s390/scm_blk: suspend writes

Stop writing to scm after certain error conditions such as a concurrent
firmware upgrade. Resume to normal state once scm_blk_set_available is
called (due to an scm availability notification).

Reviewed-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/include/asm/eadm.h b/arch/s390/include/asm/eadm.h
index a4a1ea4..78141be 100644
--- a/arch/s390/include/asm/eadm.h
+++ b/arch/s390/include/asm/eadm.h
@@ -34,6 +34,8 @@
 	u32 reserved[4];
 } __packed;
 
+#define EQC_WR_PROHIBIT 22
+
 struct msb {
 	u8 fmt:4;
 	u8 oc:4;