[S390] cio: Introduce abstract isc definitions.

Replace the numeric values for I/O interruption subclass usage
with abstract definitions and collect them all in asm/isc.h.
This gives us a better overview of which iscs are actually used
and makes it possible to better spread out isc usage in the
future.

Signed-off-by: Cornelia Huck <cornelia.huck@de.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
new file mode 100644
index 0000000..533a137
--- /dev/null
+++ b/include/asm-s390/isc.h
@@ -0,0 +1,18 @@
+#ifndef _ASM_S390_ISC_H
+#define _ASM_S390_ISC_H
+
+/*
+ * I/O interruption subclasses used by drivers.
+ * Please add all used iscs here so that it is possible to distribute
+ * isc usage between drivers.
+ * Reminder: 0 is highest priority, 7 lowest.
+ */
+#define MAX_ISC 7
+
+/* Regular I/O interrupts. */
+#define IO_SCH_ISC 3			/* regular I/O subchannels */
+#define CONSOLE_ISC 1			/* console I/O subchannel */
+/* Adapter interrupts. */
+#define QDIO_AIRQ_ISC IO_SCH_ISC	/* I/O subchannel in qdio mode */
+
+#endif /* _ASM_S390_ISC_H */