185 lines
3.7 KiB
C
185 lines
3.7 KiB
C
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/*++
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Copyright (c) 1991-1993 Microsoft Corporation
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Copyright 1994 MOTOROLA, INC. All Rights Reserved. This file
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contains copyrighted material. Use of this file is restricted
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by the provisions of a Motorola Software License Agreement.
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Module Name:
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pxcalstl.c
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Abstract:
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This module implements the calibration of the stall execution HAL
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service for a PowerPC system.
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Author:
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David N. Cutler (davec) 26-Apr-1991
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Jim Wooldridge
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Steve Johns (Motorola)
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Environment:
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Kernel mode only.
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Revision History:
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--*/
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#include "halp.h"
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#include "pxsystyp.h"
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//
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// KeQueryPerformanceCounter & KeStallExecutionProcessor are called
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// before Phase 0 initialization, so initialize it to a reasonable value.
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//
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ULONG HalpPerformanceFrequency = 80000000/16;
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extern ULONG HalpClockCount;
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extern ULONG HalpFullTickClockCount;
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//
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// Put all code for HAL initialization in the INIT section. It will be
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// deallocated by memory management when phase 1 initialization is
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// completed.
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//
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#if defined(ALLOC_PRAGMA)
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#pragma alloc_text(INIT, HalpCalibrateStall)
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#endif
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ULONG
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HalpCalibrateTBPStack(
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VOID
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);
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BOOLEAN
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HalpCalibrateStall (
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VOID
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)
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/*++
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Routine Description:
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This function calibrates the stall execution HAL service.
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N.B. This routine is only called during phase 1 initialization.
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Arguments:
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None.
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Return Value:
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A value of TRUE is returned if the calibration is successfully
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completed. Otherwise a value of FALSE is returned.
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--*/
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{ int i;
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ULARGE_INTEGER BigNumber;
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ULONG Variance;
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ULONG BusSpeed;
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static ULONG BusSpeeds [] = {
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25000000,
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33333333,
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40000000,
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41875000,
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50000000,
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55833333,
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60000000,
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66000000,
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66666666,
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67000000,
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75000000,
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80000000,
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83333333,
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83750000,
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90000000,
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99000000,
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100000000,
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111666666,
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120000000,
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132000000,
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133333332,
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134000000,
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150000000,
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160000000,
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166666666,
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167500000
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};
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//
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// Set initial scale factor
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//
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PCR->StallScaleFactor = 1;
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//
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// Compute the clock frequency of the Time Base & Decrementer
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//
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// It's possible for reads from the CMOS RTC to return odd results.
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// For this reason, We can use a do-while loop, to ensure the calibration
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// function is called at least once and is returning a reasonable value.
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//
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do {
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switch( HalpSystemType ) {
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case MOTOROLA_POWERSTACK:
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HalpPerformanceFrequency = HalpCalibrateTBPStack();
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break;
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default:
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case MOTOROLA_BIG_BEND:
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HalpPerformanceFrequency = HalpCalibrateTB();
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break;
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}
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} while( HalpPerformanceFrequency < 1000000 );
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//
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// CPU bus runs at 4 times the DECREMENTER frequency
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//
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BusSpeed = HalpPerformanceFrequency * 4;
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//
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// Choose the bus speed which is closest to calculated value.
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// If the bus speed is not "close enough", then it may be
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// a new speed which we don't know about. For this case
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// we will leave the Performance Frequency alone.
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//
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for (i=0; i< (sizeof(BusSpeeds)/sizeof(ULONG)); i++) {
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//
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// We are going to allow for a 0.1% variation
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// in calibrated frequency of the system bus clock.
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// Calculate the variance as 1/2048 the frequency.
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//
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Variance = BusSpeeds[i] >> 11;
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if ((BusSpeeds[i] - Variance < BusSpeed) &&
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(BusSpeeds[i] + Variance > BusSpeed)) {
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HalpPerformanceFrequency = BusSpeeds[i] / 4;
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break;
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}
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}
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//
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// Initialize the system clock variables
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//
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HalpClockCount = (HalpPerformanceFrequency * (MAXIMUM_INCREMENT/10000)) / 1000;
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HalpFullTickClockCount = HalpClockCount;
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return TRUE;
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}
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