[S390] Move private simple udelay function to arch/s390/lib/delay.c.

Move cio's private simple udelay function to lib/delay.c and turn it
into something much more readable. So we have all implementations
at one place.

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

@@ -15,6 +15,7 @@
 #define _S390_DELAY_H
 
 extern void __udelay(unsigned long usecs);
+extern void udelay_simple(unsigned long usecs);
 extern void __delay(unsigned long loops);
 
 #define udelay(n) __udelay(n)

arch/s390/lib/delay.c

@@ -92,3 +92,16 @@ void __udelay(unsigned long usecs)
 	local_irq_restore(flags);
 	preempt_enable();
 }
+
+/*
+ * Simple udelay variant. To be used on startup and reboot
+ * when the interrupt handler isn't working.
+ */
+void udelay_simple(unsigned long usecs)
+{
+	u64 end;
+
+	end = get_clock() + ((u64) usecs << 12);
+	while (get_clock() < end)
+		cpu_relax();
+}

drivers/s390/cio/cio.c

@@ -859,19 +859,6 @@ __disable_subchannel_easy(struct subchannel_id schid, struct schib *schib)
 	return -EBUSY; /* uhm... */
 }
 
-/* we can't use the normal udelay here, since it enables external interrupts */
-
-static void udelay_reset(unsigned long usecs)
-{
-	uint64_t start_cc, end_cc;
-
-	asm volatile ("STCK %0" : "=m" (start_cc));
-	do {
-		cpu_relax();
-		asm volatile ("STCK %0" : "=m" (end_cc));
-	} while (((end_cc - start_cc)/4096) < usecs);
-}
-
 static int
 __clear_io_subchannel_easy(struct subchannel_id schid)
 {
@@ -887,15 +874,15 @@ __clear_io_subchannel_easy(struct subchannel_id schid)
 			if (schid_equal(&ti.schid, &schid))
 				return 0;
 		}
-		udelay_reset(100);
+		udelay_simple(100);
 	}
 	return -EBUSY;
 }
 
 static void __clear_chsc_subchannel_easy(void)
 {
 	/* It seems we can only wait for a bit here :/ */
-	udelay_reset(100);
+	udelay_simple(100);
 }
 
 static int pgm_check_occured;