/* * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework * for Non-CPU Devices. * * Copyright (C) 2011 Samsung Electronics * MyungJoo Ham * * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "governor.h" static struct class *devfreq_class; /* * devfreq core provides delayed work based load monitoring helper * functions. Governors can use these or can implement their own * monitoring mechanism. */ static struct workqueue_struct *devfreq_wq; /* The list of all device-devfreq governors */ static LIST_HEAD(devfreq_governor_list); /* The list of all device-devfreq */ static LIST_HEAD(devfreq_list); static DEFINE_MUTEX(devfreq_list_lock); /** * find_device_devfreq() - find devfreq struct using device pointer * @dev: device pointer used to lookup device devfreq. * * Search the list of device devfreqs and return the matched device's * devfreq info. devfreq_list_lock should be held by the caller. */ static struct devfreq *find_device_devfreq(struct device *dev) { struct devfreq *tmp_devfreq; if (unlikely(IS_ERR_OR_NULL(dev))) { pr_err("DEVFREQ: %s: Invalid parameters\n", __func__); return ERR_PTR(-EINVAL); } WARN(!mutex_is_locked(&devfreq_list_lock), "devfreq_list_lock must be locked."); list_for_each_entry(tmp_devfreq, &devfreq_list, node) { if (tmp_devfreq->dev.parent == dev) return tmp_devfreq; } return ERR_PTR(-ENODEV); } /** * devfreq_get_freq_level() - Lookup freq_table for the frequency * @devfreq: the devfreq instance * @freq: the target frequency */ static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq) { int lev; for (lev = 0; lev < devfreq->profile->max_state; lev++) if (freq == devfreq->profile->freq_table[lev]) return lev; return -EINVAL; } /** * devfreq_update_status() - Update statistics of devfreq behavior * @devfreq: the devfreq instance * @freq: the update target frequency */ static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq) { int lev, prev_lev; unsigned long cur_time; lev = devfreq_get_freq_level(devfreq, freq); if (lev < 0) return lev; cur_time = jiffies; devfreq->time_in_state[lev] += cur_time - devfreq->last_stat_updated; if (freq != devfreq->previous_freq) { prev_lev = devfreq_get_freq_level(devfreq, devfreq->previous_freq); devfreq->trans_table[(prev_lev * devfreq->profile->max_state) + lev]++; devfreq->total_trans++; } devfreq->last_stat_updated = cur_time; return 0; } /** * find_devfreq_governor() - find devfreq governor from name * @name: name of the governor * * Search the list of devfreq governors and return the matched * governor's pointer. devfreq_list_lock should be held by the caller. */ static struct devfreq_governor *find_devfreq_governor(const char *name) { struct devfreq_governor *tmp_governor; if (unlikely(IS_ERR_OR_NULL(name))) { pr_err("DEVFREQ: %s: Invalid parameters\n", __func__); return ERR_PTR(-EINVAL); } WARN(!mutex_is_locked(&devfreq_list_lock), "devfreq_list_lock must be locked."); list_for_each_entry(tmp_governor, &devfreq_governor_list, node) { if (!strncmp(tmp_governor->name, name, DEVFREQ_NAME_LEN)) return tmp_governor; } return ERR_PTR(-ENODEV); } /* Load monitoring helper functions for governors use */ /** * update_devfreq() - Reevaluate the device and configure frequency. * @devfreq: the devfreq instance. * * Note: Lock devfreq->lock before calling update_devfreq * This function is exported for governors. */ int update_devfreq(struct devfreq *devfreq) { unsigned long freq; int err = 0; u32 flags = 0; if (!mutex_is_locked(&devfreq->lock)) { WARN(true, "devfreq->lock must be locked by the caller.