[S390] cio: introduce isc_(un)register functions.

This interface makes it easy for drivers to register usage of different
I/O interruption subclasses without needing to worry about possible
other users of the same isc.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/include/asm-s390/isc.h b/include/asm-s390/isc.h
index 533a137..fe56f7b 100644
--- a/include/asm-s390/isc.h
+++ b/include/asm-s390/isc.h
@@ -1,6 +1,8 @@
 #ifndef _ASM_S390_ISC_H
 #define _ASM_S390_ISC_H
 
+#include <linux/types.h>
+
 /*
  * I/O interruption subclasses used by drivers.
  * Please add all used iscs here so that it is possible to distribute
@@ -15,4 +17,8 @@
 /* Adapter interrupts. */
 #define QDIO_AIRQ_ISC IO_SCH_ISC	/* I/O subchannel in qdio mode */
 
+/* Functions for registration of I/O interruption subclasses */
+void isc_register(unsigned int isc);
+void isc_unregister(unsigned int isc);
+
 #endif /* _ASM_S390_ISC_H */