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 27 int 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 */ 56 int 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 76 int 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 90 int 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 } 102 103 unsigned 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