1// SPDX-License-Identifier: GPL-2.0
 2#if defined(__i386__) || defined(__x86_64__)
 3
 4#include <fcntl.h>
 5#include <stdio.h>
 6#include <unistd.h>
 7#include <stdint.h>
 8
 9#include "helpers/helpers.h"
10
11/* Intel specific MSRs */
12#define MSR_IA32_PERF_STATUS		0x198
13#define MSR_IA32_MISC_ENABLES		0x1a0
14#define MSR_NEHALEM_TURBO_RATIO_LIMIT	0x1ad
15
16/*
17 * read_msr
18 *
19 * Will return 0 on success and -1 on failure.
20 * Possible errno values could be:
21 * EFAULT -If the read/write did not fully complete
22 * EIO    -If the CPU does not support MSRs
23 * ENXIO  -If the CPU does not exist
24 */
25
26int read_msr(int cpu, unsigned int idx, unsigned long long *val)
27{
28	int fd;
29	char msr_file_name[64];
30
31	sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
32	fd = open(msr_file_name, O_RDONLY);
33	if (fd < 0)
34		return -1;
35	if (lseek(fd, idx, SEEK_CUR) == -1)
36		goto err;
37	if (read(fd, val, sizeof *val) != sizeof *val)
38		goto err;
39	close(fd);
40	return 0;
41 err:
42	close(fd);
43	return -1;
44}
45
46/*
47 * write_msr
48 *
49 * Will return 0 on success and -1 on failure.
50 * Possible errno values could be:
51 * EFAULT -If the read/write did not fully complete
52 * EIO    -If the CPU does not support MSRs
53 * ENXIO  -If the CPU does not exist
54 */
55int write_msr(int cpu, unsigned int idx, unsigned long long val)
56{
57	int fd;
58	char msr_file_name[64];
59
60	sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
61	fd = open(msr_file_name, O_WRONLY);
62	if (fd < 0)
63		return -1;
64	if (lseek(fd, idx, SEEK_CUR) == -1)
65		goto err;
66	if (write(fd, &val, sizeof val) != sizeof val)
67		goto err;
68	close(fd);
69	return 0;
70 err:
71	close(fd);
72	return -1;
73}
74
75unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu)
76{
77	unsigned long long val;
78	int ret;
79
80	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_HAS_TURBO_RATIO))
81		return -1;
82
83	ret = read_msr(cpu, MSR_NEHALEM_TURBO_RATIO_LIMIT, &val);
84	if (ret)
85		return ret;
86	return val;
87}
88#endif

 1// SPDX-License-Identifier: GPL-2.0
 2#if defined(__i386__) || defined(__x86_64__)
 3
 4#include <fcntl.h>
 5#include <stdio.h>
 6#include <unistd.h>
 7#include <stdint.h>
 8
 9#include "helpers/helpers.h"
10
11/* Intel specific MSRs */
12#define MSR_IA32_PERF_STATUS		0x198
13#define MSR_IA32_MISC_ENABLES		0x1a0
14#define MSR_NEHALEM_TURBO_RATIO_LIMIT	0x1ad
15
16/*
17 * read_msr
18 *
19 * Will return 0 on success and -1 on failure.
20 * Possible errno values could be:
21 * EFAULT -If the read/write did not fully complete
22 * EIO    -If the CPU does not support MSRs
23 * ENXIO  -If the CPU does not exist
24 */
25
26int read_msr(int cpu, unsigned int idx, unsigned long long *val)
27{
28	int fd;
29	char msr_file_name[64];
30
31	sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
32	fd = open(msr_file_name, O_RDONLY);
33	if (fd < 0)
34		return -1;
35	if (lseek(fd, idx, SEEK_CUR) == -1)
36		goto err;
37	if (read(fd, val, sizeof *val) != sizeof *val)
38		goto err;
39	close(fd);
40	return 0;
41 err:
42	close(fd);
43	return -1;
44}
45
46/*
47 * write_msr
48 *
49 * Will return 0 on success and -1 on failure.
50 * Possible errno values could be:
51 * EFAULT -If the read/write did not fully complete
52 * EIO    -If the CPU does not support MSRs
53 * ENXIO  -If the CPU does not exist
54 */
55int write_msr(int cpu, unsigned int idx, unsigned long long val)
56{
57	int fd;
58	char msr_file_name[64];
59
60	sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
61	fd = open(msr_file_name, O_WRONLY);
62	if (fd < 0)
63		return -1;
64	if (lseek(fd, idx, SEEK_CUR) == -1)
65		goto err;
66	if (write(fd, &val, sizeof val) != sizeof val)
67		goto err;
68	close(fd);
69	return 0;
70 err:
71	close(fd);
72	return -1;
73}
74
75unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu)
76{
77	unsigned long long val;
78	int ret;
79
80	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_HAS_TURBO_RATIO))
81		return -1;
82
83	ret = read_msr(cpu, MSR_NEHALEM_TURBO_RATIO_LIMIT, &val);
84	if (ret)
85		return ret;
86	return val;
87}
88#endif