\n"); return -EINVAL; } if (!devfreq->governor) return -EINVAL; /* Reevaluate the proper frequency */ err = devfreq->governor->get_target_freq(devfreq, &freq); if (err) return err; /* * Adjust the freuqency with user freq and QoS. * * List from the highest proiority * max_freq (probably called by thermal when it's too hot) * min_freq */ if (devfreq->min_freq && freq < devfreq->min_freq) { freq = devfreq->min_freq; flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */ } if (devfreq->max_freq && freq > devfreq->max_freq) { freq = devfreq->max_freq; flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */ } err = devfreq->profile->target(devfreq->dev.parent, &freq, flags); if (err) return err; if (devfreq->profile->freq_table) if (devfreq_update_status(devfreq, freq)) dev_err(&devfreq->dev, "Couldn't update frequency transition information.\n"); devfreq->previous_freq = freq; return err; } EXPORT_SYMBOL(update_devfreq); /** * devfreq_monitor() - Periodically poll devfreq objects. * @work: the work struct used to run devfreq_monitor periodically. * */ static void devfreq_monitor(struct work_struct *work) { int err; struct devfreq *devfreq = container_of(work, struct devfreq, work.work); mutex_lock(&devfreq->lock); err = update_devfreq(devfreq); if (err) dev_err(&devfreq->dev, "dvfs failed with (%d) error\n", err); queue_delayed_work(devfreq_wq, &devfreq->work, msecs_to_jiffies(devfreq->profile->polling_ms)); mutex_unlock(&devfreq->lock); } /** * devfreq_monitor_start() - Start load monitoring of devfreq instance * @devfreq: the devfreq instance. * * Helper function for starting devfreq device load monitoing. By * default delayed work based monitoring is supported. Function * to be called from governor in response to DEVFREQ_GOV_START * event when device is added to devfreq framework. */ void devfreq_monitor_start(struct devfreq *devfreq) { INIT_DEFERRABLE_WORK(&devfreq->work, devfreq_monitor); if (devfreq->profile->polling_ms) queue_delayed_work(devfreq_wq, &devfreq->work, msecs_to_jiffies(devfreq->profile->polling_ms)); } EXPORT_SYMBOL(devfreq_monitor_start); /** * devfreq_monitor_stop() - Stop load monitoring of a devfreq instance * @devfreq: the devfreq instance. * * Helper function to stop devfreq device load monitoing. Function * to be called from governor in response to DEVFREQ_GOV_STOP * event when device is removed from devfreq framework. */ void devfreq_monitor_stop(struct devfreq *devfreq) { cancel_delayed_work_sync(&devfreq->work); } EXPORT_SYMBOL(devfreq_monitor_stop); /** * devfreq_monitor_suspend() - Suspend load monitoring of a devfreq instance * @devfreq: the devfreq instance. * * Helper function to suspend devfreq device load monitoing. Function * to be called from governor in response to DEVFREQ_GOV_SUSPEND * event or when polling interval is set to zero. * * Note: Though this function is same as devfreq_monitor_stop(), * intentionally kept separate to provide hooks for collecting * transition statistics. */ void devfreq_monitor_suspend(struct devfreq *devfreq) { mutex_lock(&devfreq->lock); if (devfreq->stop_polling) { mutex_unlock(&devfreq->lock); return; } devfreq->stop_polling = true; mutex_unlock(&devfreq->lock); cancel_delayed_work_sync(&devfreq->work); } EXPORT_SYMBOL(devfreq_monitor_suspend); /** * devfreq_monitor_resume() - Resume load monitoring of a devfreq instance * @devfreq: the devfreq instance. * * Helper function to resume devfreq device load monitoing. Function * to be called from governor in response to DEVFREQ_GOV_RESUME * event or when polling interval is set to non-zero. */ void devfreq_monitor_resume(struct devfreq *devfreq) { mutex_lock(&devfreq->lock); if (!devfreq->stop_polling) goto out; if (!delayed_work_pending(&devfreq->work) && devfreq->profile->polling_ms) queue_delayed_work(devfreq_wq, &devfreq->work, msecs_to_jiffies(devfreq->profile->polling_ms)); devfreq->stop_polling = false; out: mutex_unlock(&devfreq->lock); } EXPORT_SYMBOL(devfreq_monitor_resume); /** * devfreq_interval_update() - Update device devfreq monitoring interval * @devfreq: the devfreq instance. * @delay: new polling interval to be set. * * Helper function to set new load monitoring polling interval. Function * to be called from governor in response to DEVFREQ_GOV_INTERVAL event. */ void devfreq_interval_update(struct devfreq *devfreq, unsigned int *delay) { unsigned int cur_delay = devfreq->profile->polling_ms; unsigned int new_delay = *delay; mutex_lock(&devfreq->lock); devfreq->profile->polling_ms = new_delay; if (devfreq->stop_polling) goto out; /* if new delay is zero, stop polling */ if (!new_delay) { mutex_unlock(&devfreq->lock); cancel_delayed_work_sync(&devfreq->work); return; } /* if current delay is zero, start polling with new delay */ if (!cur_delay) { queue_delayed_work(devfreq_wq, &devfreq->work, msecs_to_jiffies(devfreq->profile->polling_ms)); goto out; } /* if current delay is greater than new delay, restart polling */ if (cur_delay > new_delay) { mutex_unlock(&devfreq->lock); cancel_delayed_work_sync(&devfreq->work); mutex_lock(&devfreq->lock); if (!devfreq->stop_polling) queue_delayed_work(devfreq_wq, &devfreq->work, msecs_to_jiffies(devfreq->profile->polling_ms)); } out: mutex_unlock(&devfreq->lock); } EXPORT_SYMBOL(devfreq_interval_update); /** * devfreq_notifier_call() - Notify that the device frequency requirements * has been changed out of devfreq framework. * @nb: the notifier_block (supposed to be devfreq->nb) * @type: not used * @devp: not used * * Called by a notifier that uses devfreq->nb. */ static int devfreq_notifier_call(struct notifier_block *nb, unsigned long type, void *devp) { struct devfreq *devfreq = container_of(nb, struct devfreq, nb); int ret; mutex_lock(&devfreq->lock); ret = update_devfreq(devfreq); mutex_unlock(&devfreq->lock); return ret; } /** * _remove_devfreq() - Remove devfreq from the list and release its resources. * @devfreq: the devfreq struct * @skip: skip calling device_unregister(). */ static void _remove_devfreq(struct devfreq *devfreq, bool skip) { mutex_lock(&devfreq_list_lock); if (IS_ERR(find_device_devfreq(devfreq->dev.parent))) { mutex_unlock(&devfreq_list_lock); dev_warn(&devfreq->dev, "releasing devfreq which doesn't exist\n"); return; } list_del(&devfreq->node); mutex_unlock(&devfreq_list_lock); if (devfreq->governor) devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_STOP, NULL); if (devfreq->profile->exit) devfreq->profile->exit(devfreq->dev.parent); if (!skip && get_device(&devfreq->dev)) { device_unregister(&devfreq->dev); put_device(&devfreq->dev); } mutex_destroy(&devfreq->lock); kfree(devfreq); } /** * devfreq_dev_release() - Callback for struct device to release the device. * @dev: the devfreq device * * This calls _remove_devfreq() if _remove_devfreq() is not called. * Note that devfreq_dev_release() could be called by _remove_devfreq() as * well as by others unregistering the device. */ static void devfreq_dev_release(struct device *dev) { struct devfreq *devfreq = to_devfreq(dev); _remove_devfreq(devfreq, true); } /** * devfreq_add_device() - Add devfreq feature to the device * @dev: the device to add devfreq feature. * @profile: device-specific profile to run devfreq. * @governor_name: name of the policy to choose frequency. * @data: private data for the governor. The devfreq framework does not * touch this value. */ struct devfreq *devfreq_add_device(struct device *dev, struct devfreq_dev_profile *profile, const char *governor_name, void *data) { struct devfreq *devfreq; struct devfreq_governor *governor; int err = 0; if (!dev || !profile || !governor_name) { dev_err(dev, "%s: Invalid parameters.