[S390] service level interface.

Add a new proc interface /proc/service_levels that allows any code
to report a relevant service level, e.g. the microcode level of
devices, the service level of the hypervisor, etc.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/sysinfo.h b/arch/s390/include/asm/sysinfo.h
index 79d0134..ad93212 100644
--- a/arch/s390/include/asm/sysinfo.h
+++ b/arch/s390/include/asm/sysinfo.h
@@ -118,4 +118,15 @@
 	return r0;
 }
 
+/*
+ * Service level reporting interface.
+ */
+struct service_level {
+	struct list_head list;
+	void (*seq_print)(struct seq_file *, struct service_level *);
+};
+
+int register_service_level(struct service_level *);
+int unregister_service_level(struct service_level *);
+
 #endif /* __ASM_S390_SYSINFO_H */