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Diffstat (limited to 'arch/s390/lib/delay.c')
-rw-r--r--arch/s390/lib/delay.c101
1 files changed, 67 insertions, 34 deletions
diff --git a/arch/s390/lib/delay.c b/arch/s390/lib/delay.c
index fc6ab6094df..6ccb9fab055 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();
}