LXR linux/tools/power/cpupower/debug/i386/centrino-decode.c

   1/*
   2 *  (C) 2003 - 2004  Dominik Brodowski <linux@dominikbrodowski.de>
   3 *
   4 *  Licensed under the terms of the GNU GPL License version 2.
   5 *
   6 * Based on code found in
   7 * linux/arch/i386/kernel/cpu/cpufreq/speedstep-centrino.c
   8 * and originally developed by Jeremy Fitzhardinge.
   9 *
  10 * USAGE: simply run it to decode the current settings on CPU 0,
  11 *        or pass the CPU number as argument, or pass the MSR content
  12 *        as argument.
  13 */
  14
  15#include <stdio.h>
  16#include <stdlib.h>
  17#include <stdint.h>
  18#include <unistd.h>
  19#include <errno.h>
  20#include <fcntl.h>
  21
  22#include <sys/types.h>
  23#include <sys/stat.h>
  24
  25#define MCPU    32
  26
  27#define MSR_IA32_PERF_STATUS    0x198
  28
  29static int rdmsr(unsigned int cpu, unsigned int msr,
  30                 unsigned int *lo, unsigned int *hi)
  31{
  32        int fd;
  33        char file[20];
  34        unsigned long long val;
  35        int retval = -1;
  36
  37        *lo = *hi = 0;
  38
  39        if (cpu > MCPU)
  40                goto err1;
  41
  42        sprintf(file, "/dev/cpu/%d/msr", cpu);
  43        fd = open(file, O_RDONLY);
  44
  45        if (fd < 0)
  46                goto err1;
  47
  48        if (lseek(fd, msr, SEEK_CUR) == -1)
  49                goto err2;
  50
  51        if (read(fd, &val, 8) != 8)
  52                goto err2;
  53
  54        *lo = (uint32_t )(val & 0xffffffffull);
  55        *hi = (uint32_t )(val>>32 & 0xffffffffull);
  56
  57        retval = 0;
  58err2:
  59        close(fd);
  60err1:
  61        return retval;
  62}
  63
  64static void decode (unsigned int msr)
  65{
  66        unsigned int multiplier;
  67        unsigned int mv;
  68
  69        multiplier = ((msr >> 8) & 0xFF);
  70
  71        mv = (((msr & 0xFF) * 16) + 700);
  72
  73        printf("0x%x means multiplier %d @ %d mV\n", msr, multiplier, mv);
  74}
  75
  76static int decode_live(unsigned int cpu)
  77{
  78        unsigned int lo, hi;
  79        int err;
  80
  81        err = rdmsr(cpu, MSR_IA32_PERF_STATUS, &lo, &hi);
  82
  83        if (err) {
  84                printf("can't get MSR_IA32_PERF_STATUS for cpu %d\n", cpu);
  85                printf("Possible trouble: you don't run an Enhanced SpeedStep capable cpu\n");
  86                printf("or you are not root, or the msr driver is not present\n");
  87                return 1;
  88        }
  89
  90        decode(lo);
  91
  92        return 0;
  93}
  94
  95int main (int argc, char **argv)
  96{
  97        unsigned int cpu, mode = 0;
  98
  99        if (argc < 2)
 100                cpu = 0;
 101        else {
 102                cpu = strtoul(argv[1], NULL, 0);
 103                if (cpu >= MCPU)
 104                        mode = 1;
 105        }
 106
 107        if (mode)
 108                decode(cpu);
 109        else
 110                decode_live(cpu);
 111
 112        return 0;
 113}
 114