init android origin source code

1 files changed, 814 insertions, 0 deletions

diff --git a/ANDROID_3.4.5/drivers/cpufreq/cpufreq_ondemand.c b/ANDROID_3.4.5/drivers/cpufreq/cpufreq_ondemand.c
new file mode 100644
index 00000000..836e9b06
--- /dev/null
+++ b/ANDROID_3.4.5/drivers/cpufreq/cpufreq_ondemand.c
@@ -0,0 +1,814 @@
+/*
+ *  drivers/cpufreq/cpufreq_ondemand.c
+ *
+ *  Copyright (C)  2001 Russell King
+ *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
+ *                      Jun Nakajima <jun.nakajima@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/cpufreq.h>
+#include <linux/cpu.h>
+#include <linux/jiffies.h>
+#include <linux/kernel_stat.h>
+#include <linux/mutex.h>
+#include <linux/hrtimer.h>
+#include <linux/tick.h>
+#include <linux/ktime.h>
+#include <linux/sched.h>
+
+/*
+ * dbs is used in this file as a shortform for demandbased switching
+ * It helps to keep variable names smaller, simpler
+ */
+
+#define DEF_FREQUENCY_DOWN_DIFFERENTIAL		(10)
+#define DEF_FREQUENCY_UP_THRESHOLD		(80)
+#define DEF_SAMPLING_DOWN_FACTOR		(1)
+#define MAX_SAMPLING_DOWN_FACTOR		(100000)
+#define MICRO_FREQUENCY_DOWN_DIFFERENTIAL	(3)
+#define MICRO_FREQUENCY_UP_THRESHOLD		(95)
+#define MICRO_FREQUENCY_MIN_SAMPLE_RATE		(10000)
+#define MIN_FREQUENCY_UP_THRESHOLD		(11)
+#define MAX_FREQUENCY_UP_THRESHOLD		(100)
+
+/*
+ * The polling frequency of this governor depends on the capability of
+ * the processor. Default polling frequency is 1000 times the transition
+ * latency of the processor. The governor will work on any processor with
+ * transition latency <= 10mS, using appropriate sampling
+ * rate.
+ * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
+ * this governor will not work.
+ * All times here are in uS.
+ */
+#define MIN_SAMPLING_RATE_RATIO			(2)
+
+static unsigned int min_sampling_rate;
+
+#define LATENCY_MULTIPLIER			(1000)
+#define MIN_LATENCY_MULTIPLIER			(100)
+#define TRANSITION_LATENCY_LIMIT		(10 * 1000 * 1000)
+
+static void do_dbs_timer(struct work_struct *work);
+static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
+				unsigned int event);
+
+#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
+static
+#endif
+struct cpufreq_governor cpufreq_gov_ondemand = {
+       .name                   = "ondemand",
+       .governor               = cpufreq_governor_dbs,
+       .max_transition_latency = TRANSITION_LATENCY_LIMIT,
+       .owner                  = THIS_MODULE,
+};
+
+/* Sampling types */
+enum {DBS_NORMAL_SAMPLE, DBS_SUB_SAMPLE};
+
+struct cpu_dbs_info_s {
+	cputime64_t prev_cpu_idle;
+	cputime64_t prev_cpu_iowait;
+	cputime64_t prev_cpu_wall;
+	cputime64_t prev_cpu_nice;
+	struct cpufreq_policy *cur_policy;
+	struct delayed_work work;
+	struct cpufreq_frequency_table *freq_table;
+	unsigned int freq_lo;
+	unsigned int freq_lo_jiffies;
+	unsigned int freq_hi_jiffies;
+	unsigned int rate_mult;
+	int cpu;
+	unsigned int sample_type:1;
+	/*
+	 * percpu mutex that serializes governor limit change with
+	 * do_dbs_timer invocation. We do not want do_dbs_timer to run
+	 * when user is changing the governor or limits.
+	 */
+	struct mutex timer_mutex;
+};
+static DEFINE_PER_CPU(struct cpu_dbs_info_s, od_cpu_dbs_info);
+
+static unsigned int dbs_enable;	/* number of CPUs using this policy */
+
+/*
+ * dbs_mutex protects dbs_enable in governor start/stop.
