4 files changed, 225 insertions, 148 deletions

diff --git a/drivers/base/power/common.c b/drivers/base/power/common.c
index b0f138806bbc..f32b802b98f4 100644
--- a/drivers/base/power/common.c
+++ b/drivers/base/power/common.c
@@ -19,8 +19,8 @@
  * @dev: Device to handle.
  *
  * If power.subsys_data is NULL, point it to a new object, otherwise increment
- * its reference counter.  Return 1 if a new object has been created, otherwise
- * return 0 or error code.
+ * its reference counter.  Return 0 if new object has been created or refcount
+ * increased, otherwise negative error code.
  */
 int dev_pm_get_subsys_data(struct device *dev)
 {
@@ -56,13 +56,11 @@ EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data);
  * @dev: Device to handle.
  *
  * If the reference counter of power.subsys_data is zero after dropping the
- * reference, power.subsys_data is removed.  Return 1 if that happens or 0
- * otherwise.
+ * reference, power.subsys_data is removed.
  */
-int dev_pm_put_subsys_data(struct device *dev)
+void dev_pm_put_subsys_data(struct device *dev)
 {
 	struct pm_subsys_data *psd;
-	int ret = 1;
 
 	spin_lock_irq(&dev->power.lock);
 
@@ -70,18 +68,14 @@ int dev_pm_put_subsys_data(struct device *dev)
 	if (!psd)
 		goto out;
 
-	if (--psd->refcount == 0) {
+	if (--psd->refcount == 0)
 		dev->power.subsys_data = NULL;
-	} else {
+	else
 		psd = NULL;
-		ret = 0;
-	}
 
  out:
 	spin_unlock_irq(&dev->power.lock);
 	kfree(psd);
-
-	return ret;
 }
 EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);
 
diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 0d8780c04a5e..ba4abbe4693c 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -344,14 +344,7 @@ static int genpd_dev_pm_qos_notifier(struct notifier_block *nb,
 	struct device *dev;
 
 	gpd_data = container_of(nb, struct generic_pm_domain_data, nb);
-
-	mutex_lock(&gpd_data->lock);
 	dev = gpd_data->base.dev;
-	if (!dev) {
-		mutex_unlock(&gpd_data->lock);
-		return NOTIFY_DONE;
-	}
-	mutex_unlock(&gpd_data->lock);
 
 	for (;;) {
 		struct generic_pm_domain *genpd;
@@ -1384,25 +1377,66 @@ EXPORT_SYMBOL_GPL(pm_genpd_syscore_poweron);
 
 #endif /* CONFIG_PM_SLEEP */
 
-static struct generic_pm_domain_data *__pm_genpd_alloc_dev_data(struct device *dev)
+static struct generic_pm_domain_data *genpd_alloc_dev_data(struct device *dev,
+					struct generic_pm_domain *genpd,
+					struct gpd_timing_data *td)
 {
 	struct generic_pm_domain_data *gpd_data;
+	int ret;
+
+	ret = dev_pm_get_subsys_data(dev);
+	if (ret)
+		return ERR_PTR(ret);
 
 	gpd_data = kzalloc(sizeof(*gpd_data), GFP_KERNEL);
-	if (!gpd_data)
-		return NULL;
+	if (!gpd_data) {
+		ret = -ENOMEM;
+		goto err_put;
+	}
+
+	if (td)
+		gpd_data->td = *td;
 
-	mutex_init(&gpd_data->lock);
+	gpd_data->base.dev = dev;
+	gpd_data->need_restore = -1;
+	gpd_data->td.constraint_changed = true;
+	gpd_data->td.effective_constraint_ns = -1;
 	gpd_data->nb.notifier_call = genpd_dev_pm_qos_notifier;
-	dev_pm_qos_add_notifier(dev, &gpd_data->nb);
+
+	spin_lock_irq(&dev->power.lock);
+
+	if (dev->power.subsys_data->domain_data) {
+		ret = -EINVAL;
+		goto err_free;
+	}
+
+	dev->power.subsys_data->domain_data = &gpd_data->base;
+	dev->pm_domain = &genpd->domain;
+
+	spin_unlock_irq(&dev->power.lock);
+
 	return gpd_data;
+
+ err_free:
+	spin_unlock_irq(&dev->power.lock);
+	kfree(gpd_data);
+ err_put:
+	dev_pm_put_subsys_data(dev);
+	return ERR_PTR(ret);
 }
 
