1 files changed, 51 insertions, 0 deletions

diff --git a/arch/s390/lib/delay.c b/arch/s390/lib/delay.c
new file mode 100644
index 000000000000..e96c35bddac7
--- /dev/null
+++ b/arch/s390/lib/delay.c
@@ -0,0 +1,51 @@
+/*
+ *  arch/s390/kernel/delay.c
+ *    Precise Delay Loops for S390
+ *
+ *  S390 version
+ *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
+ *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
+ *
+ *  Derived from "arch/i386/lib/delay.c"
+ *    Copyright (C) 1993 Linus Torvalds
+ *    Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
+ */
+
+#include <linux/config.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+
+#ifdef CONFIG_SMP
+#include <asm/smp.h>
+#endif
+
+void __delay(unsigned long loops)
+{
+        /*
+         * To end the bloody studid and useless discussion about the
+         * BogoMips number I took the liberty to define the __delay
+         * function in a way that that resulting BogoMips number will
+         * yield the megahertz number of the cpu. The important function
+         * is udelay and that is done using the tod clock. -- martin.
+         */
+        __asm__ __volatile__(
+                "0: brct %0,0b"
+                : /* no outputs */ : "r" (loops/2) );
+}
+
+/*
+ * Waits for 'usecs' microseconds using the tod clock, giving up the time slice
+ * of the virtual PU inbetween to avoid congestion.
+ */
+void __udelay(unsigned long usecs)
+{
+        uint64_t start_cc, end_cc;
+
+        if (usecs == 0)
+                return;
+        asm volatile ("STCK %0" : "=m" (start_cc));
+        do {
+                cpu_relax();
+                asm volatile ("STCK %0" : "=m" (end_cc));
+        } while (((end_cc - start_cc)/4096) < usecs);
+}