nvme-fc: create fc class and transport device

Added a new fc class and a device node for udev events under it.  I
expect the fc class will eventually be the location where the FC SCSI and
FC NVME merge in the future. Therefore names are kept somewhat generic.
Signed-off-by: James Smart <james.smart@broadcom.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/fc.c

@@ -213,6 +213,13 @@ static DEFINE_IDA(nvme_fc_ctrl_cnt);
 
 
 
+/*
+ * These items are short-term. They will eventually be moved into
+ * a generic FC class. See comments in module init.
+ */
+static struct class *fc_class;
+static struct device *fc_udev_device;
+
 
 /* *********************** FC-NVME Port Management ************************ */
 
@@ -3046,7 +3053,50 @@ static struct nvmf_transport_ops nvme_fc_transport = {
 
 static int __init nvme_fc_init_module(void)
 {
-	return nvmf_register_transport(&nvme_fc_transport);
+	int ret;
+
+	/*
+	 * NOTE:
+	 * It is expected that in the future the kernel will combine
+	 * the FC-isms that are currently under scsi and now being
+	 * added to by NVME into a new standalone FC class. The SCSI
+	 * and NVME protocols and their devices would be under this
+	 * new FC class.
+	 *
+	 * As we need something to post FC-specific udev events to,
+	 * specifically for nvme probe events, start by creating the
+	 * new device class.  When the new standalone FC class is
+	 * put in place, this code will move to a more generic
+	 * location for the class.
+	 */
+	fc_class = class_create(THIS_MODULE, "fc");
+	if (IS_ERR(fc_class)) {
+		pr_err("couldn't register class fc\n");
+		return PTR_ERR(fc_class);
+	}
+
+	/*
+	 * Create a device for the FC-centric udev events
+	 */
+	fc_udev_device = device_create(fc_class, NULL, MKDEV(0, 0), NULL,
+				"fc_udev_device");
+	if (IS_ERR(fc_udev_device)) {
+		pr_err("couldn't create fc_udev device!\n");
+		ret = PTR_ERR(fc_udev_device);
+		goto out_destroy_class;
+	}
+
+	ret = nvmf_register_transport(&nvme_fc_transport);
+	if (ret)
+		goto out_destroy_device;
+
+	return 0;
+
+out_destroy_device:
+	device_destroy(fc_class, MKDEV(0, 0));
+out_destroy_class:
+	class_destroy(fc_class);
+	return ret;
 }
 
 static void __exit nvme_fc_exit_module(void)
@@ -3059,6 +3109,9 @@ static void __exit nvme_fc_exit_module(void)
 
 	ida_destroy(&nvme_fc_local_port_cnt);
 	ida_destroy(&nvme_fc_ctrl_cnt);
+
+	device_destroy(fc_class, MKDEV(0, 0));
+	class_destroy(fc_class);
 }
 
 module_init(nvme_fc_init_module);