mirror of https://github.com/acidanthera/audk.git
97 lines
2.7 KiB
C
97 lines
2.7 KiB
C
/** @file
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Copyright (c) 2004 - 2014, Intel Corporation. All rights reserved.<BR>
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This program and the accompanying materials are licensed and made available under
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the terms and conditions of the BSD License that accompanies this distribution.
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The full text of the license may be found at
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http://opensource.org/licenses/bsd-license.php.
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THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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Module Name:
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Stall.c
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Abstract:
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Produce Stall Ppi.
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--*/
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#include "PlatformEarlyInit.h"
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/**
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Waits for at least the given number of microseconds.
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@param PeiServices General purpose services available to every PEIM.
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@param This PPI instance structure.
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@param Microseconds Desired length of time to wait.
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@retval EFI_SUCCESS If the desired amount of time was passed.
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*/
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EFI_STATUS
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EFIAPI
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Stall (
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IN CONST EFI_PEI_SERVICES **PeiServices,
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IN CONST EFI_PEI_STALL_PPI *This,
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IN UINTN Microseconds
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)
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{
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UINTN Ticks;
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UINTN Counts;
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UINT32 CurrentTick;
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UINT32 OriginalTick;
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UINT32 RemainingTick;
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if (Microseconds == 0) {
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return EFI_SUCCESS;
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}
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OriginalTick = IoRead32 (ACPI_BASE_ADDRESS + R_PCH_ACPI_PM1_TMR);
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OriginalTick &= (V_PCH_ACPI_PM1_TMR_MAX_VAL - 1);
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CurrentTick = OriginalTick;
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//
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// The timer frequency is 3.579545MHz, so 1 ms corresponds to 3.58 clocks
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//
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Ticks = Microseconds * 358 / 100 + OriginalTick + 1;
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//
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// The loops needed for timer overflow
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//
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Counts = (UINTN)RShiftU64((UINT64)Ticks, 24);
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//
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// Remaining clocks within one loop
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//
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RemainingTick = Ticks & 0xFFFFFF;
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//
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// Do not intend to use TMROF_STS bit of register PM1_STS, because this add extra
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// one I/O operation, and may generate SMI
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//
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while (Counts != 0) {
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CurrentTick = IoRead32 (ACPI_BASE_ADDRESS + R_PCH_ACPI_PM1_TMR) & B_PCH_ACPI_PM1_TMR_VAL;
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if (CurrentTick <= OriginalTick) {
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Counts--;
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}
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OriginalTick = CurrentTick;
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}
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while ((RemainingTick > CurrentTick) && (OriginalTick <= CurrentTick)) {
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OriginalTick = CurrentTick;
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CurrentTick = IoRead32 (ACPI_BASE_ADDRESS + R_PCH_ACPI_PM1_TMR) & B_PCH_ACPI_PM1_TMR_VAL;
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}
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return EFI_SUCCESS;
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}
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