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#include <common.h>
#include <init.h>
#include <driver.h>
#include <efi.h>
#include <efi/efi.h>
#include <clock.h>
#ifdef __x86_64__
static uint64_t ticks_read(void)
{
uint64_t a, d;
__asm__ volatile ("rdtsc" : "=a" (a), "=d" (d));
return (d << 32) | a;
}
#else
static uint64_t ticks_read(void)
{
uint64_t val;
__asm__ volatile ("rdtsc" : "=A" (val));
return val;
}
#endif
static uint64_t freq;
/* count TSC ticks during a millisecond delay */
static uint64_t ticks_freq(void)
{
uint64_t ticks_start, ticks_end;
ticks_start = ticks_read();
BS->stall(1000);
ticks_end = ticks_read();
return (ticks_end - ticks_start) * 1000;
}
static uint64_t efi_x86_cs_read(void)
{
return 1000 * 1000 * ticks_read() / freq;
}
static int efi_x86_cs_init(struct clocksource *cs)
{
cs->mult = clocksource_hz2mult(1000 * 1000, cs->shift);
freq = ticks_freq();
return 0;
}
static struct clocksource efi_x86_cs = {
.read = efi_x86_cs_read,
.mask = CLOCKSOURCE_MASK(64),
.shift = 0,
.priority = 100,
.init = efi_x86_cs_init,
};
static int efi_x86_cs_probe(struct device_d *dev)
{
return init_clock(&efi_x86_cs);
}
static struct driver_d efi_x86_cs_driver = {
.name = "efi-cs-x86",
.probe = efi_x86_cs_probe,
};
static int efi_x86_cs_initcall(void)
{
return platform_driver_register(&efi_x86_cs_driver);
}
/* for efi the time must be init at core initcall level */
core_initcall(efi_x86_cs_initcall);
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