1 files changed, 18 insertions, 103 deletions

diff --git a/arch/s390/lib/delay.c b/arch/s390/lib/delay.c
index c61b9fad43cc..c1ea14e3c927 100644
--- a/arch/s390/lib/delay.c
+++ b/arch/s390/lib/delay.c
@@ -1,131 +1,46 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  *    Precise Delay Loops for S390
  *
  *    Copyright IBM Corp. 1999, 2008
  *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
- *		 Heiko Carstens <heiko.carstens@de.ibm.com>,
  */
 
-#include <linux/sched.h>
+#include <linux/processor.h>
+#include <linux/export.h>
 #include <linux/delay.h>
-#include <linux/timex.h>
-#include <linux/module.h>
-#include <linux/irqflags.h>
-#include <linux/interrupt.h>
-#include <asm/vtimer.h>
 #include <asm/div64.h>
+#include <asm/timex.h>
 
 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.
-         */
+	/*
+	 * Loop 'loops' times. Callers must not assume a specific
+	 * amount of time passes before this function returns.
+	 */
 	asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1));
 }
+EXPORT_SYMBOL(__delay);
 
-static void __udelay_disabled(unsigned long long usecs)
+static void delay_loop(unsigned long delta)
 {
-	unsigned long cr0, cr6, new;
-	u64 clock_saved, end;
+	unsigned long end;
 
-	end = get_tod_clock() + (usecs << 12);
-	clock_saved = local_tick_disable();
-	__ctl_store(cr0, 0, 0);
-	__ctl_store(cr6, 6, 6);
-	new = (cr0 &  0xffff00e0) | 0x00000800;
-	__ctl_load(new , 0, 0);
-	new = 0;
-	__ctl_load(new, 6, 6);
-	lockdep_off();
-	do {
-		set_clock_comparator(end);
-		vtime_stop_cpu();
-		local_irq_disable();
-	} while (get_tod_clock() < end);
-	lockdep_on();
-	__ctl_load(cr0, 0, 0);
-	__ctl_load(cr6, 6, 6);
-	local_tick_enable(clock_saved);
-}
-
-static void __udelay_enabled(unsigned long long usecs)
-{
-	u64 clock_saved, end;
-
-	end = get_tod_clock() + (usecs << 12);
-	do {
-		clock_saved = 0;
-		if (end < S390_lowcore.clock_comparator) {
-			clock_saved = local_tick_disable();
-			set_clock_comparator(end);
-		}
-		vtime_stop_cpu();
-		local_irq_disable();
-		if (clock_saved)
-			local_tick_enable(clock_saved);
-	} while (get_tod_clock() < end);
+	end = get_tod_clock_monotonic() + delta;
+	while (!tod_after(get_tod_clock_monotonic(), end))
+		cpu_relax();
 }
 
-/*
- * Waits for 'usecs' microseconds using the TOD clock comparator.
- */
-void __udelay(unsigned long long usecs)
+void __udelay(unsigned long usecs)
 {
-	unsigned long flags;
-
-	preempt_disable();
-	local_irq_save(flags);
-	if (in_irq()) {
-		__udelay_disabled(usecs);
-		goto out;
-	}
-	if (in_softirq()) {
-		if (raw_irqs_disabled_flags(flags))
-			__udelay_disabled(usecs);
-		else
-			__udelay_enabled(usecs);
-		goto out;
-	}
-	if (raw_irqs_disabled_flags(flags)) {
-		local_bh_disable();
-		__udelay_disabled(usecs);
-		_local_bh_enable();
-		goto out;
-	}
-	__udelay_enabled(usecs);
-out:
-	local_irq_restore(flags);
-	preempt_enable();
+	delay_loop(usecs << 12);
 }
 EXPORT_SYMBOL(__udelay);
 
-/*
- * Simple udelay variant. To be used on startup and reboot
- * when the interrupt handler isn't working.
- */
-void udelay_simple(unsigned long long usecs)
-{
-	u64 end;
-
-	end = get_tod_clock() + (usecs << 12);
-	while (get_tod_clock() < end)
-		cpu_relax();
-}
-
-void __ndelay(unsigned long long nsecs)
+void __ndelay(unsigned long nsecs)
 {
-	u64 end;
-
 	nsecs <<= 9;
 	do_div(nsecs, 125);
-	end = get_tod_clock() + nsecs;
-	if (nsecs & ~0xfffUL)
-		__udelay(nsecs >> 12);
-	while (get_tod_clock() < end)
-		barrier();
+	delay_loop(nsecs);
 }
 EXPORT_SYMBOL(__ndelay);