1 files changed, 532 insertions, 0 deletions

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
new file mode 100644
index 000000000000..f3100b19f798
--- /dev/null
+++ b/drivers/devfreq/devfreq.c
@@ -0,0 +1,532 @@
+/*
+ * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
+ *          for Non-CPU Devices.
+ *
+ * Copyright (C) 2011 Samsung Electronics
+ *      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/kernel.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/opp.h>
+#include <linux/devfreq.h>
+#include <linux/workqueue.h>
+#include <linux/platform_device.h>
+#include <linux/list.h>
+#include <linux/printk.h>
+#include <linux/hrtimer.h>
+#include "governor.h"
+
+struct class *devfreq_class;
+
+/*
+ * devfreq_work periodically monitors every registered device.
+ * The minimum polling interval is one jiffy. The polling interval is
+ * determined by the minimum polling period among all polling devfreq
+ * devices. The resolution of polling interval is one jiffy.
+ */
+static bool polling;
+static struct workqueue_struct *devfreq_wq;
+static struct delayed_work devfreq_work;
+
+/* wait removing if this is to be removed */
+static struct devfreq *wait_remove_device;
+
+/* 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);
+}
+
+/**
+ * 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;
+
+        if (!mutex_is_locked(&devfreq->lock)) {
+                WARN(true, "devfreq->lock must be locked by the caller.\n");
+                return -EINVAL;
+        }
+
+        /* Reevaluate the proper frequency */
+        err = devfreq->governor->get_target_freq(devfreq, &freq);
+        if (err)
+                return err;
+
+        err = devfreq->profile->target(devfreq->dev.parent, &freq);
+        if (err)
+                return err;
+
+        devfreq->previous_freq = freq;
+        return err;
+}
+
+/**
+ * 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 device.
+ * @devfreq:    the devfreq struct
+ * @skip:       skip calling device_unregister().
+ *
+ * Note that the caller should lock devfreq->lock before calling
+ * this. _remove_devfreq() will unlock it and free devfreq
+ * internally. devfreq_list_lock should be locked by the caller
+ * as well (not relased at return)
+ *
+ * Lock usage:
+ * devfreq->lock: locked before call.
+ *                unlocked at return (and freed)
+ * devfreq_list_lock: locked before call.
+ *                    kept locked at return.
+ *                    if devfreq is centrally polled.
+ *
+ * Freed memory:
+ * devfreq
+ */
+static void _remove_devfreq(struct devfreq *devfreq, bool skip)
+{
+        if (!mutex_is_locked(&devfreq->lock)) {
+                WARN(true, "devfreq->lock must be locked by the caller.\n");
+                return;
+        }
+        if (!devfreq->governor->no_central_polling &&
+            !mutex_is_locked(&devfreq_list_lock)) {
+                WARN(true, "devfreq_list_lock must be locked by the caller.\n");
+                return;
+        }
+
+        if (devfreq->being_removed)
+                return;
+
+        devfreq->being_removed = true;
+
+        if (devfreq->profile->exit)
+                devfreq->profile->exit(devfreq->dev.parent);
+
+        if (devfreq->governor->exit)
+                devfreq->governor->exit(devfreq);
+
+        if (!skip && get_device(&devfreq->dev)) {
+                device_unregister(&devfreq->dev);
+                put_device(&devfreq->dev);
+        }
+
+        if (!devfreq->governor->no_central_polling)
+                list_del(&devfreq->node);
+
+        mutex_unlock(&devfreq->lock);
+        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);
+        bool central_polling = !devfreq->governor->no_central_polling;
+
+        /*
+         * If devfreq_dev_release() was called by device_unregister() of
+         * _remove_devfreq(), we cannot mutex_lock(&devfreq->lock) and
+         * being_removed is already set. This also partially checks the case
+         * where devfreq_dev_release() is called from a thread other than
+         * the one called _remove_devfreq(); however, this case is
+         * dealt completely with another following being_removed check.
+         *
+         * Because being_removed is never being
+         * unset, we do not need to worry about race conditions on
+         * being_removed.
