1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * (C) 2004 Bruno Ducrot <ducrot@poupinou.org>
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Based on code found in
6*4882a593Smuzhiyun * linux/arch/i386/kernel/cpu/cpufreq/powernow-k8.c
7*4882a593Smuzhiyun * and originally developed by Paul Devriendt
8*4882a593Smuzhiyun */
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun #include <stdio.h>
11*4882a593Smuzhiyun #include <stdlib.h>
12*4882a593Smuzhiyun #include <stdint.h>
13*4882a593Smuzhiyun #include <unistd.h>
14*4882a593Smuzhiyun #include <errno.h>
15*4882a593Smuzhiyun #include <fcntl.h>
16*4882a593Smuzhiyun
17*4882a593Smuzhiyun #include <sys/types.h>
18*4882a593Smuzhiyun #include <sys/stat.h>
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun #define MCPU 32
21*4882a593Smuzhiyun
22*4882a593Smuzhiyun #define MSR_FIDVID_STATUS 0xc0010042
23*4882a593Smuzhiyun
24*4882a593Smuzhiyun #define MSR_S_HI_CURRENT_VID 0x0000001f
25*4882a593Smuzhiyun #define MSR_S_LO_CURRENT_FID 0x0000003f
26*4882a593Smuzhiyun
get_fidvid(uint32_t cpu,uint32_t * fid,uint32_t * vid)27*4882a593Smuzhiyun static int get_fidvid(uint32_t cpu, uint32_t *fid, uint32_t *vid)
28*4882a593Smuzhiyun {
29*4882a593Smuzhiyun int err = 1;
30*4882a593Smuzhiyun uint64_t msr = 0;
31*4882a593Smuzhiyun int fd;
32*4882a593Smuzhiyun char file[20];
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun if (cpu > MCPU)
35*4882a593Smuzhiyun goto out;
36*4882a593Smuzhiyun
37*4882a593Smuzhiyun sprintf(file, "/dev/cpu/%d/msr", cpu);
38*4882a593Smuzhiyun
39*4882a593Smuzhiyun fd = open(file, O_RDONLY);
40*4882a593Smuzhiyun if (fd < 0)
41*4882a593Smuzhiyun goto out;
42*4882a593Smuzhiyun lseek(fd, MSR_FIDVID_STATUS, SEEK_CUR);
43*4882a593Smuzhiyun if (read(fd, &msr, 8) != 8)
44*4882a593Smuzhiyun goto err1;
45*4882a593Smuzhiyun
46*4882a593Smuzhiyun *fid = ((uint32_t )(msr & 0xffffffffull)) & MSR_S_LO_CURRENT_FID;
47*4882a593Smuzhiyun *vid = ((uint32_t )(msr>>32 & 0xffffffffull)) & MSR_S_HI_CURRENT_VID;
48*4882a593Smuzhiyun err = 0;
49*4882a593Smuzhiyun err1:
50*4882a593Smuzhiyun close(fd);
51*4882a593Smuzhiyun out:
52*4882a593Smuzhiyun return err;
53*4882a593Smuzhiyun }
54*4882a593Smuzhiyun
55*4882a593Smuzhiyun
56*4882a593Smuzhiyun /* Return a frequency in MHz, given an input fid */
find_freq_from_fid(uint32_t fid)57*4882a593Smuzhiyun static uint32_t find_freq_from_fid(uint32_t fid)
58*4882a593Smuzhiyun {
59*4882a593Smuzhiyun return 800 + (fid * 100);
60*4882a593Smuzhiyun }
61*4882a593Smuzhiyun
62*4882a593Smuzhiyun /* Return a voltage in miliVolts, given an input vid */
find_millivolts_from_vid(uint32_t vid)63*4882a593Smuzhiyun static uint32_t find_millivolts_from_vid(uint32_t vid)
64*4882a593Smuzhiyun {
65*4882a593Smuzhiyun return 1550-vid*25;
66*4882a593Smuzhiyun }
67*4882a593Smuzhiyun
main(int argc,char * argv[])68*4882a593Smuzhiyun int main (int argc, char *argv[])
69*4882a593Smuzhiyun {
70*4882a593Smuzhiyun int err;
71*4882a593Smuzhiyun int cpu;
72*4882a593Smuzhiyun uint32_t fid, vid;
73*4882a593Smuzhiyun
74*4882a593Smuzhiyun if (argc < 2)
75*4882a593Smuzhiyun cpu = 0;
76*4882a593Smuzhiyun else
77*4882a593Smuzhiyun cpu = strtoul(argv[1], NULL, 0);
78*4882a593Smuzhiyun
79*4882a593Smuzhiyun err = get_fidvid(cpu, &fid, &vid);
80*4882a593Smuzhiyun
81*4882a593Smuzhiyun if (err) {
82*4882a593Smuzhiyun printf("can't get fid, vid from MSR\n");
83*4882a593Smuzhiyun printf("Possible trouble: you don't run a powernow-k8 capable cpu\n");
84*4882a593Smuzhiyun printf("or you are not root, or the msr driver is not present\n");
85*4882a593Smuzhiyun exit(1);
86*4882a593Smuzhiyun }
87*4882a593Smuzhiyun
88*4882a593Smuzhiyun
89*4882a593Smuzhiyun printf("cpu %d currently at %d MHz and %d mV\n",
90*4882a593Smuzhiyun cpu,
91*4882a593Smuzhiyun find_freq_from_fid(fid),
92*4882a593Smuzhiyun find_millivolts_from_vid(vid));
93*4882a593Smuzhiyun
94*4882a593Smuzhiyun return 0;
95*4882a593Smuzhiyun }
96