1 files changed, 586 insertions, 0 deletions

diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
new file mode 100644
index 000000000000..e1df376e709e
--- /dev/null
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -0,0 +1,586 @@
+/*
+ *  drivers/cpufreq/cpufreq_conservative.c
+ *
+ *  Copyright (C)  2001 Russell King
+ *            (C)  2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
+ *                      Jun Nakajima <jun.nakajima@intel.com>
+ *            (C)  2004 Alexander Clouter <alex-kernel@digriz.org.uk>
+ *
+ * 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/smp.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/ctype.h>
+#include <linux/cpufreq.h>
+#include <linux/sysctl.h>
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/sysfs.h>
+#include <linux/sched.h>
+#include <linux/kmod.h>
+#include <linux/workqueue.h>
+#include <linux/jiffies.h>
+#include <linux/kernel_stat.h>
+#include <linux/percpu.h>
+
+/*
+ * dbs is used in this file as a shortform for demandbased switching
+ * It helps to keep variable names smaller, simpler
+ */
+
+#define DEF_FREQUENCY_UP_THRESHOLD              (80)
+#define MIN_FREQUENCY_UP_THRESHOLD              (0)
+#define MAX_FREQUENCY_UP_THRESHOLD              (100)
+
+#define DEF_FREQUENCY_DOWN_THRESHOLD            (20)
+#define MIN_FREQUENCY_DOWN_THRESHOLD            (0)
+#define MAX_FREQUENCY_DOWN_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.
+ */
+static unsigned int                             def_sampling_rate;
+#define MIN_SAMPLING_RATE                       (def_sampling_rate / 2)
+#define MAX_SAMPLING_RATE                       (500 * def_sampling_rate)
+#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER    (100000)
+#define DEF_SAMPLING_DOWN_FACTOR                (5)
+#define TRANSITION_LATENCY_LIMIT                (10 * 1000)
+
+static void do_dbs_timer(void *data);
+
+struct cpu_dbs_info_s {
+        struct cpufreq_policy   *cur_policy;
+        unsigned int            prev_cpu_idle_up;
+        unsigned int            prev_cpu_idle_down;
+        unsigned int            enable;
+};
+static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
+
+static unsigned int dbs_enable; /* number of CPUs using this policy */
+
+static DECLARE_MUTEX    (dbs_sem);
+static DECLARE_WORK     (dbs_work, do_dbs_timer, NULL);
+
+struct dbs_tuners {
+        unsigned int            sampling_rate;
+        unsigned int            sampling_down_factor;
+        unsigned int            up_threshold;
+        unsigned int            down_threshold;
+        unsigned int            ignore_nice;
+        unsigned int            freq_step;
+};
+
+static struct dbs_tuners dbs_tuners_ins = {
+        .up_threshold           = DEF_FREQUENCY_UP_THRESHOLD,
+        .down_threshold         = DEF_FREQUENCY_DOWN_THRESHOLD,
+        .sampling_down_factor   = DEF_SAMPLING_DOWN_FACTOR,
+};
+
+static inline unsigned int get_cpu_idle_time(unsigned int cpu)
+{
+        return  kstat_cpu(cpu).cpustat.idle +
+                kstat_cpu(cpu).cpustat.iowait +
+                ( !dbs_tuners_ins.ignore_nice ? 