\n", __func__); return ERR_PTR(-EINVAL); } mutex_lock(&devfreq_list_lock); devfreq = find_device_devfreq(dev); mutex_unlock(&devfreq_list_lock); if (!IS_ERR(devfreq)) { dev_err(dev, "%s: Unable to create devfreq for the device. It already has one.\n", __func__); err = -EINVAL; goto err_out; } devfreq = kzalloc(sizeof(struct devfreq), GFP_KERNEL); if (!devfreq) { dev_err(dev, "%s: Unable to create devfreq for the device\n", __func__); err = -ENOMEM; goto err_out; } mutex_init(&devfreq->lock); mutex_lock(&devfreq->lock); devfreq->dev.parent = dev; devfreq->dev.class = devfreq_class; devfreq->dev.release = devfreq_dev_release; devfreq->profile = profile; strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN); devfreq->previous_freq = profile->initial_freq; devfreq->data = data; devfreq->nb.notifier_call = devfreq_notifier_call; devfreq->trans_table = devm_kzalloc(dev, sizeof(unsigned int) * devfreq->profile->max_state * devfreq->profile->max_state, GFP_KERNEL); devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned int) * devfreq->profile->max_state, GFP_KERNEL); devfreq->last_stat_updated = jiffies; dev_set_name(&devfreq->dev, dev_name(dev)); err = device_register(&devfreq->dev); if (err) { put_device(&devfreq->dev); mutex_unlock(&devfreq->lock); goto err_dev; } mutex_unlock(&devfreq->lock); mutex_lock(&devfreq_list_lock); list_add(&devfreq->node, &devfreq_list); governor = find_devfreq_governor(devfreq->governor_name); if (!IS_ERR(governor)) devfreq->governor = governor; if (devfreq->governor) err = devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_START, NULL); mutex_unlock(&devfreq_list_lock); if (err) { dev_err(dev, "%s: Unable to start governor for the device\n", __func__); goto err_init; } return devfreq; err_init: list_del(&devfreq->node); device_unregister(&devfreq->dev); err_dev: kfree(devfreq); err_out: return ERR_PTR(err); } EXPORT_SYMBOL(devfreq_add_device); /** * devfreq_remove_device() - Remove devfreq feature from a device. * @devfreq: the devfreq instance to be removed */ int devfreq_remove_device(struct devfreq *devfreq) { if (!devfreq) return -EINVAL; _remove_devfreq(devfreq, false); return 0; } EXPORT_SYMBOL(devfreq_remove_device); /** * devfreq_suspend_device() - Suspend devfreq of a device. * @devfreq: the devfreq instance to be suspended */ int devfreq_suspend_device(struct devfreq *devfreq) { if (!devfreq) return -EINVAL; if (!devfreq->governor) return 0; return devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_SUSPEND, NULL); } EXPORT_SYMBOL(devfreq_suspend_device); /** * devfreq_resume_device() - Resume devfreq of a device. * @devfreq: the devfreq instance to be resumed */ int devfreq_resume_device(struct devfreq *devfreq) { if (!devfreq) return -EINVAL; if (!devfreq->governor) return 0; return devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_RESUME, NULL); } EXPORT_SYMBOL(devfreq_resume_device); /** * devfreq_add_governor() - Add devfreq governor * @governor: the devfreq governor to be added */ int devfreq_add_governor(struct devfreq_governor *governor) { struct devfreq_governor *g; struct devfreq *devfreq; int err = 0; if (!governor) { pr_err("%s: Invalid parameters.