              << hostTimeUsec.count() << std::endl;
+
+    if (config.getCurrTimeOwner() == TimeConfig::timeOwners::SPLIT)
+    {
+        // Adjust the host offset
+        auto bmcTimeUsec = duration_cast<microseconds>
+                           (system_clock::now().time_since_epoch());
+
+        // We are not doing any time settings in BMC
+        std::cout << "Updated: host_time: [  " << hostTimeUsec.count()
+                  << " ] host_offset: [ " << iv_Offset.count()
+                  << " ] " << std::endl;
+
+        // Communicate the offset back to manager to update needed.
+        changedOffset = hostTimeUsec - bmcTimeUsec;
+
+        return 0;
+    }
+
+    // We are okay to update time in as long as BMC is not the owner
+    r = setTimeOfDay(hostTimeUsec);
+    if (r < 0)
+    {
+        std::cerr <<"Error: " << strerror(-r)
+                  << "setting HOST time" << std::endl;
+        *retError = SD_BUS_ERROR_MAKE_CONST(
+                        SD_BUS_ERROR_FAILED, "Error setting time");
+    }
+
+    return r < 0 ? r : 0;
+}
+
+// Gets called into by sd_event on an activity seen on sd_bus
+int TimeManager::processSdBusMessage(sd_event_source* es, int fd,
+                                     uint32_t revents, void* userdata)
+{
+    auto tmgr = static_cast<TimeManager*>(userdata);
+    auto r = sd_bus_process(tmgr->getTimeBus(), nullptr);
+    if (r < 0)
+    {
+        std::cerr <<"Error: " << strerror(-r)
+                  <<" processing sd_bus message:" << std::endl;
+    }
+    return r;
+}
+
+// Gets called into by sd_event on any time SET event
+int TimeManager::processTimeChange(sd_event_source* es, int fd,
+                                   uint32_t revents, void* userdata)
+{
+    using namespace std::chrono;
+    std::cout << "BMC time changed" << std::endl;
+
+    auto tmgr = static_cast<TimeManager*>(userdata);
+
+    std::array<char, 64> time {};
+
+    // We are not interested in the data here. Need to read time again .
+    // So read until there is something here in the FD
+    while (read(fd, time.data(), time.max_size()) > 0);
+
+    std::cout <<" Curr_Mode: " << TimeConfig::modeStr(tmgr->config.getCurrTimeMode())
+              << " Curr_Owner : " << TimeConfig::ownerStr(tmgr->config.getCurrTimeOwner())
+              << " Host_Offset: " << tmgr->getHostOffset().count() << std::endl;
+
+    // Read the current BMC time and adjust the
+    // host time offset if the mode is  SPLIT
+    if (tmgr->config.getCurrTimeOwner() == TimeConfig::timeOwners::SPLIT)
+    {
+        // Delta between REAL and Monotonic.
+        auto uptimeUsec = duration_cast<microseconds>
+                          (system_clock::now().time_since_epoch() -
+                           steady_clock::now().time_since_epoch());
+
+        auto deltaTimeUsec = uptimeUsec - tmgr->getUptimeUsec();
+
+        // If the BMC time goes backwards, then - of - will handle that.
+        auto newHostOffset = tmgr->getHostOffset() - deltaTimeUsec;
+        tmgr->updateHostOffset(newHostOffset);
+
+        std::cout << " UPDATED HOST_OFFSET: "
+                  << tmgr->getHostOffset().count() << std::endl;
+        tmgr->updateUptimeUsec(uptimeUsec);
+
+        // Persist this
+        auto r = tmgr->config.writeData<decltype(tmgr->getHostOffset().count())>
+                 (TimeManager::cv_HostOffsetFile,
+                  tmgr->getHostOffset().count());
+        if (r < 0)
+        {
+            std::cerr << "Error saving host_offset: "
+                      << tmgr->getHostOffset().count() << std::endl;
+            return r;
+        }
+        std::cout << " Updated: Host_Offset: "
+                  << tmgr->getHostOffset().count() << std::endl;
+    }
+    return 0;
+}
+
+// Resets iv_HostOffset. Needed when we move away from SPLIT.
