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+/*
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+ * drivers/cpufreq/cpufreq_conservative.c
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+ *
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+ * Copyright (C) 2001 Russell King
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+ * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
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+ * Jun Nakajima <jun.nakajima@intel.com>
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+ * (C) 2004 Alexander Clouter <alex-kernel@digriz.org.uk>
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+ *
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+ * This program is free software; you can redistribute it and/or modify
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+ * it under the terms of the GNU General Public License version 2 as
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+ * published by the Free Software Foundation.
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+ */
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+
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+#include <linux/kernel.h>
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+#include <linux/module.h>
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+#include <linux/smp.h>
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+#include <linux/init.h>
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+#include <linux/interrupt.h>
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+#include <linux/ctype.h>
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+#include <linux/cpufreq.h>
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+#include <linux/sysctl.h>
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+#include <linux/types.h>
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+#include <linux/fs.h>
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+#include <linux/sysfs.h>
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+#include <linux/sched.h>
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+#include <linux/kmod.h>
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+#include <linux/workqueue.h>
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+#include <linux/jiffies.h>
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+#include <linux/kernel_stat.h>
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+#include <linux/percpu.h>
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+
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+/*
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+ * dbs is used in this file as a shortform for demandbased switching
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+ * It helps to keep variable names smaller, simpler
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+ */
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+
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+#define DEF_FREQUENCY_UP_THRESHOLD (80)
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+#define MIN_FREQUENCY_UP_THRESHOLD (0)
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+#define MAX_FREQUENCY_UP_THRESHOLD (100)
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+
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+#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
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+#define MIN_FREQUENCY_DOWN_THRESHOLD (0)
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+#define MAX_FREQUENCY_DOWN_THRESHOLD (100)
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+
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+/*
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+ * The polling frequency of this governor depends on the capability of
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+ * the processor. Default polling frequency is 1000 times the transition
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+ * latency of the processor. The governor will work on any processor with
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+ * transition latency <= 10mS, using appropriate sampling
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+ * rate.
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+ * For CPUs with transition latency > 10mS (mostly drivers with CPUFREQ_ETERNAL)
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+ * this governor will not work.
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+ * All times here are in uS.
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+ */
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+static unsigned int def_sampling_rate;
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+#define MIN_SAMPLING_RATE (def_sampling_rate / 2)
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+#define MAX_SAMPLING_RATE (500 * def_sampling_rate)
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+#define DEF_SAMPLING_RATE_LATENCY_MULTIPLIER (100000)
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+#define DEF_SAMPLING_DOWN_FACTOR (5)
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+#define TRANSITION_LATENCY_LIMIT (10 * 1000)
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+
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+static void do_dbs_timer(void *data);
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+
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+struct cpu_dbs_info_s {
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+ struct cpufreq_policy *cur_policy;
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+ unsigned int prev_cpu_idle_up;
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+ unsigned int prev_cpu_idle_down;
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+ unsigned int enable;
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+};
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+static DEFINE_PER_CPU(struct cpu_dbs_info_s, cpu_dbs_info);
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+
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+static unsigned int dbs_enable; /* number of CPUs using this policy */
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+
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+static DECLARE_MUTEX (dbs_sem);
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+static DECLARE_WORK (dbs_work, do_dbs_timer, NULL);
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+
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+struct dbs_tuners {
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+ unsigned int sampling_rate;
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+ unsigned int sampling_down_factor;
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+ unsigned int up_threshold;
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+ unsigned int down_threshold;
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+ unsigned int ignore_nice;
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+ unsigned int freq_step;
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+};
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+
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+static struct dbs_tuners dbs_tuners_ins = {
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+ .up_threshold = DEF_FREQUENCY_UP_THRESHOLD,
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+ .down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD,
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+ .sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR,
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+};
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+
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+static inline unsigned int get_cpu_idle_time(unsigned int cpu)
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+{
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+ return kstat_cpu(cpu).cpustat.idle +
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+ kstat_cpu(cpu).cpustat.iowait +
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+ ( !dbs_tuners_ins.ignore_nice ?
