text: /* Microsoft Reference Implementation for TPM 2.0
   *
   *  The copyright in this software is being made available under the BSD License,
   *  included below. This software may be subject to other third party and
   *  contributor rights, including patent rights, and no such rights are granted
   *  under this license.
   *
   *  Copyright (c) Microsoft Corporation
   *
   *  All rights reserved.
   *
   *  BSD License
   *
   *  Redistribution and use in source and binary forms, with or without modification,
   *  are permitted provided that the following conditions are met:
   *
   *  Redistributions of source code must retain the above copyright notice, this list
   *  of conditions and the following disclaimer.
   *
   *  Redistributions in binary form must reproduce the above copyright notice, this
   *  list of conditions and the following disclaimer in the documentation and/or
   *  other materials provided with the distribution.
   *
   *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ""AS IS""
   *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   *  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
   *  ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
   *  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   *  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
   *  ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
   *  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  //** Introduction
  // This file contains the functions relating to the TPM's time functions including
  // the interface to the implementation-specific time functions.
  //
  //** Includes
  #include "Tpm.h"
  #include "PlatformClock.h"
  
  //** Functions
  
  //*** TimePowerOn()
  // This function initialize time info at _TPM_Init().
  //
  // This function is called at _TPM_Init() so that the TPM time can start counting
  // as soon as the TPM comes out of reset and doesn't have to wait until
  // TPM2_Startup() in order to begin the new time epoch. This could be significant
  // for systems that could get powered up but not run any TPM commands for some
  // period of time.
  //
  void
  TimePowerOn(
      void
      )
  {
      g_time = _plat__TimerRead();
  }
  
  //*** TimeNewEpoch()
  // This function does the processing to generate a new time epoch nonce and
  // set NV for update. This function is only called when NV is known to be available
  // and the clock is running. The epoch is updated to persistent data.
  static void
  TimeNewEpoch(
      void
      )
  {
  #if CLOCK_STOPS
      CryptRandomGenerate(sizeof(CLOCK_NONCE), (BYTE *)&g_timeEpoch);
  #else
      // if the epoch is kept in NV, update it.
      gp.timeEpoch++;
      NV_SYNC_PERSISTENT(timeEpoch);
  #endif
      // Clean out any lingering state
      _plat__TimerWasStopped();
  }
  
  //*** TimeStartup()
  // This function updates the resetCount and restartCount components of
  // TPMS_CLOCK_INFO structure at TPM2_Startup().
  //
  // This function will deal with the deferred creation of a new epoch.
  // TimeUpdateToCurrent() will not start a new epoch even if one is due when
  // TPM_Startup() has not been run. This is because the state of NV is not known
  // until startup completes. When Startup is done, then it will create the epoch
  // nonce to complete the initializations by calling this function.
  BOOL
  TimeStartup(
      STARTUP_TYPE     type           // IN: start up type
      )
  {
      NOT_REFERENCED(type);
      // If the previous cycle is orderly shut down, the value of the safe bit
      // the same as previously saved.  Otherwise, it is not safe.
      if(!NV_IS_ORDERLY)
          go.clockSafe = NO;
      return TRUE;
  }
  
  //*** TimeClockUpdate()
  // This function updates go.clock. If 'newTime' requires an update of NV, then
  // NV is checked for availability. If it is not available or is rate limiting, then
  // go.clock is not updated and the function returns an error. If 'newTime' would
  // not cause an NV write, then go.clock is updated. If an NV write occurs, then
  // go.safe is SET.
  void
  TimeClockUpdate(
      UINT64           newTime    // IN: New time value in mS.
      )
  {
  #define CLOCK_UPDATE_MASK  ((1ULL << NV_CLOCK_UPDATE_INTERVAL)- 1)
  
      // Check to see if the update will cause a need for an nvClock update
      if((newTime | CLOCK_UPDATE_MASK) > (go.clock | CLOCK_UPDATE_MASK))
      {
          pAssert(g_NvStatus == TPM_RC_SUCCESS);
  
          // Going to update the NV time state so SET the safe flag
          go.clockSafe = YES;
  
          // update the time
          go.clock = newTime;
  
          NvWrite(NV_ORDERLY_DATA, sizeof(go), &go);
      }
      else
          // No NV update needed so just update
          go.clock = newTime;
  