+int TimeManager::resetHostOffset()
+{
+    iv_HostOffset = std::chrono::microseconds(0);
+    auto r = config.writeData<decltype(iv_HostOffset.count())>
+             (cv_HostOffsetFile,
+              iv_HostOffset.count());
+    config.updateSplitModeFlag(false);
+    return r;
+}
+
+// Called by sd_event when Pgood is changed in Power
+int TimeManager::processPgoodChange(sd_bus_message* m, void* userdata,
+                                    sd_bus_error* retError)
+{
+    auto tmgr = static_cast<TimeManager*>(userdata);
+    const char* key = nullptr;
+    const char* value = nullptr;
+
+    auto newPgood = -1;
+    auto r = 0;
+
+    std::cout <<" PGOOD has changed.." << std::endl;
+
+    // input data is "sa{sv}as" and we are just interested in a{sv}
+    r = sd_bus_message_skip(m, "s");
+    if (r < 0)
+    {
+        std::cerr << "Error: " << strerror(-r) <<
+                  "skipping interface name in data" << std::endl;
+        return r;
+    }
+
+    r = sd_bus_message_enter_container(m, SD_BUS_TYPE_ARRAY, "{sv}");
+    if (r < 0)
+    {
+        std::cerr << "Error: " << strerror(-r)
+                  <<"entering the dictionary" << std::endl;
+        return r;
+    }
+
+    while ((r = sd_bus_message_enter_container(m, SD_BUS_TYPE_DICT_ENTRY,
+                "sv")) > 0)
+    {
+        r = sd_bus_message_read(m, "s", &key);
+        if (r < 0)
+        {
+            std::cerr << "Error: " << strerror(-r)
+                      <<" reading the key from dict" << std::endl;
+            // Can not continue here since the next
+            // enter would result in error anyway
+            return r;
+        }
+
+        if (!strcmp(key, "pgood"))
+        {
+            r = sd_bus_message_read(m, "v", "i", &newPgood);
+            if (r < 0)
+            {
+                std::cerr << "Error: " << strerror(-r)
+                          << "reading pgood" << std::endl;
+                return r;
+            }
+            r = tmgr->config.updatePropertyVal(key, std::to_string(newPgood));
+            if (r < 0)
+            {
+                std::cerr << "Error: " << strerror(-r)
+                          << "processing pgood" << std::endl;
+                return r;
+            }
+        }
+        else
+        {
+            sd_bus_message_skip(m, "v");
+        }
+    }
+    return 0;
+}
+
+// Called by sd_event when Properties are changed in settingsd.
+// Interested in changes to 'timeMode', 'timeOwner' and 'use_dhcp_ntp'
+int TimeManager::processPropertyChange(sd_bus_message* m, void* userdata,
+                                       sd_bus_error* retError)
+{
+    auto tmgr = static_cast<TimeManager*>(userdata);
+    const char* key = nullptr;
+    const char* value = nullptr;
+    auto r = 0;
+
+    std::cout <<" User Settings have changed.." << std::endl;
+
+    // input data is "sa{sv}as" and we are just interested in a{sv}
+    r = sd_bus_message_skip(m, "s");
+    if (r < 0)
+    {
+        std::cerr << "Error: " << strerror(-r) <<
+                  "skipping interface name in data" << std::endl;
+        goto finish;
+    }
+
+    r = sd_bus_message_enter_container(m, SD_BUS_TYPE_ARRAY, "{sv}");
+    if (r < 0)
+    {
+        std::cerr << "Error: " << strerror(-r)
+                  <<"entering the dictionary" << std::endl;
+        goto finish;
+    }
+
+    while ((r = sd_bus_message_enter_container(m, SD_BUS_TYPE_DICT_ENTRY,
+                "sv")) > 0)
+    {
+        r = sd_bus_message_read(m, "s", &key);
+        if (r < 0)
+        {
+            std::cerr << "Error: " << strerror(-r)
+                      <<" reading the key from dict" << std::endl;
+            // Can not continue here since the next
+            // enter would result in error anyway
+            goto finish;
+        }
+
+        if (!strcmp(key, "time_mode"))
+        {
+            r = sd_bus_message_read(m, "v", "s", &value);
+            if (r < 0)
+            {
+                std::cerr << "Error: " << strerror(-r)
+                          << "reading timeMode" << std::endl;
+                goto finish;
+            }
+            r = tmgr->config.updatePropertyVal(key, value);