-static void __pm_genpd_free_dev_data(struct device *dev,
-				     struct generic_pm_domain_data *gpd_data)
+static void genpd_free_dev_data(struct device *dev,
+				struct generic_pm_domain_data *gpd_data)
 {
-	dev_pm_qos_remove_notifier(dev, &gpd_data->nb);
+	spin_lock_irq(&dev->power.lock);
+
+	dev->pm_domain = NULL;
+	dev->power.subsys_data->domain_data = NULL;
+
+	spin_unlock_irq(&dev->power.lock);
+
 	kfree(gpd_data);
+	dev_pm_put_subsys_data(dev);
 }
 
 /**
@@ -1414,8 +1448,7 @@ static void __pm_genpd_free_dev_data(struct device *dev,
 int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 			  struct gpd_timing_data *td)
 {
-	struct generic_pm_domain_data *gpd_data_new, *gpd_data = NULL;
-	struct pm_domain_data *pdd;
+	struct generic_pm_domain_data *gpd_data;
 	int ret = 0;
 
 	dev_dbg(dev, "%s()\n", __func__);
@@ -1423,9 +1456,9 @@ int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(dev))
 		return -EINVAL;
 
-	gpd_data_new = __pm_genpd_alloc_dev_data(dev);
-	if (!gpd_data_new)
-		return -ENOMEM;
+	gpd_data = genpd_alloc_dev_data(dev, genpd, td);
+	if (IS_ERR(gpd_data))
+		return PTR_ERR(gpd_data);
 
 	genpd_acquire_lock(genpd);
 
@@ -1434,50 +1467,22 @@ int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
 		goto out;
 	}
 
-	list_for_each_entry(pdd, &genpd->dev_list, list_node)
-		if (pdd->dev == dev) {
-			ret = -EINVAL;
-			goto out;
-		}
-
-	ret = dev_pm_get_subsys_data(dev);
+	ret = genpd->attach_dev ? genpd->attach_dev(genpd, dev) : 0;
 	if (ret)
 		goto out;
 
 	genpd->device_count++;
 	genpd->max_off_time_changed = true;
 
-	spin_lock_irq(&dev->power.lock);
-
-	dev->pm_domain = &genpd->domain;
-	if (dev->power.subsys_data->domain_data) {
-		gpd_data = to_gpd_data(dev->power.subsys_data->domain_data);
-	} else {
-		gpd_data = gpd_data_new;
-		dev->power.subsys_data->domain_data = &gpd_data->base;
-	}
-	gpd_data->refcount++;
-	if (td)
-		gpd_data->td = *td;
-
-	spin_unlock_irq(&dev->power.lock);
-
-	if (genpd->attach_dev)
-		genpd->attach_dev(genpd, dev);
-
-	mutex_lock(&gpd_data->lock);
-	gpd_data->base.dev = dev;
 	list_add_tail(&gpd_data->base.list_node, &genpd->dev_list);
-	gpd_data->need_restore = -1;
-	gpd_data->td.constraint_changed = true;
-	gpd_data->td.effective_constraint_ns = -1;
-	mutex_unlock(&gpd_data->lock);
 
  out:
 	genpd_release_lock(genpd);
 
-	if (gpd_data != gpd_data_new)
-		__pm_genpd_free_dev_data(dev, gpd_data_new);
+	if (ret)
+		genpd_free_dev_data(dev, gpd_data);
+	else
+		dev_pm_qos_add_notifier(dev, &gpd_data->nb);
 
 	return ret;
 }
@@ -1504,7 +1509,6 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
 {
 	struct generic_pm_domain_data *gpd_data;
 	struct pm_domain_data *pdd;
-	bool remove = false;
 	int ret = 0;
 
 	dev_dbg(dev, "%s()\n", __func__);
@@ -1514,6 +1518,11 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
 	    ||  pd_to_genpd(dev->pm_domain) != genpd)
 		return -EINVAL;
 
