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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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