mirror of https://github.com/acidanthera/audk.git
84 lines
2.0 KiB
C
84 lines
2.0 KiB
C
/** @file
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Provide constructor and GetTick for Dxe instance of ACPI Timer Library
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Copyright (C) 2014, Gabriel L. Somlo <somlo@cmu.edu>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#include <Library/DebugLib.h>
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#include <Library/IoLib.h>
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#include <Library/PcdLib.h>
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#include <Library/PciLib.h>
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#include <OvmfPlatforms.h>
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//
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// Cached ACPI Timer IO Address
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//
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STATIC UINT32 mAcpiTimerIoAddr;
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/**
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The constructor function caches the ACPI tick counter address
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At the time this constructor runs (DXE_CORE or later), ACPI IO space
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has already been enabled by either PlatformPei or by the "Base"
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instance of this library.
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In order to avoid querying the underlying platform type during each
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tick counter read operation, we cache the counter address during
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initialization of this instance of the Timer Library.
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@retval EFI_SUCCESS The constructor always returns RETURN_SUCCESS.
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**/
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RETURN_STATUS
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EFIAPI
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AcpiTimerLibConstructor (
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VOID
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)
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{
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UINT16 HostBridgeDevId;
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UINTN Pmba;
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//
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// Query Host Bridge DID to determine platform type
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//
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HostBridgeDevId = PcdGet16 (PcdOvmfHostBridgePciDevId);
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switch (HostBridgeDevId) {
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case INTEL_82441_DEVICE_ID:
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Pmba = POWER_MGMT_REGISTER_PIIX4 (PIIX4_PMBA);
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break;
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case INTEL_Q35_MCH_DEVICE_ID:
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Pmba = POWER_MGMT_REGISTER_Q35 (ICH9_PMBASE);
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break;
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default:
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DEBUG ((EFI_D_ERROR, "%a: Unknown Host Bridge Device ID: 0x%04x\n",
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__FUNCTION__, HostBridgeDevId));
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ASSERT (FALSE);
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return RETURN_UNSUPPORTED;
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}
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mAcpiTimerIoAddr = (PciRead32 (Pmba) & ~PMBA_RTE) + ACPI_TIMER_OFFSET;
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return RETURN_SUCCESS;
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}
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/**
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Internal function to read the current tick counter of ACPI.
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Read the current ACPI tick counter using the counter address cached
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by this instance's constructor.
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@return The tick counter read.
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**/
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UINT32
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InternalAcpiGetTimerTick (
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VOID
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)
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{
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//
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// Return the current ACPI timer value.
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//
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return IoRead32 (mAcpiTimerIoAddr);
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}
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