Vlv2TbltDevicePkg/Library/StallSmmLib/StallSmm.c

   1 /*++
   2
   3 Copyright (c)  1999  - 2014, Intel Corporation. All rights reserved
   4
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7
   8
   9
  10 Module Name:
  11
  12   SmmIo.c
  13
  14 Abstract:
  15
  16   SMM I/O access utility implementation file, for Ia32
  17
  18 --*/
  19
  20 //
  21 // Include files
  22 //
  23 #include "Library/StallSmmLib.h"
  24 #include "Pi/PiSmmCis.h"
  25 #include "PiDxe.h"
  26 #include <Library/IoLib.h>
  27 #include <Library/PcdLib.h>
  28 #include "PchAccess.h"
  29
  30 /**
  31   Delay for at least the request number of microseconds.
  32   Timer used is ACPI time counter, which has 1us granularity.
  33
  34   @param Microseconds  Number of microseconds to delay.
  35
  36   @retval None
  37
  38 **/
  39 VOID
  40 SmmStall (
  41   IN  UINTN   Microseconds
  42   )
  43 {
  44   UINTN   Ticks;
  45   UINTN   Counts;
  46   UINTN   CurrentTick;
  47   UINTN   OriginalTick;
  48   UINTN   RemainingTick;
  49   UINT16  AcpiBaseAddr;
  50
  51   if (Microseconds == 0) {
  52     return;
  53   }
  54
  55   AcpiBaseAddr = PchLpcPciCfg16 (R_PCH_LPC_ACPI_BASE) & B_PCH_LPC_ACPI_BASE_BAR;
  56
  57   OriginalTick = IoRead32 (AcpiBaseAddr + R_PCH_ACPI_PM1_TMR);
  58   CurrentTick = OriginalTick;
  59
  60   //
  61   // The timer frequency is 3.579545 MHz, so 1 ms corresponds 3.58 clocks
  62   //
  63   Ticks = Microseconds * 358 / 100 + OriginalTick + 1;
  64
  65   //
  66   // The loops needed by timer overflow
  67   //
  68   Counts = Ticks / V_PCH_ACPI_PM1_TMR_MAX_VAL;
  69
  70   //
  71   // Remaining clocks within one loop
  72   //
  73   RemainingTick = Ticks % V_PCH_ACPI_PM1_TMR_MAX_VAL;
  74
  75   //
  76   // not intend to use TMROF_STS bit of register PM1_STS, because this adds extra
  77   // one I/O operation, and maybe generate SMI
  78   //
  79   while ((Counts != 0) || (RemainingTick > CurrentTick)) {
  80     CurrentTick = IoRead32 (AcpiBaseAddr + R_PCH_ACPI_PM1_TMR);
  81     //
  82     // Check if timer overflow
  83     //
  84     if (CurrentTick < OriginalTick) {
  85       Counts--;
  86     }
  87     OriginalTick = CurrentTick;
  88   }
  89 }