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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * (C) 2004 Bruno Ducrot <ducrot@poupinou.org>4 *5 * Based on code found in6 * linux/arch/i386/kernel/cpu/cpufreq/powernow-k8.c7 * and originally developed by Paul Devriendt8 */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 3221 22#define MSR_FIDVID_STATUS 0xc001004223 24#define MSR_S_HI_CURRENT_VID 0x0000001f25#define MSR_S_LO_CURRENT_FID 0x0000003f26 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 else77 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