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_IA32_ENERGY_PERF_BIAS	0x1b0
15#define MSR_NEHALEM_TURBO_RATIO_LIMIT	0x1ad
16
17/*
18 * read_msr
19 *
20 * Will return 0 on success and -1 on failure.
21 * Possible errno values could be:
22 * EFAULT -If the read/write did not fully complete
23 * EIO    -If the CPU does not support MSRs
24 * ENXIO  -If the CPU does not exist
25 */
26
27int read_msr(int cpu, unsigned int idx, unsigned long long *val)
28{
29	int fd;
30	char msr_file_name[64];
31
32	sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
33	fd = open(msr_file_name, O_RDONLY);
34	if (fd < 0)
35		return -1;
36	if (lseek(fd, idx, SEEK_CUR) == -1)
37		goto err;
38	if (read(fd, val, sizeof *val) != sizeof *val)
39		goto err;
40	close(fd);
41	return 0;
42 err:
43	close(fd);
44	return -1;
45}
46
47/*
48 * write_msr
49 *
50 * Will return 0 on success and -1 on failure.
51 * Possible errno values could be:
52 * EFAULT -If the read/write did not fully complete
53 * EIO    -If the CPU does not support MSRs
54 * ENXIO  -If the CPU does not exist
55 */
56int write_msr(int cpu, unsigned int idx, unsigned long long val)
57{
58	int fd;
59	char msr_file_name[64];
60
61	sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
62	fd = open(msr_file_name, O_WRONLY);
63	if (fd < 0)
64		return -1;
65	if (lseek(fd, idx, SEEK_CUR) == -1)
66		goto err;
67	if (write(fd, &val, sizeof val) != sizeof val)
68		goto err;
69	close(fd);
70	return 0;
71 err:
72	close(fd);
73	return -1;
74}
75
76int msr_intel_get_perf_bias(unsigned int cpu)
77{
78	unsigned long long val;
79	int ret;
80
81	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
82		return -1;
83
84	ret = read_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &val);
85	if (ret)
86		return ret;
87	return val;
88}
89
90int msr_intel_set_perf_bias(unsigned int cpu, unsigned int val)
91{
92	int ret;
93
94	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
95		return -1;
96
97	ret = write_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, val);
98	if (ret)
99		return ret;
100	return 0;
101}
102
103unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu)
104{
105	unsigned long long val;
106	int ret;
107
108	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_HAS_TURBO_RATIO))
109		return -1;
110
111	ret = read_msr(cpu, MSR_NEHALEM_TURBO_RATIO_LIMIT, &val);
112	if (ret)
113		return ret;
114	return val;
115}
116#endif
117