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+ kstat_cpu(cpu).cpustat.nice :
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+ 0);
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+}
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+
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+/************************** sysfs interface ************************/
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+static ssize_t show_sampling_rate_max(struct cpufreq_policy *policy, char *buf)
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+{
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+ return sprintf (buf, "%u\n", MAX_SAMPLING_RATE);
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+}
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+
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+static ssize_t show_sampling_rate_min(struct cpufreq_policy *policy, char *buf)
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+{
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+ return sprintf (buf, "%u\n", MIN_SAMPLING_RATE);
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+}
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+
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+#define define_one_ro(_name) \
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+static struct freq_attr _name = \
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+__ATTR(_name, 0444, show_##_name, NULL)
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+
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+define_one_ro(sampling_rate_max);
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+define_one_ro(sampling_rate_min);
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+
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+/* cpufreq_conservative Governor Tunables */
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+#define show_one(file_name, object) \
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+static ssize_t show_##file_name \
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+(struct cpufreq_policy *unused, char *buf) \
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+{ \
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+ return sprintf(buf, "%u\n", dbs_tuners_ins.object); \
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+}
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+show_one(sampling_rate, sampling_rate);
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+show_one(sampling_down_factor, sampling_down_factor);
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+show_one(up_threshold, up_threshold);
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+show_one(down_threshold, down_threshold);
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+show_one(ignore_nice, ignore_nice);
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+show_one(freq_step, freq_step);
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+
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+static ssize_t store_sampling_down_factor(struct cpufreq_policy *unused,
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+ const char *buf, size_t count)
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+{
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+ unsigned int input;
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+ int ret;
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+ ret = sscanf (buf, "%u", &input);
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+ if (ret != 1 )
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+ return -EINVAL;
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+
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+ down(&dbs_sem);
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+ dbs_tuners_ins.sampling_down_factor = input;
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+ up(&dbs_sem);
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+
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+ return count;
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+}
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+
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+static ssize_t store_sampling_rate(struct cpufreq_policy *unused,
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+ const char *buf, size_t count)
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+{
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+ unsigned int input;
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+ int ret;
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+ ret = sscanf (buf, "%u", &input);
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+
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+ down(&dbs_sem);
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+ if (ret != 1 || input > MAX_SAMPLING_RATE || input < MIN_SAMPLING_RATE) {
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+ up(&dbs_sem);
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+ return -EINVAL;
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+ }
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+
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+ dbs_tuners_ins.sampling_rate = input;
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+ up(&dbs_sem);
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+
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+ return count;
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+}
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+
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+static ssize_t store_up_threshold(struct cpufreq_policy *unused,
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+ const char *buf, size_t count)
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+{
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+ unsigned int input;
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+ int ret;
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+ ret = sscanf (buf, "%u", &input);
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+
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+ down(&dbs_sem);
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+ if (ret != 1 || input > MAX_FREQUENCY_UP_THRESHOLD ||
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+ input < MIN_FREQUENCY_UP_THRESHOLD ||
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+ input <= dbs_tuners_ins.down_threshold) {
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+ up(&dbs_sem);
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+ return -EINVAL;
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+ }
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+
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+ dbs_tuners_ins.up_threshold = input;
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+ up(&dbs_sem);
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+
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+ return count;
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+}
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+
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+static ssize_t store_down_threshold(struct cpufreq_policy *unused,
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+ const char *buf, size_t count)
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+{
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+ unsigned int input;
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+ int ret;
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+ ret = sscanf (buf, "%u", &input);
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+
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+ down(&dbs_sem);
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+ if (ret != 1 || input > MAX_FREQUENCY_DOWN_THRESHOLD ||
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+ input < MIN_FREQUENCY_DOWN_THRESHOLD ||
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+ input >= dbs_tuners_ins.up_threshold) {
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+ up(&dbs_sem);
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+ return -EINVAL;
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+ }
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+
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+ dbs_tuners_ins.down_threshold = input;
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+ up(&dbs_sem);
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+
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+ return count;
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+}
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+
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+static ssize_t store_ignore_nice(struct cpufreq_policy *policy,
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+ const char *buf, size_t count)
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+{
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+ unsigned int input;
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+ int ret;
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+
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+ unsigned int j;
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+
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+ ret = sscanf (buf, "%u", &input);
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+ if ( ret != 1 )
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+ return -EINVAL;
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+
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+ if ( input > 1 )
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+ input = 1;
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+
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+ down(&dbs_sem);
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+ if ( input == dbs_tuners_ins.ignore_nice ) { /* nothing to do */
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+ up(&dbs_sem);
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+ return count;
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+ }
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+ dbs_tuners_ins.ignore_nice = input;
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+
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+ /* we need to re-evaluate prev_cpu_idle_up and prev_cpu_idle_down */
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+ for_each_online_cpu(j) {
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+ struct cpu_dbs_info_s *j_dbs_info;
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+ j_dbs_info = &per_cpu(cpu_dbs_info, j);
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+ j_dbs_info->prev_cpu_idle_up = get_cpu_idle_time(j);
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+ j_dbs_info->prev_cpu_idle_down = j_dbs_info->prev_cpu_idle_up;
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+ }
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+ up(&dbs_sem);
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+
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+ return count;
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+}
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+
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+static ssize_t store_freq_step(struct cpufreq_policy *policy,
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+ const char *buf, size_t count)
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+{
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+ unsigned int input;
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+ int ret;
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+
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+ ret = sscanf (buf, "%u", &input);
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+
