drivers/cpufreq/cpufreq_governor.c

   1 /*
   2  * drivers/cpufreq/cpufreq_governor.c
   3  *
   4  * CPUFREQ governors common code
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <asm/cputime.h>
  12 #include <linux/export.h>
  13 #include <linux/kernel_stat.h>
  14 #include <linux/tick.h>
  15 #include <linux/types.h>
  16 /*
  17  * Code picked from earlier governer implementations
  18  */
  19 static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
  20 {
  21         u64 idle_time;
  22         u64 cur_wall_time;
  23         u64 busy_time;
  24
  25         cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
  26
  27         busy_time = kcpustat_cpu(cpu).cpustat[CPUTIME_USER];
  28         busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SYSTEM];
  29         busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_IRQ];
  30         busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SOFTIRQ];
  31         busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_STEAL];
  32         busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_NICE];
  33
  34         idle_time = cur_wall_time - busy_time;
  35         if (wall)
  36                 *wall = cputime_to_usecs(cur_wall_time);
  37
  38         return cputime_to_usecs(idle_time);
  39 }
  40
  41 cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
  42 {
  43         u64 idle_time = get_cpu_idle_time_us(cpu, NULL);
  44
  45         if (idle_time == -1ULL)
  46                 return get_cpu_idle_time_jiffy(cpu, wall);
  47         else
  48                 idle_time += get_cpu_iowait_time_us(cpu, wall);
  49
  50         return idle_time;
  51 }
  52 EXPORT_SYMBOL_GPL(get_cpu_idle_time);