+                  kstat_cpu(cpu).cpustat.nice :
+                  0);
+}
+
+/************************** sysfs interface ************************/
+static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
+{
+        return sprintf (buf, "%u\n", MAX_SAMPLING_RATE);
+}
+
+static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
+{
+        return sprintf (buf, "%u\n", MIN_SAMPLING_RATE);
+}
+
+#define define_one_ro(_name)                                    \
+static struct freq_attr _name =                                 \
+__ATTR(_name, 0444, show_##_name, NULL)
+
+define_one_ro(sampling_rate_max);
+define_one_ro(sampling_rate_min);
+
+/* cpufreq_conservative Governor Tunables */
+#define show_one(file_name, object)                                     \
+static ssize_t show_##file_name                                         \
+(struct cpufreq_policy *unused, char *buf)                              \
+{                                                                       \
+        return sprintf(buf, "%u\n", dbs_tuners_ins.object);             \
+}
+show_one(sampling_rate, sampling_rate);
+show_one(sampling_down_factor, sampling_down_factor);
+show_one(up_threshold, up_threshold);
+show_one(down_threshold, down_threshold);
+show_one(ignore_nice, ignore_nice);
+show_one(freq_step, freq_step);
+
+static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused, 
+                const char *buf, size_t count)
+{
+        unsigned int input;
+        int ret;
+        ret = sscanf (buf, "%u", &input);
+        if (ret != 1 )
+                return -EINVAL;
+
+        down(&dbs_sem);
+        dbs_tuners_ins.sampling_down_factor = input;
+        up(&dbs_sem);
+
+        return count;
+}
+
+static ssize_t store_sampling_rate(struct cpufreq_policy *unused, 
+                const char *buf, size_t count)
+{
+        unsigned int input;
+        int ret;
+        ret = sscanf (buf, "%u", &input);
+
+        down(&dbs_sem);
+        if (ret != 1 || input > MAX_SAMPLING_RATE || input < MIN_SAMPLING_RATE) {
+                up(&dbs_sem);
+                return -EINVAL;
+        }
+
+        dbs_tuners_ins.sampling_rate = input;
+        up(&dbs_sem);
+
+        return count;
+}
+
+static ssize_t store_up_threshold(struct cpufreq_policy *unused, 
+                const char *buf, size_t count)
+{
+        unsigned int input;
+        int ret;
+        ret = sscanf (buf, "%u", &input);
+
+        down(&dbs_sem);
+        if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD || 
+                        input < MIN_FREQUENCY_UP_THRESHOLD ||
+                        input <= dbs_tuners_ins.down_threshold) {
+                up(&dbs_sem);
+                return -EINVAL;
+        }
+
+        dbs_tuners_ins.up_threshold = input;
+        up(&dbs_sem);
+
+        return count;
+}
+
+static ssize_t store_down_threshold(struct cpufreq_policy *unused, 
+                const char *buf, size_t count)
+{
+        unsigned int input;
+        int ret;
+        ret = sscanf (buf, "%u", &input);
+
+        down(&dbs_sem);
+        if (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD || 
+                        input < MIN_FREQUENCY_DOWN_THRESHOLD ||
+                        input >= dbs_tuners_ins.up_threshold) {
+                up(&dbs_sem);
+                return -EINVAL;
+        }
+
+        dbs_tuners_ins.down_threshold = input;
+        up(&dbs_sem);
+
+        return count;
+}
+
+static ssize_t store_ignore_nice(struct cpufreq_policy *policy,
+                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;
+        
+        down(&dbs_sem);
+        if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */
+                up(&dbs_sem);
+                return count;
+        }
+        dbs_tuners_ins.ignore_nice = input;
+
+        /* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
+        for_each_online_cpu(j) {
+                struct cpu_dbs_info_s *j_dbs_info;
+                j_dbs_info = &per_cpu(cpu_dbs_info, j);
+                j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
+                j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
+        }
+        up(&dbs_sem);
+
+        return count;
+}
+
+static ssize_t store_freq_step(struct cpufreq_policy *policy,
+                const char *buf, size_t count)
+{
+        unsigned int input;
+        int ret;
+
+        ret = sscanf (buf, "%u", &input);
+
+        if ( ret != 1 )
+                return -EINVAL;
+
+        if ( input > 100 )
+                input = 100;
+        
+        /* no need to test here if freq_step is zero as the user might actually
+         * want this, they would be crazy though :) */
+        down(&dbs_sem);
+        dbs_tuners_ins.freq_step = input;
+        up(&dbs_sem);
+
+        return count;
+}
+
+#define define_one_rw(_name) \
+static struct freq_attr _name = \
+__ATTR(_name, 0644, show_##_name, store_##_name)
+
+define_one_rw(sampling_rate);
+define_one_rw(sampling_down_factor);
+define_one_rw(up_threshold);
+define_one_rw(down_threshold);
+define_one_rw(ignore_nice);
+define_one_rw(freq_step);
+
+static struct attribute * dbs_attributes[] = {
+        &sampling_rate_max.attr,
+        &sampling_rate_min.attr,
+        &sampling_rate.attr,
+        &sampling_down_factor.attr,
+        &up_threshold.attr,
+        &down_threshold.attr,
+        &ignore_nice.attr,
+        &freq_step.attr,
+        NULL
+};
+
+static struct attribute_group dbs_attr_group = {
+        .attrs = dbs_attributes,
+        .name = "conservative",
+};
+
+/************************** sysfs end ************************/
+
+static void dbs_check_cpu(int cpu)
+{
+        unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
+        unsigned int freq_step;
+        unsigned int freq_down_sampling_rate;
+        static int down_skip[NR_CPUS];
+        static int requested_freq[NR_CPUS];
+        static unsigned short init_flag = 0;
+        struct cpu_dbs_info_s *this_dbs_info;
+        struct cpu_dbs_info_s *dbs_info;
+
+        struct cpufreq_policy *policy;
+        unsigned int j;
+
+        this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
+        if (!this_dbs_info->enable)
+                return;
+
+        policy = this_dbs_info->cur_policy;
+
+        if ( init_flag == 0 ) {
+                for ( /* NULL */; init_flag < NR_CPUS; init_flag++ ) {
+                        dbs_info = &per_cpu(cpu_dbs_info, init_flag);
+                        requested_freq[cpu] = dbs_info->cur_policy->cur;
+                }
+                init_flag = 1;
+        }
+        
+        /* 
+         * The default safe range is 20% to 80% 
+         * Every sampling_rate, we check
+         *      - If current idle time is less than 20%, then we try to 
+         *        increase frequency
+         * Every sampling_rate*sampling_down_factor, we check
+         *      - If current idle time is more than 80%, then we try to
+         *        decrease frequency
+         *
+         * Any frequency increase takes it to the maximum frequency. 
