misc: genwqe: make class_genwqe a static const structure

Now that the driver core allows for struct class to be in read-only
memory, move the class_genwqe structure to be declared at build time
placing it into read-only memory, instead of having to be dynamically
allocated at boot time. Update the 'class_genwqe' field of the
'genwqe_dev' struct correspondingly.

Suggested-by: Greg Kroah-Hartman <[e-mail]>
Signed-off-by: Ivan Orlov <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/misc/genwqe/card_base.c

···
 MODULE_LICENSE("GPL");
 
 static char genwqe_driver_name[] = GENWQE_DEVNAME;
-static struct class *class_genwqe;
+
 static struct dentry *debugfs_genwqe;
 static struct genwqe_dev *genwqe_devices[GENWQE_CARD_NO_MAX];
 
···
 MODULE_DEVICE_TABLE(pci, genwqe_device_table);
 
 /**
+ * genwqe_devnode() - Set default access mode for genwqe devices.
+ * @dev:	Pointer to device (unused)
+ * @mode:	Carrier to pass-back given mode (permissions)
+ *
+ * Default mode should be rw for everybody. Do not change default
+ * device name.
+ */
+static char *genwqe_devnode(const struct device *dev, umode_t *mode)
+{
+	if (mode)
+		*mode = 0666;
+	return NULL;
+}
+
+static const struct class class_genwqe = {
+	.name = GENWQE_DEVNAME,
+	.devnode = genwqe_devnode,
+};
+
+/**
  * genwqe_dev_alloc() - Create and prepare a new card descriptor
  *
  * Return: Pointer to card descriptor, or ERR_PTR(err) on error
···
 		return ERR_PTR(-ENOMEM);
 
 	cd->card_idx = i;
-	cd->class_genwqe = class_genwqe;
+	cd->class_genwqe = &class_genwqe;
 	cd->debugfs_genwqe = debugfs_genwqe;
 
 	/*
···
 };
 
 /**
- * genwqe_devnode() - Set default access mode for genwqe devices.
- * @dev:	Pointer to device (unused)
- * @mode:	Carrier to pass-back given mode (permissions)
- *
- * Default mode should be rw for everybody. Do not change default
- * device name.
- */
-static char *genwqe_devnode(const struct device *dev, umode_t *mode)
-{
-	if (mode)
-		*mode = 0666;
-	return NULL;
-}
-
-/**
  * genwqe_init_module() - Driver registration and initialization
  */
 static int __init genwqe_init_module(void)
 {
 	int rc;
 
-	class_genwqe = class_create(GENWQE_DEVNAME);
-	if (IS_ERR(class_genwqe)) {
+	rc = class_register(&class_genwqe);
+	if (rc) {
 		pr_err("[%s] create class failed\n", __func__);
 		return -ENOMEM;
 	}
-
-	class_genwqe->devnode = genwqe_devnode;
 
 	debugfs_genwqe = debugfs_create_dir(GENWQE_DEVNAME, NULL);
 
···
 
  err_out0:
 	debugfs_remove(debugfs_genwqe);
-	class_destroy(class_genwqe);
+	class_unregister(&class_genwqe);
 	return rc;
 }
 
···
 {
 	pci_unregister_driver(&genwqe_driver);
 	debugfs_remove(debugfs_genwqe);
-	class_destroy(class_genwqe);
+	class_unregister(&class_genwqe);
 }
 
 module_init(genwqe_init_module);

drivers/misc/genwqe/card_base.h

···
 
 	/* char device */
 	dev_t  devnum_genwqe;		/* major/minor num card */
-	struct class *class_genwqe;	/* reference to class object */
+	const struct class *class_genwqe;	/* reference to class object */
 	struct device *dev;		/* for device creation */
 	struct cdev cdev_genwqe;	/* char device for card */