Vlv2TbltDevicePkg/Library/StallSmmLib/StallSmm.c

   1 /*++
   2
   3 Copyright (c)  1999  - 2014, Intel Corporation. All rights reserved
   4
   5   This program and the accompanying materials are licensed and made available under
   6   the terms and conditions of the BSD License that accompanies this distribution.
   7   The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php.
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13
  14
  15 Module Name:
  16
  17   SmmIo.c
  18
  19 Abstract:
  20
  21   SMM I/O access utility implementation file, for Ia32
  22
  23 --*/
  24
  25 //
  26 // Include files
  27 //
  28 #include "Library/StallSmmLib.h"
  29 #include "Pi/PiSmmCis.h"
  30 #include "PiDxe.h"
  31 #include <Library/IoLib.h>
  32 #include <Library/PcdLib.h>
  33 #include "PchAccess.h"
  34
  35 /**
  36   Delay for at least the request number of microseconds.
  37   Timer used is ACPI time counter, which has 1us granularity.
  38
  39   @param Microseconds  Number of microseconds to delay.
  40
  41   @retval None
  42
  43 **/
  44 VOID
  45 SmmStall (
  46   IN  UINTN   Microseconds
  47   )
  48 {
  49   UINTN   Ticks;
  50   UINTN   Counts;
  51   UINTN   CurrentTick;
  52   UINTN   OriginalTick;
  53   UINTN   RemainingTick;
  54   UINT16  AcpiBaseAddr;
  55
  56   if (Microseconds == 0) {
  57     return;
  58   }
  59
  60   AcpiBaseAddr = PchLpcPciCfg16 (R_PCH_LPC_ACPI_BASE) & B_PCH_LPC_ACPI_BASE_BAR;
  61
  62   OriginalTick = IoRead32 (AcpiBaseAddr + R_PCH_ACPI_PM1_TMR);
  63   CurrentTick = OriginalTick;
  64
  65   //
  66   // The timer frequency is 3.579545 MHz, so 1 ms corresponds 3.58 clocks
  67   //
  68   Ticks = Microseconds * 358 / 100 + OriginalTick + 1;
  69
  70   //
  71   // The loops needed by timer overflow
  72   //
  73   Counts = Ticks / V_PCH_ACPI_PM1_TMR_MAX_VAL;
  74
  75   //
  76   // Remaining clocks within one loop
  77   //
  78   RemainingTick = Ticks % V_PCH_ACPI_PM1_TMR_MAX_VAL;
  79
  80   //
  81   // not intend to use TMROF_STS bit of register PM1_STS, because this adds extra
  82   // one I/O operation, and maybe generate SMI
  83   //
  84   while ((Counts != 0) || (RemainingTick > CurrentTick)) {
  85     CurrentTick = IoRead32 (AcpiBaseAddr + R_PCH_ACPI_PM1_TMR);
  86     //
  87     // Check if timer overflow
  88     //
  89     if (CurrentTick < OriginalTick) {
  90       Counts--;
  91     }
  92     OriginalTick = CurrentTick;
  93   }
  94 }