+ */
+static DEFINE_MUTEX(dbs_mutex);
+
+static struct dbs_tuners {
+	unsigned int sampling_rate;
+	unsigned int up_threshold;
+	unsigned int down_differential;
+	unsigned int ignore_nice;
+	unsigned int sampling_down_factor;
+	unsigned int powersave_bias;
+	unsigned int io_is_busy;
+} dbs_tuners_ins = {
+	.up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
+	.sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
+	.down_differential = DEF_FREQUENCY_DOWN_DIFFERENTIAL,
+	.ignore_nice = 0,
+	.powersave_bias = 0,
+};
+
+static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
+{
+	u64 idle_time;
+	u64 cur_wall_time;
+	u64 busy_time;
+
+	cur_wall_time = jiffies64_to_cputime64(get_jiffies_64());
+
+	busy_time  = kcpustat_cpu(cpu).cpustat[CPUTIME_USER];
+	busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SYSTEM];
+	busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_IRQ];
+	busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SOFTIRQ];
+	busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_STEAL];
+	busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_NICE];
+
+	idle_time = cur_wall_time - busy_time;
+	if (wall)
+		*wall = jiffies_to_usecs(cur_wall_time);
+
+	return jiffies_to_usecs(idle_time);
+}
+
+static inline cputime64_t get_cpu_idle_time(unsigned int cpu, cputime64_t *wall)
+{
+	u64 idle_time = get_cpu_idle_time_us(cpu, NULL);
+
+	if (idle_time == -1ULL)
+		return get_cpu_idle_time_jiffy(cpu, wall);
+	else
+		idle_time += get_cpu_iowait_time_us(cpu, wall);
+
+	return idle_time;
+}
+
+static inline cputime64_t get_cpu_iowait_time(unsigned int cpu, cputime64_t *wall)
+{
+	u64 iowait_time = get_cpu_iowait_time_us(cpu, wall);
+
+	if (iowait_time == -1ULL)
+		return 0;
+
+	return iowait_time;
+}
+
+/*
+ * Find right freq to be set now with powersave_bias on.
+ * Returns the freq_hi to be used right now and will set freq_hi_jiffies,
+ * freq_lo, and freq_lo_jiffies in percpu area for averaging freqs.
+ */
+static unsigned int powersave_bias_target(struct cpufreq_policy *policy,
+					  unsigned int freq_next,
+					  unsigned int relation)
+{
+	unsigned int freq_req, freq_reduc, freq_avg;
+	unsigned int freq_hi, freq_lo;
+	unsigned int index = 0;
+	unsigned int jiffies_total, jiffies_hi, jiffies_lo;
+	struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info,
+						   policy->cpu);
+
+	if (!dbs_info->freq_table) {
+		dbs_info->freq_lo = 0;
+		dbs_info->freq_lo_jiffies = 0;
+		return freq_next;
+	}
+
+	cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_next,
+			relation, &index);
+	freq_req = dbs_info->freq_table[index].frequency;
+	freq_reduc = freq_req * dbs_tuners_ins.powersave_bias / 1000;
+	freq_avg = freq_req - freq_reduc;
+
+	/* Find freq bounds for freq_avg in freq_table */
+	index = 0;
+	cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
+			CPUFREQ_RELATION_H, &index);
+	freq_lo = dbs_info->freq_table[index].frequency;
+	index = 0;
+	cpufreq_frequency_table_target(policy, dbs_info->freq_table, freq_avg,
+			CPUFREQ_RELATION_L, &index);
+	freq_hi = dbs_info->freq_table[index].frequency;
+
+	/* Find out how long we have to be in hi and lo freqs */
+	if (freq_hi == freq_lo) {
+		dbs_info->freq_lo = 0;
+		dbs_info->freq_lo_jiffies = 0;
+		return freq_lo;
+	}
+	jiffies_total = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
+	jiffies_hi = (freq_avg - freq_lo) * jiffies_total;
+	jiffies_hi += ((freq_hi - freq_lo) / 2);
+	jiffies_hi /= (freq_hi - freq_lo);
+	jiffies_lo = jiffies_total - jiffies_hi;
+	dbs_info->freq_lo = freq_lo;
+	dbs_info->freq_lo_jiffies = jiffies_lo;
