cputemp.c

#include "common.h"
#include "sys/cpuinfo.h"
#include "sys/msr.h"
#include "sys/cpuid.h"
 
// X86 CPU Temperature support (partially based on memtest86+ code)
 
size_t cputemp_calibrate_value = 0;
 
bool is_temperature_module_present() {
    if(cpu_get_id() == INTEL_MAGIC && get_max_cpuid_count() >= 6) { // Only possible on real hardware (not QEMU)
        uint32_t info[4] = {0};
 
        cpuid(0x6,
              info[0],
              info[1],  // Not needed
              info[2],  // Not needed
              info[3]   // Not needed
        );
 
        return (bool)(info[0] & 1);
    }
 
    return false;
}
 
void cputemp_calibrate() {
    uint32_t a = 0;
    uint32_t b = 0;
 
    if(is_temperature_module_present()) {
        rdmsr(INTEL_TEMPERATURE_TARGET, a, b);
        cputemp_calibrate_value = (a >> 16) & 0x7F;
 
        // From memtest86+ code
 
        if (cputemp_calibrate_value < 50 || cputemp_calibrate_value > 125) {
            cputemp_calibrate_value = 100;
        }
    }
}
 
size_t get_cpu_temperature() {
    if(is_temperature_module_present()) {
        uint32_t a = 0;
        uint32_t b = 0;
 
        rdmsr(INTEL_THERMAL_STATUS, a, b);
 
        uint32_t absolute = (a >> 16) & 0x7F;
 
        return cputemp_calibrate_value - absolute;
    }
 
    return 0;
}