s390/iucv: Provide iucv_alloc_device() / iucv_release_device()

Provide iucv_alloc_device() and iucv_release_device() helper functions,
which can be used to deduplicate more or less identical IUCV device
allocation and release code in four different drivers.

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Alexandra Winter <wintera@linux.ibm.com>
Link: https://lore.kernel.org/r/20240506194454.1160315-2-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

include/net/iucv/iucv.h

@@ -84,6 +84,12 @@ struct iucv_array {
 extern const struct bus_type iucv_bus;
 extern struct device *iucv_root;
 
+struct device_driver;
+
+struct device *iucv_alloc_device(const struct attribute_group **attrs,
+				 struct device_driver *driver, void *priv,
+				 const char *fmt, ...) __printf(4, 5);
+
 /*
  * struct iucv_path
  * pathid: 16 bit path identification

net/iucv/iucv.c

@@ -76,6 +76,41 @@ EXPORT_SYMBOL(iucv_bus);
 struct device *iucv_root;
 EXPORT_SYMBOL(iucv_root);
 
+static void iucv_release_device(struct device *device)
+{
+	kfree(device);
+}
+
+struct device *iucv_alloc_device(const struct attribute_group **attrs,
+				 struct device_driver *driver,
+				 void *priv, const char *fmt, ...)
+{
+	struct device *dev;
+	va_list vargs;
+	int rc;
+
+	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		goto out_error;
+	va_start(vargs, fmt);
+	rc = dev_set_name(dev, fmt, vargs);
+	va_end(vargs);
+	if (rc)
+		goto out_error;
+	dev->bus = &iucv_bus;
+	dev->parent = iucv_root;
+	dev->driver = driver;
+	dev->groups = attrs;
+	dev->release = iucv_release_device;
+	dev_set_drvdata(dev, priv);
+	return dev;
+
+out_error:
+	kfree(dev);
+	return NULL;
+}
+EXPORT_SYMBOL(iucv_alloc_device);
+
 static int iucv_available;
 
 /* General IUCV interrupt structure */