/** @file Copyright (c) 2004 - 2014, Intel Corporation. All rights reserved.
SPDX-License-Identifier: BSD-2-Clause-Patent Module Name: Stall.c Abstract: Produce Stall Ppi. --*/ #include "CommonHeader.h" #include "PlatformBaseAddresses.h" #include "PchRegs.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; }