PCI: switchtec: Make switchtec_class constant

Now that the driver core allows for struct class to be in read-only memory,
we should make all 'class' structures declared at build time placing them
into read-only memory, instead of having to be dynamically allocated at
runtime.

Link: https://lore.kernel.org/r/2024061053-online-unwound-b173@gregkh
Signed-off-by: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>
Reviewed-by: Dave Jiang <[e-mail]>
Reviewed-By: Logan Gunthorpe <[e-mail]>
Cc: Kurt Schwemmer <[e-mail]>
Cc: Jon Mason <[e-mail]>
Cc: Allen Hubbe <[e-mail]>

drivers/ntb/hw/mscc/ntb_hw_switchtec.c

···
 
 static int __init switchtec_ntb_init(void)
 {
-	switchtec_interface.class = switchtec_class;
+	switchtec_interface.class = &switchtec_class;
 	return class_interface_register(&switchtec_interface);
 }
 module_init(switchtec_ntb_init);

drivers/pci/switch/switchtec.c

···
 static dev_t switchtec_devt;
 static DEFINE_IDA(switchtec_minor_ida);
 
-struct class *switchtec_class;
+const struct class switchtec_class = {
+	.name = "switchtec",
+};
 EXPORT_SYMBOL_GPL(switchtec_class);
 
 enum mrpc_state {
···
 
 	dev = &stdev->dev;
 	device_initialize(dev);
-	dev->class = switchtec_class;
+	dev->class = &switchtec_class;
 	dev->parent = &pdev->dev;
 	dev->groups = switchtec_device_groups;
 	dev->release = stdev_release;
···
 	if (rc)
 		return rc;
 
-	switchtec_class = class_create("switchtec");
-	if (IS_ERR(switchtec_class)) {
-		rc = PTR_ERR(switchtec_class);
+	rc = class_register(&switchtec_class);
+	if (rc)
 		goto err_create_class;
-	}
 
 	rc = pci_register_driver(&switchtec_pci_driver);
 	if (rc)
···
 	return 0;
 
 err_pci_register:
-	class_destroy(switchtec_class);
+	class_unregister(&switchtec_class);
 
 err_create_class:
 	unregister_chrdev_region(switchtec_devt, max_devices);
···
 static void __exit switchtec_exit(void)
 {
 	pci_unregister_driver(&switchtec_pci_driver);
-	class_destroy(switchtec_class);
+	class_unregister(&switchtec_class);
 	unregister_chrdev_region(switchtec_devt, max_devices);
 	ida_destroy(&switchtec_minor_ida);
 

include/linux/switchtec.h

···
 	return container_of(dev, struct switchtec_dev, dev);
 }
 
-extern struct class *switchtec_class;
+extern const struct class switchtec_class;
 
 #endif