+            if (r < 0)
+            {
+                std::cerr << "Error: " << strerror(-r)
+                          << "processing timeMode" << std::endl;
+                goto finish;
+            }
+        }
+        else if (!strcmp(key, "time_owner"))
+        {
+            r = sd_bus_message_read(m, "v", "s", &value);
+            if (r < 0)
+            {
+                std::cerr << "Error: " << strerror(-r)
+                          << "reading timeOwner" << std::endl;
+                goto finish;
+            }
+            r = tmgr->config.updatePropertyVal(key, value);
+            if (r < 0)
+            {
+                std::cerr << "Error: " << strerror(-r)
+                          << "processing time_owner" << std::endl;
+                goto finish;
+            }
+            else if (tmgr->config.isSplitModeChanged())
+            {
+                // Must have been a change away from mode SPLIT
+                tmgr->resetHostOffset();
+            }
+        }
+        else if (!strcmp(key, "use_dhcp_ntp"))
+        {
+            r = sd_bus_message_read(m, "v", "s", &value);
+            if (r < 0)
+            {
+                std::cerr << "Error: " << strerror(-r)
+                          <<"reading use_dhcp_ntp" << std::endl;
+                goto finish;
+            }
+            r = tmgr->config.updatePropertyVal(key, value);
+            if (r < 0)
+            {
+                std::cerr << "Error: " << strerror(-r)
+                          << "processing dhcp_ntp" << std::endl;
+                goto finish;
+            }
+        }
+        else
+        {
+            sd_bus_message_skip(m, "v");
+        }
+    }
+finish:
+    return r;
+}
+
+// Sets up callback handlers for activities on :
+// 1) user request on SD_BUS
+// 2) Time change
+// 3) Settings change
+// 4) System state change;
+int TimeManager::registerCallbackHandlers()
+{
+    constexpr auto WATCH_SETTING_CHANGE =
+        "type='signal',interface='org.freedesktop.DBus.Properties',"
+        "path='/org/openbmc/settings/host0',member='PropertiesChanged'";
+
+    constexpr auto WATCH_PGOOD_CHANGE =
+        "type='signal',interface='org.freedesktop.DBus.Properties',"
+        "path='/org/openbmc/control/power0',member='PropertiesChanged'";
+
+    // Extract the descriptor out of sd_bus construct.
+    auto sdBusFd = sd_bus_get_fd(iv_TimeBus);
+
+    auto r = sd_event_add_io(iv_Event, &iv_EventSource, sdBusFd, EPOLLIN,
+                             processSdBusMessage, this);
+    if (r < 0)
+    {
+        std::cerr << "Error: " << strerror(-r)
+                  <<" adding sd_bus_message handler" << std::endl;
+        return r;
+    }
+
+    // Choose the MAX time that is possible to aviod mis fires.
+    itimerspec maxTime {};
+    maxTime.it_value.tv_sec = TIME_T_MAX;
+
+    auto timeFd = timerfd_create(CLOCK_REALTIME, 0);
+    if (timeFd < 0)
+    {
+        std::cerr << "Errorno: " << errno << " creating timerfd" << std::endl;
+        return -1;
+    }
+
+    r = timerfd_settime(timeFd, TFD_TIMER_ABSTIME | TFD_TIMER_CANCEL_ON_SET,
+                        &maxTime, nullptr);
+    if (r)
+    {
+        std::cerr << "Errorno: " << errno << "Setting timerfd" << std::endl;
+        return -1;
+    }
+
+    // Wake me up *only* if someone SETS the time
+    r = sd_event_add_io(iv_Event, &iv_EventSource, timeFd, EPOLLIN,
+                        processTimeChange, this);
+    if (r < 0)
+    {
+        std::cerr << "Error: " << strerror(-r)
+                  << "adding time_change handler" << std::endl;
+        return r;
+    }
+
+    // Watch for property changes in settingsd
+    r = sd_bus_add_match(iv_TimeBus, NULL, WATCH_SETTING_CHANGE,
+                         processPropertyChange, this);
+    if (r < 0)
+    {
+        std::cerr << "Error: " << strerror(-r)
+                  <<" adding property change listener" << std::endl;
+        return r;
+    }
+
+    // Watch for state change. Only reliable one to count on is
+    // state of [pgood]. value of [1] meaning host is powering on / powered
+    // on. [0] means powered off.
