[PATCH 05/31] opp: Add devres wrapper for dev_pm_opp_register_notifier

[Yangtao Li <tiny.windzz@gmail.com>]

Add devres wrapper for dev_pm_opp_register_notifier() to simplify driver
code.

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
---
 drivers/opp/core.c     | 38 ++++++++++++++++++++++++++++++++++++++
 include/linux/pm_opp.h |  6 ++++++
 2 files changed, 44 insertions(+)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 6b83e373f0d8..ef3544f8cecd 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -2599,6 +2599,44 @@ int dev_pm_opp_unregister_notifier(struct device *dev,
 }
 EXPORT_SYMBOL(dev_pm_opp_unregister_notifier);
 
+static void devm_pm_opp_notifier_release(struct device *dev, void *res)
+{
+	struct notifier_block *nb = *(struct notifier_block **)res;
+
+	WARN_ON(dev_pm_opp_unregister_notifier(dev, nb));
+}
+
+/**
+ * devm_pm_opp_register_notifier() - Register OPP notifier for the device
+ * @dev:	Device for which notifier needs to be registered
+ * @nb:		Notifier block to be registered
+ *
+ * Return: 0 on success or a negative error value.
+ *
+ * The notifier will be unregistered after the device is destroyed.
+ */
+int devm_pm_opp_register_notifier(struct device *dev, struct notifier_block *nb)
+{
+	struct notifier_block **ptr;
+	int ret;
+
+	ptr = devres_alloc(devm_pm_opp_notifier_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	ret = dev_pm_opp_register_notifier(dev, nb);
+	if (ret) {
+		devres_free(ptr);
+		return ret;
+	}
+
+	*ptr = nb;
+	devres_add(dev, ptr);
+
+	return 0;
+}
+EXPORT_SYMBOL(devm_pm_opp_register_notifier);
+
 /**
  * dev_pm_opp_remove_table() - Free all OPPs associated with the device
  * @dev:	device pointer used to lookup OPP table.
diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index e8bdac5f9555..c24bd34339d7 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -136,6 +136,7 @@ int dev_pm_opp_disable(struct device *dev, unsigned long freq);
 
 int dev_pm_opp_register_notifier(struct device *dev, struct notifier_block *nb);
 int dev_pm_opp_unregister_notifier(struct device *dev, struct notifier_block *nb);
+int devm_pm_opp_register_notifier(struct device *dev, struct notifier_block *nb);
 
 struct opp_table *dev_pm_opp_set_supported_hw(struct device *dev, const u32 *versions, unsigned int count);
 void dev_pm_opp_put_supported_hw(struct opp_table *opp_table);
@@ -288,6 +289,11 @@ static inline int dev_pm_opp_register_notifier(struct device *dev, struct notifi
 	return -ENOTSUPP;
 }
 
+static inline int devm_pm_opp_register_notifier(struct device *dev, struct notifier_block *nb)
+{
+	return -ENOTSUPP;
+}
+
 static inline int dev_pm_opp_unregister_notifier(struct device *dev, struct notifier_block *nb)
 {
 	return -ENOTSUPP;
-- 
2.25.1