+	/* The above validation also means we have existing domain_data. */
+	pdd = dev->power.subsys_data->domain_data;
+	gpd_data = to_gpd_data(pdd);
+	dev_pm_qos_remove_notifier(dev, &gpd_data->nb);
+
 	genpd_acquire_lock(genpd);
 
 	if (genpd->prepared_count > 0) {
@@ -1527,58 +1536,22 @@ int pm_genpd_remove_device(struct generic_pm_domain *genpd,
 	if (genpd->detach_dev)
 		genpd->detach_dev(genpd, dev);
 
-	spin_lock_irq(&dev->power.lock);
-
-	dev->pm_domain = NULL;
-	pdd = dev->power.subsys_data->domain_data;
 	list_del_init(&pdd->list_node);
-	gpd_data = to_gpd_data(pdd);
-	if (--gpd_data->refcount == 0) {
-		dev->power.subsys_data->domain_data = NULL;
-		remove = true;
-	}
-
-	spin_unlock_irq(&dev->power.lock);
-
-	mutex_lock(&gpd_data->lock);
-	pdd->dev = NULL;
-	mutex_unlock(&gpd_data->lock);
 
 	genpd_release_lock(genpd);
 
-	dev_pm_put_subsys_data(dev);
-	if (remove)
-		__pm_genpd_free_dev_data(dev, gpd_data);
+	genpd_free_dev_data(dev, gpd_data);
 
 	return 0;
 
  out:
 	genpd_release_lock(genpd);
+	dev_pm_qos_add_notifier(dev, &gpd_data->nb);
 
 	return ret;
 }
 
 /**
- * pm_genpd_dev_need_restore - Set/unset the device's "need restore" flag.
- * @dev: Device to set/unset the flag for.
- * @val: The new value of the device's "need restore" flag.
- */
-void pm_genpd_dev_need_restore(struct device *dev, bool val)
-{
-	struct pm_subsys_data *psd;
-	unsigned long flags;
-
-	spin_lock_irqsave(&dev->power.lock, flags);
-
-	psd = dev_to_psd(dev);
-	if (psd && psd->domain_data)
-		to_gpd_data(psd->domain_data)->need_restore = val ? 1 : 0;
-
-	spin_unlock_irqrestore(&dev->power.lock, flags);
-}
-EXPORT_SYMBOL_GPL(pm_genpd_dev_need_restore);
-
-/**
  * pm_genpd_add_subdomain - Add a subdomain to an I/O PM domain.
  * @genpd: Master PM domain to add the subdomain to.
  * @subdomain: Subdomain to be added.
diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index 106c69359306..15bf29974c31 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -117,20 +117,20 @@ do {									\
 } while (0)
 
 /**
- * find_device_opp() - find device_opp struct using device pointer
+ * _find_device_opp() - find device_opp struct using device pointer
  * @dev:	device pointer used to lookup device OPPs
  *
  * Search list of device OPPs for one containing matching device. Does a RCU
  * reader operation to grab the pointer needed.
  *
- * Returns pointer to 'struct device_opp' if found, otherwise -ENODEV or
+ * Return: pointer to 'struct device_opp' if found, otherwise -ENODEV or
  * -EINVAL based on type of error.
  *
  * Locking: This function must be called under rcu_read_lock(). device_opp
  * is a RCU protected pointer. This means that device_opp is valid as long
  * as we are under RCU lock.
  */
-static struct device_opp *find_device_opp(struct device *dev)
+static struct device_opp *_find_device_opp(struct device *dev)
 {
 	struct device_opp *tmp_dev_opp, *dev_opp = ERR_PTR(-ENODEV);
 
@@ -153,7 +153,7 @@ static struct device_opp *find_device_opp(struct device *dev)
  * dev_pm_opp_get_voltage() - Gets the voltage corresponding to an available opp
  * @opp:	opp for which voltage has to be returned for
  *
- * Return voltage in micro volt corresponding to the opp, else
+ * Return: voltage in micro volt corresponding to the opp, else
  * return 0
  *
  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
@@ -169,6 +169,8 @@ unsigned long dev_pm_opp_get_voltage(struct dev_pm_opp *opp)
 	struct dev_pm_opp *tmp_opp;
 	unsigned long v = 0;
 
