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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2007-2008 coresystems GmbH
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc.
*/
#include <delay.h>
#include <stdint.h>
#include <cpu/x86/tsc.h>
#include <cpu/x86/msr.h>
#include <cpu/intel/speedstep.h>
/**
* Intel Core(tm) CPUs always run the TSC at the maximum possible CPU clock
*/
void udelay(u32 us)
{
u32 dword;
tsc_t tsc, tsc1, tscd;
msr_t msr;
u32 fsb = 0, divisor;
u32 d; /* ticks per us */
msr = rdmsr(MSR_FSB_FREQ);
switch (msr.lo & 0x07) {
case 5:
fsb = 400;
break;
case 1:
fsb = 533;
break;
case 3:
fsb = 667;
break;
case 2:
fsb = 800;
break;
case 0:
fsb = 1067;
break;
case 4:
fsb = 1333;
break;
case 6:
fsb = 1600;
break;
}
msr = rdmsr(0x198);
divisor = (msr.hi >> 8) & 0x1f;
d = (fsb * divisor) / 4; /* CPU clock is always a quarter. */
multiply_to_tsc(&tscd, us, d);
tsc1 = rdtsc();
dword = tsc1.lo + tscd.lo;
if ((dword < tsc1.lo) || (dword < tscd.lo)) {
tsc1.hi++;
}
tsc1.lo = dword;
tsc1.hi += tscd.hi;
do {
tsc = rdtsc();
} while ((tsc.hi < tsc1.hi)
|| ((tsc.hi == tsc1.hi) && (tsc.lo < tsc1.lo)));
}
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