+	dbs_info->freq_hi_jiffies = jiffies_hi;
+	return freq_hi;
+}
+
+static void ondemand_powersave_bias_init_cpu(int cpu)
+{
+	struct cpu_dbs_info_s *dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
+	dbs_info->freq_table = cpufreq_frequency_get_table(cpu);
+	dbs_info->freq_lo = 0;
+}
+
+static void ondemand_powersave_bias_init(void)
+{
+	int i;
+	for_each_online_cpu(i) {
+		ondemand_powersave_bias_init_cpu(i);
+	}
+}
+
+/************************** sysfs interface ************************/
+
+static ssize_t show_sampling_rate_min(struct kobject *kobj,
+				      struct attribute *attr, char *buf)
+{
+	return sprintf(buf, "%u\n", min_sampling_rate);
+}
+
+define_one_global_ro(sampling_rate_min);
+
+/* cpufreq_ondemand Governor Tunables */
+#define show_one(file_name, object)					\
+static ssize_t show_##file_name						\
+(struct kobject *kobj, struct attribute *attr, char *buf)              \
+{									\
+	return sprintf(buf, "%u\n", dbs_tuners_ins.object);		\
+}
+show_one(sampling_rate, sampling_rate);
+show_one(io_is_busy, io_is_busy);
+show_one(up_threshold, up_threshold);
+show_one(sampling_down_factor, sampling_down_factor);
+show_one(ignore_nice_load, ignore_nice);
+show_one(powersave_bias, powersave_bias);
+
+/**
+ * update_sampling_rate - update sampling rate effective immediately if needed.
+ * @new_rate: new sampling rate
+ *
+ * If new rate is smaller than the old, simply updaing
+ * dbs_tuners_int.sampling_rate might not be appropriate. For example,
+ * if the original sampling_rate was 1 second and the requested new sampling
+ * rate is 10 ms because the user needs immediate reaction from ondemand
+ * governor, but not sure if higher frequency will be required or not,
+ * then, the governor may change the sampling rate too late; up to 1 second
+ * later. Thus, if we are reducing the sampling rate, we need to make the
+ * new value effective immediately.
+ */
+static void update_sampling_rate(unsigned int new_rate)
+{
+	int cpu;
+
+	dbs_tuners_ins.sampling_rate = new_rate
+				     = max(new_rate, min_sampling_rate);
+
+	for_each_online_cpu(cpu) {
+		struct cpufreq_policy *policy;
+		struct cpu_dbs_info_s *dbs_info;
+		unsigned long next_sampling, appointed_at;
+
+		policy = cpufreq_cpu_get(cpu);
+		if (!policy)
+			continue;
+		dbs_info = &per_cpu(od_cpu_dbs_info, policy->cpu);
+		cpufreq_cpu_put(policy);
+
+		mutex_lock(&dbs_info->timer_mutex);
+
+		if (!delayed_work_pending(&dbs_info->work)) {
+			mutex_unlock(&dbs_info->timer_mutex);
+			continue;
+		}
+
+		next_sampling  = jiffies + usecs_to_jiffies(new_rate);
+		appointed_at = dbs_info->work.timer.expires;
+
+
+		if (time_before(next_sampling, appointed_at)) {
+
+			mutex_unlock(&dbs_info->timer_mutex);
+			cancel_delayed_work_sync(&dbs_info->work);
+			mutex_lock(&dbs_info->timer_mutex);
+
+			schedule_delayed_work_on(dbs_info->cpu, &dbs_info->work,
+						 usecs_to_jiffies(new_rate));
+
+		}
+		mutex_unlock(&dbs_info->timer_mutex);
+	}
+}
+
+static ssize_t store_sampling_rate(struct kobject *a, struct attribute *b,
+				   const char *buf, size_t count)
+{
+	unsigned int input;
+	int ret;
+	ret = sscanf(buf, "%u", &input);
+	if (ret != 1)
+		return -EINVAL;
+	update_sampling_rate(input);
+	return count;
+}
+
+static ssize_t store_io_is_busy(struct kobject *a, struct attribute *b,
+				   const char *buf, size_t count)
+{
+	unsigned int input;
+	int ret;
+
+	ret = sscanf(buf, "%u", &input);
+	if (ret != 1)
+		return -EINVAL;
+	dbs_tuners_ins.io_is_busy = !!input;
+	return count;
+}
+
+static ssize_t store_up_threshold(struct kobject *a, struct attribute *b,