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+ if ( ret != 1 )
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+ return -EINVAL;
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+
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+ if ( input > 100 )
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+ input = 100;
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+
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+ /* no need to test here if freq_step is zero as the user might actually
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+ * want this, they would be crazy though :) */
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+ down(&dbs_sem);
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+ dbs_tuners_ins.freq_step = input;
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+ up(&dbs_sem);
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+
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+ return count;
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+}
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+
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+#define define_one_rw(_name) \
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+static struct freq_attr _name = \
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+__ATTR(_name, 0644, show_##_name, store_##_name)
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+
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+define_one_rw(sampling_rate);
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+define_one_rw(sampling_down_factor);
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+define_one_rw(up_threshold);
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+define_one_rw(down_threshold);
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+define_one_rw(ignore_nice);
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+define_one_rw(freq_step);
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+
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+static struct attribute * dbs_attributes[] = {
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+ &sampling_rate_max.attr,
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+ &sampling_rate_min.attr,
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+ &sampling_rate.attr,
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+ &sampling_down_factor.attr,
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+ &up_threshold.attr,
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+ &down_threshold.attr,
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+ &ignore_nice.attr,
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+ &freq_step.attr,
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+ NULL
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+};
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+
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+static struct attribute_group dbs_attr_group = {
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+ .attrs = dbs_attributes,
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+ .name = "conservative",
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+};
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+
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+/************************** sysfs end ************************/
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+
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+static void dbs_check_cpu(int cpu)
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+{
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+ unsigned int idle_ticks, up_idle_ticks, down_idle_ticks;
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+ unsigned int freq_step;
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+ unsigned int freq_down_sampling_rate;
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+ static int down_skip[NR_CPUS];
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+ static int requested_freq[NR_CPUS];
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+ static unsigned short init_flag = 0;
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+ struct cpu_dbs_info_s *this_dbs_info;
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+ struct cpu_dbs_info_s *dbs_info;
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+
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+ struct cpufreq_policy *policy;
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+ unsigned int j;
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+
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+ this_dbs_info = &per_cpu(cpu_dbs_info, cpu);
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+ if (!this_dbs_info->enable)
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+ return;
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+
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+ policy = this_dbs_info->cur_policy;
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+
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+ if ( init_flag == 0 ) {
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+ for ( /* NULL */; init_flag < NR_CPUS; init_flag++ ) {
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+ dbs_info = &per_cpu(cpu_dbs_info, init_flag);
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+ requested_freq[cpu] = dbs_info->cur_policy->cur;
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+ }
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+ init_flag = 1;
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+ }
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+
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+ /*
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+ * The default safe range is 20% to 80%
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+ * Every sampling_rate, we check
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+ * - If current idle time is less than 20%, then we try to
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+ * increase frequency
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+ * Every sampling_rate*sampling_down_factor, we check
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+ * - If current idle time is more than 80%, then we try to
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+ * decrease frequency
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+ *
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+ * Any frequency increase takes it to the maximum frequency.
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+ * Frequency reduction happens at minimum steps of
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+ * 5% (default) of max_frequency
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+ */
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+
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+ /* Check for frequency increase */
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+
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+ idle_ticks = UINT_MAX;
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+ for_each_cpu_mask(j, policy->cpus) {
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+ unsigned int tmp_idle_ticks, total_idle_ticks;
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+ struct cpu_dbs_info_s *j_dbs_info;
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+
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+ j_dbs_info = &per_cpu(cpu_dbs_info, j);
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+ /* Check for frequency increase */
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+ total_idle_ticks = get_cpu_idle_time(j);
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+ tmp_idle_ticks = total_idle_ticks -
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+ j_dbs_info->prev_cpu_idle_up;
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+ j_dbs_info->prev_cpu_idle_up = total_idle_ticks;
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+
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+ if (tmp_idle_ticks < idle_ticks)
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+ idle_ticks = tmp_idle_ticks;
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+ }
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+
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+ /* Scale idle ticks by 100 and compare with up and down ticks */
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+ idle_ticks *= 100;
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+ up_idle_ticks = (100 - dbs_tuners_ins.up_threshold) *
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+ usecs_to_jiffies(dbs_tuners_ins.sampling_rate);
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+
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+ if (idle_ticks < up_idle_ticks) {
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+ down_skip[cpu] = 0;
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+ for_each_cpu_mask(j, policy->cpus) {
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+ struct cpu_dbs_info_s *j_dbs_info;
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+
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+ j_dbs_info = &per_cpu(cpu_dbs_info, j);
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+ j_dbs_info->prev_cpu_idle_down =
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+ j_dbs_info->prev_cpu_idle_up;
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+ }
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+ /* if we are already at full speed then break out early */
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+ if (requested_freq[cpu] == policy->max)
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+ return;
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+
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+ freq_step = (dbs_tuners_ins.freq_step * policy->max) / 100;
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+
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+ /* max freq cannot be less than 100. But who knows.... */
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+ if (unlikely(freq_step == 0))
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+ freq_step = 5;
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+
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+ requested_freq[cpu] += freq_step;
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+ if (requested_freq[cpu] > policy->max)
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+ requested_freq[cpu] = policy->max;
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+
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+ __cpufreq_driver_target(policy, requested_freq[cpu],
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+ CPUFREQ_RELATION_H);
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+ return;
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+ }
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+
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+ /* Check for frequency decrease */
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+ down_skip[cpu]++;
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+ if (down_skip[cpu] < dbs_tuners_ins.sampling_down_factor)
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+ return;
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+
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+ idle_ticks = UINT_MAX;
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+ for_each_cpu_mask(j, policy->cpus) {
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+ unsigned int tmp_idle_ticks, total_idle_ticks;
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|
+ 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);
|