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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  (C) 2004 Bruno Ducrot <ducrot@poupinou.org>
   4  *
   5  * Based on code found in
   6  * linux/arch/i386/kernel/cpu/cpufreq/powernow-k8.c
   7  * and originally developed by Paul Devriendt
   8  */
   9
  10 #include <stdio.h>
  11 #include <stdlib.h>
  12 #include <stdint.h>
  13 #include <unistd.h>
  14 #include <errno.h>
  15 #include <fcntl.h>
  16
  17 #include <sys/types.h>
  18 #include <sys/stat.h>
  19
  20 #define MCPU 32
  21
  22 #define MSR_FIDVID_STATUS       0xc0010042
  23
  24 #define MSR_S_HI_CURRENT_VID    0x0000001f
  25 #define MSR_S_LO_CURRENT_FID    0x0000003f
  26
  27 static int get_fidvid(uint32_t cpu, uint32_t *fid, uint32_t *vid)
  28 {
  29         int err = 1;
  30         uint64_t msr = 0;
  31         int fd;
  32         char file[20];
  33
  34         if (cpu > MCPU)
  35                 goto out;
  36
  37         sprintf(file, "/dev/cpu/%d/msr", cpu);
  38
  39         fd = open(file, O_RDONLY);
  40         if (fd < 0)
  41                 goto out;
  42         lseek(fd, MSR_FIDVID_STATUS, SEEK_CUR);
  43         if (read(fd, &msr, 8) != 8)
  44                 goto err1;
  45
  46         *fid = ((uint32_t )(msr & 0xffffffffull)) & MSR_S_LO_CURRENT_FID;
  47         *vid = ((uint32_t )(msr>>32 & 0xffffffffull)) & MSR_S_HI_CURRENT_VID;
  48         err = 0;
  49 err1:
  50         close(fd);
  51 out:
  52         return err;
  53 }
  54
  55
  56 /* Return a frequency in MHz, given an input fid */
  57 static uint32_t find_freq_from_fid(uint32_t fid)
  58 {
  59         return 800 + (fid * 100);
  60 }
  61
  62 /* Return a voltage in miliVolts, given an input vid */
  63 static uint32_t find_millivolts_from_vid(uint32_t vid)
  64 {
  65         return 1550-vid*25;
  66 }
  67
  68 int main (int argc, char *argv[])
  69 {
  70         int err;
  71         int cpu;
  72         uint32_t fid, vid;
  73
  74         if (argc < 2)
  75                 cpu = 0;
  76         else
  77                 cpu = strtoul(argv[1], NULL, 0);
  78
  79         err = get_fidvid(cpu, &fid, &vid);
  80
  81         if (err) {
  82                 printf("can't get fid, vid from MSR\n");
  83                 printf("Possible trouble: you don't run a powernow-k8 capable cpu\n");
  84                 printf("or you are not root, or the msr driver is not present\n");
  85                 exit(1);
  86         }
  87
  88
  89         printf("cpu %d currently at %d MHz and %d mV\n",
  90                         cpu,
  91                         find_freq_from_fid(fid),
  92                         find_millivolts_from_vid(vid));
  93
  94         return 0;
  95 }