+				  const char *buf, size_t count)
+{
+	unsigned int input;
+	int ret;
+	ret = sscanf(buf, "%u", &input);
+
+	if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
+			input < MIN_FREQUENCY_UP_THRESHOLD) {
+		return -EINVAL;
+	}
+	dbs_tuners_ins.up_threshold = input;
+	return count;
+}
+
+static ssize_t store_sampling_down_factor(struct kobject *a,
+			struct attribute *b, const char *buf, size_t count)
+{
+	unsigned int input, j;
+	int ret;
+	ret = sscanf(buf, "%u", &input);
+
+	if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
+		return -EINVAL;
+	dbs_tuners_ins.sampling_down_factor = input;
+
+	/* Reset down sampling multiplier in case it was active */
+	for_each_online_cpu(j) {
+		struct cpu_dbs_info_s *dbs_info;
+		dbs_info = &per_cpu(od_cpu_dbs_info, j);
+		dbs_info->rate_mult = 1;
+	}
+	return count;
+}
+
+static ssize_t store_ignore_nice_load(struct kobject *a, struct attribute *b,
+				      const char *buf, size_t count)
+{
+	unsigned int input;
+	int ret;
+
+	unsigned int j;
+
+	ret = sscanf(buf, "%u", &input);
+	if (ret != 1)
+		return -EINVAL;
+
+	if (input > 1)
+		input = 1;
+
+	if (input == dbs_tuners_ins.ignore_nice) { /* nothing to do */
+		return count;
+	}
+	dbs_tuners_ins.ignore_nice = input;
+
+	/* we need to re-evaluate prev_cpu_idle */
+	for_each_online_cpu(j) {
+		struct cpu_dbs_info_s *dbs_info;
+		dbs_info = &per_cpu(od_cpu_dbs_info, j);
+		dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
+						&dbs_info->prev_cpu_wall);
+		if (dbs_tuners_ins.ignore_nice)
+			dbs_info->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
+
+	}
+	return count;
+}
+
+static ssize_t store_powersave_bias(struct kobject *a, struct attribute *b,
+				    const char *buf, size_t count)
+{
+	unsigned int input;
+	int ret;
+	ret = sscanf(buf, "%u", &input);
+
+	if (ret != 1)
+		return -EINVAL;
+
+	if (input > 1000)
+		input = 1000;
+
+	dbs_tuners_ins.powersave_bias = input;
+	ondemand_powersave_bias_init();
+	return count;
+}
+
+define_one_global_rw(sampling_rate);
+define_one_global_rw(io_is_busy);
+define_one_global_rw(up_threshold);
+define_one_global_rw(sampling_down_factor);
+define_one_global_rw(ignore_nice_load);
+define_one_global_rw(powersave_bias);
+
+static struct attribute *dbs_attributes[] = {
+	&sampling_rate_min.attr,
+	&sampling_rate.attr,
+	&up_threshold.attr,
+	&sampling_down_factor.attr,
+	&ignore_nice_load.attr,
+	&powersave_bias.attr,
+	&io_is_busy.attr,
+	NULL
+};
+
+static struct attribute_group dbs_attr_group = {
+	.attrs = dbs_attributes,
+	.name = "ondemand",
+};
+
+/************************** sysfs end ************************/
+
+static void dbs_freq_increase(struct cpufreq_policy *p, unsigned int freq)
+{
+	if (dbs_tuners_ins.powersave_bias)
+		freq = powersave_bias_target(p, freq, CPUFREQ_RELATION_H);
+	else if (p->cur == p->max)
+		return;
+
+	__cpufreq_driver_target(p, freq, dbs_tuners_ins.powersave_bias ?
+			CPUFREQ_RELATION_L : CPUFREQ_RELATION_H);
+}
+
+static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
+{
+	unsigned int max_load_freq;
+
+	struct cpufreq_policy *policy;
+	unsigned int j;
+
+	this_dbs_info->freq_lo = 0;
+	policy = this_dbs_info->cur_policy;
+
+	/*
+	 * Every sampling_rate, we check, if current idle time is less
+	 * than 20% (default), then we try to increase frequency
+	 * Every sampling_rate, we look for a the lowest
+	 * frequency which can sustain the load while keeping idle time over
+	 * 30%. If such a frequency exist, we try to decrease to this frequency.
+	 *
+	 * Any frequency increase takes it to the maximum frequency.