+	opp_rcu_lockdep_assert();
+
 	tmp_opp = rcu_dereference(opp);
 	if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available)
 		pr_err("%s: Invalid parameters\n", __func__);
@@ -183,7 +185,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_voltage);
  * dev_pm_opp_get_freq() - Gets the frequency corresponding to an available opp
  * @opp:	opp for which frequency has to be returned for
  *
- * Return frequency in hertz corresponding to the opp, else
+ * Return: frequency in hertz corresponding to the opp, else
  * return 0
  *
  * Locking: This function must be called under rcu_read_lock(). opp is a rcu
@@ -199,6 +201,8 @@ unsigned long dev_pm_opp_get_freq(struct dev_pm_opp *opp)
 	struct dev_pm_opp *tmp_opp;
 	unsigned long f = 0;
 
+	opp_rcu_lockdep_assert();
+
 	tmp_opp = rcu_dereference(opp);
 	if (unlikely(IS_ERR_OR_NULL(tmp_opp)) || !tmp_opp->available)
 		pr_err("%s: Invalid parameters\n", __func__);
@@ -213,7 +217,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_freq);
  * dev_pm_opp_get_opp_count() - Get number of opps available in the opp list
  * @dev:	device for which we do this operation
  *
- * This function returns the number of available opps if there are any,
+ * Return: This function returns the number of available opps if there are any,
  * else returns 0 if none or the corresponding error value.
  *
  * Locking: This function takes rcu_read_lock().
@@ -226,7 +230,7 @@ int dev_pm_opp_get_opp_count(struct device *dev)
 
 	rcu_read_lock();
 
-	dev_opp = find_device_opp(dev);
+	dev_opp = _find_device_opp(dev);
 	if (IS_ERR(dev_opp)) {
 		count = PTR_ERR(dev_opp);
 		dev_err(dev, "%s: device OPP not found (%d)\n",
@@ -251,9 +255,9 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_opp_count);
  * @freq:		frequency to search for
  * @available:		true/false - match for available opp
  *
- * Searches for exact match in the opp list and returns pointer to the matching
- * opp if found, else returns ERR_PTR in case of error and should be handled
- * using IS_ERR. Error return values can be:
+ * Return: Searches for exact match in the opp list and returns pointer to the
+ * matching opp if found, else returns ERR_PTR in case of error and should
+ * be handled using IS_ERR. Error return values can be:
  * EINVAL:	for bad pointer
  * ERANGE:	no match found for search
  * ENODEV:	if device not found in list of registered devices
@@ -280,7 +284,7 @@ struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev,
 
 	opp_rcu_lockdep_assert();
 
-	dev_opp = find_device_opp(dev);
+	dev_opp = _find_device_opp(dev);
 	if (IS_ERR(dev_opp)) {
 		int r = PTR_ERR(dev_opp);
 		dev_err(dev, "%s: device OPP not found (%d)\n", __func__, r);
@@ -307,7 +311,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_exact);
  * Search for the matching ceil *available* OPP from a starting freq
  * for a device.
  *
- * Returns matching *opp and refreshes *freq accordingly, else returns
+ * Return: matching *opp and refreshes *freq accordingly, else returns
  * ERR_PTR in case of error and should be handled using IS_ERR. Error return
  * values can be:
  * EINVAL:	for bad pointer
@@ -333,7 +337,7 @@ struct dev_pm_opp *dev_pm_opp_find_freq_ceil(struct device *dev,
 		return ERR_PTR(-EINVAL);
 	}
 
-	dev_opp = find_device_opp(dev);
+	dev_opp = _find_device_opp(dev);
 	if (IS_ERR(dev_opp))
 		return ERR_CAST(dev_opp);
 