+    r = sd_bus_add_match(iv_TimeBus, NULL, WATCH_PGOOD_CHANGE,
+                         processPgoodChange, this);
+    if (r < 0)
+    {
+        std::cerr << "Error: " << strerror(-r)
+                  << " adding pgood change listener" << std::endl;
+    }
+    return r;
+}
+
+int TimeManager::setupTimeManager()
+{
+    auto r = sd_bus_default_system(&iv_TimeBus);
+    if (r < 0)
+    {
+        std::cerr << "Error" << strerror(-r)
+                  <<" connecting to system bus" << std::endl;
+        goto finish;
+    }
+
+    r = sd_bus_add_object_manager(iv_TimeBus, NULL, cv_ObjPath);
+    if (r < 0)
+    {
+        std::cerr << "Error" << strerror(-r)
+                  <<" adding object manager" << std::endl;
+        goto finish;
+    }
+
+    std::cout <<"Registering dbus methods" << std::endl;
+    r = sd_bus_add_object_vtable(iv_TimeBus,
+                                 NULL,
+                                 cv_ObjPath,
+                                 cv_BusName,
+                                 timeServicesVtable,
+                                 this);
+    if (r < 0)
+    {
+        std::cerr << "Error: " << strerror(-r)
+                  <<" adding timer services vtable" << std::endl;
+        goto finish;
+    }
+
+    // create a sd_event object and add handlers
+    r = sd_event_default(&iv_Event);
+    if (r < 0)
+    {
+        std::cerr << "Error: " << strerror(-r)
+                  <<"creating an sd_event" << std::endl;
+        goto finish;
+    }
+
+    // Handlers called by sd_event when an activity
+    // is observed in event loop
+    r = registerCallbackHandlers();
+    if (r < 0)
+    {
+        std::cerr << "Error setting up callback handlers" << std::endl;
+        goto finish;
+    }
+
+    // Need to do this here since TimeConfig may update the necessary owners
+    r = config.processInitialSettings(iv_TimeBus);
+    if (r < 0)
+    {
+        std::cerr << "Error setting up configuration params" << std::endl;
+        goto finish;
+    }
+
+    // Read saved values from previous run
+    r = readPersistentData();
+    if (r < 0)
+    {
+        std::cerr << "Error reading persistent data" << std::endl;
+        goto finish;
+    }
+
+    // Claim the bus
+    r = sd_bus_request_name(iv_TimeBus, cv_BusName, 0);
+    if (r < 0)
+    {
+        std::cerr << "Error: " << strerror(-r)
+                  << "acquiring service name" << std::endl;
+        goto finish;
+    }
+finish:
+    if (r < 0)
+    {
+        iv_EventSource = sd_event_source_unref(iv_EventSource);
+        iv_Event = sd_event_unref(iv_Event);
+    }
+    return r;
+}
+
+int TimeManager::readPersistentData()
+{
+    using namespace std::chrono;
+
+    // Get current host_offset
+    // When we reach here, TimeConfig would have been populated and would have
+    // applied the owner to SPLIT *if* the system allowed it. So check if we
+    // moved away from SPLIT and if so, make offset:0
+    if (config.isSplitModeChanged())
+    {
+        iv_HostOffset = microseconds(0);
+        auto r = config.writeData<decltype(iv_HostOffset.count())>
+                 (cv_HostOffsetFile,
+                  iv_HostOffset.count());
+        if (r < 0)
+        {
+            std::cerr <<" Error saving offset to file" << std::endl;
+            return r;
+        }
+    }
+    else
+    {
+        auto hostTimeOffset = config.readData<long long int>(cv_HostOffsetFile);
+        iv_HostOffset = microseconds(hostTimeOffset);
+        std::cout <<"Last known host_offset:" << hostTimeOffset << std::endl;
+    }
+
+    //How long was the FSP up prior to 'this' start
+    iv_UptimeUsec = duration_cast<microseconds>
+                    (system_clock::now().time_since_epoch() -
+                     steady_clock::now().time_since_epoch());
+    if (iv_UptimeUsec.count() < 0)
+    {
+        std::cerr <<"Error reading uptime" << std::endl;
+        return -1;
+    }
+    std::cout <<"Initial Uptime Usec: "
+              << iv_UptimeUsec.count() << std::endl;
+    return 0;
+}
+
+// Forever loop
+int TimeManager::waitForClientRequest()
+{
+    return sd_event_loop(iv_Event);
+}
+
+int main(int argc, char* argv[])
+{
+    auto tmgr = std::make_unique<TimeManager>();
+
+    // Wait for the work
+    auto r = tmgr->waitForClientRequest();
+
+    return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
+}
diff --git a/time-manager.hpp b/time-manager.hpp
new file mode 100644
index 0000000..5e32a72
--- /dev/null
+++ b/time-manager.hpp
@@ -0,0 +1,303 @@
