1 files changed, 67 insertions, 34 deletions

diff --git a/arch/s390/lib/delay.c b/arch/s390/lib/delay.c
index fc6ab6094df8..6ccb9fab055a 100644
--- a/arch/s390/lib/delay.c
+++ b/arch/s390/lib/delay.c
@@ -1,14 +1,9 @@
 /*
- *  arch/s390/lib/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>
+ *    Copyright IBM Corp. 1999,2008
+ *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
+ *		 Heiko Carstens <heiko.carstens@de.ibm.com>,
  */
 
 #include <linux/sched.h>
@@ -29,30 +24,31 @@ void __delay(unsigned long loops)
 	asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1));
 }
 
-/*
- * Waits for 'usecs' microseconds using the TOD clock comparator.
- */
-void __udelay(unsigned long usecs)
+static void __udelay_disabled(unsigned long usecs)
 {
-	u64 end, time, old_cc = 0;
-	unsigned long flags, cr0, mask, dummy;
-	int irq_context;
+	unsigned long mask, cr0, cr0_saved;
+	u64 clock_saved;
 
-	irq_context = in_interrupt();
-	if (!irq_context)
-		local_bh_disable();
-	local_irq_save(flags);
-	if (raw_irqs_disabled_flags(flags)) {
-		old_cc = local_tick_disable();
-		S390_lowcore.clock_comparator = -1ULL;
-		__ctl_store(cr0, 0, 0);
-		dummy = (cr0 & 0xffff00e0) | 0x00000800;
-		__ctl_load(dummy , 0, 0);
-		mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT;
-	} else
-		mask = psw_kernel_bits | PSW_MASK_WAIT |
-			PSW_MASK_EXT | PSW_MASK_IO;
+	clock_saved = local_tick_disable();
+	set_clock_comparator(get_clock() + ((u64) usecs << 12));
+	__ctl_store(cr0_saved, 0, 0);
+	cr0 = (cr0_saved & 0xffff00e0) | 0x00000800;
+	__ctl_load(cr0 , 0, 0);
+	mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT;
+	trace_hardirqs_on();
+	__load_psw_mask(mask);
+	local_irq_disable();
+	__ctl_load(cr0_saved, 0, 0);
+	local_tick_enable(clock_saved);
+	set_clock_comparator(S390_lowcore.clock_comparator);
+}
+
+static void __udelay_enabled(unsigned long usecs)
+{
+	unsigned long mask;
+	u64 end, time;
 
+	mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT | PSW_MASK_IO;
 	end = get_clock() + ((u64) usecs << 12);
 	do {
 		time = end < S390_lowcore.clock_comparator ?
@@ -62,13 +58,50 @@ void __udelay(unsigned long usecs)
 		__load_psw_mask(mask);
 		local_irq_disable();
 	} while (get_clock() < end);
+	set_clock_comparator(S390_lowcore.clock_comparator);
+}
 
-	if (raw_irqs_disabled_flags(flags)) {
-		__ctl_load(cr0, 0, 0);
-		local_tick_enable(old_cc);
+/*
+ * Waits for 'usecs' microseconds using the TOD clock comparator.
+ */
+void __udelay(unsigned long usecs)
+{
+	unsigned long flags;
+
+	preempt_disable();
+	local_irq_save(flags);
+	if (in_irq()) {
+		__udelay_disabled(usecs);
+		goto out;
 	}
-	if (!irq_context)
+	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();
-	set_clock_comparator(S390_lowcore.clock_comparator);
+		goto out;
+	}
+	__udelay_enabled(usecs);
+out:
 	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();
 }