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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.
*/
#include <delay.h>
#include <stdint.h>
#include <cpu/x86/tsc.h>
#include <cpu/x86/msr.h>
#define MSR_PLATFORM_INFO 0xce
/**
* Intel Rangeley CPUs always run the TSC at BCLK = 100MHz
*/
/* Simple 32- to 64-bit multiplication. Uses 16-bit words to avoid overflow.
* This code is used to prevent use of libgcc's umoddi3.
*/
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);
}
void udelay(u32 us)
{
u32 dword;
tsc_t tsc, tsc1, tscd;
msr_t msr;
u32 fsb = 100, divisor;
u32 d; /* ticks per us */
msr = rdmsr(MSR_PLATFORM_INFO);
divisor = (msr.lo >> 8) & 0xff;
d = fsb * divisor;
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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