3cbfba02fe
https://svn.code.sf.net/p/edk2/code/trunk/edk2/, which are for MinnowBoard MAX open source project. Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: David Wei <david.wei@intel.com> Reviewed-by: Mike Wu <mike.wu@intel.com> Reviewed-by: Hot Tian <hot.tian@intel.com> git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16599 6f19259b-4bc3-4df7-8a09-765794883524
95 lines
2.5 KiB
C
95 lines
2.5 KiB
C
/*++
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Copyright (c) 1999 - 2014, Intel Corporation. All rights reserved
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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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SmmIo.c
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Abstract:
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SMM I/O access utility implementation file, for Ia32
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--*/
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//
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// Include files
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//
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#include "Library/StallSmmLib.h"
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#include "Pi/PiSmmCis.h"
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#include "PiDxe.h"
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#include <Library/IoLib.h>
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#include <Library/PcdLib.h>
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#include "PchAccess.h"
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/**
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Delay for at least the request number of microseconds.
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Timer used is ACPI time counter, which has 1us granularity.
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@param Microseconds Number of microseconds to delay.
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@retval None
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**/
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VOID
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SmmStall (
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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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UINTN CurrentTick;
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UINTN OriginalTick;
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UINTN RemainingTick;
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UINT16 AcpiBaseAddr;
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if (Microseconds == 0) {
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return;
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}
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AcpiBaseAddr = PchLpcPciCfg16 (R_PCH_LPC_ACPI_BASE) & B_PCH_LPC_ACPI_BASE_BAR;
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OriginalTick = IoRead32 (AcpiBaseAddr + R_PCH_ACPI_PM1_TMR);
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CurrentTick = OriginalTick;
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//
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// The timer frequency is 3.579545 MHz, so 1 ms corresponds 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 by timer overflow
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//
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Counts = Ticks / V_PCH_ACPI_PM1_TMR_MAX_VAL;
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//
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// Remaining clocks within one loop
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//
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RemainingTick = Ticks % V_PCH_ACPI_PM1_TMR_MAX_VAL;
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//
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// not intend to use TMROF_STS bit of register PM1_STS, because this adds extra
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// one I/O operation, and maybe generate SMI
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//
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while ((Counts != 0) || (RemainingTick > CurrentTick)) {
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CurrentTick = IoRead32 (AcpiBaseAddr + R_PCH_ACPI_PM1_TMR);
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//
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// Check if timer overflow
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//
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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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}
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