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#include <gpxe/init.h>
#include <gpxe/timer.h>
#include <stdio.h>
#include <bits/cpu.h>
#include <bits/timer2.h>
#include <io.h>
#define rdtsc(low,high) \
__asm__ __volatile__("rdtsc" : "=a" (low), "=d" (high))
#define rdtscll(val) \
__asm__ __volatile__ ("rdtsc" : "=A" (val))
static unsigned long long calibrate_tsc(void)
{
uint32_t startlow, starthigh;
uint32_t endlow, endhigh;
rdtsc(startlow,starthigh);
i386_timer2_udelay(USECS_IN_MSEC/2);
rdtsc(endlow,endhigh);
/* 64-bit subtract - gcc just messes up with long longs */
/* XXX ORLY? Check it. */
__asm__("subl %2,%0\n\t"
"sbbl %3,%1"
:"=a" (endlow), "=d" (endhigh)
:"g" (startlow), "g" (starthigh),
"0" (endlow), "1" (endhigh));
/* Error: ECPUTOOFAST */
if (endhigh)
goto bad_ctc;
endlow *= MSECS_IN_SEC*2;
return endlow;
/*
* The CTC wasn't reliable: we got a hit on the very first read,
* or the CPU was so fast/slow that the quotient wouldn't fit in
* 32 bits..
*/
bad_ctc:
return 0;
}
static uint32_t clocks_per_second = 0;
static tick_t rtdsc_currticks(void)
{
uint32_t clocks_high, clocks_low;
uint32_t currticks;
/* Read the Time Stamp Counter */
rdtsc(clocks_low, clocks_high);
/* currticks = clocks / clocks_per_tick; */
__asm__("divl %1"
:"=a" (currticks)
:"r" (clocks_per_second/USECS_IN_SEC), "0" (clocks_low), "d" (clocks_high));
return currticks;
}
static int rtdsc_ts_init(void)
{
struct cpuinfo_x86 cpu_info;
get_cpuinfo(&cpu_info);
if (cpu_info.features & X86_FEATURE_TSC) {
clocks_per_second = calibrate_tsc();
if (clocks_per_second) {
DBG("RTDSC Ticksource installed. CPU running at %ld Mhz\n",
clocks_per_second/(1000*1000));
return 0;
}
}
printf("RTDSC timer not available on this machine.\n");
return 1;
}
struct timer rtdsc_ts __timer (01) = {
.init = rtdsc_ts_init,
.udelay = generic_currticks_udelay,
.currticks = rtdsc_currticks,
};
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