+	 * Frequency reduction happens at minimum steps of
+	 * 5% (default) of current frequency
+	 */
+
+	/* Get Absolute Load - in terms of freq */
+	max_load_freq = 0;
+
+	for_each_cpu(j, policy->cpus) {
+		struct cpu_dbs_info_s *j_dbs_info;
+		cputime64_t cur_wall_time, cur_idle_time, cur_iowait_time;
+		unsigned int idle_time, wall_time, iowait_time;
+		unsigned int load, load_freq;
+		int freq_avg;
+
+		j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
+
+		cur_idle_time = get_cpu_idle_time(j, &cur_wall_time);
+		cur_iowait_time = get_cpu_iowait_time(j, &cur_wall_time);
+
+		wall_time = (unsigned int)
+			(cur_wall_time - j_dbs_info->prev_cpu_wall);
+		j_dbs_info->prev_cpu_wall = cur_wall_time;
+
+		idle_time = (unsigned int)
+			(cur_idle_time - j_dbs_info->prev_cpu_idle);
+		j_dbs_info->prev_cpu_idle = cur_idle_time;
+
+		iowait_time = (unsigned int)
+			(cur_iowait_time - j_dbs_info->prev_cpu_iowait);
+		j_dbs_info->prev_cpu_iowait = cur_iowait_time;
+
+		if (dbs_tuners_ins.ignore_nice) {
+			u64 cur_nice;
+			unsigned long cur_nice_jiffies;
+
+			cur_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE] -
+					 j_dbs_info->prev_cpu_nice;
+			/*
+			 * Assumption: nice time between sampling periods will
+			 * be less than 2^32 jiffies for 32 bit sys
+			 */
+			cur_nice_jiffies = (unsigned long)
+					cputime64_to_jiffies64(cur_nice);
+
+			j_dbs_info->prev_cpu_nice = kcpustat_cpu(j).cpustat[CPUTIME_NICE];
+			idle_time += jiffies_to_usecs(cur_nice_jiffies);
+		}
+
+		/*
+		 * For the purpose of ondemand, waiting for disk IO is an
+		 * indication that you're performance critical, and not that
+		 * the system is actually idle. So subtract the iowait time
+		 * from the cpu idle time.
+		 */
+
+		if (dbs_tuners_ins.io_is_busy && idle_time >= iowait_time)
+			idle_time -= iowait_time;
+
+		if (unlikely(!wall_time || wall_time < idle_time))
+			continue;
+
+		load = 100 * (wall_time - idle_time) / wall_time;
+
+		freq_avg = __cpufreq_driver_getavg(policy, j);
+		if (freq_avg <= 0)
+			freq_avg = policy->cur;
+
+		load_freq = load * freq_avg;
+		if (load_freq > max_load_freq)
+			max_load_freq = load_freq;
+	}
+
+	/* Check for frequency increase */
+	if (max_load_freq > dbs_tuners_ins.up_threshold * policy->cur) {
+		/* If switching to max speed, apply sampling_down_factor */
+		if (policy->cur < policy->max)
+			this_dbs_info->rate_mult =
+				dbs_tuners_ins.sampling_down_factor;
+		dbs_freq_increase(policy, policy->max);
+		return;
+	}
+
+	/* Check for frequency decrease */
+	/* if we cannot reduce the frequency anymore, break out early */
+	if (policy->cur == policy->min)
+		return;
+
+	/*
+	 * The optimal frequency is the frequency that is the lowest that
+	 * can support the current CPU usage without triggering the up
+	 * policy. To be safe, we focus 10 points under the threshold.
