86 lines
2.7 KiB
C
86 lines
2.7 KiB
C
#include <zinnia/clock.h>
|
|
#include <zinnia/cmdline.h>
|
|
#include <zinnia/print.h>
|
|
#include <zinnia/utils.h>
|
|
#include <stdint.h>
|
|
#include <x86_64/asm.h>
|
|
#include <x86_64/defs.h>
|
|
|
|
static bool use_tsc = true;
|
|
static void tsc_option(bool opt) {
|
|
use_tsc = opt;
|
|
}
|
|
CMDLINE_OPTION("x86_64.tsc", "Enable timestamp counter", tsc_option);
|
|
|
|
constexpr uint64_t nanos_per_sec = 1'000'000'000;
|
|
static uint64_t tsc_freq = 0;
|
|
static uint64_t tsc_base_cycles = 0;
|
|
|
|
static uint64_t cycles_to_ns(uint64_t cycles, uint64_t freq) {
|
|
uint64_t seconds = cycles / freq;
|
|
uint64_t remaining_cycles = cycles % freq;
|
|
uint64_t fractional_ns = (uint64_t)((__uint128_t)remaining_cycles * (__uint128_t)nanos_per_sec / (__uint128_t)freq);
|
|
uint64_t ns = seconds * nanos_per_sec + fractional_ns;
|
|
|
|
return MIN(ns, UINT64_MAX);
|
|
}
|
|
|
|
static void tsc_reset(struct clock* clock) {
|
|
tsc_base_cycles = asm_rdtsc();
|
|
}
|
|
|
|
static uint64_t tsc_get_elapsed_ns(struct clock* clock) {
|
|
uint64_t cycles = asm_rdtsc() - tsc_base_cycles;
|
|
return cycles_to_ns(cycles, tsc_freq);
|
|
}
|
|
|
|
static struct clock tsc_clock = {
|
|
.name = "tsc",
|
|
.priority = 255,
|
|
.reset = tsc_reset,
|
|
.get_elapsed_ns = tsc_get_elapsed_ns,
|
|
};
|
|
|
|
void tsc_init() {
|
|
if (!use_tsc)
|
|
return;
|
|
|
|
if (!(asm_cpuid(1, 0).edx & CPUID_1D_TSC) || !(asm_cpuid(0x8000'0007, 0).edx & (1 << 8))) {
|
|
log("x86_64/tsc: No invariant TSC detected!\n");
|
|
return;
|
|
}
|
|
|
|
// Check for the TSC info leaf.
|
|
bool has_tsc_leaf = false;
|
|
struct cpuid tsc_leaf = {0};
|
|
if (asm_cpuid(0, 0).eax >= 0x15) {
|
|
tsc_leaf = asm_cpuid(0x15, 0);
|
|
has_tsc_leaf = true;
|
|
}
|
|
|
|
if (clock_available()) {
|
|
// Calibrate using existing clock.
|
|
uint64_t t1 = asm_rdtsc();
|
|
clock_spin_ns(10'000'000);
|
|
uint64_t t2 = asm_rdtsc();
|
|
tsc_freq = (t2 - t1) * 100;
|
|
} else if (has_tsc_leaf) {
|
|
// If we have no timer (yet), the only way we can calibrate the TSC is if CPUID gives us the frequency.
|
|
// On a normal system, this should usually never be called and is a last resort
|
|
// since at this point we have at least the HPET timer.
|
|
if (tsc_leaf.ecx != 0 && tsc_leaf.ebx != 0 && tsc_leaf.eax != 0) {
|
|
log("x86_64/tsc: Calibrating TSC using CPUID 0x15");
|
|
tsc_freq = (uint64_t)tsc_leaf.ecx * tsc_leaf.ebx / tsc_leaf.eax;
|
|
} else {
|
|
log("x86_64/tsc: Unable to calibrate TSC using CPUID frequency information");
|
|
return;
|
|
}
|
|
} else {
|
|
log("x86_64/tsc: Unable to calibrate the TSC without a clock or static frequency info!\n");
|
|
return;
|
|
}
|
|
|
|
log("x86_64/tsc: Timer frequency is %lu MHz\n", tsc_freq / 1'000'000);
|
|
clock_switch(&tsc_clock);
|
|
}
|