[S390] delay: implement ndelay

Implement ndelay() on s390 as well.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/delay.h

@@ -14,10 +14,12 @@
 #ifndef _S390_DELAY_H
 #define _S390_DELAY_H
 
-extern void __udelay(unsigned long long usecs);
-extern void udelay_simple(unsigned long long usecs);
-extern void __delay(unsigned long loops);
+void __ndelay(unsigned long long nsecs);
+void __udelay(unsigned long long usecs);
+void udelay_simple(unsigned long long usecs);
+void __delay(unsigned long loops);
 
+#define ndelay(n) __ndelay((unsigned long long) (n))
 #define udelay(n) __udelay((unsigned long long) (n))
 #define mdelay(n) __udelay((unsigned long long) (n) * 1000)
 

arch/s390/lib/delay.c

@@ -12,6 +12,7 @@
 #include <linux/module.h>
 #include <linux/irqflags.h>
 #include <linux/interrupt.h>
+#include <asm/div64.h>
 
 void __delay(unsigned long loops)
 {
@@ -116,3 +117,17 @@ void udelay_simple(unsigned long long usecs)
 	while (get_clock() < end)
 		cpu_relax();
 }
+
+void __ndelay(unsigned long long nsecs)
+{
+	u64 end;
+
+	nsecs <<= 9;
+	do_div(nsecs, 125);
+	end = get_clock() + nsecs;
+	if (nsecs & ~0xfffUL)
+		__udelay(nsecs >> 12);
+	while (get_clock() < end)
+		barrier();
+}
+EXPORT_SYMBOL(__ndelay);