@@ -357,7 +361,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_ceil);
  * Search for the matching floor *available* OPP from a starting freq
  * for a device.
  *
- * Returns matching *opp and refreshes *freq accordingly, else returns
+ * Return: matching *opp and refreshes *freq accordingly, else returns
  * ERR_PTR in case of error and should be handled using IS_ERR. Error return
  * values can be:
  * EINVAL:	for bad pointer
@@ -383,7 +387,7 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev,
 		return ERR_PTR(-EINVAL);
 	}
 
-	dev_opp = find_device_opp(dev);
+	dev_opp = _find_device_opp(dev);
 	if (IS_ERR(dev_opp))
 		return ERR_CAST(dev_opp);
 
@@ -403,7 +407,16 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor);
 
-static struct device_opp *add_device_opp(struct device *dev)
+/**
+ * _add_device_opp() - Allocate a new device OPP table
+ * @dev:	device for which we do this operation
+ *
+ * New device node which uses OPPs - used when multiple devices with OPP tables
+ * are maintained.
+ *
+ * Return: valid device_opp pointer if success, else NULL.
+ */
+static struct device_opp *_add_device_opp(struct device *dev)
 {
 	struct device_opp *dev_opp;
 
@@ -424,8 +437,35 @@ static struct device_opp *add_device_opp(struct device *dev)
 	return dev_opp;
 }
 
-static int dev_pm_opp_add_dynamic(struct device *dev, unsigned long freq,
-				  unsigned long u_volt, bool dynamic)
+/**
+ * _opp_add_dynamic() - Allocate a dynamic OPP.
+ * @dev:	device for which we do this operation
+ * @freq:	Frequency in Hz for this OPP
+ * @u_volt:	Voltage in uVolts for this OPP
+ * @dynamic:	Dynamically added OPPs.
+ *
+ * This function adds an opp definition to the opp list and returns status.
+ * The opp is made available by default and it can be controlled using
+ * dev_pm_opp_enable/disable functions and may be removed by dev_pm_opp_remove.
+ *
+ * NOTE: "dynamic" parameter impacts OPPs added by the of_init_opp_table and
+ * freed by of_free_opp_table.
+ *
+ * Locking: The internal device_opp and opp structures are RCU protected.
+ * Hence this function internally uses RCU updater strategy with mutex locks
+ * to keep the integrity of the internal data structures. Callers should ensure
+ * that this function is *NOT* called under RCU protection or in contexts where
+ * mutex cannot be locked.
+ *
+ * Return:
+ * 0		On success OR
+ *		Duplicate OPPs (both freq and volt are same) and opp->available
+ * -EEXIST	Freq are same and volt are different OR
+ *		Duplicate OPPs (both freq and volt are same) and !opp->available
+ * -ENOMEM	Memory allocation failure
+ */
+static int _opp_add_dynamic(struct device *dev, unsigned long freq,
+			    long u_volt, bool dynamic)
 {
 	struct device_opp *dev_opp = NULL;
 	struct dev_pm_opp *opp, *new_opp;
@@ -449,9 +489,9 @@ static int dev_pm_opp_add_dynamic(struct device *dev, unsigned long freq,
 	new_opp->dynamic = dynamic;
 
 	/* Check for existing list for 'dev' */
-	dev_opp = find_device_opp(dev);
+	dev_opp = _find_device_opp(dev);
 	if (IS_ERR(dev_opp)) {
-		dev_opp = add_device_opp(dev);
+		dev_opp = _add_device_opp(dev);
 		if (!dev_opp) {
 			ret = -ENOMEM;
 			goto free_opp;
@@ -519,34 +559,53 @@ free_opp:
  * mutex cannot be locked.
  *
  * Return:
- * 0:		On success OR
+ * 0		On success OR
  *		Duplicate OPPs (both freq and volt are same) and opp->available
- * -EEXIST:	Freq are same and volt are different OR
+ * -EEXIST	Freq are same and volt are different OR
  *		Duplicate OPPs (both freq and volt are same) and !opp->available
- * -ENOMEM:	Memory allocation failure
+ * -ENOMEM	Memory allocation failure
  */
 int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
 {
-	return dev_pm_opp_add_dynamic(dev, freq, u_volt, true);
+	return _opp_add_dynamic(dev, freq, u_volt, true);
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_add);
 
