tools/power/cpupower/debug/i386/powernow-k8-decode.c

   1 /*
   2  *  (C) 2004 Bruno Ducrot <ducrot@poupinou.org>
   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/powernow-k8.c
   8  * and originally developed by Paul Devriendt
   9  */
  10
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <stdint.h>
  14 #include <unistd.h>
  15 #include <errno.h>
  16 #include <fcntl.h>
  17
  18 #include <sys/types.h>
  19 #include <sys/stat.h>
  20
  21 #define MCPU 32
  22
  23 #define MSR_FIDVID_STATUS       0xc0010042
  24
  25 #define MSR_S_HI_CURRENT_VID    0x0000001f
  26 #define MSR_S_LO_CURRENT_FID    0x0000003f
  27
  28 static int get_fidvid(uint32_t cpu, uint32_t *fid, uint32_t *vid)
  29 {
  30         int err = 1;
  31         uint64_t msr = 0;
  32         int fd;
  33         char file[20];
  34
  35         if (cpu > MCPU)
  36                 goto out;
  37
  38         sprintf(file, "/dev/cpu/%d/msr", cpu);
  39
  40         fd = open(file, O_RDONLY);
  41         if (fd < 0)
  42                 goto out;
  43         lseek(fd, MSR_FIDVID_STATUS, SEEK_CUR);
  44         if (read(fd, &msr, 8) != 8)
  45                 goto err1;
  46
  47         *fid = ((uint32_t )(msr & 0xffffffffull)) & MSR_S_LO_CURRENT_FID;
  48         *vid = ((uint32_t )(msr>>32 & 0xffffffffull)) & MSR_S_HI_CURRENT_VID;
  49         err = 0;
  50 err1:
  51         close(fd);
  52 out:
  53         return err;
  54 }
  55
  56
  57 /* Return a frequency in MHz, given an input fid */
  58 static uint32_t find_freq_from_fid(uint32_t fid)
  59 {
  60         return 800 + (fid * 100);
  61 }
  62
  63 /* Return a voltage in miliVolts, given an input vid */
  64 static uint32_t find_millivolts_from_vid(uint32_t vid)
  65 {
  66         return 1550-vid*25;
  67 }
  68
  69 int main (int argc, char *argv[])
  70 {
  71         int err;
  72         int cpu;
  73         uint32_t fid, vid;
  74
  75         if (argc < 2)
  76                 cpu = 0;
  77         else
  78                 cpu = strtoul(argv[1], NULL, 0);
  79
  80         err = get_fidvid(cpu, &fid, &vid);
  81
  82         if (err) {
  83                 printf("can't get fid, vid from MSR\n");
  84                 printf("Possible trouble: you don't run a powernow-k8 capable cpu\n");
  85                 printf("or you are not root, or the msr driver is not present\n");
  86                 exit(1);
  87         }
  88
  89
  90         printf("cpu %d currently at %d MHz and %d mV\n",
  91                         cpu,
  92                         find_freq_from_fid(fid),
  93                         find_millivolts_from_vid(vid));
  94
  95         return 0;
  96 }