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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2007-2008 coresystems GmbH
* 2012 secunet Security Networks AG
*
* 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdint.h>
#include <cpu/x86/tsc.h>
#include <cpu/x86/msr.h>
#include "delay.h"
/* Simple 32- to 64-bit multiplication. Uses 16-bit words to avoid overflow. */
static inline void multiply_to_tsc(tsc_t *const tsc, const u32 a, const u32 b)
{
tsc->lo = (a & 0xffff) * (b & 0xffff);
tsc->hi = ((tsc->lo >> 16)
+ ((a & 0xffff) * (b >> 16))
+ ((b & 0xffff) * (a >> 16)));
tsc->lo = ((tsc->hi & 0xffff) << 16) | (tsc->lo & 0xffff);
tsc->hi = ((a >> 16) * (b >> 16)) + (tsc->hi >> 16);
}
/**
* Intel Core(tm) cpus always run the TSC at the maximum possible CPU clock
*/
static void _udelay(const u32 us, const u32 numerator, const int total)
{
u32 dword;
tsc_t tsc, tsc1, tscd;
msr_t msr;
u32 fsb = 0, divisor;
u32 d; /* ticks per us */
msr = rdmsr(0xcd);
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;
/* CPU clock is always a quarter. */
d = ((fsb * divisor) / numerator) / 4;
multiply_to_tsc(&tscd, us, d);
if (!total) {
tsc1 = rdtsc();
dword = tsc1.lo + tscd.lo;
if ((dword < tsc1.lo) || (dword < tscd.lo)) {
tsc1.hi++;
}
tsc1.lo = dword;
tsc1.hi += tscd.hi;
} else {
tsc1 = tscd;
}
do {
tsc = rdtsc();
} while ((tsc.hi < tsc1.hi)
|| ((tsc.hi == tsc1.hi) && (tsc.lo < tsc1.lo)));
}
void udelay(const u32 us)
{
_udelay(us, 1, 0);
}
void ns100delay(const u32 ns100)
{
_udelay(ns100, 10, 0);
}
void udelay_from_reset(const u32 us)
{
_udelay(us, 1, 1);
}
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