tools/power/cpupower/utils/helpers/msr.c

   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
  15 /*
  16  * read_msr
  17  *
  18  * Will return 0 on success and -1 on failure.
  19  * Possible errno values could be:
  20  * EFAULT -If the read/write did not fully complete
  21  * EIO    -If the CPU does not support MSRs
  22  * ENXIO  -If the CPU does not exist
  23  */
  24
  25 int read_msr(int cpu, unsigned int idx, unsigned long long *val)
  26 {
  27         int fd;
  28         char msr_file_name[64];
  29
  30         sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
  31         fd = open(msr_file_name, O_RDONLY);
  32         if (fd < 0)
  33                 return -1;
  34         if (lseek(fd, idx, SEEK_CUR) == -1)
  35                 goto err;
  36         if (read(fd, val, sizeof *val) != sizeof *val)
  37                 goto err;
  38         close(fd);
  39         return 0;
  40  err:
  41         close(fd);
  42         return -1;
  43 }
  44
  45 /*
  46  * write_msr
  47  *
  48  * Will return 0 on success and -1 on failure.
  49  * Possible errno values could be:
  50  * EFAULT -If the read/write did not fully complete
  51  * EIO    -If the CPU does not support MSRs
  52  * ENXIO  -If the CPU does not exist
  53  */
  54 int write_msr(int cpu, unsigned int idx, unsigned long long val)
  55 {
  56         int fd;
  57         char msr_file_name[64];
  58
  59         sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
  60         fd = open(msr_file_name, O_WRONLY);
  61         if (fd < 0)
  62                 return -1;
  63         if (lseek(fd, idx, SEEK_CUR) == -1)
  64                 goto err;
  65         if (write(fd, &val, sizeof val) != sizeof val)
  66                 goto err;
  67         close(fd);
  68         return 0;
  69  err:
  70         close(fd);
  71         return -1;
  72 }
  73
  74 int msr_intel_has_boost_support(unsigned int cpu)
  75 {
  76         unsigned long long misc_enables;
  77         int ret;
  78
  79         ret = read_msr(cpu, MSR_IA32_MISC_ENABLES, &misc_enables);
  80         if (ret)
  81                 return ret;
  82         return (misc_enables >> 38) & 0x1;
  83 }
  84
  85 int msr_intel_boost_is_active(unsigned int cpu)
  86 {
  87         unsigned long long perf_status;
  88         int ret;
  89
  90         ret = read_msr(cpu, MSR_IA32_PERF_STATUS, &perf_status);
  91         if (ret)
  92                 return ret;
  93         return (perf_status >> 32) & 0x1;
  94 }
  95
  96 int msr_intel_get_perf_bias(unsigned int cpu)
  97 {
  98         unsigned long long val;
  99         int ret;
 100
 101         if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
 102                 return -1;
 103
 104         ret = read_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &val);
 105         if (ret)
 106                 return ret;
 107         return val;
 108 }
 109
 110 int msr_intel_set_perf_bias(unsigned int cpu, unsigned int val)
 111 {
 112         int ret;
 113
 114         if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_PERF_BIAS))
 115                 return -1;
 116
 117         ret = write_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, val);
 118         if (ret)
 119                 return ret;
 120         return 0;
 121 }
 122 #endif