/*++
|
|
Copyright (c) 1999 - 2014, Intel Corporation. All rights reserved
|
|
SPDX-License-Identifier: BSD-2-Clause-Patent
|
|
|
|
|
Module Name:
|
|
SmmIo.c
|
|
Abstract:
|
|
SMM I/O access utility implementation file, for Ia32
|
|
--*/
|
|
//
|
// Include files
|
//
|
#include "Library/StallSmmLib.h"
|
#include "Pi/PiSmmCis.h"
|
#include "PiDxe.h"
|
#include <Library/IoLib.h>
|
#include <Library/PcdLib.h>
|
#include "PchAccess.h"
|
|
/**
|
Delay for at least the request number of microseconds.
|
Timer used is ACPI time counter, which has 1us granularity.
|
|
@param Microseconds Number of microseconds to delay.
|
|
@retval None
|
|
**/
|
VOID
|
SmmStall (
|
IN UINTN Microseconds
|
)
|
{
|
UINTN Ticks;
|
UINTN Counts;
|
UINTN CurrentTick;
|
UINTN OriginalTick;
|
UINTN RemainingTick;
|
UINT16 AcpiBaseAddr;
|
|
if (Microseconds == 0) {
|
return;
|
}
|
|
AcpiBaseAddr = PchLpcPciCfg16 (R_PCH_LPC_ACPI_BASE) & B_PCH_LPC_ACPI_BASE_BAR;
|
|
OriginalTick = IoRead32 (AcpiBaseAddr + R_PCH_ACPI_PM1_TMR);
|
CurrentTick = OriginalTick;
|
|
//
|
// The timer frequency is 3.579545 MHz, so 1 ms corresponds 3.58 clocks
|
//
|
Ticks = Microseconds * 358 / 100 + OriginalTick + 1;
|
|
//
|
// The loops needed by timer overflow
|
//
|
Counts = Ticks / V_PCH_ACPI_PM1_TMR_MAX_VAL;
|
|
//
|
// Remaining clocks within one loop
|
//
|
RemainingTick = Ticks % V_PCH_ACPI_PM1_TMR_MAX_VAL;
|
|
//
|
// not intend to use TMROF_STS bit of register PM1_STS, because this adds extra
|
// one I/O operation, and maybe generate SMI
|
//
|
while ((Counts != 0) || (RemainingTick > CurrentTick)) {
|
CurrentTick = IoRead32 (AcpiBaseAddr + R_PCH_ACPI_PM1_TMR);
|
//
|
// Check if timer overflow
|
//
|
if (CurrentTick < OriginalTick) {
|
Counts--;
|
}
|
OriginalTick = CurrentTick;
|
}
|
}
|
