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/** @file
Copyright (c) 2004 - 2014, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
Module Name:
Stall.c
Abstract:
Produce Stall Ppi.
--*/
#include "PlatformEarlyInit.h"
/**
Waits for at least the given number of microseconds.
@param PeiServices General purpose services available to every PEIM.
@param This PPI instance structure.
@param Microseconds Desired length of time to wait.
@retval EFI_SUCCESS If the desired amount of time was passed.
*/
EFI_STATUS
EFIAPI
Stall (
IN CONST EFI_PEI_SERVICES **PeiServices,
IN CONST EFI_PEI_STALL_PPI *This,
IN UINTN Microseconds
)
{
UINTN Ticks;
UINTN Counts;
UINT32 CurrentTick;
UINT32 OriginalTick;
UINT32 RemainingTick;
if (Microseconds == 0) {
return EFI_SUCCESS;
}
OriginalTick = IoRead32 (ACPI_BASE_ADDRESS + R_PCH_ACPI_PM1_TMR);
OriginalTick &= (V_PCH_ACPI_PM1_TMR_MAX_VAL - 1);
CurrentTick = OriginalTick;
//
// The timer frequency is 3.579545MHz, so 1 ms corresponds to 3.58 clocks
//
Ticks = Microseconds * 358 / 100 + OriginalTick + 1;
//
// The loops needed for timer overflow
//
Counts = (UINTN)RShiftU64((UINT64)Ticks, 24);
//
// Remaining clocks within one loop
//
RemainingTick = Ticks & 0xFFFFFF;
//
// Do not intend to use TMROF_STS bit of register PM1_STS, because this add extra
// one I/O operation, and may generate SMI
//
while (Counts != 0) {
CurrentTick = IoRead32 (ACPI_BASE_ADDRESS + R_PCH_ACPI_PM1_TMR) & B_PCH_ACPI_PM1_TMR_VAL;
if (CurrentTick <= OriginalTick) {
Counts--;
}
OriginalTick = CurrentTick;
}
while ((RemainingTick > CurrentTick) && (OriginalTick <= CurrentTick)) {
OriginalTick = CurrentTick;
CurrentTick = IoRead32 (ACPI_BASE_ADDRESS + R_PCH_ACPI_PM1_TMR) & B_PCH_ACPI_PM1_TMR_VAL;
}
return EFI_SUCCESS;
}
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