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