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
  29 static 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;
  58 err2:
  59         close(fd);
  60 err1:
  61         return retval;
  62 }
  63
  64 static 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
  76 static 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
  95 int 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 }