1 files changed, 150 insertions, 24 deletions

diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index 8638204..5d699e3 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -86,16 +86,33 @@ struct dev_pm_opp {
 };
 
 /**
+ * struct device_list_opp - devices managed by 'struct device_opp'
+ * @node:	list node
+ * @dev:	device to which the struct object belongs
+ * @rcu_head:	RCU callback head used for deferred freeing
+ *
+ * This is an internal data structure maintaining the list of devices that are
+ * managed by 'struct device_opp'.
+ */
+struct device_list_opp {
+	struct list_head node;
+	const struct device *dev;
+	struct rcu_head rcu_head;
+};
+
+/**
  * struct device_opp - Device opp structure
  * @node:	list node - contains the devices with OPPs that
  *		have been registered. Nodes once added are not modified in this
  *		list.
  *		RCU usage: nodes are not modified in the list of device_opp,
  *		however addition is possible and is secured by dev_opp_list_lock
- * @dev:	device pointer
  * @srcu_head:	notifier head to notify the OPP availability changes.
  * @rcu_head:	RCU callback head used for deferred freeing
+ * @dev_list:	list of devices that share these OPPs
  * @opp_list:	list of opps
+ * @np:		struct device_node pointer for opp's DT node.
+ * @shared_opp: OPP is shared between multiple devices.
  *
  * This is an internal data structure maintaining the link to opps attached to
  * a device. This structure is not meant to be shared to users as it is
@@ -108,12 +125,14 @@ struct dev_pm_opp {
 struct device_opp {
 	struct list_head node;
 
-	struct device *dev;
 	struct srcu_notifier_head srcu_head;
 	struct rcu_head rcu_head;
+	struct list_head dev_list;
 	struct list_head opp_list;
 
+	struct device_node *np;
 	unsigned long clock_latency_ns_max;
+	bool shared_opp;
 };
 
 /*
@@ -133,6 +152,38 @@ do {									\
 			   "dev_opp_list_lock protection");		\
 } while (0)
 
+static struct device_list_opp *_find_list_dev(const struct device *dev,
+					      struct device_opp *dev_opp)
+{
+	struct device_list_opp *list_dev;
+
+	list_for_each_entry(list_dev, &dev_opp->dev_list, node)
+		if (list_dev->dev == dev)
+			return list_dev;
+
+	return NULL;
+}
+
+static struct device_opp *_managed_opp(const struct device_node *np)
+{
+	struct device_opp *dev_opp;
+
+	list_for_each_entry_rcu(dev_opp, &dev_opp_list, node) {
+		if (dev_opp->np == np) {
+			/*
+			 * Multiple devices can point to the same OPP table and
+			 * so will have same node-pointer, np.
+			 *
+			 * But the OPPs will be considered as shared only if the
+			 * OPP table contains a "opp-shared" property.
+			 */
+			return dev_opp->shared_opp ? dev_opp : NULL;
+		}
+	}
+
+	return NULL;
+}
+
 /**
  * _find_device_opp() - find device_opp struct using device pointer
  * @dev:	device pointer used to lookup device OPPs
@@ -149,21 +200,18 @@ do {									\
  */
 static struct device_opp *_find_device_opp(struct device *dev)
 {
-	struct device_opp *tmp_dev_opp, *dev_opp = ERR_PTR(-ENODEV);
+	struct device_opp *dev_opp;
 
 	if (unlikely(IS_ERR_OR_NULL(dev))) {
 		pr_err("%s: Invalid parameters\n", __func__);
 		return ERR_PTR(-EINVAL);
 	}
 
-	list_for_each_entry_rcu(tmp_dev_opp, &dev_opp_list, node) {
-		if (tmp_dev_opp->dev == dev) {
-			dev_opp = tmp_dev_opp;
-			break;
-		}
-	}
+	list_for_each_entry_rcu(dev_opp, &dev_opp_list, node)
+		if (_find_list_dev(dev, dev_opp))
+			return dev_opp;
 
-	return dev_opp;
+	return ERR_PTR(-ENODEV);
 }
 
 /**
@@ -450,6 +498,39 @@ struct dev_pm_opp *dev_pm_opp_find_freq_floor(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor);
 
