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 */
 42enum {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). */
 54struct 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 */
 74struct dbs_data;
 75struct 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)					\
 83static 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)					\
 91static 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)						\
 98static struct governor_attr _name =					\
 99__ATTR(_name, 0444, show_##_name, NULL)
100
101#define gov_attr_rw(_name)						\
102static struct governor_attr _name =					\
103__ATTR(_name, 0644, show_##_name, store_##_name)
104
105/* Common to all CPUs of a policy */
106struct 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
129static 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 */
136struct 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 */
152struct 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
170static 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 */
176struct od_ops {
177	unsigned int (*powersave_bias_target)(struct cpufreq_policy *policy,
178			unsigned int freq_next, unsigned int relation);
179};
180
181unsigned int dbs_update(struct cpufreq_policy *policy);
182int cpufreq_governor_dbs(struct cpufreq_policy *policy, unsigned int event);
183void od_register_powersave_bias_handler(unsigned int (*f)
184		(struct cpufreq_policy *, unsigned int, unsigned int),
185		unsigned int powersave_bias);
186void od_unregister_powersave_bias_handler(void);
187ssize_t store_sampling_rate(struct dbs_data *dbs_data, const char *buf,
188			    size_t count);
189void gov_update_cpu_data(struct dbs_data *dbs_data);
190#endif /* _CPUFREQ_GOVERNOR_H */