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// SPDX-License-Identifier: GPL-2.0-only
/*
* (C) 2003 - 2004 Dominik Brodowski <linux@dominikbrodowski.de>
*
* Based on code found in
* linux/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c
* and originally developed by Jeremy Fitzhardinge.
*
* USAGE: simply run it to decode the current settings on CPU 0,
* or pass the CPU number as argument, or pass the MSR content
* as argument.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#define MCPU 32
#define MSR_IA32_PERF_STATUS 0x198
static int rdmsr(unsigned int cpu, unsigned int msr,
unsigned int *lo, unsigned int *hi)
{
int fd;
char file[20];
unsigned long long val;
int retval = -1;
*lo = *hi = 0;
if (cpu > MCPU)
goto err1;
sprintf(file, "/dev/cpu/%d/msr", cpu);
fd = open(file, O_RDONLY);
if (fd < 0)
goto err1;
if (lseek(fd, msr, SEEK_CUR) == -1)
goto err2;
if (read(fd, &val, 8) != 8)
goto err2;
*lo = (uint32_t )(val & 0xffffffffull);
*hi = (uint32_t )(val>>32 & 0xffffffffull);
retval = 0;
err2:
close(fd);
err1:
return retval;
}
static void decode (unsigned int msr)
{
unsigned int multiplier;
unsigned int mv;
multiplier = ((msr >> 8) & 0xFF);
mv = (((msr & 0xFF) * 16) + 700);
printf("0x%x means multiplier %d @ %d mV\n", msr, multiplier, mv);
}
static int decode_live(unsigned int cpu)
{
unsigned int lo, hi;
int err;
err = rdmsr(cpu, MSR_IA32_PERF_STATUS, &lo, &hi);
if (err) {
printf("can't get MSR_IA32_PERF_STATUS for cpu %d\n", cpu);
printf("Possible trouble: you don't run an Enhanced SpeedStep capable cpu\n");
printf("or you are not root, or the msr driver is not present\n");
return 1;
}
decode(lo);
return 0;
}
int main (int argc, char **argv)
{
unsigned int cpu, mode = 0;
if (argc < 2)
cpu = 0;
else {
cpu = strtoul(argv[1], NULL, 0);
if (cpu >= MCPU)
mode = 1;
}
if (mode)
decode(cpu);
else
decode_live(cpu);
return 0;
}
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