  }
  
  //*** TimeUpdate()
  // This function is used to update the time and clock values. If the TPM
  // has run TPM2_Startup(), this function is called at the start of each command.
  // If the TPM has not run TPM2_Startup(), this is called from TPM2_Startup() to
  // get the clock values initialized. It is not called on command entry because, in
  // this implementation, the go structure is not read from NV until TPM2_Startup().
  // The reason for this is that the initialization code (_TPM_Init()) may run before
  // NV is accessible.
  void
  TimeUpdate(
      void
      )
  {
      UINT64          elapsed;
  //
      // Make sure that we consume the current _plat__TimerWasStopped() state.
     if(_plat__TimerWasStopped())
      {
          TimeNewEpoch();
      }
      // Get the difference between this call and the last time we updated the tick
      // timer.
      elapsed = _plat__TimerRead() - g_time;
      // Don't read +
      g_time += elapsed;
  
      // Don't need to check the result because it has to be success because have
      // already checked that NV is available.
      TimeClockUpdate(go.clock + elapsed);
  
      // Call self healing logic for dictionary attack parameters
      DASelfHeal();
  }
  
  //*** TimeUpdateToCurrent()
  // This function updates the 'Time' and 'Clock' in the global
  // TPMS_TIME_INFO structure.
  //
  // In this implementation, 'Time' and 'Clock' are updated at the beginning
  // of each command and the values are unchanged for the duration of the
  // command.
  //
  // Because 'Clock' updates may require a write to NV memory, 'Time' and 'Clock'
  // are not allowed to advance if NV is not available. When clock is not advancing,
  // any function that uses 'Clock' will fail and return TPM_RC_NV_UNAVAILABLE or
  // TPM_RC_NV_RATE.
  //
  // This implementation does not do rate limiting. If the implementation does do
  // rate limiting, then the 'Clock' update should not be inhibited even when doing
  // rate limiting.
  void
  TimeUpdateToCurrent(
      void
  )
  {
      // Can't update time during the dark interval or when rate limiting so don't
      // make any modifications to the internal clock value. Also, defer any clock
      // processing until TPM has run TPM2_Startup()
      if(!NV_IS_AVAILABLE || !TPMIsStarted())
          return;
  
      TimeUpdate();
  }
  
  
  //*** TimeSetAdjustRate()
  // This function is used to perform rate adjustment on 'Time' and 'Clock'.
  void
  TimeSetAdjustRate(
      TPM_CLOCK_ADJUST     adjust         // IN: adjust constant
      )
  {
      switch(adjust)
      {
          case TPM_CLOCK_COARSE_SLOWER:
              _plat__ClockAdjustRate(CLOCK_ADJUST_COARSE);
              break;
          case TPM_CLOCK_COARSE_FASTER:
              _plat__ClockAdjustRate(-CLOCK_ADJUST_COARSE);
              break;
          case TPM_CLOCK_MEDIUM_SLOWER:
              _plat__ClockAdjustRate(CLOCK_ADJUST_MEDIUM);
              break;
          case TPM_CLOCK_MEDIUM_FASTER:
              _plat__ClockAdjustRate(-CLOCK_ADJUST_MEDIUM);
              break;
          case TPM_CLOCK_FINE_SLOWER:
              _plat__ClockAdjustRate(CLOCK_ADJUST_FINE);
              break;
          case TPM_CLOCK_FINE_FASTER:
              _plat__ClockAdjustRate(-CLOCK_ADJUST_FINE);
              break;
          case TPM_CLOCK_NO_CHANGE:
              break;
          default:
              FAIL(FATAL_ERROR_INTERNAL);
              break;
      }
  
      return;
  }
  
  //*** TimeGetMarshaled()
  // This function is used to access TPMS_TIME_INFO in canonical form.
  // The function collects the time information and marshals it into 'dataBuffer'
  // and returns the marshaled size
  UINT16
  TimeGetMarshaled(
      TIME_INFO       *dataBuffer     // OUT: result buffer
      )
  {
      TPMS_TIME_INFO      timeInfo;
  
      // Fill TPMS_TIME_INFO structure
      timeInfo.time = g_time;
      TimeFillInfo(&timeInfo.clockInfo);
  
      // Marshal TPMS_TIME_INFO to canonical form
      return TPMS_TIME_INFO_Marshal(&timeInfo, (BYTE **)&dataBuffer, NULL);
  }
  
  //*** TimeFillInfo
  // This function gathers information to fill in a TPMS_CLOCK_INFO structure.
  void
  TimeFillInfo(
      TPMS_CLOCK_INFO     *clockInfo
      )
  {
      clockInfo->clock = go.clock;
      clockInfo->resetCount = gp.resetCount;
      clockInfo->restartCount = gr.restartCount;
  
      // If NV is not available, clock stopped advancing and the value reported is
      // not "safe".
      if(NV_IS_AVAILABLE)
          clockInfo->safe = go.clockSafe;
      else
          clockInfo->safe = NO;
  
      return;
  }