+#include <systemd/sd-bus.h>
+#include <fstream>
+#include <string>
+#include <chrono>
+#include "time-config.hpp"
+
+/** @class Time
+ *  @brief Base class catering to common data needed by implementations
+ */
+class Time
+{
+public:
+    /** @brief Takes time in microseconds and uses systemd/timedated
+     *         to set the system time
+     *
+     *  @param[in] timeOfDayUsec - Time value in microseconds
+     *  @return                  - Status of time set operation
+     */
+    int setTimeOfDay(const std::chrono::microseconds& timeOfDayUsec);
+
+    /** @brief Reads BMC time
+     *
+     *  @param[in]  - None
+     *  @return     - time read in microseconds
+     */
+    std::chrono::microseconds getBaseTime();
+
+    /** @brief Converts microseconds to human readable time value
+     *
+     *  @param[in] timeInUsec  - Time value in microseconds
+     *  @return                - Time converted to human readable format
+     */
+    std::string convertToStr(const std::chrono::microseconds& timeInUsec);
+
+    /** @brief Reference to config information due to need of policy data */
+    const TimeConfig& config;
+
+    /** Needed to access configuration variables */
+    Time(const TimeConfig&);
+
+private:
+    Time();
+};
+
+/** @class BmcTime
+ *  @brief Provides time Set and time Get operations for BMC target
+ */
+class BmcTime: public Time
+{
+public:
+    /** @brief Called when the time is to be read on BMC
+     *
+     *  @param[in] m          - sd_bus message.
+     *  @param[out] retError  - Error reporting structure
+     *  @return               - On no error, time read which is specified in
+     *                          microseonds and also in human readable format.
+     *
+     *                        - On error, retError populated
+     */
+    int getTime(sd_bus_message* m, sd_bus_error* retError);
+
+    /** @brief Called when the time is to be set on BMC
+     *
+     *  @param[in] m          - sd_bus message encapsulating time string
+     *  @param[out] retError  - Error reporting structure
+     *  @return               - On no error, 0, -1 otherwise or retError thrown
+     */
+    int setTime(sd_bus_message* m, sd_bus_error* retError);
+
+    /** @brief constructor */
+    BmcTime(const TimeConfig&);
+
+private:
+    BmcTime();
+};
+
+/** @class HostTime
+ *  @brief Provides time Set and time Get operations for BMC target
+ */
+class HostTime: public Time
+{
+public:
+    /** @brief Called when IPMI_GET_SEL_TIME is called
+     *
+     *  @param[in] m          - sd_bus message.
+     *  @param[out] retError  - Error reporting structure
+     *  @return               - On no error, time read which is specified in
+     *                          microseonds and also in human readable format.
+     *
+     *                        - On error, retError populated
+     */
+    int getTime(sd_bus_message*, sd_bus_error*);
+
+    /** @brief Called when the IPMI_SET_SEL_TIME is called
+     *
+     *  @param[in] m          - sd_bus message encapsulating time in seconds
+     *  @param[out] retError  - Error reporting structure
+     *  @return               - On no error, 0, -1 otherwise or retError thrown
+     */
+    int setTime(sd_bus_message*, sd_bus_error*);
+
+    /** @brief constructor */
+    HostTime(const TimeConfig&, const std::chrono::microseconds&);
+
+    /** @brief When the owner is SPLIT, the delta between HOST's time and BMC's
+     *         time needs to be saved and this  function returns current delta.
+     *
+     *  @param[in] - None
+     *  @return    - offset in microseconds
+     */
+    inline std::chrono::microseconds getChangedOffset() const
+    {
+        return changedOffset;
+    }
+
+    /** @brief Reference to host's offset in case of SPLIT owner */
+    const std::chrono::microseconds& iv_Offset;
+
+private:
+    HostTime();
+
+    /** @brief The delta offset of Host and BMC time */
+    std::chrono::microseconds changedOffset;
+};
+
+/** @class TimeManager
+ *  @brief Caters to client requests with Set and Get time and configuration
+ *         changes
+ */
+class TimeManager
+{
+public:
+    // Do not have a usecase of copying this object so disable
+    TimeManager();
+    ~TimeManager() = default;
+    TimeManager(const TimeManager&) = delete;
+    TimeManager& operator=(const TimeManager&) = delete;
+    TimeManager(TimeManager&&) = delete;
+    TimeManager& operator=(TimeManager&&) = delete;
+
+    // Maintains *all* the config that is needed for TimeManager.
