@@ -64,6 +64,13 @@ config DEVFREQ_GOV_USERSPACE
Otherwise, the governor does not change the frequency
given at the initialization.
+config DEVFREQ_GOV_PASSIVE
+ tristate "Passive"
+ help
+ Sets the frequency based on the frequency of its parent devfreq
+ device. This governor does not change the frequency by itself
+ through sysfs entries.
+
comment "DEVFREQ Drivers"
config ARM_EXYNOS_BUS_DEVFREQ
@@ -4,6 +4,7 @@ obj-$(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND) += governor_simpleondemand.o
obj-$(CONFIG_DEVFREQ_GOV_PERFORMANCE) += governor_performance.o
obj-$(CONFIG_DEVFREQ_GOV_POWERSAVE) += governor_powersave.o
obj-$(CONFIG_DEVFREQ_GOV_USERSPACE) += governor_userspace.o
+obj-$(CONFIG_DEVFREQ_GOV_PASSIVE) += governor_passive.o
# DEVFREQ Drivers
obj-$(CONFIG_ARM_EXYNOS_BUS_DEVFREQ) += exynos-bus.o
@@ -478,7 +478,13 @@ static void _remove_devfreq(struct devfreq *devfreq)
dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n");
return;
}
+
+ if (devfreq->governor->type == DEVFREQ_GOV_PASSIVE)
+ devfreq_passive_unregister_notifier(devfreq);
+
list_del(&devfreq->node);
+ list_del_init(&devfreq->passive_node);
+
mutex_unlock(&devfreq_list_lock);
if (devfreq->governor)
@@ -598,6 +604,17 @@ struct devfreq *devfreq_add_device(struct device *dev,
goto err_init;
}
+ if (devfreq->governor->type == DEVFREQ_GOV_PASSIVE) {
+ struct devfreq *parent_devfreq = (struct devfreq *)data;
+ list_add(&devfreq->passive_node, &parent_devfreq->passive_node);
+
+ err = devfreq_passive_register_notifier(devfreq);
+ if (err <0)
+ goto err_init;
+ } else {
+ INIT_LIST_HEAD(&devfreq->passive_node);
+ }
+
return devfreq;
err_init:
@@ -23,6 +23,7 @@
#define DEVFREQ_GOV_PERFORMANCE 0x2
#define DEVFREQ_GOV_POWERSAVE 0x3
#define DEVFREQ_GOV_USERSPACE 0x4
+#define DEVFREQ_GOV_PASSIVE 0x5
/* Devfreq events */
#define DEVFREQ_GOV_START 0x1
@@ -44,4 +45,18 @@ extern void devfreq_interval_update(struct devfreq *devfreq,
extern int devfreq_add_governor(struct devfreq_governor *governor);
extern int devfreq_remove_governor(struct devfreq_governor *governor);
+#if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
+extern int devfreq_passive_register_notifier(struct devfreq *passive);
+extern void devfreq_passive_unregister_notifier(struct devfreq *passive);
+#else
+static inline int devfreq_passive_register_notifier(struct devfreq *passive)
+{
+ return 0;
+}
+
+static inline void devfreq_passive_unregister_notifier(struct devfreq *passive)
+{
+}
+#endif
+
#endif /* _GOVERNOR_H */
new file mode 100644
@@ -0,0 +1,192 @@
+/*
+ * linux/drivers/devfreq/governor_passive.c
+ *
+ * Copyright (C) 2016 Samsung Electronics
+ * Author: Chanwoo Choi <cw00.choi@samsung.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/devfreq.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/devfreq.h>
+#include "governor.h"
+
+static int devfreq_passive_get_target_freq(struct devfreq *passive,
+ unsigned long *freq)
+{
+ struct devfreq *parent_devfreq = (struct devfreq *)passive->data;
+ unsigned long child_freq = ULONG_MAX;
+ struct dev_pm_opp *opp;
+ int i, count;
+ u32 flags;
+
+ /*
+ * Each devfreq has the OPP table. After deciding the new frequency
+ * from the governor of parent devfreq device, the passive governor
+ * need to get the index of new frequency on OPP table of parent
+ * device. And then the index is used for getting the suitable
+ * new frequency for passive devfreq device.
+ */
+
+ if (!passive->profile || !passive->profile->freq_table
+ || passive->profile->max_state <= 0)
+ return -EINVAL;
+
+ /*
+ * The passive governor have to get the correct frequency from OPP
+ * list of parent device. Because in this case, *freq is temporary
+ * value which is decided by ondemand governor.
+ */
+ if (parent_devfreq->previous_freq < *freq)
+ flags = DEVFREQ_FLAG_LEAST_UPPER_BOUND;
+
+ rcu_read_lock();
+ opp = devfreq_recommended_opp(parent_devfreq->dev.parent, freq, flags);
+ rcu_read_unlock();
+ if (IS_ERR_OR_NULL(opp))
+ return PTR_ERR(opp);
+
+ /*
+ * Get the OPP table's index of decided freqeuncy by governor
+ * of parent device.