-static void kfree_opp_rcu(struct rcu_head *head)
+/**
+ * _kfree_opp_rcu() - Free OPP RCU handler
+ * @head:	RCU head
+ */
+static void _kfree_opp_rcu(struct rcu_head *head)
 {
 	struct dev_pm_opp *opp = container_of(head, struct dev_pm_opp, rcu_head);
 
 	kfree_rcu(opp, rcu_head);
 }
 
-static void kfree_device_rcu(struct rcu_head *head)
+/**
+ * _kfree_device_rcu() - Free device_opp RCU handler
+ * @head:	RCU head
+ */
+static void _kfree_device_rcu(struct rcu_head *head)
 {
 	struct device_opp *device_opp = container_of(head, struct device_opp, rcu_head);
 
 	kfree_rcu(device_opp, rcu_head);
 }
 
-static void __dev_pm_opp_remove(struct device_opp *dev_opp,
-				struct dev_pm_opp *opp)
+/**
+ * _opp_remove()  - Remove an OPP from a table definition
+ * @dev_opp:	points back to the device_opp struct this opp belongs to
+ * @opp:	pointer to the OPP to remove
+ *
+ * This function removes an opp definition from the opp list.
+ *
+ * Locking: The internal device_opp and opp structures are RCU protected.
+ * It is assumed that the caller holds required mutex for an RCU updater
+ * strategy.
+ */
+static void _opp_remove(struct device_opp *dev_opp,
+			struct dev_pm_opp *opp)
 {
 	/*
 	 * Notify the changes in the availability of the operable
@@ -554,12 +613,12 @@ static void __dev_pm_opp_remove(struct device_opp *dev_opp,
 	 */
 	srcu_notifier_call_chain(&dev_opp->srcu_head, OPP_EVENT_REMOVE, opp);
 	list_del_rcu(&opp->node);
-	call_srcu(&dev_opp->srcu_head.srcu, &opp->rcu_head, kfree_opp_rcu);
+	call_srcu(&dev_opp->srcu_head.srcu, &opp->rcu_head, _kfree_opp_rcu);
 
 	if (list_empty(&dev_opp->opp_list)) {
 		list_del_rcu(&dev_opp->node);
 		call_srcu(&dev_opp->srcu_head.srcu, &dev_opp->rcu_head,
-			  kfree_device_rcu);
+			  _kfree_device_rcu);
 	}
 }
 
@@ -569,6 +628,12 @@ static void __dev_pm_opp_remove(struct device_opp *dev_opp,
  * @freq:	OPP to remove with matching 'freq'
  *
  * This function removes an opp from the opp list.
+ *
+ * Locking: The internal device_opp and opp structures are RCU protected.
+ * Hence this function internally uses RCU updater strategy with mutex locks
+ * to keep the integrity of the internal data structures. Callers should ensure
+ * that this function is *NOT* called under RCU protection or in contexts where
+ * mutex cannot be locked.
  */
 void dev_pm_opp_remove(struct device *dev, unsigned long freq)
 {
@@ -579,7 +644,7 @@ void dev_pm_opp_remove(struct device *dev, unsigned long freq)
 	/* Hold our list modification lock here */
 	mutex_lock(&dev_opp_list_lock);
 
-	dev_opp = find_device_opp(dev);
+	dev_opp = _find_device_opp(dev);
 	if (IS_ERR(dev_opp))
 		goto unlock;
 
@@ -596,14 +661,14 @@ void dev_pm_opp_remove(struct device *dev, unsigned long freq)
 		goto unlock;
 	}
 
-	__dev_pm_opp_remove(dev_opp, opp);
+	_opp_remove(dev_opp, opp);
 unlock:
 	mutex_unlock(&dev_opp_list_lock);
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_remove);
 