+    TimeConfig config;
+
+    /** @brief Callback handlers invoked by dbus on GetTime client requests
+     *
+     *  @param[in] m         - sd_bus message encapsulating the time target
+     *  @param[in] userdata  - context that is filled while registering this
+     *  @param[out] retError - Error reporting mechanism
+     *
+     *  @return              - On no error, time in microseconds and human
+     *                         readable string. retError otherwise.
+     */
+    int getTime(sd_bus_message* m, void* userdata, sd_bus_error* retError);
+
+    /** @brief Callback handlers invoked by dbus on SetTime client requests
+     *
+     *  @param[in] m         - sd_bus message encapsulating the time target and
+     *                         time value either in string or in seconds.
+     *  @param[in] userdata  - client context that is filled while registering
+     *  @param[out] retError - Error reporting mechanism
+     *
+     *  @return              - On no error, time in microseconds and human
+     *                         readable string. retError otherwise.
+     */
+    int setTime(sd_bus_message* m, void* userdata, sd_bus_error* retError);
+
+    /** @brief sd_event callback handlers on the requests coming in dbus
+     *         These are actually GetTime and SetTime requests
+     *
+     * @param[in] es       - Event Structure
+     * @param[in] fd       - file descriptor that had 'read' activity
+     * @param[in] revents  - generic linux style return event
+     * @param[in] userdata - Client context filled while registering
+     *
+     * @return             - 0 for success, failure otherwise.
+     */
+    static int processSdBusMessage(sd_event_source* es, int fd,
+                                   uint32_t revents, void* userdata);
+
+    /** @brief sd_event callback handler called whenever there is a
+     *         time change event indicated by timerfd expiring. This happens
+     *         whenever the time is set on BMC by any source.
+     *
+     * @param[in] es       - Event Structure
+     * @param[in] fd       - file descriptor that had 'read' activity
+     * @param[in] revents  - generic linux style return event
+     * @param[in] userdata - Client context filled while registering
+     *
+     * @return             - 0 for success, failure otherwise.
+     */
+    static int processTimeChange(sd_event_source* es, int fd,
+                                 uint32_t revents, void* userdata);
+
+    /** @brief sd_event callback handler called whenever a settings
+     *         property is changed.
+     *         This gets called into whenever "time_mode", "time_owner",
+     *         "use_dhcp_ntp" properties are changed
+     *
+     * @param[in] es       - Event Structure
+     * @param[in] fd       - file descriptor that had 'read' activity
+     * @param[in] revents  - generic linux style return event
+     * @param[in] userdata - Client context filled while registering
+     *
+     * @return             - 0 for success, failure otherwise.
+     */
+    static int processPropertyChange(sd_bus_message*,
+                                     void*,sd_bus_error*);
+
+    /** @brief sd_event callback handler called whenever Pgood property is
+     *         changed
+     *
+     * @param[in] es       - Event Structure
+     * @param[in] fd       - file descriptor that had 'read' activity
+     * @param[in] revents  - generic linux style return event
+     * @param[in] userdata - Client context filled while registering
+     *
+     * @return             - 0 for success, failure otherwise.
+     */
+    static int processPgoodChange(sd_bus_message*,
+                                  void*,sd_bus_error*);
+
+    /** @brief registers callsback handlers for sd_event loop
+     *
+     * @param[in] - None
+     * @return    - 0 if everything goes well, -1 otherwise
+     */
+    int registerCallbackHandlers();
+
+    /** @brief Makes the Delta between Host and BMC time as 'ZERO'. This
+     *         essentially only means that time owner was SPLIT before
+     *         and now changed to something else.
+     *
+     *  @param[in]  - None
+     *  @return     - 0 if everything goes well, -1 otherwise.
+     */
+    int resetHostOffset();
+
+    /** @brief Reads what was the last delta offset stored in file
+     *
+     *  @param[in] - None
+     *  @return    - 0 if everything goes well, -1 otherwise.
+     */
+    int readPersistentData();
+
+    /** @brief waits on sd_events loop for client requests
+     *
+     *  @param[in]  - None
+     *  @return     - 0 if everything goes well, -1 otherwise.
