diff options
Diffstat (limited to 'drivers/devfreq/governor_passive.c')
| -rw-r--r-- | drivers/devfreq/governor_passive.c | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c new file mode 100644 index 000000000000..9ef46e2592c4 --- /dev/null +++ b/drivers/devfreq/governor_passive.c @@ -0,0 +1,205 @@ +/* + * 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); +} +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"); |