1 files changed, 140 insertions, 51 deletions

diff --git a/drivers/base/auxiliary.c b/drivers/base/auxiliary.c
index 8c5e65930617..04bdbff4dbe5 100644
--- a/drivers/base/auxiliary.c
+++ b/drivers/base/auxiliary.c
@@ -92,7 +92,7 @@
  * Auxiliary devices are created and registered by a subsystem-level core
  * device that needs to break up its functionality into smaller fragments. One
  * way to extend the scope of an auxiliary_device is to encapsulate it within a
- * domain- pecific structure defined by the parent device. This structure
+ * domain-specific structure defined by the parent device. This structure
  * contains the auxiliary_device and any associated shared data/callbacks
  * needed to establish the connection with the parent.
  *
@@ -156,36 +156,47 @@
  *		},
  *		.ops = my_custom_ops,
  *	};
+ *
+ * Please note that such custom ops approach is valid, but it is hard to implement
+ * it right without global locks per-device to protect from auxiliary_drv removal
+ * during call to that ops. In addition, this implementation lacks proper module
+ * dependency, which causes to load/unload races between auxiliary parent and devices
+ * modules.
+ *
+ * The most easiest way to provide these ops reliably without needing to
+ * have a lock is to EXPORT_SYMBOL*() them and rely on already existing
+ * modules infrastructure for validity and correct dependencies chains.
  */
 
 static const struct auxiliary_device_id *auxiliary_match_id(const struct auxiliary_device_id *id,
 							    const struct auxiliary_device *auxdev)
 {
-	for (; id->name[0]; id++) {
-		const char *p = strrchr(dev_name(&auxdev->dev), '.');
-		int match_size;
+	const char *auxdev_name = dev_name(&auxdev->dev);
+	const char *p = strrchr(auxdev_name, '.');
+	int match_size;
 
-		if (!p)
-			continue;
-		match_size = p - dev_name(&auxdev->dev);
+	if (!p)
+		return NULL;
+	match_size = p - auxdev_name;
 
+	for (; id->name[0]; id++) {
 		/* use dev_name(&auxdev->dev) prefix before last '.' char to match to */
 		if (strlen(id->name) == match_size &&
-		    !strncmp(dev_name(&auxdev->dev), id->name, match_size))
+		    !strncmp(auxdev_name, id->name, match_size))
 			return id;
 	}
 	return NULL;
 }
 
-static int auxiliary_match(struct device *dev, struct device_driver *drv)
+static int auxiliary_match(struct device *dev, const struct device_driver *drv)
 {
 	struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
-	struct auxiliary_driver *auxdrv = to_auxiliary_drv(drv);
+	const struct auxiliary_driver *auxdrv = to_auxiliary_drv(drv);
 
 	return !!auxiliary_match_id(auxdrv->id_table, auxdev);
 }
 
-static int auxiliary_uevent(struct device *dev, struct kobj_uevent_env *env)
+static int auxiliary_uevent(const struct device *dev, struct kobj_uevent_env *env)
 {
 	const char *name, *p;
 
@@ -203,36 +214,32 @@ static const struct dev_pm_ops auxiliary_dev_pm_ops = {
 
 static int auxiliary_bus_probe(struct device *dev)
 {
-	struct auxiliary_driver *auxdrv = to_auxiliary_drv(dev->driver);
+	const struct auxiliary_driver *auxdrv = to_auxiliary_drv(dev->driver);
 	struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
 	int ret;
 
-	ret = dev_pm_domain_attach(dev, true);
+	ret = dev_pm_domain_attach(dev, PD_FLAG_ATTACH_POWER_ON |
+					PD_FLAG_DETACH_POWER_OFF);
 	if (ret) {
 		dev_warn(dev, "Failed to attach to PM Domain : %d\n", ret);
 		return ret;
 	}
 
-	ret = auxdrv->probe(auxdev, auxiliary_match_id(auxdrv->id_table, auxdev));
-	if (ret)
-		dev_pm_domain_detach(dev, true);
-
-	return ret;
+	return auxdrv->probe(auxdev, auxiliary_match_id(auxdrv->id_table, auxdev));
 }
 
 static void auxiliary_bus_remove(struct device *dev)
 {
-	struct auxiliary_driver *auxdrv = to_auxiliary_drv(dev->driver);
+	const struct auxiliary_driver *auxdrv = to_auxiliary_drv(dev->driver);
 	struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
 
 	if (auxdrv->remove)
 		auxdrv->remove(auxdev);
-	dev_pm_domain_detach(dev, true);
 }
 
 static void auxiliary_bus_shutdown(struct device *dev)
 {
-	struct auxiliary_driver *auxdrv = NULL;
+	const struct auxiliary_driver *auxdrv = NULL;
 	struct auxiliary_device *auxdev;
 
 	if (dev->driver) {
@@ -244,7 +251,7 @@ static void auxiliary_bus_shutdown(struct device *dev)
 		auxdrv->shutdown(auxdev);
 }
 
-static struct bus_type auxiliary_bus_type = {
+static const struct bus_type auxiliary_bus_type = {
 	.name = "auxiliary",
 	.probe = auxiliary_bus_probe,
 	.remove = auxiliary_bus_remove,
@@ -287,6 +294,7 @@ int auxiliary_device_init(struct auxiliary_device *auxdev)
 
 	dev->bus = &auxiliary_bus_type;
 	device_initialize(&auxdev->dev);
+	mutex_init(&auxdev->sysfs.lock);
 	return 0;
 }
 EXPORT_SYMBOL_GPL(auxiliary_device_init);
@@ -335,35 +343,6 @@ int __auxiliary_device_add(struct auxiliary_device *auxdev, const char *modname)
 EXPORT_SYMBOL_GPL(__auxiliary_device_add);
 