+	 */
+	if (max_load_freq <
+	    (dbs_tuners_ins.up_threshold - dbs_tuners_ins.down_differential) *
+	     policy->cur) {
+		unsigned int freq_next;
+		freq_next = max_load_freq /
+				(dbs_tuners_ins.up_threshold -
+				 dbs_tuners_ins.down_differential);
+
+		/* No longer fully busy, reset rate_mult */
+		this_dbs_info->rate_mult = 1;
+
+		if (freq_next < policy->min)
+			freq_next = policy->min;
+
+		if (!dbs_tuners_ins.powersave_bias) {
+			__cpufreq_driver_target(policy, freq_next,
+					CPUFREQ_RELATION_L);
+		} else {
+			int freq = powersave_bias_target(policy, freq_next,
+					CPUFREQ_RELATION_L);
+			__cpufreq_driver_target(policy, freq,
+				CPUFREQ_RELATION_L);
+		}
+	}
+}
+
+static void do_dbs_timer(struct work_struct *work)
+{
+	struct cpu_dbs_info_s *dbs_info =
+		container_of(work, struct cpu_dbs_info_s, work.work);
+	unsigned int cpu = dbs_info->cpu;
+	int sample_type = dbs_info->sample_type;
+
+	int delay;
+
+	mutex_lock(&dbs_info->timer_mutex);
+
+	/* Common NORMAL_SAMPLE setup */
+	dbs_info->sample_type = DBS_NORMAL_SAMPLE;
+	if (!dbs_tuners_ins.powersave_bias ||
+	    sample_type == DBS_NORMAL_SAMPLE) {
+		dbs_check_cpu(dbs_info);
+		if (dbs_info->freq_lo) {
+			/* Setup timer for SUB_SAMPLE */
+			dbs_info->sample_type = DBS_SUB_SAMPLE;
+			delay = dbs_info->freq_hi_jiffies;
+		} else {
+			/* We want all CPUs to do sampling nearly on
+			 * same jiffy
+			 */
+			delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate
+				* dbs_info->rate_mult);
+
+			if (num_online_cpus() > 1)
+				delay -= jiffies % delay;
+		}
+	} else {
+		__cpufreq_driver_target(dbs_info->cur_policy,
+			dbs_info->freq_lo, CPUFREQ_RELATION_H);
+		delay = dbs_info->freq_lo_jiffies;
+	}
+	schedule_delayed_work_on(cpu, &dbs_info->work, delay);
+	mutex_unlock(&dbs_info->timer_mutex);
+}
+
+static inline void dbs_timer_init(struct cpu_dbs_info_s *dbs_info)
+{
+	/* We want all CPUs to do sampling nearly on same jiffy */
+	int delay = usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
+
+	if (num_online_cpus() > 1)
+		delay -= jiffies % delay;
+
+	dbs_info->sample_type = DBS_NORMAL_SAMPLE;
+	INIT_DELAYED_WORK_DEFERRABLE(&dbs_info->work, do_dbs_timer);
+	schedule_delayed_work_on(dbs_info->cpu, &dbs_info->work, delay);
+}
+
+static inline void dbs_timer_exit(struct cpu_dbs_info_s *dbs_info)
+{
+	cancel_delayed_work_sync(&dbs_info->work);
+}
+
+/*
+ * Not all CPUs want IO time to be accounted as busy; this dependson how
+ * efficient idling at a higher frequency/voltage is.
+ * Pavel Machek says this is not so for various generations of AMD and old
+ * Intel systems.
+ * Mike Chan (androidlcom) calis this is also not true for ARM.
+ * Because of this, whitelist specific known (series) of CPUs by default, and
+ * leave all others up to the user.
+ */
+static int should_io_be_busy(void)
+{
+#if defined(CONFIG_X86)
+	/*
+	 * For Intel, Core 2 (model 15) andl later have an efficient idle.
+	 */
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
+	    boot_cpu_data.x86 == 6 &&
+	    boot_cpu_data.x86_model >= 15)
+		return 1;
+#endif
+	return 0;
+}
+
+static int cpufreq_governor_dbs(struct cpufreq_policy *policy,
+				   unsigned int event)
+{
+	unsigned int cpu = policy->cpu;
+	struct cpu_dbs_info_s *this_dbs_info;
+	unsigned int j;
+	int rc;
+
+	this_dbs_info = &per_cpu(od_cpu_dbs_info, cpu);
+
+	switch (event) {
+	case CPUFREQ_GOV_START:
+		if ((!cpu_online(cpu)) || (!policy->cur))
+			return -EINVAL;
+
+		mutex_lock(&dbs_mutex);
+
+		dbs_enable++;
+		for_each_cpu(j, policy->cpus) {
