v4.19.13 snapshot.
diff --git a/arch/s390/lib/delay.c b/arch/s390/lib/delay.c
new file mode 100644
index 0000000..d4aa107
--- /dev/null
+++ b/arch/s390/lib/delay.c
@@ -0,0 +1,129 @@
+// 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/delay.h>
+#include <linux/timex.h>
+#include <linux/export.h>
+#include <linux/irqflags.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <asm/vtimer.h>
+#include <asm/div64.h>
+#include <asm/idle.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.
+ */
+ asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1));
+}
+EXPORT_SYMBOL(__delay);
+
+static void __udelay_disabled(unsigned long long usecs)
+{
+ unsigned long cr0, cr0_new, psw_mask;
+ struct s390_idle_data idle;
+ u64 end;
+
+ end = get_tod_clock() + (usecs << 12);
+ __ctl_store(cr0, 0, 0);
+ cr0_new = cr0 & ~CR0_IRQ_SUBCLASS_MASK;
+ cr0_new |= (1UL << (63 - 52)); /* enable clock comparator irq */
+ __ctl_load(cr0_new, 0, 0);
+ psw_mask = __extract_psw() | PSW_MASK_EXT | PSW_MASK_WAIT;
+ set_clock_comparator(end);
+ set_cpu_flag(CIF_IGNORE_IRQ);
+ psw_idle(&idle, psw_mask);
+ clear_cpu_flag(CIF_IGNORE_IRQ);
+ set_clock_comparator(S390_lowcore.clock_comparator);
+ __ctl_load(cr0, 0, 0);
+}
+
+static void __udelay_enabled(unsigned long long usecs)
+{
+ u64 clock_saved, end;
+
+ end = get_tod_clock_fast() + (usecs << 12);
+ do {
+ clock_saved = 0;
+ if (tod_after(S390_lowcore.clock_comparator, end)) {
+ clock_saved = local_tick_disable();
+ set_clock_comparator(end);
+ }
+ enabled_wait();
+ if (clock_saved)
+ local_tick_enable(clock_saved);
+ } while (get_tod_clock_fast() < end);
+}
+
+/*
+ * Waits for 'usecs' microseconds using the TOD clock comparator.
+ */
+void __udelay(unsigned long 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();
+}
+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_fast() + (usecs << 12);
+ while (get_tod_clock_fast() < end)
+ cpu_relax();
+}
+
+void __ndelay(unsigned long long nsecs)
+{
+ u64 end;
+
+ nsecs <<= 9;
+ do_div(nsecs, 125);
+ end = get_tod_clock_fast() + nsecs;
+ if (nsecs & ~0xfffUL)
+ __udelay(nsecs >> 12);
+ while (get_tod_clock_fast() < end)
+ barrier();
+}
+EXPORT_SYMBOL(__ndelay);