Vlv2TbltDevicePkg/PlatformInitPei/Stall.c

   1 /** @file
   2
   3   Copyright (c) 2004  - 2014, Intel Corporation. All rights reserved.<BR>
   4
   5   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7
   8
   9
  10
  11 Module Name:
  12
  13   Stall.c
  14
  15 Abstract:
  16
  17   Produce Stall Ppi.
  18
  19 --*/
  20
  21
  22 #include "PlatformEarlyInit.h"
  23
  24
  25 /**
  26
  27   Waits for at least the given number of microseconds.
  28
  29   @param PeiServices     General purpose services available to every PEIM.
  30   @param This            PPI instance structure.
  31   @param Microseconds    Desired length of time to wait.
  32
  33   @retval EFI_SUCCESS    If the desired amount of time was passed.
  34
  35 */
  36 EFI_STATUS
  37 EFIAPI
  38 Stall (
  39   IN CONST EFI_PEI_SERVICES   **PeiServices,
  40   IN CONST EFI_PEI_STALL_PPI      *This,
  41   IN UINTN              Microseconds
  42   )
  43 {
  44   UINTN   Ticks;
  45   UINTN   Counts;
  46   UINT32  CurrentTick;
  47   UINT32  OriginalTick;
  48   UINT32  RemainingTick;
  49
  50   if (Microseconds == 0) {
  51     return EFI_SUCCESS;
  52   }
  53
  54   OriginalTick = IoRead32 (ACPI_BASE_ADDRESS + R_PCH_ACPI_PM1_TMR);
  55   OriginalTick &= (V_PCH_ACPI_PM1_TMR_MAX_VAL - 1);
  56   CurrentTick = OriginalTick;
  57
  58   //
  59   // The timer frequency is 3.579545MHz, so 1 ms corresponds to 3.58 clocks
  60   //
  61   Ticks = Microseconds * 358 / 100 + OriginalTick + 1;
  62
  63   //
  64   // The loops needed for timer overflow
  65   //
  66   Counts = (UINTN)RShiftU64((UINT64)Ticks, 24);
  67
  68   //
  69   // Remaining clocks within one loop
  70   //
  71   RemainingTick = Ticks & 0xFFFFFF;
  72
  73   //
  74   // Do not intend to use TMROF_STS bit of register PM1_STS, because this add extra
  75   // one I/O operation, and may generate SMI
  76   //
  77   while (Counts != 0) {
  78     CurrentTick = IoRead32 (ACPI_BASE_ADDRESS + R_PCH_ACPI_PM1_TMR) & B_PCH_ACPI_PM1_TMR_VAL;
  79     if (CurrentTick <= OriginalTick) {
  80       Counts--;
  81     }
  82     OriginalTick = CurrentTick;
  83   }
  84
  85   while ((RemainingTick > CurrentTick) && (OriginalTick <= CurrentTick)) {
  86     OriginalTick  = CurrentTick;
  87     CurrentTick   = IoRead32 (ACPI_BASE_ADDRESS + R_PCH_ACPI_PM1_TMR) & B_PCH_ACPI_PM1_TMR_VAL;
  88   }
  89
  90   return EFI_SUCCESS;
  91 }