system76-edk2/SecurityPkg/Library/TpmCommLib/TisPc.c

/** @file
  Basic TIS (TPM Interface Specification) functions.

Copyright (c) 2005 - 2012, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials 
are licensed and made available under the terms and conditions of the BSD License 
which accompanies this distribution.  The full text of the license may be found at 
http://opensource.org/licenses/bsd-license.php

THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, 
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.

**/

#include "CommonHeader.h"

/**
  Check whether TPM chip exist.

  @param[in] TisReg  Pointer to TIS register.

  @retval    TRUE    TPM chip exists.
  @retval    FALSE   TPM chip is not found.
**/
BOOLEAN
TisPcPresenceCheck (
  IN      TIS_PC_REGISTERS_PTR      TisReg
  )
{
  UINT8                             RegRead;
  
  RegRead = MmioRead8 ((UINTN)&TisReg->Access);
  return (BOOLEAN)(RegRead != (UINT8)-1);
}

/**
  Check whether the value of a TPM chip register satisfies the input BIT setting.

  @param[in]  Register     Address port of register to be checked.
  @param[in]  BitSet       Check these data bits are set.
  @param[in]  BitClear     Check these data bits are clear.
  @param[in]  TimeOut      The max wait time (unit MicroSecond) when checking register.

  @retval     EFI_SUCCESS  The register satisfies the check bit.
  @retval     EFI_TIMEOUT  The register can't run into the expected status in time.
**/
EFI_STATUS
EFIAPI
TisPcWaitRegisterBits (
  IN      UINT8                     *Register,
  IN      UINT8                     BitSet,
  IN      UINT8                     BitClear,
  IN      UINT32                    TimeOut
  )
{
  UINT8                             RegRead;
  UINT32                            WaitTime;

  for (WaitTime = 0; WaitTime < TimeOut; WaitTime += 30){
    RegRead = MmioRead8 ((UINTN)Register);
    if ((RegRead & BitSet) == BitSet && (RegRead & BitClear) == 0)
      return EFI_SUCCESS;
    MicroSecondDelay (30);
  }
  return EFI_TIMEOUT;
}

/**
  Get BurstCount by reading the burstCount field of a TIS regiger 
  in the time of default TIS_TIMEOUT_D.

  @param[in]  TisReg                Pointer to TIS register.
  @param[out] BurstCount            Pointer to a buffer to store the got BurstConut.

  @retval     EFI_SUCCESS           Get BurstCount.
  @retval     EFI_INVALID_PARAMETER TisReg is NULL or BurstCount is NULL.
  @retval     EFI_TIMEOUT           BurstCount can't be got in time.
**/
EFI_STATUS
EFIAPI
TisPcReadBurstCount (
  IN      TIS_PC_REGISTERS_PTR      TisReg,
     OUT  UINT16                    *BurstCount
  )
{
  UINT32                            WaitTime;
  UINT8                             DataByte0;
  UINT8                             DataByte1;

  if (BurstCount == NULL || TisReg == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  WaitTime = 0;
  do {
    //
    // TIS_PC_REGISTERS_PTR->burstCount is UINT16, but it is not 2bytes aligned,
    // so it needs to use MmioRead8 to read two times
    //
    DataByte0   = MmioRead8 ((UINTN)&TisReg->BurstCount);
    DataByte1   = MmioRead8 ((UINTN)&TisReg->BurstCount + 1);
    *BurstCount = (UINT16)((DataByte1 << 8) + DataByte0);
    if (*BurstCount != 0) {
      return EFI_SUCCESS;
    }
    MicroSecondDelay (30);
    WaitTime += 30;
  } while (WaitTime < TIS_TIMEOUT_D);

  return EFI_TIMEOUT;
}

/**
  Set TPM chip to ready state by sending ready command TIS_PC_STS_READY 
  to Status Register in time.

  @param[in] TisReg                Pointer to TIS register.

  @retval    EFI_SUCCESS           TPM chip enters into ready state.
  @retval    EFI_INVALID_PARAMETER TisReg is NULL.
  @retval    EFI_TIMEOUT           TPM chip can't be set to ready state in time.
**/
EFI_STATUS
EFIAPI
TisPcPrepareCommand (
  IN      TIS_PC_REGISTERS_PTR      TisReg
  )
{
  EFI_STATUS                        Status;

  if (TisReg == NULL) {
    return EFI_INVALID_PARAMETER;
  }

  MmioWrite8((UINTN)&TisReg->Status, TIS_PC_STS_READY);
  Status = TisPcWaitRegisterBits (
             &TisReg->Status,
             TIS_PC_STS_READY,
             0,
             TIS_TIMEOUT_B
             );
  return Status;
}

/**
  Get the control of TPM chip by sending requestUse command TIS_PC_ACC_RQUUSE 
  to ACCESS Register in the time of default TIS_TIMEOUT_A.

  @param[in] TisReg                Pointer to TIS register.

  @retval    EFI_SUCCESS           Get the control of TPM chip.
  @retval    EFI_INVALID_PARAMETER TisReg is NULL.
  @retval    EFI_NOT_FOUND         TPM chip doesn't exit.
  @retval    EFI_TIMEOUT           Can't get the TPM control in time.
**/
EFI_STATUS
EFIAPI
TisPcRequestUseTpm (
  IN      TIS_PC_REGISTERS_PTR      TisReg
  )
{
  EFI_STATUS                        Status;
  
  if (TisReg == NULL) {
    return EFI_INVALID_PARAMETER;
  }
  
  if (!TisPcPresenceCheck (TisReg)) {
    return EFI_NOT_FOUND;
  }

  MmioWrite8((UINTN)&TisReg->Access, TIS_PC_ACC_RQUUSE);
  //
  // No locality set before, ACCESS_X.activeLocality MUST be valid within TIMEOUT_A
  //
  Status = TisPcWaitRegisterBits (
             &TisReg->Access,
             (UINT8)(TIS_PC_ACC_ACTIVE |TIS_PC_VALID),
             0,
             TIS_TIMEOUT_A
             );
  return Status;
}