+			struct cpu_dbs_info_s *j_dbs_info;
+			j_dbs_info = &per_cpu(od_cpu_dbs_info, j);
+			j_dbs_info->cur_policy = policy;
+
+			j_dbs_info->prev_cpu_idle = get_cpu_idle_time(j,
+						&j_dbs_info->prev_cpu_wall);
+			if (dbs_tuners_ins.ignore_nice)
+				j_dbs_info->prev_cpu_nice =
+						kcpustat_cpu(j).cpustat[CPUTIME_NICE];
+		}
+		this_dbs_info->cpu = cpu;
+		this_dbs_info->rate_mult = 1;
+		ondemand_powersave_bias_init_cpu(cpu);
+		/*
+		 * Start the timerschedule work, when this governor
+		 * is used for first time
+		 */
+		if (dbs_enable == 1) {
+			unsigned int latency;
+
+			rc = sysfs_create_group(cpufreq_global_kobject,
+						&dbs_attr_group);
+			if (rc) {
+				mutex_unlock(&dbs_mutex);
+				return rc;
+			}
+
+			/* policy latency is in nS. Convert it to uS first */
+			latency = policy->cpuinfo.transition_latency / 1000;
+			if (latency == 0)
+				latency = 1;
+			/* Bring kernel and HW constraints together */
+			min_sampling_rate = max(min_sampling_rate,
+					MIN_LATENCY_MULTIPLIER * latency);
+			dbs_tuners_ins.sampling_rate =
+				max(min_sampling_rate,
+				    latency * LATENCY_MULTIPLIER);
+			dbs_tuners_ins.io_is_busy = should_io_be_busy();
+		}
+		mutex_unlock(&dbs_mutex);
+
+		mutex_init(&this_dbs_info->timer_mutex);
+		dbs_timer_init(this_dbs_info);
+		break;
+
+	case CPUFREQ_GOV_STOP:
+		dbs_timer_exit(this_dbs_info);
+
+		mutex_lock(&dbs_mutex);
+		mutex_destroy(&this_dbs_info->timer_mutex);
+		dbs_enable--;
+		mutex_unlock(&dbs_mutex);
+		if (!dbs_enable)
+			sysfs_remove_group(cpufreq_global_kobject,
+					   &dbs_attr_group);
+
+		break;
+
+	case CPUFREQ_GOV_LIMITS:
+		mutex_lock(&this_dbs_info->timer_mutex);
+		if (policy->max < this_dbs_info->cur_policy->cur)
+			__cpufreq_driver_target(this_dbs_info->cur_policy,
+				policy->max, CPUFREQ_RELATION_H);
+		else if (policy->min > this_dbs_info->cur_policy->cur)
+			__cpufreq_driver_target(this_dbs_info->cur_policy,
+				policy->min, CPUFREQ_RELATION_L);
+		mutex_unlock(&this_dbs_info->timer_mutex);
+		break;
+	}
+	return 0;
+}
+
+static int __init cpufreq_gov_dbs_init(void)
+{
+	u64 idle_time;
+	int cpu = get_cpu();
+
+	idle_time = get_cpu_idle_time_us(cpu, NULL);
+	put_cpu();
+	if (idle_time != -1ULL) {
+		/* Idle micro accounting is supported. Use finer thresholds */
+		dbs_tuners_ins.up_threshold = MICRO_FREQUENCY_UP_THRESHOLD;
+		dbs_tuners_ins.down_differential =
+					MICRO_FREQUENCY_DOWN_DIFFERENTIAL;
+		/*
+		 * In nohz/micro accounting case we set the minimum frequency
+		 * not depending on HZ, but fixed (very low). The deferred
+		 * timer might skip some samples if idle/sleeping as needed.
+		*/
+		min_sampling_rate = MICRO_FREQUENCY_MIN_SAMPLE_RATE;
+	} else {
+		/* For correct statistics, we need 10 ticks for each measure */
+		min_sampling_rate =
+			MIN_SAMPLING_RATE_RATIO * jiffies_to_usecs(10);
+	}
+
+	return cpufreq_register_governor(&cpufreq_gov_ondemand);
+}
+
+static void __exit cpufreq_gov_dbs_exit(void)
+{
+	cpufreq_unregister_governor(&cpufreq_gov_ondemand);
+}
+
+
+MODULE_AUTHOR("Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>");
+MODULE_AUTHOR("Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>");
+MODULE_DESCRIPTION("'cpufreq_ondemand' - A dynamic cpufreq governor for "
+	"Low Latency Frequency Transition capable processors");
+MODULE_LICENSE("GPL");
+
+#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_ONDEMAND
+fs_initcall(cpufreq_gov_dbs_init);
+#else
+module_init(cpufreq_gov_dbs_init);
+#endif
+module_exit(cpufreq_gov_dbs_exit);