 /**
- * opp_set_availability() - helper to set the availability of an opp
+ * _opp_set_availability() - helper to set the availability of an opp
  * @dev:		device for which we do this operation
  * @freq:		OPP frequency to modify availability
  * @availability_req:	availability status requested for this opp
@@ -611,7 +676,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_remove);
  * Set the availability of an OPP with an RCU operation, opp_{enable,disable}
  * share a common logic which is isolated here.
  *
- * Returns -EINVAL for bad pointers, -ENOMEM if no memory available for the
+ * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
  * copy operation, returns 0 if no modifcation was done OR modification was
  * successful.
  *
@@ -621,8 +686,8 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_remove);
  * that this function is *NOT* called under RCU protection or in contexts where
  * mutex locking or synchronize_rcu() blocking calls cannot be used.
  */
-static int opp_set_availability(struct device *dev, unsigned long freq,
-		bool availability_req)
+static int _opp_set_availability(struct device *dev, unsigned long freq,
+				 bool availability_req)
 {
 	struct device_opp *dev_opp;
 	struct dev_pm_opp *new_opp, *tmp_opp, *opp = ERR_PTR(-ENODEV);
@@ -638,7 +703,7 @@ static int opp_set_availability(struct device *dev, unsigned long freq,
 	mutex_lock(&dev_opp_list_lock);
 
 	/* Find the device_opp */
-	dev_opp = find_device_opp(dev);
+	dev_opp = _find_device_opp(dev);
 	if (IS_ERR(dev_opp)) {
 		r = PTR_ERR(dev_opp);
 		dev_warn(dev, "%s: Device OPP not found (%d)\n", __func__, r);
@@ -668,7 +733,7 @@ static int opp_set_availability(struct device *dev, unsigned long freq,
 
 	list_replace_rcu(&opp->node, &new_opp->node);
 	mutex_unlock(&dev_opp_list_lock);
-	call_srcu(&dev_opp->srcu_head.srcu, &opp->rcu_head, kfree_opp_rcu);
+	call_srcu(&dev_opp->srcu_head.srcu, &opp->rcu_head, _kfree_opp_rcu);
 
 	/* Notify the change of the OPP availability */
 	if (availability_req)
@@ -700,10 +765,14 @@ unlock:
  * integrity of the internal data structures. Callers should ensure that
  * this function is *NOT* called under RCU protection or in contexts where
  * mutex locking or synchronize_rcu() blocking calls cannot be used.
+ *
+ * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
+ * copy operation, returns 0 if no modifcation was done OR modification was
+ * successful.
  */
 int dev_pm_opp_enable(struct device *dev, unsigned long freq)
 {
-	return opp_set_availability(dev, freq, true);
+	return _opp_set_availability(dev, freq, true);
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_enable);
 
@@ -722,26 +791,41 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_enable);
  * integrity of the internal data structures. Callers should ensure that
  * this function is *NOT* called under RCU protection or in contexts where
  * mutex locking or synchronize_rcu() blocking calls cannot be used.
+ *
+ * Return: -EINVAL for bad pointers, -ENOMEM if no memory available for the
+ * copy operation, returns 0 if no modifcation was done OR modification was
+ * successful.
  */
 int dev_pm_opp_disable(struct device *dev, unsigned long freq)
 {
-	return opp_set_availability(dev, freq, false);
+	return _opp_set_availability(dev, freq, false);
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_disable);
 
 /**
  * dev_pm_opp_get_notifier() - find notifier_head of the device with opp
  * @dev:	device pointer used to lookup device OPPs.
+ *
+ * Return: pointer to  notifier head if found, otherwise -ENODEV or
+ * -EINVAL based on type of error casted as pointer. value must be checked
+ *  with IS_ERR to determine valid pointer or error result.
+ *
+ * Locking: This function must be called under rcu_read_lock(). dev_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 srcu_notifier_head *dev_pm_opp_get_notifier(struct device *dev)
 {
-	struct device_opp *dev_opp = find_device_opp(dev);
+	struct device_opp *dev_opp = _find_device_opp(dev);
 
 	if (IS_ERR(dev_opp))
 		return ERR_CAST(dev_opp); /* matching type */
 
 	return &dev_opp->srcu_head;
 }
+EXPORT_SYMBOL_GPL(dev_pm_opp_get_notifier);
 