+/* List-dev Helpers */
+static void _kfree_list_dev_rcu(struct rcu_head *head)
+{
+	struct device_list_opp *list_dev;
+
+	list_dev = container_of(head, struct device_list_opp, rcu_head);
+	kfree_rcu(list_dev, rcu_head);
+}
+
+static void _remove_list_dev(struct device_list_opp *list_dev,
+			     struct device_opp *dev_opp)
+{
+	list_del(&list_dev->node);
+	call_srcu(&dev_opp->srcu_head.srcu, &list_dev->rcu_head,
+		  _kfree_list_dev_rcu);
+}
+
+static struct device_list_opp *_add_list_dev(const struct device *dev,
+					     struct device_opp *dev_opp)
+{
+	struct device_list_opp *list_dev;
+
+	list_dev = kzalloc(sizeof(*list_dev), GFP_KERNEL);
+	if (!list_dev)
+		return NULL;
+
+	/* Initialize list-dev */
+	list_dev->dev = dev;
+	list_add_rcu(&list_dev->node, &dev_opp->dev_list);
+
+	return list_dev;
+}
+
 /**
  * _add_device_opp() - Find device OPP table or allocate a new one
  * @dev:	device for which we do this operation
@@ -462,6 +543,7 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_floor);
 static struct device_opp *_add_device_opp(struct device *dev)
 {
 	struct device_opp *dev_opp;
+	struct device_list_opp *list_dev;
 
 	/* Check for existing list for 'dev' first */
 	dev_opp = _find_device_opp(dev);
@@ -476,7 +558,14 @@ static struct device_opp *_add_device_opp(struct device *dev)
 	if (!dev_opp)
 		return NULL;
 
-	dev_opp->dev = dev;
+	INIT_LIST_HEAD(&dev_opp->dev_list);
+
+	list_dev = _add_list_dev(dev, dev_opp);
+	if (!list_dev) {
+		kfree(dev_opp);
+		return NULL;
+	}
+
 	srcu_init_notifier_head(&dev_opp->srcu_head);
 	INIT_LIST_HEAD(&dev_opp->opp_list);
 
@@ -504,9 +593,19 @@ static void _kfree_device_rcu(struct rcu_head *head)
  */
 static void _remove_device_opp(struct device_opp *dev_opp)
 {
+	struct device_list_opp *list_dev;
+
 	if (!list_empty(&dev_opp->opp_list))
 		return;
 
+	list_dev = list_first_entry(&dev_opp->dev_list, struct device_list_opp,
+				    node);
+
+	_remove_list_dev(list_dev, dev_opp);
+
+	/* dev_list must be empty now */
+	WARN_ON(!list_empty(&dev_opp->dev_list));
+
 	list_del_rcu(&dev_opp->node);
 	call_srcu(&dev_opp->srcu_head.srcu, &dev_opp->rcu_head,
 		  _kfree_device_rcu);
@@ -616,7 +715,8 @@ static struct dev_pm_opp *_allocate_opp(struct device *dev,
 	return opp;
 }
 
-static int _opp_add(struct dev_pm_opp *new_opp, struct device_opp *dev_opp)
+static int _opp_add(struct device *dev, struct dev_pm_opp *new_opp,
+		    struct device_opp *dev_opp)
 {
 	struct dev_pm_opp *opp;
 	struct list_head *head = &dev_opp->opp_list;
@@ -639,7 +739,7 @@ static int _opp_add(struct dev_pm_opp *new_opp, struct device_opp *dev_opp)
 			break;
 
 		/* Duplicate OPPs */
-		dev_warn(dev_opp->dev, "%s: duplicate OPPs detected. Existing: freq: %lu, volt: %lu, enabled: %d. New: freq: %lu, volt: %lu, enabled: %d\n",
+		dev_warn(dev, "%s: duplicate OPPs detected. Existing: freq: %lu, volt: %lu, enabled: %d. New: freq: %lu, volt: %lu, enabled: %d\n",
 			 __func__, opp->rate, opp->u_volt, opp->available,
 			 new_opp->rate, new_opp->u_volt, new_opp->available);
 
