Disintegrate asm/system.h for S390

Disintegrate asm/system.h for S390.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: linux-s390@vger.kernel.org

arch/s390/include/asm/barrier.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright IBM Corp. 1999, 2009
+ *
+ * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#ifndef __ASM_BARRIER_H
+#define __ASM_BARRIER_H
+
+/*
+ * Force strict CPU ordering.
+ * And yes, this is required on UP too when we're talking
+ * to devices.
+ *
+ * This is very similar to the ppc eieio/sync instruction in that is
+ * does a checkpoint syncronisation & makes sure that 
+ * all memory ops have completed wrt other CPU's ( see 7-15 POP  DJB ).
+ */
+
+#define eieio()	asm volatile("bcr 15,0" : : : "memory")
+#define SYNC_OTHER_CORES(x)   eieio()
+#define mb()    eieio()
+#define rmb()   eieio()
+#define wmb()   eieio()
+#define read_barrier_depends() do { } while(0)
+#define smp_mb()       mb()
+#define smp_rmb()      rmb()
+#define smp_wmb()      wmb()
+#define smp_read_barrier_depends()    read_barrier_depends()
+#define smp_mb__before_clear_bit()     smp_mb()
+#define smp_mb__after_clear_bit()      smp_mb()
+
+#define set_mb(var, value)      do { var = value; mb(); } while (0)
+
+#endif /* __ASM_BARRIER_H */