macintosh/adb: make adb_dev_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 adb_dev_class structure to be declared
at build time placing it into read-only memory, instead of having to
be dynamically allocated at boot time.

Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: "Ricardo B. Marliere" <ricardo@marliere.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240305-macintosh-v1-1-9c3f4f882045@marliere.net

Author: rbmarliere

drivers/macintosh/adb.c

@@ -74,7 +74,9 @@ static struct adb_driver *adb_driver_list[] = {
 	NULL
 };
 
-static struct class *adb_dev_class;
+static const struct class adb_dev_class = {
+	.name = "adb",
+};
 
 static struct adb_driver *adb_controller;
 BLOCKING_NOTIFIER_HEAD(adb_client_list);
@@ -888,10 +890,10 @@ adbdev_init(void)
 		return;
 	}
 
-	adb_dev_class = class_create("adb");
-	if (IS_ERR(adb_dev_class))
+	if (class_register(&adb_dev_class))
 		return;
-	device_create(adb_dev_class, NULL, MKDEV(ADB_MAJOR, 0), NULL, "adb");
+
+	device_create(&adb_dev_class, NULL, MKDEV(ADB_MAJOR, 0), NULL, "adb");
 
 	platform_device_register(&adb_pfdev);
 	platform_driver_probe(&adb_pfdrv, adb_dummy_probe);