LXR linux/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
  27static 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;
  49err1:
  50        close(fd);
  51out:
  52        return err;
  53}
  54
  55
  56/* Return a frequency in MHz, given an input fid */
  57static 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 */
  63static uint32_t find_millivolts_from_vid(uint32_t vid)
  64{
  65        return 1550-vid*25;
  66}
  67
  68int 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}
  96