 #ifdef CONFIG_OF
 /**
@@ -749,6 +833,22 @@ struct srcu_notifier_head *dev_pm_opp_get_notifier(struct device *dev)
  * @dev:	device pointer used to lookup device OPPs.
  *
  * Register the initial OPP table with the OPP library for given device.
+ *
+ * Locking: The internal device_opp and opp structures are RCU protected.
+ * Hence this function indirectly uses RCU updater strategy with mutex locks
+ * to keep the integrity of the internal data structures. Callers should ensure
+ * that this function is *NOT* called under RCU protection or in contexts where
+ * mutex cannot be locked.
+ *
+ * Return:
+ * 0		On success OR
+ *		Duplicate OPPs (both freq and volt are same) and opp->available
+ * -EEXIST	Freq are same and volt are different OR
+ *		Duplicate OPPs (both freq and volt are same) and !opp->available
+ * -ENOMEM	Memory allocation failure
+ * -ENODEV	when 'operating-points' property is not found or is invalid data
+ *		in device node.
+ * -ENODATA	when empty 'operating-points' property is found
  */
 int of_init_opp_table(struct device *dev)
 {
@@ -777,7 +877,7 @@ int of_init_opp_table(struct device *dev)
 		unsigned long freq = be32_to_cpup(val++) * 1000;
 		unsigned long volt = be32_to_cpup(val++);
 
-		if (dev_pm_opp_add_dynamic(dev, freq, volt, false))
+		if (_opp_add_dynamic(dev, freq, volt, false))
 			dev_warn(dev, "%s: Failed to add OPP %ld\n",
 				 __func__, freq);
 		nr -= 2;
@@ -792,6 +892,12 @@ EXPORT_SYMBOL_GPL(of_init_opp_table);
  * @dev:	device pointer used to lookup device OPPs.
  *
  * Free OPPs created using static entries present in DT.
+ *
+ * Locking: The internal device_opp and opp structures are RCU protected.
+ * Hence this function indirectly uses RCU updater strategy with mutex locks
+ * to keep the integrity of the internal data structures. Callers should ensure
+ * that this function is *NOT* called under RCU protection or in contexts where
+ * mutex cannot be locked.
  */
 void of_free_opp_table(struct device *dev)
 {
@@ -799,7 +905,7 @@ void of_free_opp_table(struct device *dev)
 	struct dev_pm_opp *opp, *tmp;
 
 	/* Check for existing list for 'dev' */
-	dev_opp = find_device_opp(dev);
+	dev_opp = _find_device_opp(dev);
 	if (IS_ERR(dev_opp)) {
 		int error = PTR_ERR(dev_opp);
 		if (error != -ENODEV)
@@ -816,7 +922,7 @@ void of_free_opp_table(struct device *dev)
 	/* Free static OPPs */
 	list_for_each_entry_safe(opp, tmp, &dev_opp->opp_list, node) {
 		if (!opp->dynamic)
-			__dev_pm_opp_remove(dev_opp, opp);
+			_opp_remove(dev_opp, opp);
 	}
 
 	mutex_unlock(&dev_opp_list_lock);
diff --git a/drivers/base/power/qos.c b/drivers/base/power/qos.c
index a8fe4c1a8d07..e56d538d039e 100644
--- a/drivers/base/power/qos.c
+++ b/drivers/base/power/qos.c
@@ -64,6 +64,8 @@ enum pm_qos_flags_status __dev_pm_qos_flags(struct device *dev, s32 mask)
 	struct pm_qos_flags *pqf;
 	s32 val;
 
+	lockdep_assert_held(&dev->power.lock);
+
 	if (IS_ERR_OR_NULL(qos))
 		return PM_QOS_FLAGS_UNDEFINED;
 
@@ -104,6 +106,8 @@ EXPORT_SYMBOL_GPL(dev_pm_qos_flags);
  */
 s32 __dev_pm_qos_read_value(struct device *dev)
 {
+	lockdep_assert_held(&dev->power.lock);
+
 	return IS_ERR_OR_NULL(dev->power.qos) ?
 		0 : pm_qos_read_value(&dev->power.qos->resume_latency);
 }