1 #if defined(__i386__) || defined(__x86_64__)
2 
3 #include <fcntl.h>
4 #include <stdio.h>
5 #include <unistd.h>
6 #include <stdint.h>
7 
8 #include "helpers/helpers.h"
9 
10 /* Intel specific MSRs */
11 #define MSR_IA32_PERF_STATUS		0x198
12 #define MSR_IA32_MISC_ENABLES		0x1a0
13 #define MSR_IA32_ENERGY_PERF_BIAS	0x1b0
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 
26 int 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  */
55 int 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 
75 int msr_intel_get_perf_bias(unsigned int cpu)
76 {
77 	unsigned long long val;
78 	int ret;
79 
80 	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
81 		return -1;
82 
83 	ret = read_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &val);
84 	if (ret)
85 		return ret;
86 	return val;
87 }
88 
89 int msr_intel_set_perf_bias(unsigned int cpu, unsigned int val)
90 {
91 	int ret;
92 
93 	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
94 		return -1;
95 
96 	ret = write_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, val);
97 	if (ret)
98 		return ret;
99 	return 0;
100 }
101 
102 unsigned long long msr_intel_get_turbo_ratio(unsigned int cpu)
103 {
104 	unsigned long long val;
105 	int ret;
106 
107 	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_HAS_TURBO_RATIO))
108 		return -1;
109 
110 	ret = read_msr(cpu, MSR_NEHALEM_TURBO_RATIO_LIMIT, &val);
111 	if (ret)
112 		return ret;
113 	return val;
114 }
115 #endif
116