+     */
+    int waitForClientRequest();
+
+    inline auto getHostOffset() const
+    {
+        return iv_HostOffset;
+    }
+
+    inline auto updateHostOffset(const std::chrono::microseconds& newOffset)
+    {
+        iv_HostOffset = newOffset;
+    }
+
+    inline auto getUptimeUsec() const
+    {
+        return iv_UptimeUsec;
+    }
+
+    inline auto updateUptimeUsec(const std::chrono::microseconds& newUpTime)
+    {
+        iv_UptimeUsec = newUpTime;
+    }
+
+    inline sd_bus* getTimeBus() const
+    {
+        return iv_TimeBus;
+    }
+
+private:
+    // What was the last known host offset.
+    std::chrono::microseconds iv_HostOffset;
+
+    // How long was the BMC up for prior to this boot
+    std::chrono::microseconds iv_UptimeUsec;
+
+    // Used for registering sd_bus callback handlers.
+    sd_event_source* iv_EventSource;
+    sd_event* iv_Event;
+    sd_bus* iv_TimeBus;
+
+    // Dbus communication enablers.
+    static constexpr auto cv_BusName = "org.openbmc.TimeManager";
+    static constexpr auto cv_ObjPath  =  "/org/openbmc/TimeManager";
+    static constexpr auto cv_IntfName =  "org.openbmc.TimeManager";
+
+    // Store the offset in File System. Read back when TimeManager starts.
+    static constexpr auto cv_HostOffsetFile = "/var/lib/obmc/saved_host_offset";
+
+    /** @brief Sets up internal data structures and callback handler at startup
+     *
+     * @param[in] - None
+     * @return    - 0 if everything goes well, -1 otherwise
+     */
+    int setupTimeManager(void);
+};
diff --git a/time-register.c b/time-register.c
new file mode 100644
index 0000000..cdc1dd2
--- /dev/null
+++ b/time-register.c
@@ -0,0 +1,25 @@
+#include <systemd/sd-bus.h>
+#include "time-register.hpp"
+#include <sys/timerfd.h>
+#include <errno.h>
+#include <stdio.h>
+
+/* Function pointer of APIs exposed via Dbus */
+//const sd_bus_vtable timeServicesVtable[] =
+const sd_bus_vtable timeServicesVtable [] =
+{
+    SD_BUS_VTABLE_START(0),
+    SD_BUS_PROPERTY("curr_time_mode", "s", getCurrTimeModeProperty, 0,
+    SD_BUS_VTABLE_PROPERTY_CONST),
+    SD_BUS_PROPERTY("curr_time_owner", "s", getCurrTimeOwnerProperty, 0,
+    SD_BUS_VTABLE_PROPERTY_CONST),
+    SD_BUS_PROPERTY("requested_time_mode", "s", getReqTimeModeProperty, 0,
+    SD_BUS_VTABLE_PROPERTY_CONST),
+    SD_BUS_PROPERTY("requested_time_owner", "s", getReqTimeOwnerProperty, 0,
+    SD_BUS_VTABLE_PROPERTY_CONST),
+    SD_BUS_METHOD("GetTime", "s", "sx", &GetTime,
+    SD_BUS_VTABLE_UNPRIVILEGED),
+    SD_BUS_METHOD("SetTime", "ss", "i", &SetTime,
+    SD_BUS_VTABLE_UNPRIVILEGED),
+    SD_BUS_VTABLE_END,
+};
diff --git a/time-register.hpp b/time-register.hpp
new file mode 100644
index 0000000..bf776d3
--- /dev/null
+++ b/time-register.hpp
@@ -0,0 +1,17 @@
+#include <systemd/sd-bus.h>
+#ifdef __cplusplus
+extern "C" {
+#endif
+int getCurrTimeModeProperty(sd_bus*, const char*, const char*, const char*,
+                            sd_bus_message*, void*, sd_bus_error*);
+int getCurrTimeOwnerProperty(sd_bus*, const char*, const char*, const char*,
+                             sd_bus_message*, void*, sd_bus_error*);
+int getReqTimeModeProperty(sd_bus*, const char*, const char*, const char*,
+                           sd_bus_message*, void*, sd_bus_error*);
+int getReqTimeOwnerProperty(sd_bus*, const char*, const char*, const char*,
+                            sd_bus_message*, void*, sd_bus_error*);
+int GetTime(sd_bus_message*, void*, sd_bus_error*);
+int SetTime(sd_bus_message*, void*, sd_bus_error*);
+#ifdef __cplusplus
+};
+#endif