+ */
+ for (i = 0; i < parent_devfreq->profile->max_state; i++)
+ if (parent_devfreq->profile->freq_table[i] == *freq)
+ break;
+
+ if (i == parent_devfreq->profile->max_state)
+ return -EINVAL;
+
+ /* Get the suitable frequency by using index of parent device. */
+ if (i < passive->profile->max_state) {
+ child_freq = passive->profile->freq_table[i];
+ } else {
+ count = passive->profile->max_state;
+ child_freq = passive->profile->freq_table[count - 1];
+ }
+
+ /* Return the suitable frequency for passive device. */
+ *freq = child_freq;
+
+ return 0;
+}
+
+static int devfreq_passive_event_handler(struct devfreq *devfreq,
+ unsigned int event, void *data)
+{
+ return 0;
+}
+
+static struct devfreq_governor devfreq_passive = {
+ .name = "passive",
+ .type = DEVFREQ_GOV_PASSIVE,
+ .get_target_freq = devfreq_passive_get_target_freq,
+ .event_handler = devfreq_passive_event_handler,
+};
+
+static int update_devfreq_passive(struct devfreq *parent, unsigned long freq)
+{
+ struct devfreq *passive;
+ unsigned long rate;
+ int ret;
+
+ list_for_each_entry(passive, &parent->passive_node, passive_node) {
+ if (!passive->governor)
+ continue;
+ rate = freq;
+
+ ret = passive->governor->get_target_freq(passive, &rate);
+ if (ret)
+ return ret;
+
+ ret = passive->profile->target(passive->dev.parent, &rate, 0);
+ if (ret)
+ return ret;
+
+ passive->previous_freq = rate;
+ }
+
+ return 0;
+}
+
+static int devfreq_passive_notifier_call(struct notifier_block *nb,
+ unsigned long event, void *ptr)
+{
+ struct devfreq *passive = container_of(nb, struct devfreq, passive_nb);
+ struct devfreq *parent = (struct devfreq *)passive->data;
+ struct devfreq_freqs *freqs = (struct devfreq_freqs *)ptr;
+ unsigned long freq = freqs->new;
+
+ switch (event) {
+ case DEVFREQ_PRECHANGE:
+ if (parent->previous_freq > freq);
+ update_devfreq_passive(parent, freq);
+ break;
+ case DEVFREQ_POSTCHANGE:
+ if (parent->previous_freq < freq);
+ update_devfreq_passive(parent, freq);
+ break;
+ }
+
+ return NOTIFY_DONE;
+}
+
+/**
+ * devfreq_passive_register_notifier() - Register notifier block of passive
+ * devfreq to parent devfreq device.
+ * @passive: The parent devfreq object using passive governor.
+ *
+ * Register notifier block of passive devfreq device to receive the changed
+ * frequency of parent devfreq device through DEVFREQ_TRANSITION_NOTIFIER.
+ */
+int devfreq_passive_register_notifier(struct devfreq *passive)
+{
+ struct device *dev = passive->dev.parent;
+ struct devfreq *parent = (struct devfreq *)passive->data;
+ struct notifier_block *nb = &passive->passive_nb;
+
+ nb->notifier_call = devfreq_passive_notifier_call;
+ return devm_devfreq_register_notifier(dev, parent, nb,
+ DEVFREQ_TRANSITION_NOTIFIER);
+}
+
+/**
+ * devfreq_passive_register_notifier() - Unregister notifier block of passive
+ * devfreq from parent devfreq device.
+ * @passive: The parent devfreq object using passive governor.
+ */
+void devfreq_passive_unregister_notifier(struct devfreq *passive)
+{
+ struct devfreq *parent = (struct devfreq *)passive->data;
+ struct device *dev = passive->dev.parent;
+ struct notifier_block *nb = &passive->passive_nb;
+
+ devm_devfreq_unregister_notifier(dev, parent, nb,
+ DEVFREQ_TRANSITION_NOTIFIER);
+}
+
+static int __init devfreq_passive_init(void)
+{
+ return devfreq_add_governor(&devfreq_passive);
+}
+subsys_initcall(devfreq_passive_init);
+
+static void __exit devfreq_passive_exit(void)
+{
+ int ret;
+
+ ret = devfreq_remove_governor(&devfreq_passive);
+ if (ret)
+ pr_err("%s: failed remove governor %d\n", __func__, ret);
+
+ return;
+}
+module_exit(devfreq_passive_exit);
+
+MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>");
+MODULE_DESCRIPTION("DEVFREQ Passive governor");
+MODULE_LICENSE("GPL v2");
@@ -188,6 +188,9 @@ struct devfreq {
unsigned long last_stat_updated;
struct srcu_notifier_head transition_notifier_list;
+
+ struct list_head passive_node;
+ struct notifier_block passive_nb;
};
struct devfreq_freqs {