+         */
+        if (devfreq->being_removed)
+                return;
+
+        if (central_polling)
+                mutex_lock(&devfreq_list_lock);
+
+        mutex_lock(&devfreq->lock);
+
+        /*
+         * Check being_removed flag again for the case where
+         * devfreq_dev_release() was called in a thread other than the one
+         * possibly called _remove_devfreq().
+         */
+        if (devfreq->being_removed) {
+                mutex_unlock(&devfreq->lock);
+                goto out;
+        }
+
+        /* devfreq->lock is unlocked and removed in _removed_devfreq() */
+        _remove_devfreq(devfreq, true);
+
+out:
+        if (central_polling)
+                mutex_unlock(&devfreq_list_lock);
+}
+
+/**
+ * devfreq_monitor() - Periodically poll devfreq objects.
+ * @work: the work struct used to run devfreq_monitor periodically.
+ *
+ */
+static void devfreq_monitor(struct work_struct *work)
+{
+        static unsigned long last_polled_at;
+        struct devfreq *devfreq, *tmp;
+        int error;
+        unsigned long jiffies_passed;
+        unsigned long next_jiffies = ULONG_MAX, now = jiffies;
+        struct device *dev;
+
+        /* Initially last_polled_at = 0, polling every device at bootup */
+        jiffies_passed = now - last_polled_at;
+        last_polled_at = now;
+        if (jiffies_passed == 0)
+                jiffies_passed = 1;
+
+        mutex_lock(&devfreq_list_lock);
+        list_for_each_entry_safe(devfreq, tmp, &devfreq_list, node) {
+                mutex_lock(&devfreq->lock);
+                dev = devfreq->dev.parent;
+
+                /* Do not remove tmp for a while */
+                wait_remove_device = tmp;
+
+                if (devfreq->governor->no_central_polling ||
+                    devfreq->next_polling == 0) {
+                        mutex_unlock(&devfreq->lock);
+                        continue;
+                }
+                mutex_unlock(&devfreq_list_lock);
+
+                /*
+                 * Reduce more next_polling if devfreq_wq took an extra
+                 * delay. (i.e., CPU has been idled.)
+                 */
+                if (devfreq->next_polling <= jiffies_passed) {
+                        error = update_devfreq(devfreq);
+
+                        /* Remove a devfreq with an error. */
+                        if (error && error != -EAGAIN) {
+
+                                dev_err(dev, "Due to update_devfreq error(%d), devfreq(%s) is removed from the device\n",
+                                        error, devfreq->governor->name);
+
+                                /*
+                                 * Unlock devfreq before locking the list
+                                 * in order to avoid deadlock with
+                                 * find_device_devfreq or others
+                                 */
+                                mutex_unlock(&devfreq->lock);
+                                mutex_lock(&devfreq_list_lock);
+                                /* Check if devfreq is already removed */
+                                if (IS_ERR(find_device_devfreq(dev)))
+                                        continue;
+                                mutex_lock(&devfreq->lock);
+                                /* This unlocks devfreq->lock and free it */
+                                _remove_devfreq(devfreq, false);
+                                continue;
+                        }
+                        devfreq->next_polling = devfreq->polling_jiffies;
+                } else {
+                        devfreq->next_polling -= jiffies_passed;
+                }
+
+                if (devfreq->next_polling)
+                        next_jiffies = (next_jiffies > devfreq->next_polling) ?
+                                        devfreq->next_polling : next_jiffies;
+
+                mutex_unlock(&devfreq->lock);
+                mutex_lock(&devfreq_list_lock);
+        }
+        wait_remove_device = NULL;
+        mutex_unlock(&devfreq_list_lock);
+
+        if (next_jiffies > 0 && next_jiffies < ULONG_MAX) {
+                polling = true;
+                queue_delayed_work(devfreq_wq, &devfreq_work, next_jiffies);
+        } else {
+                polling = false;
+        }
+}
+
+/**
+ * devfreq_add_device() - Add devfreq feature to the device
+ * @dev:        the device to add devfreq feature.
+ * @profile:    device-specific profile to run devfreq.
