Vlv2TbltDevicePkg/PlatformPei/Stall.c

   1 /** @file
   2
   3   Copyright (c) 2004  - 2014, Intel Corporation. All rights reserved.<BR>
   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   Stall.c
  18
  19 Abstract:
  20
  21   Produce Stall Ppi.
  22
  23 --*/
  24
  25
  26 #include "CommonHeader.h"
  27 #include "PlatformBaseAddresses.h"
  28 #include "PchRegs.h"
  29
  30 /**
  31   Waits for at least the given number of microseconds.
  32
  33   @param PeiServices     General purpose services available to every PEIM.
  34   @param This            PPI instance structure.
  35   @param Microseconds    Desired length of time to wait.
  36
  37   @retval EFI_SUCCESS    If the desired amount of time was passed.
  38
  39 **/
  40 EFI_STATUS
  41 EFIAPI
  42 Stall (
  43   IN CONST EFI_PEI_SERVICES   **PeiServices,
  44   IN CONST EFI_PEI_STALL_PPI      *This,
  45   IN UINTN              Microseconds
  46   )
  47 {
  48   UINTN   Ticks;
  49   UINTN   Counts;
  50   UINT32  CurrentTick;
  51   UINT32  OriginalTick;
  52   UINT32  RemainingTick;
  53
  54   if (Microseconds == 0) {
  55     return EFI_SUCCESS;
  56   }
  57
  58   OriginalTick = IoRead32 (ACPI_BASE_ADDRESS + R_PCH_ACPI_PM1_TMR);
  59   OriginalTick &= (V_PCH_ACPI_PM1_TMR_MAX_VAL - 1);
  60   CurrentTick = OriginalTick;
  61
  62   //
  63   // The timer frequency is 3.579545MHz, so 1 ms corresponds to 3.58 clocks
  64   //
  65   Ticks = Microseconds * 358 / 100 + OriginalTick + 1;
  66
  67   //
  68   // The loops needed for timer overflow
  69   //
  70   Counts = (UINTN)RShiftU64((UINT64)Ticks, 24);
  71
  72   //
  73   // Remaining clocks within one loop
  74   //
  75   RemainingTick = Ticks & 0xFFFFFF;
  76
  77   //
  78   // Do not intend to use TMROF_STS bit of register PM1_STS, because this add extra
  79   // one I/O operation, and may generate SMI
  80   //
  81   while (Counts != 0) {
  82     CurrentTick = IoRead32 (ACPI_BASE_ADDRESS + R_PCH_ACPI_PM1_TMR) & B_PCH_ACPI_PM1_TMR_VAL;
  83     if (CurrentTick <= OriginalTick) {
  84       Counts--;
  85     }
  86     OriginalTick = CurrentTick;
  87   }
  88
  89   while ((RemainingTick > CurrentTick) && (OriginalTick <= CurrentTick)) {
  90     OriginalTick  = CurrentTick;
  91     CurrentTick   = IoRead32 (ACPI_BASE_ADDRESS + R_PCH_ACPI_PM1_TMR) & B_PCH_ACPI_PM1_TMR_VAL;
  92   }
  93
  94   return EFI_SUCCESS;
  95 }