libnvdimm: Export nvdimm shutdown helper, nvdimm_delete()

CXL is a hotplug bus and arranges for nvdimm devices to be dynamically
discovered and removed. The libnvdimm core manages shutdown of nvdimm
security operations when the device is unregistered. That functionality
is moved to nvdimm_delete() and invoked by the CXL-to-nvdimm glue code.

Reviewed-by: Jonathan Cameron <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dan Williams <[e-mail]>

drivers/nvdimm/bus.c

···
 	if (dev->class)
 		return 0;
 
-	if (is_nvdimm(dev)) {
-		struct nvdimm *nvdimm = to_nvdimm(dev);
-		bool dev_put = false;
-
-		/* We are shutting down. Make state frozen artificially. */
-		nvdimm_bus_lock(dev);
-		set_bit(NVDIMM_SECURITY_FROZEN, &nvdimm->sec.flags);
-		if (test_and_clear_bit(NDD_WORK_PENDING, &nvdimm->flags))
-			dev_put = true;
-		nvdimm_bus_unlock(dev);
-		cancel_delayed_work_sync(&nvdimm->dwork);
-		if (dev_put)
-			put_device(dev);
-	}
-	nd_device_unregister(dev, ND_SYNC);
+	if (is_nvdimm(dev))
+		nvdimm_delete(to_nvdimm(dev));
+	else
+		nd_device_unregister(dev, ND_SYNC);
 
 	return 0;
 }

drivers/nvdimm/dimm_devs.c

···
 }
 EXPORT_SYMBOL_GPL(__nvdimm_create);
 
+void nvdimm_delete(struct nvdimm *nvdimm)
+{
+	struct device *dev = &nvdimm->dev;
+	bool dev_put = false;
+
+	/* We are shutting down. Make state frozen artificially. */
+	nvdimm_bus_lock(dev);
+	set_bit(NVDIMM_SECURITY_FROZEN, &nvdimm->sec.flags);
+	if (test_and_clear_bit(NDD_WORK_PENDING, &nvdimm->flags))
+		dev_put = true;
+	nvdimm_bus_unlock(dev);
+	cancel_delayed_work_sync(&nvdimm->dwork);
+	if (dev_put)
+		put_device(dev);
+	nd_device_unregister(dev, ND_SYNC);
+}
+EXPORT_SYMBOL_GPL(nvdimm_delete);
+
 static void shutdown_security_notify(void *data)
 {
 	struct nvdimm *nvdimm = data;

include/linux/libnvdimm.h

···
 	return __nvdimm_create(nvdimm_bus, provider_data, groups, flags,
 			cmd_mask, num_flush, flush_wpq, NULL, NULL, NULL);
 }
+void nvdimm_delete(struct nvdimm *nvdimm);
 
 const struct nd_cmd_desc *nd_cmd_dimm_desc(int cmd);
 const struct nd_cmd_desc *nd_cmd_bus_desc(int cmd);