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#include <gpxe/init.h>
#include <gpxe/timer.h>
#include <errno.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))
/* Measure how many clocks we get in one microsecond */
static inline uint64_t calibrate_tsc(void)
{
uint64_t rdtsc_start;
uint64_t rdtsc_end;
rdtscll(rdtsc_start);
i386_timer2_udelay(USECS_IN_MSEC);
rdtscll(rdtsc_end);
return (rdtsc_end - rdtsc_start) / USECS_IN_MSEC;
}
static uint32_t clocks_per_usec = 0;
/* We measure time in microseconds. */
static tick_t rdtsc_currticks(void)
{
uint64_t clocks;
/* Read the Time Stamp Counter */
rdtscll(clocks);
return clocks / clocks_per_usec;
}
static int rdtsc_ts_init(void)
{
struct cpuinfo_x86 cpu_info;
get_cpuinfo(&cpu_info);
if (cpu_info.features & X86_FEATURE_TSC) {
clocks_per_usec= calibrate_tsc();
if (clocks_per_usec) {
DBG("RDTSC ticksource installed. CPU running at %ld Mhz\n",
clocks_per_usec);
return 0;
}
}
DBG("RDTSC ticksource not available on this machine.\n");
return -ENODEV;
}
struct timer rdtsc_ts __timer (01) = {
.init = rdtsc_ts_init,
.udelay = generic_currticks_udelay,
.currticks = rdtsc_currticks,
};
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