drivers/cpufreq/cpufreq_governor.h

   1 /*
   2  * drivers/cpufreq/cpufreq_governor.h
   3  *
   4  * Header file for CPUFreq governors common code
   5  *
   6  * Copyright    (C) 2001 Russell King
   7  *              (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
   8  *              (C) 2003 Jun Nakajima <jun.nakajima@intel.com>
   9  *              (C) 2009 Alexander Clouter <alex@digriz.org.uk>
  10  *              (c) 2012 Viresh Kumar <viresh.kumar@linaro.org>
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License version 2 as
  14  * published by the Free Software Foundation.
  15  */
  16
  17 #ifndef _CPUFREQ_GOVERNOR_H
  18 #define _CPUFREQ_GOVERNOR_H
  19
  20 #include <linux/atomic.h>
  21 #include <linux/irq_work.h>
  22 #include <linux/cpufreq.h>
  23 #include <linux/kernel_stat.h>
  24 #include <linux/module.h>
  25 #include <linux/mutex.h>
  26
  27 /*
  28  * The polling frequency depends on the capability of the processor. Default
  29  * polling frequency is 1000 times the transition latency of the processor. The
  30  * governor will work on any processor with transition latency <= 10ms, using
  31  * appropriate sampling rate.
  32  *
  33  * For CPUs with transition latency > 10ms (mostly drivers with CPUFREQ_ETERNAL)
  34  * this governor will not work. All times here are in us (micro seconds).
  35  */
  36 #define MIN_SAMPLING_RATE_RATIO                 (2)
  37 #define LATENCY_MULTIPLIER                      (1000)
  38 #define MIN_LATENCY_MULTIPLIER                  (20)
  39 #define TRANSITION_LATENCY_LIMIT                (10 * 1000 * 1000)
  40
  41 /* Ondemand Sampling types */
  42 enum {OD_NORMAL_SAMPLE, OD_SUB_SAMPLE};
  43
  44 /*
  45  * Abbreviations:
  46  * dbs: used as a shortform for demand based switching It helps to keep variable
  47  *      names smaller, simpler
  48  * cdbs: common dbs
  49  * od_*: On-demand governor
  50  * cs_*: Conservative governor
  51  */
  52
  53 /* Governor demand based switching data (per-policy or global). */
  54 struct dbs_data {
  55         int usage_count;
  56         void *tuners;
  57         unsigned int min_sampling_rate;
  58         unsigned int ignore_nice_load;
  59         unsigned int sampling_rate;
  60         unsigned int sampling_down_factor;
  61         unsigned int up_threshold;
  62         unsigned int io_is_busy;
  63
  64         struct kobject kobj;
  65         struct list_head policy_dbs_list;
  66         /*
  67          * Protect concurrent updates to governor tunables from sysfs,
  68          * policy_dbs_list and usage_count.
  69          */
  70         struct mutex mutex;
  71 };
  72
  73 /* Governor's specific attributes */
  74 struct dbs_data;
  75 struct governor_attr {
  76         struct attribute attr;
  77         ssize_t (*show)(struct dbs_data *dbs_data, char *buf);
  78         ssize_t (*store)(struct dbs_data *dbs_data, const char *buf,
  79                          size_t count);
  80 };
  81
  82 #define gov_show_one(_gov, file_name)                                   \
  83 static ssize_t show_##file_name                                         \
  84 (struct dbs_data *dbs_data, char *buf)                                  \
  85 {                                                                       \
  86         struct _gov##_dbs_tuners *tuners = dbs_data->tuners;            \
  87         return sprintf(buf, "%u\n", tuners->file_name);                 \
  88 }
  89
  90 #define gov_show_one_common(file_name)                                  \
  91 static ssize_t show_##file_name                                         \
  92 (struct dbs_data *dbs_data, char *buf)                                  \
  93 {                                                                       \
  94         return sprintf(buf, "%u\n", dbs_data->file_name);               \
  95 }
  96
  97 #define gov_attr_ro(_name)                                              \
  98 static struct governor_attr _name =                                     \
  99 __ATTR(_name, 0444, show_##_name, NULL)
 100
 101 #define gov_attr_rw(_name)                                              \
 102 static struct governor_attr _name =                                     \
 103 __ATTR(_name, 0644, show_##_name, store_##_name)
 104
 105 /* Common to all CPUs of a policy */
 106 struct policy_dbs_info {
 107         struct cpufreq_policy *policy;
 108         /*
 109          * Per policy mutex that serializes load evaluation from limit-change
 110          * and work-handler.
