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/*++
This file contains an 'Intel Peripheral Driver' and uniquely
identified as "Intel Reference Module" and is
licensed for Intel CPUs and chipsets under the terms of your
license agreement with Intel or your vendor. This file may
be modified by the user, subject to additional terms of the
license agreement
--*/
/*++
Copyright (c) 2006 - 2010 Intel Corporation. All rights reserved
This software and associated documentation (if any) is furnished
under a license and may only be used or copied in accordance
with the terms of the license. Except as permitted by such
license, no part of this software or documentation may be
reproduced, stored in a retrieval system, or transmitted in any
form or by any means without the express written consent of
Intel Corporation.
Module Name:
HeciHpet.c
Abstract:
Definitions for HECI driver
--*/
#include "HeciHpet.h"
#include "HeciRegs.h"
#include "HeciCore.h"
//
// Extern for shared HECI data and protocols
//
extern HECI_INSTANCE_SMM *mHeciContext;
VOLATILE UINT32 mSaveHpetConfigReg;
VOID
SaveHpet (
VOID
)
/*++
Routine Description:
Store the value of High Performance Timer
Arguments:
None
Returns:
None
--*/
{
mSaveHpetConfigReg = MmioRead32 (PCH_RCRB_BASE + R_PCH_RCRB_HPTC);
}
VOID
RestoreHpet (
VOID
)
/*++
Routine Description:
Restore the value of High Performance Timer
Arguments:
None
Returns:
None
--*/
{
MmioWrite32 (PCH_RCRB_BASE + R_PCH_RCRB_HPTC, mSaveHpetConfigReg);
}
VOID
StartTimer (
OUT UINT32 *Start,
OUT UINT32 *End,
IN UINT32 Time
)
/*++
Routine Description:
Used for calculating timeouts
Arguments:
Start - Snapshot of the HPET timer
End - Calculated time when timeout period will be done
Time - Timeout period in microseconds
Returns:
VOID
--*/
{
UINT32 Ticks;
//
// Make sure that HPET is enabled and running
//
EnableHpet ();
//
// Read current timer value into start time from HPET
//
*Start = mHeciContext->HpetTimer[HPET_MAIN_COUNTER_LOW];
//
// Convert microseconds into 70ns timer ticks
//
Ticks = Time * HPET_TICKS_PER_MICRO;
//
// Compute end time
//
*End = *Start + Ticks;
return ;
}
EFI_STATUS
Timeout (
IN UINT32 Start,
IN UINT32 End
)
/*++
Routine Description:
Used to determine if a timeout has occured.
Arguments:
Start - Snapshot of the HPET timer when the timeout period started.
End - Calculated time when timeout period will be done.
Returns:
EFI_STATUS
--*/
{
UINT32 Current;
//
// Read HPET and assign the value as the current time.
//
Current = mHeciContext->HpetTimer[HPET_MAIN_COUNTER_LOW];
//
// Test basic case (no overflow)
//
if ((Start < End) && (End <= Current)) {
return EFI_TIMEOUT;
}
//
// Test basic start/end conditions with overflowed timer
//
if ((Start < End) && (Current < Start)) {
return EFI_TIMEOUT;
}
//
// Test for overflowed start/end condition
//
if ((Start > End) && ((Current < Start) && (Current > End))) {
return EFI_TIMEOUT;
}
//
// Catch corner case of broken arguments
//
if (Start == End) {
return EFI_TIMEOUT;
}
//
// Else, we have not yet timed out
//
return EFI_SUCCESS;
}
VOID
IoDelay (
UINT32 delayTime
)
/*++
Routine Description:
Delay for at least the request number of microseconds
Arguments:
delayTime - Number of microseconds to delay.
Returns:
None.
--*/
{
SmmStall (delayTime);
}
VOID
SmmStall (
IN UINTN Microseconds
)
/*++
Routine Description:
Delay for at least the request number of microseconds.
Timer used is DMA refresh timer, which has 15us granularity.
You can call with any number of microseconds, but this
implementation cannot support 1us granularity.
Arguments:
Microseconds - Number of microseconds to delay.
Returns:
None
--*/
{
UINT8 Data;
UINT8 InitialState;
UINTN CycleIterations;
CycleIterations = 0;
Data = 0;
InitialState = 0;
//
// The time-source is 15 us granular, so calibrate the timing loop
// based on this baseline
// Error is possible 15us.
//
CycleIterations = (Microseconds / 15) + 1;
//
// Use the DMA Refresh timer in port 0x61. Cheap but effective.
// The only issue is that the granularity is 15us, and we want to
// guarantee "at least" one full transition to avoid races.
//
//
// _____________/----------\__________/--------
//
// |<--15us-->|
//
// --------------------------------------------------> Time (us)
//
while (CycleIterations--) {
Data = IoRead8 (0x61);
InitialState = Data;
//
// Capture first transition (strictly less than one period)
//
while (InitialState == Data) {
Data = IoRead8 (0x61);
}
InitialState = Data;
//
// Capture next transition (guarantee at least one full pulse)
//
while (InitialState == Data) {
Data = IoRead8 (0x61);
}
}
}
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