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 }
97