+         * Frequency reduction happens at minimum steps of 
+         * 5% (default) of max_frequency 
+         */
+
+        /* Check for frequency increase */
+
+        idle_ticks = UINT_MAX;
+        for_each_cpu_mask(j, policy->cpus) {
+                unsigned int tmp_idle_ticks, total_idle_ticks;
+                struct cpu_dbs_info_s *j_dbs_info;
+
+                j_dbs_info = &per_cpu(cpu_dbs_info, j);
+                /* Check for frequency increase */
+                total_idle_ticks = get_cpu_idle_time(j);
+                tmp_idle_ticks = total_idle_ticks -
+                        j_dbs_info->prev_cpu_idle_up;
+                j_dbs_info->prev_cpu_idle_up = total_idle_ticks;
+
+                if (tmp_idle_ticks < idle_ticks)
+                        idle_ticks = tmp_idle_ticks;
+        }
+
+        /* Scale idle ticks by 100 and compare with up and down ticks */
+        idle_ticks *= 100;
+        up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
+                usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
+
+        if (idle_ticks < up_idle_ticks) {
+                down_skip[cpu] = 0;
+                for_each_cpu_mask(j, policy->cpus) {
+                        struct cpu_dbs_info_s *j_dbs_info;
+
+                        j_dbs_info = &per_cpu(cpu_dbs_info, j);
+                        j_dbs_info->prev_cpu_idle_down = 
+                                        j_dbs_info->prev_cpu_idle_up;
+                }
+                /* if we are already at full speed then break out early */
+                if (requested_freq[cpu] == policy->max)
+                        return;
+                
+                freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
+
+                /* max freq cannot be less than 100. But who knows.... */
+                if (unlikely(freq_step == 0))
+                        freq_step = 5;
+                
+                requested_freq[cpu] += freq_step;
+                if (requested_freq[cpu] > policy->max)
+                        requested_freq[cpu] = policy->max;
+
+                __cpufreq_driver_target(policy, requested_freq[cpu], 
+                        CPUFREQ_RELATION_H);
+                return;
+        }
+
+        /* Check for frequency decrease */
+        down_skip[cpu]++;
+        if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor)
+                return;
+
+        idle_ticks = UINT_MAX;
+        for_each_cpu_mask(j, policy->cpus) {
+                unsigned int tmp_idle_ticks, total_idle_ticks;
+                struct cpu_dbs_info_s *j_dbs_info;
+
+                j_dbs_info = &per_cpu(cpu_dbs_info, j);
+                total_idle_ticks = j_dbs_info->prev_cpu_idle_up;
+                tmp_idle_ticks = total_idle_ticks -
+                        j_dbs_info->prev_cpu_idle_down;
+                j_dbs_info->prev_cpu_idle_down = total_idle_ticks;
+
+                if (tmp_idle_ticks < idle_ticks)
+                        idle_ticks = tmp_idle_ticks;
+        }
+
+        /* Scale idle ticks by 100 and compare with up and down ticks */
+        idle_ticks *= 100;
+        down_skip[cpu] = 0;
+
+        freq_down_sampling_rate = dbs_tuners_ins.sampling_rate *
+                dbs_tuners_ins.sampling_down_factor;
+        down_idle_ticks = (100 - dbs_tuners_ins.down_threshold) *
+                        usecs_to_jiffies(freq_down_sampling_rate);
+
+        if (idle_ticks > down_idle_ticks) {
+                /* if we are already at the lowest speed then break out early
+                 * or if we 'cannot' reduce the speed as the user might want
+                 * freq_step to be zero */
+                if (requested_freq[cpu] == policy->min
+                                || dbs_tuners_ins.freq_step == 0)
+                        return;
+
+                freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
+
+                /* max freq cannot be less than 100. But who knows.... */
+                if (unlikely(freq_step == 0))
+                        freq_step = 5;
+
+                requested_freq[cpu] -= freq_step;
+                if (requested_freq[cpu] < policy->min)
+                        requested_freq[cpu] = policy->min;
+
+                __cpufreq_driver_target(policy,
+                        requested_freq[cpu],
+                        CPUFREQ_RELATION_H);
+                return;
+        }
+}
+
+static void do_dbs_timer(void *data)
+{ 
