@@ -64,6 +64,14 @@ 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. The passive governor recommends that
+ devfreq device uses the OPP table to get the frequency/voltage.
+
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
new file mode 100644
@@ -0,0 +1,207 @@
+/*
+ * linux/drivers/devfreq/governor_passive.c
+ *
+ * Copyright (C) 2016 Samsung Electronics
+ * Author: Chanwoo Choi <cw00.choi@samsung.com>
+ * Author: MyungJoo Ham <myungjoo.ham@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/module.h>
+#include <linux/device.h>
+#include <linux/devfreq.h>
+#include "governor.h"
+
+static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
+ unsigned long *freq)
+{
+ struct devfreq_passive_data *p_data
+ = (struct devfreq_passive_data *)devfreq->data;
+ struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
+ unsigned long child_freq = ULONG_MAX;
+ struct dev_pm_opp *opp;
+ int i, count, ret = 0;
+
+ /*
+ * If the devfreq device with passive governor has the specific method
+ * to determine the next frequency, should use the get_target_freq()
+ * of struct devfreq_passive_data.
+ */
+ if (p_data->get_target_freq) {
+ ret = p_data->get_target_freq(devfreq, freq);
+ goto out;
+ }
+
+ /*
+ * If the parent and passive devfreq device uses the OPP table,
+ * get the next frequency by using the OPP table.
+ */
+
+ /*
+ * - parent devfreq device uses the governors except for passive.
+ * - passive devfreq device uses the passive governor.
+ *
+ * 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 (!devfreq->profile || !devfreq->profile->freq_table
+ || devfreq->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.
+ */
+ rcu_read_lock();
+ opp = devfreq_recommended_opp(parent_devfreq->dev.parent, freq, 0);
+ rcu_read_unlock();
+ if (IS_ERR(opp)) {
+ ret = PTR_ERR(opp);
+ goto out;
+ }
+
+ /*
+ * 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) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ /* Get the suitable frequency by using index of parent device. */
+ if (i < devfreq->profile->max_state) {
+ child_freq = devfreq->profile->freq_table[i];
+ } else {
+ count = devfreq->profile->max_state;
+ child_freq = devfreq->profile->freq_table[count - 1];
+ }
+
+ /* Return the suitable frequency for passive device. */
+ *freq = child_freq;
+
+out:
+ return ret;
+}
+
+static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq)
+{
+ int ret;
+
+ if (!devfreq->governor)
+ return -EINVAL;
+
+ mutex_lock_nested(&devfreq->lock, SINGLE_DEPTH_NESTING);
+
+ ret = devfreq->governor->get_target_freq(devfreq, &freq);
+ if (ret < 0)
+ goto out;
+
+ ret = devfreq->profile->target(devfreq->dev.parent, &freq, 0);
+ if (ret < 0)
+ goto out;
+
+ devfreq->previous_freq = freq;
+
+out:
+ mutex_unlock(&devfreq->lock);
+
+ return 0;
+}
+
+static int devfreq_passive_notifier_call(struct notifier_block *nb,
+ unsigned long event, void *ptr)
+{
+ struct devfreq_passive_data *data
+ = container_of(nb, struct devfreq_passive_data, nb);
+ struct devfreq *devfreq = (struct devfreq *)data->this;
+ struct devfreq *parent = (struct devfreq *)data->parent;
+ 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(devfreq, freq);
+ break;
+ case DEVFREQ_POSTCHANGE:
+ if (parent->previous_freq < freq)
+ update_devfreq_passive(devfreq, freq);
+ break;
+ }
+
+ return NOTIFY_DONE;
+}
+
+static int devfreq_passive_event_handler(struct devfreq *devfreq,
+ unsigned int event, void *data)
+{
+ struct device *dev = devfreq->dev.parent;
+ struct devfreq_passive_data *p_data
+ = (struct devfreq_passive_data *)devfreq->data;
+ struct devfreq *parent = (struct devfreq *)p_data->parent;
+ struct notifier_block *nb = &p_data->nb;
+ int ret = 0;
+
+ if (!parent)
+ return -EPROBE_DEFER;
+
+ switch (event) {
+ case DEVFREQ_GOV_START:
+ if (!p_data->this)
+ p_data->this = devfreq;
+
+ nb->notifier_call = devfreq_passive_notifier_call;
+ ret = devm_devfreq_register_notifier(dev, parent, nb,
+ DEVFREQ_TRANSITION_NOTIFIER);
+ break;
+ case DEVFREQ_GOV_STOP:
+ devm_devfreq_unregister_notifier(dev, parent, nb,
+ DEVFREQ_TRANSITION_NOTIFIER);
+ break;
+ default:
+ break;
+ }
+
+ return ret;
+}
+
+static struct devfreq_governor devfreq_passive = {
+ .name = "passive",
+ .get_target_freq = devfreq_passive_get_target_freq,
+ .event_handler = devfreq_passive_event_handler,
+};
+
+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_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
+MODULE_DESCRIPTION("DEVFREQ Passive governor");
+MODULE_LICENSE("GPL v2");
@@ -272,6 +272,39 @@ struct devfreq_simple_ondemand_data {
};
#endif
+#if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
+/**
+ * struct devfreq_passive_data - void *data fed to struct devfreq
+ * and devfreq_add_device
+ * @parent: the devfreq instance of parent device.
+ * @get_target_freq: Optional callback, Returns desired operating frequency
+ * for the device using passive governor. That is called
+ * when passive governor should decide the next frequency
+ * by using the new frequency of parent devfreq device
+ * using governors except for passive governor.
+ * If the devfreq device has the specific method to decide
+ * the next frequency, should use this callback.
+ * @this: the devfreq instance of own device.
+ * @nb: the notifier block for DEVFREQ_TRANSITION_NOTIFIER list
+ *
+ * The devfreq_passive_data have to set the devfreq instance of parent
+ * device with governors except for the passive governor. But, don't need to
+ * initialize the 'this' and 'nb' field because the devfreq core will handle
+ * them.
+ */
+struct devfreq_passive_data {
+ /* Should set the devfreq instance of parent device */
+ struct devfreq *parent;
+
+ /* Optional callback to decide the next frequency of passvice device */
+ int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
+
+ /* For passive governor's internal use. Don't need to set them */
+ struct devfreq *this;
+ struct notifier_block nb;
+};
+#endif
+
#else /* !CONFIG_PM_DEVFREQ */
static inline struct devfreq *devfreq_add_device(struct device *dev,
struct devfreq_dev_profile *profile,