1 files changed, 344 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
new file mode 100644
index 0000000000..b6bd0ff353
--- /dev/null
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -0,0 +1,344 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  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)  2009 Alexander Clouter <alex@digriz.org.uk>
+ */
+
+#include <linux/slab.h>
+#include "cpufreq_governor.h"
+
+struct cs_policy_dbs_info {
+	struct policy_dbs_info policy_dbs;
+	unsigned int down_skip;
+	unsigned int requested_freq;
+};
+
+static inline struct cs_policy_dbs_info *to_dbs_info(struct policy_dbs_info *policy_dbs)
+{
+	return container_of(policy_dbs, struct cs_policy_dbs_info, policy_dbs);
+}
+
+struct cs_dbs_tuners {
+	unsigned int down_threshold;
+	unsigned int freq_step;
+};
+
+/* Conservative governor macros */
+#define DEF_FREQUENCY_UP_THRESHOLD		(80)
+#define DEF_FREQUENCY_DOWN_THRESHOLD		(20)
+#define DEF_FREQUENCY_STEP			(5)
+#define DEF_SAMPLING_DOWN_FACTOR		(1)
+#define MAX_SAMPLING_DOWN_FACTOR		(10)
+
+static inline unsigned int get_freq_step(struct cs_dbs_tuners *cs_tuners,
+					 struct cpufreq_policy *policy)
+{
+	unsigned int freq_step = (cs_tuners->freq_step * policy->max) / 100;
+
+	/* max freq cannot be less than 100. But who knows... */
+	if (unlikely(freq_step == 0))
+		freq_step = DEF_FREQUENCY_STEP;
+
+	return freq_step;
+}
+
+/*
+ * Every sampling_rate, we check, if current idle time is less than 20%
+ * (default), then we try to increase frequency. Every sampling_rate *
+ * sampling_down_factor, we check, if current idle time is more than 80%
+ * (default), then we try to decrease frequency
+ *
+ * Frequency updates happen at minimum steps of 5% (default) of maximum
+ * frequency
+ */
+static unsigned int cs_dbs_update(struct cpufreq_policy *policy)
+{
+	struct policy_dbs_info *policy_dbs = policy->governor_data;
+	struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
+	unsigned int requested_freq = dbs_info->requested_freq;
+	struct dbs_data *dbs_data = policy_dbs->dbs_data;
+	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
+	unsigned int load = dbs_update(policy);
+	unsigned int freq_step;
+
+	/*
+	 * break out if we 'cannot' reduce the speed as the user might
+	 * want freq_step to be zero
+	 */
+	if (cs_tuners->freq_step == 0)
+		goto out;
+
+	/*
+	 * If requested_freq is out of range, it is likely that the limits
+	 * changed in the meantime, so fall back to current frequency in that
+	 * case.
+	 */
+	if (requested_freq > policy->max || requested_freq < policy->min) {
+		requested_freq = policy->cur;
+		dbs_info->requested_freq = requested_freq;
+	}
+
+	freq_step = get_freq_step(cs_tuners, policy);
+
+	/*
+	 * Decrease requested_freq one freq_step for each idle period that
+	 * we didn't update the frequency.
+	 */
+	if (policy_dbs->idle_periods < UINT_MAX) {
+		unsigned int freq_steps = policy_dbs->idle_periods * freq_step;
+
+		if (requested_freq > policy->min + freq_steps)
+			requested_freq -= freq_steps;
+		else
+			requested_freq = policy->min;
+
+		policy_dbs->idle_periods = UINT_MAX;
+	}
+
+	/* Check for frequency increase */
+	if (load > dbs_data->up_threshold) {
+		dbs_info->down_skip = 0;
+
+		/* if we are already at full speed then break out early */
+		if (requested_freq == policy->max)
+			goto out;
+
+		requested_freq += freq_step;
+		if (requested_freq > policy->max)
+			requested_freq = policy->max;
+
+		__cpufreq_driver_target(policy, requested_freq,
+					CPUFREQ_RELATION_HE);
+		dbs_info->requested_freq = requested_freq;
+		goto out;
+	}
+
+	/* if sampling_down_factor is active break out early */
+	if (++dbs_info->down_skip < dbs_data->sampling_down_factor)
+		goto out;
+	dbs_info->down_skip = 0;
+
+	/* Check for frequency decrease */
+	if (load < cs_tuners->down_threshold) {
+		/*
+		 * if we cannot reduce the frequency anymore, break out early
+		 */
+		if (requested_freq == policy->min)
+			goto out;
+
+		if (requested_freq > freq_step)
+			requested_freq -= freq_step;
+		else
+			requested_freq = policy->min;
+
+		__cpufreq_driver_target(policy, requested_freq,
+					CPUFREQ_RELATION_LE);
+		dbs_info->requested_freq = requested_freq;
+	}
+
+ out:
+	return dbs_data->sampling_rate;
+}
+
+/************************** sysfs interface ************************/
+
+static ssize_t sampling_down_factor_store(struct gov_attr_set *attr_set,
+					  const char *buf, size_t count)
+{
+	struct dbs_data *dbs_data = to_dbs_data(attr_set);
+	unsigned int input;