@@ -702,7 +802,7 @@ static int _opp_add_dynamic(struct device *dev, unsigned long freq,
 	new_opp->available = true;
 	new_opp->dynamic = dynamic;
 
-	ret = _opp_add(new_opp, dev_opp);
+	ret = _opp_add(dev, new_opp, dev_opp);
 	if (ret)
 		goto free_opp;
 
@@ -819,7 +919,7 @@ static int _opp_add_static_v2(struct device *dev, struct device_node *np)
 
 	of_property_read_u32(np, "opp-microamp", (u32 *)&new_opp->u_amp);
 
-	ret = _opp_add(new_opp, dev_opp);
+	ret = _opp_add(dev, new_opp, dev_opp);
 	if (ret)
 		goto free_opp;
 
@@ -1052,6 +1152,9 @@ void of_free_opp_table(struct device *dev)
 	struct device_opp *dev_opp;
 	struct dev_pm_opp *opp, *tmp;
 
+	/* Hold our list modification lock here */
+	mutex_lock(&dev_opp_list_lock);
+
 	/* Check for existing list for 'dev' */
 	dev_opp = _find_device_opp(dev);
 	if (IS_ERR(dev_opp)) {
@@ -1062,18 +1165,21 @@ void of_free_opp_table(struct device *dev)
 			     IS_ERR_OR_NULL(dev) ?
 					"Invalid device" : dev_name(dev),
 			     error);
-		return;
+		goto unlock;
 	}
 
-	/* Hold our list modification lock here */
-	mutex_lock(&dev_opp_list_lock);
-
-	/* Free static OPPs */
-	list_for_each_entry_safe(opp, tmp, &dev_opp->opp_list, node) {
-		if (!opp->dynamic)
-			_opp_remove(dev_opp, opp, true);
+	/* Find if dev_opp manages a single device */
+	if (list_is_singular(&dev_opp->dev_list)) {
+		/* Free static OPPs */
+		list_for_each_entry_safe(opp, tmp, &dev_opp->opp_list, node) {
+			if (!opp->dynamic)
+				_opp_remove(dev_opp, opp, true);
+		}
+	} else {
+		_remove_list_dev(_find_list_dev(dev, dev_opp), dev_opp);
 	}
 
+unlock:
 	mutex_unlock(&dev_opp_list_lock);
 }
 EXPORT_SYMBOL_GPL(of_free_opp_table);
@@ -1099,6 +1205,7 @@ static int _of_init_opp_table_v2(struct device *dev,
 				 const struct property *prop)
 {
 	struct device_node *opp_np, *np;
+	struct device_opp *dev_opp;
 	int ret = 0, count = 0;
 
 	if (!prop->value)
@@ -1109,6 +1216,14 @@ static int _of_init_opp_table_v2(struct device *dev,
 	if (IS_ERR(opp_np))
 		return PTR_ERR(opp_np);
 
+	dev_opp = _managed_opp(opp_np);
+	if (dev_opp) {
+		/* OPPs are already managed */
+		if (!_add_list_dev(dev, dev_opp))
+			ret = -ENOMEM;
+		goto put_opp_np;
+	}
+
 	/* We have opp-list node now, iterate over it and add OPPs */
 	for_each_available_child_of_node(opp_np, np) {
 		count++;
@@ -1125,8 +1240,19 @@ static int _of_init_opp_table_v2(struct device *dev,
 	if (WARN_ON(!count))
 		goto put_opp_np;
 
-	if (ret)
+	if (!ret) {
+		if (!dev_opp) {
+			dev_opp = _find_device_opp(dev);
+			if (WARN_ON(!dev_opp))
+				goto put_opp_np;
+		}
+
+		dev_opp->np = opp_np;
+		dev_opp->shared_opp = of_property_read_bool(opp_np,
+							    "opp-shared");
+	} else {
 		of_free_opp_table(dev);
+	}
 
 put_opp_np:
 	of_node_put(opp_np);