\n", __func__); return -EINVAL; } mutex_lock(&devfreq_list_lock); g = find_devfreq_governor(governor->name); if (!IS_ERR(g)) { pr_err("%s: governor %s already registered\n", __func__, g->name); err = -EINVAL; goto err_out; } list_add(&governor->node, &devfreq_governor_list); list_for_each_entry(devfreq, &devfreq_list, node) { int ret = 0; struct device *dev = devfreq->dev.parent; if (!strncmp(devfreq->governor_name, governor->name, DEVFREQ_NAME_LEN)) { /* The following should never occur */ if (devfreq->governor) { dev_warn(dev, "%s: Governor %s already present\n", __func__, devfreq->governor->name); ret = devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_STOP, NULL); if (ret) { dev_warn(dev, "%s: Governor %s stop = %d\n", __func__, devfreq->governor->name, ret); } /* Fall through */ } devfreq->governor = governor; ret = devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_START, NULL); if (ret) { dev_warn(dev, "%s: Governor %s start=%d\n", __func__, devfreq->governor->name, ret); } } } err_out: mutex_unlock(&devfreq_list_lock); return err; } EXPORT_SYMBOL(devfreq_add_governor); /** * devfreq_remove_device() - Remove devfreq feature from a device. * @governor: the devfreq governor to be removed */ int devfreq_remove_governor(struct devfreq_governor *governor) { struct devfreq_governor *g; struct devfreq *devfreq; int err = 0; if (!governor) { pr_err("%s: Invalid parameters.\n", __func__); return -EINVAL; } mutex_lock(&devfreq_list_lock); g = find_devfreq_governor(governor->name); if (IS_ERR(g)) { pr_err("%s: governor %s not registered\n", __func__, governor->name); err = PTR_ERR(g); goto err_out; } list_for_each_entry(devfreq, &devfreq_list, node) { int ret; struct device *dev = devfreq->dev.parent; if (!strncmp(devfreq->governor_name, governor->name, DEVFREQ_NAME_LEN)) { /* we should have a devfreq governor! */ if (!devfreq->governor) { dev_warn(dev, "%s: Governor %s NOT present\n", __func__, governor->name); continue; /* Fall through */ } ret = devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_STOP, NULL); if (ret) { dev_warn(dev, "%s: Governor %s stop=%d\n", __func__, devfreq->governor->name, ret); } devfreq->governor = NULL; } } list_del(&governor->node); err_out: mutex_unlock(&devfreq_list_lock); return err; } EXPORT_SYMBOL(devfreq_remove_governor); static ssize_t show_governor(struct device *dev, struct device_attribute *attr, char *buf) { if (!to_devfreq(dev)->governor) return -EINVAL; return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name); } static ssize_t store_governor(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { struct devfreq *df = to_devfreq(dev); int ret; char str_governor[DEVFREQ_NAME_LEN + 1]; struct devfreq_governor *governor; ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor); if (ret != 1) return -EINVAL; mutex_lock(&devfreq_list_lock); governor = find_devfreq_governor(str_governor); if (IS_ERR(governor)) { ret = PTR_ERR(governor); goto out; } if (df->governor == governor) goto out; if (df->governor) { ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL); if (ret) { dev_warn(dev, "%s: Governor %s not stopped(%d)\n", __func__, df->governor->name, ret); goto out; } } df->governor = governor; strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN); ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL); if (ret) dev_warn(dev, "%s: Governor %s not started(%d)\n", __func__, df->governor->name, ret); out: mutex_unlock(&devfreq_list_lock); if (!ret) ret = count; return ret; } static ssize_t show_available_governors(struct device *d, struct device_attribute *attr, char *buf) { struct devfreq_governor *tmp_governor; ssize_t count = 0; mutex_lock(&devfreq_list_lock); list_for_each_entry(tmp_governor, &devfreq_governor_list, node) count += scnprintf(&buf[count], (PAGE_SIZE - count - 2), "%s ", tmp_governor->name); mutex_unlock(&devfreq_list_lock); /* Truncate the trailing space */ if (count) count--; count += sprintf(&buf[count], "\n"); return count; } static ssize_t show_freq(struct device *dev, struct device_attribute *attr, char *buf) { unsigned long freq; struct