 111          */
 112         struct mutex timer_mutex;
 113
 114         u64 last_sample_time;
 115         s64 sample_delay_ns;
 116         atomic_t work_count;
 117         struct irq_work irq_work;
 118         struct work_struct work;
 119         /* dbs_data may be shared between multiple policy objects */
 120         struct dbs_data *dbs_data;
 121         struct list_head list;
 122         /* Multiplier for increasing sample delay temporarily. */
 123         unsigned int rate_mult;
 124         /* Status indicators */
 125         bool is_shared;         /* This object is used by multiple CPUs */
 126         bool work_in_progress;  /* Work is being queued up or in progress */
 127 };
 128
 129 static inline void gov_update_sample_delay(struct policy_dbs_info *policy_dbs,
 130                                            unsigned int delay_us)
 131 {
 132         policy_dbs->sample_delay_ns = delay_us * NSEC_PER_USEC;
 133 }
 134
 135 /* Per cpu structures */
 136 struct cpu_dbs_info {
 137         u64 prev_cpu_idle;
 138         u64 prev_cpu_wall;
 139         u64 prev_cpu_nice;
 140         /*
 141          * Used to keep track of load in the previous interval. However, when
 142          * explicitly set to zero, it is used as a flag to ensure that we copy
 143          * the previous load to the current interval only once, upon the first
 144          * wake-up from idle.
 145          */
 146         unsigned int prev_load;
 147         struct update_util_data update_util;
 148         struct policy_dbs_info *policy_dbs;
 149 };
 150
 151 /* Common Governor data across policies */
 152 struct dbs_governor {
 153         struct cpufreq_governor gov;
 154         struct kobj_type kobj_type;
 155
 156         /*
 157          * Common data for platforms that don't set
 158          * CPUFREQ_HAVE_GOVERNOR_PER_POLICY
 159          */
 160         struct dbs_data *gdbs_data;
 161
 162         unsigned int (*gov_dbs_timer)(struct cpufreq_policy *policy);
 163         struct policy_dbs_info *(*alloc)(void);
 164         void (*free)(struct policy_dbs_info *policy_dbs);
 165         int (*init)(struct dbs_data *dbs_data, bool notify);
 166         void (*exit)(struct dbs_data *dbs_data, bool notify);
 167         void (*start)(struct cpufreq_policy *policy);
 168 };
 169
 170 static inline struct dbs_governor *dbs_governor_of(struct cpufreq_policy *policy)
 171 {
 172         return container_of(policy->governor, struct dbs_governor, gov);
 173 }
 174
 175 /* Governor specific operations */
 176 struct od_ops {
 177         unsigned int (*powersave_bias_target)(struct cpufreq_policy *policy,
 178                         unsigned int freq_next, unsigned int relation);
 179 };
 180
 181 unsigned int dbs_update(struct cpufreq_policy *policy);
 182 int cpufreq_governor_dbs(struct cpufreq_policy *policy, unsigned int event);
 183 void od_register_powersave_bias_handler(unsigned int (*f)
 184                 (struct cpufreq_policy *, unsigned int, unsigned int),
 185                 unsigned int powersave_bias);
 186 void od_unregister_powersave_bias_handler(void);
 187 ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
 188                             size_t count);
 189 void gov_update_cpu_data(struct dbs_data *dbs_data);
 190 #endif /* _CPUFREQ_GOVERNOR_H */