+        int i;
+        down(&dbs_sem);
+        for_each_online_cpu(i)
+                dbs_check_cpu(i);
+        schedule_delayed_work(&dbs_work, 
+                        usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
+        up(&dbs_sem);
+} 
+
+static inline void dbs_timer_init(void)
+{
+        INIT_WORK(&dbs_work, do_dbs_timer, NULL);
+        schedule_delayed_work(&dbs_work,
+                        usecs_to_jiffies(dbs_tuners_ins.sampling_rate));
+        return;
+}
+
+static inline void dbs_timer_exit(void)
+{
+        cancel_delayed_work(&dbs_work);
+        return;
+}
+
+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;
+
+        this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
+
+        switch (event) {
+        case CPUFREQ_GOV_START:
+                if ((!cpu_online(cpu)) || 
+                    (!policy->cur))
+                        return -EINVAL;
+
+                if (policy->cpuinfo.transition_latency >
+                                (TRANSITION_LATENCY_LIMIT * 1000))
+                        return -EINVAL;
+                if (this_dbs_info->enable) /* Already enabled */
+                        break;
+                 
+                down(&dbs_sem);
+                for_each_cpu_mask(j, policy->cpus) {
+                        struct cpu_dbs_info_s *j_dbs_info;
+                        j_dbs_info = &per_cpu(cpu_dbs_info, j);
+                        j_dbs_info->cur_policy = policy;
+                
+                        j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
+                        j_dbs_info->prev_cpu_idle_down
+                                = j_dbs_info->prev_cpu_idle_up;
+                }
+                this_dbs_info->enable = 1;
+                sysfs_create_group(&policy->kobj, &dbs_attr_group);
+                dbs_enable++;
+                /*
+                 * Start the timerschedule work, when this governor
+                 * is used for first time
+                 */
+                if (dbs_enable == 1) {
+                        unsigned int latency;
+                        /* policy latency is in nS. Convert it to uS first */
+
+                        latency = policy->cpuinfo.transition_latency;
+                        if (latency < 1000)
+                                latency = 1000;
+
+                        def_sampling_rate = (latency / 1000) *
+                                        DEF_SAMPLING_RATE_LATENCY_MULTIPLIER;
+                        dbs_tuners_ins.sampling_rate = def_sampling_rate;
+                        dbs_tuners_ins.ignore_nice = 0;
+                        dbs_tuners_ins.freq_step = 5;
+
+                        dbs_timer_init();
+                }
+                
+                up(&dbs_sem);
+                break;
+
+        case CPUFREQ_GOV_STOP:
+                down(&dbs_sem);
+                this_dbs_info->enable = 0;
+                sysfs_remove_group(&policy->kobj, &dbs_attr_group);
+                dbs_enable--;
+                /*
+                 * Stop the timerschedule work, when this governor
+                 * is used for first time
+                 */
+                if (dbs_enable == 0) 
+                        dbs_timer_exit();
+                
+                up(&dbs_sem);
+
+                break;
+
+        case CPUFREQ_GOV_LIMITS:
+                down(&dbs_sem);
+                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);
+                up(&dbs_sem);
+                break;
+        }
+        return 0;
+}
+
+static struct cpufreq_governor cpufreq_gov_dbs = {
+        .name           = "conservative",
+        .governor       = cpufreq_governor_dbs,
+        .owner          = THIS_MODULE,
+};
+
+static int __init cpufreq_gov_dbs_init(void)
+{
+        return cpufreq_register_governor(&cpufreq_gov_dbs);
+}
+
+static void __exit cpufreq_gov_dbs_exit(void)
+{
+        /* Make sure that the scheduled work is indeed not running */
+        flush_scheduled_work();
+
+        cpufreq_unregister_governor(&cpufreq_gov_dbs);
+}
+
+
+MODULE_AUTHOR ("Alexander Clouter <alex-kernel@digriz.org.uk>");
+MODULE_DESCRIPTION ("'cpufreq_conservative' - A dynamic cpufreq governor for "
+                "Low Latency Frequency Transition capable processors "
+                "optimised for use in a battery environment");
+MODULE_LICENSE ("GPL");
+
+module_init(cpufreq_gov_dbs_init);
+module_exit(cpufreq_gov_dbs_exit);