spmi: do not use bus internal data

The variable p is a data structure which is used by the driver core
internally and it is not expected that busses will be directly accessing
these driver core internal only data.
Signed-off-by: NSudip Mukherjee <sudip.mukherjee@codethink.co.uk>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/spmi/spmi.c

@@ -25,6 +25,7 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/spmi.h>
 
+static bool is_registered;
 static DEFINE_IDA(ctrl_ida);
 
 static void spmi_dev_release(struct device *dev)
@@ -507,7 +508,7 @@ int spmi_controller_add(struct spmi_controller *ctrl)
 	int ret;
 
 	/* Can't register until after driver model init */
-	if (WARN_ON(!spmi_bus_type.p))
+	if (WARN_ON(!is_registered))
 		return -EAGAIN;
 
 	ret = device_add(&ctrl->dev);
@@ -576,7 +577,14 @@ module_exit(spmi_exit);
 
 static int __init spmi_init(void)
 {
-	return bus_register(&spmi_bus_type);
+	int ret;
+
+	ret = bus_register(&spmi_bus_type);
+	if (ret)
+		return ret;
+
+	is_registered = true;
+	return 0;
 }
 postcore_initcall(spmi_init);