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
28static 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;
50err1:
51	close(fd);
52out:
53	return err;
54}
55
56
57/* Return a frequency in MHz, given an input fid */
58static 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 */
64static uint32_t find_millivolts_from_vid(uint32_t vid)
65{
66	return 1550-vid*25;
67}
68
69int 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