devfreq *devfreq = to_devfreq(dev); if (devfreq->profile->get_cur_freq && !devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq)) return sprintf(buf, "%lu\n", freq); return sprintf(buf, "%lu\n", devfreq->previous_freq); } static ssize_t show_target_freq(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq); } static ssize_t show_polling_interval(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "%d\n", to_devfreq(dev)->profile->polling_ms); } static ssize_t store_polling_interval(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { struct devfreq *df = to_devfreq(dev); unsigned int value; int ret; if (!df->governor) return -EINVAL; ret = sscanf(buf, "%u", &value); if (ret != 1) return -EINVAL; df->governor->event_handler(df, DEVFREQ_GOV_INTERVAL, &value); ret = count; return ret; } static ssize_t store_min_freq(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { struct devfreq *df = to_devfreq(dev); unsigned long value; int ret; unsigned long max; ret = sscanf(buf, "%lu", &value); if (ret != 1) return -EINVAL; mutex_lock(&df->lock); max = df->max_freq; if (value && max && value > max) { ret = -EINVAL; goto unlock; } df->min_freq = value; update_devfreq(df); ret = count; unlock: mutex_unlock(&df->lock); return ret; } static ssize_t show_min_freq(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "%lu\n", to_devfreq(dev)->min_freq); } static ssize_t store_max_freq(struct device *dev, struct device_attribute *attr, const char *buf, size_t count) { struct devfreq *df = to_devfreq(dev); unsigned long value; int ret; unsigned long min; ret = sscanf(buf, "%lu", &value); if (ret != 1) return -EINVAL; mutex_lock(&df->lock); min = df->min_freq; if (value && min && value < min) { ret = -EINVAL; goto unlock; } df->max_freq = value; update_devfreq(df); ret = count; unlock: mutex_unlock(&df->lock); return ret; } static ssize_t show_max_freq(struct device *dev, struct device_attribute *attr, char *buf) { return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq); } static ssize_t show_available_freqs(struct device *d, struct device_attribute *attr, char *buf) { struct devfreq *df = to_devfreq(d); struct device *dev = df->dev.parent; struct opp *opp; ssize_t count = 0; unsigned long freq = 0; rcu_read_lock(); do { opp = opp_find_freq_ceil(dev, &freq); if (IS_ERR(opp)) break; count += scnprintf(&buf[count], (PAGE_SIZE - count - 2), "%lu ", freq); freq++; } while (1); rcu_read_unlock(); /* Truncate the trailing space */ if (count) count--; count += sprintf(&buf[count], "\n"); return count; } static ssize_t show_trans_table(struct device *dev, struct device_attribute *attr, char *buf) { struct devfreq *devfreq = to_devfreq(dev); ssize_t len; int i, j, err; unsigned int max_state = devfreq->profile->max_state; err = devfreq_update_status(devfreq, devfreq->previous_freq); if (err) return 0; len = sprintf(buf, " From : To\n"); len += sprintf(buf + len, " :"); for (i = 0; i < max_state; i++) len += sprintf(buf + len, "%8u", devfreq->profile->freq_table[i]); len += sprintf(buf + len, " time(ms)\n"); for (i = 0; i < max_state; i++) { if (devfreq->profile->freq_table[i] == devfreq->previous_freq) { len += sprintf(buf + len, "*"); } else { len += sprintf(buf + len, " "); } len += sprintf(buf + len, "%8u:", devfreq->profile->freq_table[i]); for (j = 0; j < max_state; j++) len += sprintf(buf + len, "%8u", devfreq->trans_table[(i * max_state) + j]); len += sprintf(buf + len, "%10u\n", jiffies_to_msecs(devfreq->time_in_state[i])); } len += sprintf(buf + len, "Total transition : %u\n", devfreq->total_trans); return len; } static struct device_attribute devfreq_attrs[] = { __ATTR(governor, S_IRUGO | S_IWUSR, show_governor, store_governor), __ATTR(available_governors, S_IRUGO, show_available_governors, NULL), __ATTR(cur_freq, S_IRUGO, show_freq, NULL), __ATTR(available_frequencies, S_IRUGO, show_available_freqs, NULL), __ATTR(target_freq, S_IRUGO, show_target_freq, NULL), __ATTR(polling_interval, S_IRUGO | S_IWUSR, show_polling_interval, store_polling_interval), __ATTR(min_freq, S_IRUGO | S_IWUSR, show_min_freq, store_min_freq), __ATTR(max_freq, S_IRUGO | S_IWUSR, show_max_freq, store_max_freq), __ATTR(trans_stat, S_IRUGO, show_trans_table, NULL), { }, }; static int __init devfreq_init(void) { devfreq_class = class_create(THIS_MODULE, "devfreq"); if (IS_ERR(devfreq_class)) { pr_err("%s: couldn't create class\n", __FILE__); return PTR_ERR(devfreq_class); } devfreq_wq = create_freezable_workqueue("devfreq_wq"); if (IS_ERR(devfreq_wq)) { class_destroy(devfreq_class); pr_err("%s: couldn't create workqueue\n", __FILE__); return PTR_ERR(devfreq_wq); } devfreq_class->dev_attrs = devfreq_attrs; return 0; } subsys_initcall(devfreq_init); static void __exit devfreq_exit(void) { class_destroy(devfreq_class); destroy_workqueue(devfreq_wq); } module_exit(devfreq_exit); /* * The followings are helper functions for devfreq user device drivers with * OPP framework. */ /** * devfreq_recommended_opp() - Helper function to get proper OPP for the * freq value given to target callback. * @dev: The devfreq user device. (parent of devfreq) * @freq: The frequency given to target function * @flags: Flags handed from devfreq framework. * * Locking: This function must be called under rcu_read_lock(). opp is a rcu * protected pointer. The reason for the same is that the opp pointer which is * returned will remain valid for use with opp_get_{voltage, freq} only while * under the locked area. The pointer returned must be used prior to unlocking * with rcu_read_unlock() to maintain the integrity of the pointer. */ struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq, u32 flags) { struct opp *opp; if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) { /* The freq is an upper bound. opp should be lower */ opp = opp_find_freq_floor(dev, freq); /* If not available, use the closest opp */ if (opp == ERR_PTR(-ERANGE)) opp = opp_find_freq_ceil(dev, freq); } else { /* The freq is an lower bound. opp should be higher */ opp = opp_find_freq_ceil(dev, freq); /* If not available, use the closest opp */ if (opp == ERR_PTR(-ERANGE)) opp = opp_find_freq_floor(dev, freq); } return opp; } /** * devfreq_register_opp_notifier() - Helper function to get devfreq notified * for any changes in the OPP availability * changes * @dev: The devfreq user device. (parent of devfreq) * @devfreq: The devfreq object. */ int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq) { struct srcu_notifier_head *nh; int ret = 0; rcu_read_lock(); nh = opp_get_notifier(dev); if (IS_ERR(nh)) ret = PTR_ERR(nh); rcu_read_unlock(); if (!ret) ret = srcu_notifier_chain_register(nh, &devfreq->nb); return ret; } /** * devfreq_unregister_opp_notifier() - Helper function to stop getting devfreq * notified for any changes in the OPP * availability changes anymore. * @dev: The devfreq user device. (parent of devfreq) * @devfreq: The devfreq object. * * At exit() callback of devfreq_dev_profile, this must be included if * devfreq_recommended_opp is used. */ int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq) { struct srcu_notifier_head *nh; int ret = 0; rcu_read_lock(); nh = opp_get_notifier(dev); if (IS_ERR(nh)) ret = PTR_ERR(nh); rcu_read_unlock(); if (!ret) ret = srcu_notifier_chain_unregister(nh, &devfreq->nb); return ret; } MODULE_AUTHOR("MyungJoo Ham "); MODULE_DESCRIPTION("devfreq class support"); MODULE_LICENSE("GPL");