+ * @governor:   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 struct devfreq_governor *governor,
+                                   void *data)
+{
+        struct devfreq *devfreq;
+        int err = 0;
+
+        if (!dev || !profile || !governor) {
+                dev_err(dev, "%s: Invalid parameters.\n", __func__);
+                return ERR_PTR(-EINVAL);
+        }
+
+
+        if (!governor->no_central_polling) {
+                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 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 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;
+        devfreq->governor = governor;
+        devfreq->previous_freq = profile->initial_freq;
+        devfreq->data = data;
+        devfreq->next_polling = devfreq->polling_jiffies
+                              = msecs_to_jiffies(devfreq->profile->polling_ms);
+        devfreq->nb.notifier_call = devfreq_notifier_call;
+
+        dev_set_name(&devfreq->dev, dev_name(dev));
+        err = device_register(&devfreq->dev);
+        if (err) {
+                put_device(&devfreq->dev);
+                goto err_dev;
+        }
+
+        if (governor->init)
+                err = governor->init(devfreq);
+        if (err)
+                goto err_init;
+
+        mutex_unlock(&devfreq->lock);
+
+        if (governor->no_central_polling)
+                goto out;
+
+        mutex_lock(&devfreq_list_lock);
+
+        list_add(&devfreq->node, &devfreq_list);
+
+        if (devfreq_wq && devfreq->next_polling && !polling) {
+                polling = true;
+                queue_delayed_work(devfreq_wq, &devfreq_work,
+                                   devfreq->next_polling);
+        }
+        mutex_unlock(&devfreq_list_lock);
+        goto out;
+err_init:
+        device_unregister(&devfreq->dev);
+err_dev:
+        mutex_unlock(&devfreq->lock);
+        kfree(devfreq);
+out:
+        if (err)
+                return ERR_PTR(err);
+        else
+                return devfreq;
+}
+
+/**
+ * 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;
+
+        if (!devfreq->governor->no_central_polling) {
+                mutex_lock(&devfreq_list_lock);
+                while (wait_remove_device == devfreq) {
+                        mutex_unlock(&devfreq_list_lock);
+                        schedule();
+                        mutex_lock(&devfreq_list_lock);
+                }
+        }
+
+        mutex_lock(&devfreq->lock);
+        _remove_devfreq(devfreq, false); /* it unlocks devfreq->lock */
+
+        if (!devfreq->governor->no_central_polling)
+                mutex_unlock(&devfreq_list_lock);
+
+        return 0;
+}
+
+/**
+ * devfreq_start_polling() - Initialize data structure for devfreq framework and
+ *                         start polling registered devfreq devices.
+ */
+static int __init devfreq_start_polling(void)
+{
+        mutex_lock(&devfreq_list_lock);
+        polling = false;
+        devfreq_wq = create_freezable_workqueue("devfreq_wq");
+        INIT_DELAYED_WORK_DEFERRABLE(&devfreq_work, devfreq_monitor);
+        mutex_unlock(&devfreq_list_lock);
+
+        devfreq_monitor(&devfreq_work.work);
+        return 0;
+}
+late_initcall(devfreq_start_polling);
+
+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);
+        }
+        return 0;
+}
+subsys_initcall(devfreq_init);
+
+static void __exit devfreq_exit(void)
+{
+        class_destroy(devfreq_class);
+}
+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
+ *
+ */
+struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq)
+{
+        struct opp *opp = opp_find_freq_ceil(dev, freq);
+
+        if (opp == ERR_PTR(-ENODEV))
+                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 = opp_get_notifier(dev);
+
+        if (IS_ERR(nh))
+                return PTR_ERR(nh);
+        return srcu_notifier_chain_register(nh, &devfreq->nb);
+}
+
+/**
+ * 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 = opp_get_notifier(dev);
+
+        if (IS_ERR(nh))
+                return PTR_ERR(nh);
+        return srcu_notifier_chain_unregister(nh, &devfreq->nb);
+}
+
+MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");
+MODULE_DESCRIPTION("devfreq class support");
+MODULE_LICENSE("GPL");