rpmsg: core: Make rpmsg_class constant

Since commit 43a7206 ("driver core: class: make class_register() take
a const *"), the driver core allows for struct class to be in read-only
memory, so move the rpmsg_class structure to be declared at build time
placing it into read-only memory, instead of having to be dynamically
allocated at boot time.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
Link: https://lore.kernel.org/r/20240305-class_cleanup-remoteproc-v1-1-19373374e003@marliere.net
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

drivers/rpmsg/rpmsg_char.c

@@ -423,7 +423,7 @@ static struct rpmsg_eptdev *rpmsg_chrdev_eptdev_alloc(struct rpmsg_device *rpdev
 	init_waitqueue_head(&eptdev->readq);
 
 	device_initialize(dev);
-	dev->class = rpmsg_class;
+	dev->class = &rpmsg_class;
 	dev->parent = parent;
 	dev->groups = rpmsg_eptdev_groups;
 	dev_set_drvdata(dev, eptdev);

drivers/rpmsg/rpmsg_core.c

@@ -20,7 +20,9 @@
 
 #include "rpmsg_internal.h"
 
-struct class *rpmsg_class;
+const struct class rpmsg_class = {
+	.name = "rpmsg",
+};
 EXPORT_SYMBOL(rpmsg_class);
 
 /**
@@ -715,16 +717,16 @@ static int __init rpmsg_init(void)
 {
 	int ret;
 
-	rpmsg_class = class_create("rpmsg");
-	if (IS_ERR(rpmsg_class)) {
-		pr_err("failed to create rpmsg class\n");
-		return PTR_ERR(rpmsg_class);
+	ret = class_register(&rpmsg_class);
+	if (ret) {
+		pr_err("failed to register rpmsg class\n");
+		return ret;
 	}
 
 	ret = bus_register(&rpmsg_bus);
 	if (ret) {
 		pr_err("failed to register rpmsg bus: %d\n", ret);
-		class_destroy(rpmsg_class);
+		class_destroy(&rpmsg_class);
 	}
 	return ret;
 }
@@ -733,7 +735,7 @@ postcore_initcall(rpmsg_init);
 static void __exit rpmsg_fini(void)
 {
 	bus_unregister(&rpmsg_bus);
-	class_destroy(rpmsg_class);
+	class_destroy(&rpmsg_class);
 }
 module_exit(rpmsg_fini);
 

drivers/rpmsg/rpmsg_ctrl.c

@@ -150,7 +150,7 @@ static int rpmsg_ctrldev_probe(struct rpmsg_device *rpdev)
 	dev = &ctrldev->dev;
 	device_initialize(dev);
 	dev->parent = &rpdev->dev;
-	dev->class = rpmsg_class;
+	dev->class = &rpmsg_class;
 
 	mutex_init(&ctrldev->ctrl_lock);
 	cdev_init(&ctrldev->cdev, &rpmsg_ctrldev_fops);

drivers/rpmsg/rpmsg_internal.h

@@ -18,7 +18,7 @@
 #define to_rpmsg_device(d) container_of(d, struct rpmsg_device, dev)
 #define to_rpmsg_driver(d) container_of(d, struct rpmsg_driver, drv)
 
-extern struct class *rpmsg_class;
+extern const struct class rpmsg_class;
 
 /**
  * struct rpmsg_device_ops - indirection table for the rpmsg_device operations