+	int ret;
+	ret = sscanf(buf, "%u", &input);
+
+	if (ret != 1 || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
+		return -EINVAL;
+
+	dbs_data->sampling_down_factor = input;
+	return count;
+}
+
+static ssize_t up_threshold_store(struct gov_attr_set *attr_set,
+				  const char *buf, size_t count)
+{
+	struct dbs_data *dbs_data = to_dbs_data(attr_set);
+	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
+	unsigned int input;
+	int ret;
+	ret = sscanf(buf, "%u", &input);
+
+	if (ret != 1 || input > 100 || input <= cs_tuners->down_threshold)
+		return -EINVAL;
+
+	dbs_data->up_threshold = input;
+	return count;
+}
+
+static ssize_t down_threshold_store(struct gov_attr_set *attr_set,
+				    const char *buf, size_t count)
+{
+	struct dbs_data *dbs_data = to_dbs_data(attr_set);
+	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
+	unsigned int input;
+	int ret;
+	ret = sscanf(buf, "%u", &input);
+
+	/* cannot be lower than 1 otherwise freq will not fall */
+	if (ret != 1 || input < 1 || input > 100 ||
+			input >= dbs_data->up_threshold)
+		return -EINVAL;
+
+	cs_tuners->down_threshold = input;
+	return count;
+}
+
+static ssize_t ignore_nice_load_store(struct gov_attr_set *attr_set,
+				      const char *buf, size_t count)
+{
+	struct dbs_data *dbs_data = to_dbs_data(attr_set);
+	unsigned int input;
+	int ret;
+
+	ret = sscanf(buf, "%u", &input);
+	if (ret != 1)
+		return -EINVAL;
+
+	if (input > 1)
+		input = 1;
+
+	if (input == dbs_data->ignore_nice_load) /* nothing to do */
+		return count;
+
+	dbs_data->ignore_nice_load = input;
+
+	/* we need to re-evaluate prev_cpu_idle */
+	gov_update_cpu_data(dbs_data);
+
+	return count;
+}
+
+static ssize_t freq_step_store(struct gov_attr_set *attr_set, const char *buf,
+			       size_t count)
+{
+	struct dbs_data *dbs_data = to_dbs_data(attr_set);
+	struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
+	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 :)
+	 */
+	cs_tuners->freq_step = input;
+	return count;
+}
+
+gov_show_one_common(sampling_rate);
+gov_show_one_common(sampling_down_factor);
+gov_show_one_common(up_threshold);
+gov_show_one_common(ignore_nice_load);
+gov_show_one(cs, down_threshold);
+gov_show_one(cs, freq_step);
+
+gov_attr_rw(sampling_rate);
+gov_attr_rw(sampling_down_factor);
+gov_attr_rw(up_threshold);
+gov_attr_rw(ignore_nice_load);
+gov_attr_rw(down_threshold);
+gov_attr_rw(freq_step);
+
+static struct attribute *cs_attrs[] = {
+	&sampling_rate.attr,
+	&sampling_down_factor.attr,
+	&up_threshold.attr,
+	&down_threshold.attr,
+	&ignore_nice_load.attr,
+	&freq_step.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(cs);
+
+/************************** sysfs end ************************/
+
+static struct policy_dbs_info *cs_alloc(void)
+{
+	struct cs_policy_dbs_info *dbs_info;
+
+	dbs_info = kzalloc(sizeof(*dbs_info), GFP_KERNEL);
+	return dbs_info ? &dbs_info->policy_dbs : NULL;
+}
+
+static void cs_free(struct policy_dbs_info *policy_dbs)
+{
+	kfree(to_dbs_info(policy_dbs));
+}
+
+static int cs_init(struct dbs_data *dbs_data)
+{
+	struct cs_dbs_tuners *tuners;
+
+	tuners = kzalloc(sizeof(*tuners), GFP_KERNEL);
+	if (!tuners)
+		return -ENOMEM;
+
+	tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
+	tuners->freq_step = DEF_FREQUENCY_STEP;
+	dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
+	dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
+	dbs_data->ignore_nice_load = 0;
+	dbs_data->tuners = tuners;
+
+	return 0;
+}
+
+static void cs_exit(struct dbs_data *dbs_data)
+{
+	kfree(dbs_data->tuners);
+}
+
+static void cs_start(struct cpufreq_policy *policy)
+{
+	struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
+
+	dbs_info->down_skip = 0;
+	dbs_info->requested_freq = policy->cur;
+}
+
+static struct dbs_governor cs_governor = {
+	.gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("conservative"),
+	.kobj_type = { .default_groups = cs_groups },
+	.gov_dbs_update = cs_dbs_update,
+	.alloc = cs_alloc,
+	.free = cs_free,
+	.init = cs_init,
+	.exit = cs_exit,
+	.start = cs_start,
+};
+
+#define CPU_FREQ_GOV_CONSERVATIVE	(cs_governor.gov)
+
+MODULE_AUTHOR("Alexander Clouter <alex@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");
+
+#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
+struct cpufreq_governor *cpufreq_default_governor(void)
+{
+	return &CPU_FREQ_GOV_CONSERVATIVE;
+}
+#endif
+
+cpufreq_governor_init(CPU_FREQ_GOV_CONSERVATIVE);
+cpufreq_governor_exit(CPU_FREQ_GOV_CONSERVATIVE);