 /**
- * auxiliary_find_device - auxiliary device iterator for locating a particular device.
- * @start: Device to begin with
- * @data: Data to pass to match function
- * @match: Callback function to check device
- *
- * This function returns a reference to a device that is 'found'
- * for later use, as determined by the @match callback.
- *
- * The reference returned should be released with put_device().
- *
- * The callback should return 0 if the device doesn't match and non-zero
- * if it does.  If the callback returns non-zero, this function will
- * return to the caller and not iterate over any more devices.
- */
-struct auxiliary_device *auxiliary_find_device(struct device *start,
-					       const void *data,
-					       int (*match)(struct device *dev, const void *data))
-{
-	struct device *dev;
-
-	dev = bus_find_device(&auxiliary_bus_type, start, data, match);
-	if (!dev)
-		return NULL;
-
-	return to_auxiliary_dev(dev);
-}
-EXPORT_SYMBOL_GPL(auxiliary_find_device);
-
-/**
  * __auxiliary_driver_register - register a driver for auxiliary bus devices
  * @auxdrv: auxiliary_driver structure
  * @owner: owning module/driver
@@ -413,6 +392,116 @@ void auxiliary_driver_unregister(struct auxiliary_driver *auxdrv)
 }
 EXPORT_SYMBOL_GPL(auxiliary_driver_unregister);
 
+static void auxiliary_device_release(struct device *dev)
+{
+	struct auxiliary_device *auxdev = to_auxiliary_dev(dev);
+
+	of_node_put(dev->of_node);
+	kfree(auxdev);
+}
+
+/**
+ * auxiliary_device_create - create a device on the auxiliary bus
+ * @dev: parent device
+ * @modname: module name used to create the auxiliary driver name.
+ * @devname: auxiliary bus device name
+ * @platform_data: auxiliary bus device platform data
+ * @id: auxiliary bus device id
+ *
+ * Helper to create an auxiliary bus device.
+ * The device created matches driver 'modname.devname' on the auxiliary bus.
+ */
+struct auxiliary_device *auxiliary_device_create(struct device *dev,
+						 const char *modname,
+						 const char *devname,
+						 void *platform_data,
+						 int id)
+{
+	struct auxiliary_device *auxdev;
+	int ret;
+
+	auxdev = kzalloc(sizeof(*auxdev), GFP_KERNEL);
+	if (!auxdev)
+		return NULL;
+
+	auxdev->id = id;
+	auxdev->name = devname;
+	auxdev->dev.parent = dev;
+	auxdev->dev.platform_data = platform_data;
+	auxdev->dev.release = auxiliary_device_release;
+	device_set_of_node_from_dev(&auxdev->dev, dev);
+
+	ret = auxiliary_device_init(auxdev);
+	if (ret) {
+		of_node_put(auxdev->dev.of_node);
+		kfree(auxdev);
+		return NULL;
+	}
+
+	ret = __auxiliary_device_add(auxdev, modname);
+	if (ret) {
+		/*
+		 * It may look odd but auxdev should not be freed here.
+		 * auxiliary_device_uninit() calls device_put() which call
+		 * the device release function, freeing auxdev.
+		 */
+		auxiliary_device_uninit(auxdev);
+		return NULL;
+	}
+
+	return auxdev;
+}
+EXPORT_SYMBOL_GPL(auxiliary_device_create);
+
+/**
+ * auxiliary_device_destroy - remove an auxiliary device
+ * @auxdev: pointer to the auxdev to be removed
+ *
+ * Helper to remove an auxiliary device created with
+ * auxiliary_device_create()
+ */
+void auxiliary_device_destroy(void *auxdev)
+{
+	struct auxiliary_device *_auxdev = auxdev;
+
+	auxiliary_device_delete(_auxdev);
+	auxiliary_device_uninit(_auxdev);
+}
+EXPORT_SYMBOL_GPL(auxiliary_device_destroy);
+
+/**
+ * __devm_auxiliary_device_create - create a managed device on the auxiliary bus
+ * @dev: parent device
+ * @modname: module name used to create the auxiliary driver name.
+ * @devname: auxiliary bus device name
+ * @platform_data: auxiliary bus device platform data
+ * @id: auxiliary bus device id
+ *
+ * Device managed helper to create an auxiliary bus device.
+ * The device created matches driver 'modname.devname' on the auxiliary bus.
+ */
+struct auxiliary_device *__devm_auxiliary_device_create(struct device *dev,
+							const char *modname,
+							const char *devname,
+							void *platform_data,
+							int id)
+{
+	struct auxiliary_device *auxdev;
+	int ret;
+
+	auxdev = auxiliary_device_create(dev, modname, devname, platform_data, id);
+	if (!auxdev)
+		return NULL;
+
+	ret = devm_add_action_or_reset(dev, auxiliary_device_destroy,
+				       auxdev);
+	if (ret)
+		return NULL;
+
+	return auxdev;
+}
+EXPORT_SYMBOL_GPL(__devm_auxiliary_device_create);
+
 void __init auxiliary_bus_init(void)
 {
 	WARN_ON(bus_register(&auxiliary_bus_type));