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authorDan Williams <dan.j.williams@intel.com>2009-09-08 17:55:21 -0700
committerDan Williams <dan.j.williams@intel.com>2009-09-08 17:55:21 -0700
commitbbb20089a3275a19e475dbc21320c3742e3ca423 (patch)
tree216fdc1cbef450ca688135c5b8969169482d9a48 /arch/powerpc/include/asm/delay.h
parent3e48e656903e9fd8bc805c6a2c4264d7808d315b (diff)
parent657a77fa7284d8ae28dfa48f1dc5d919bf5b2843 (diff)
Merge branch 'dmaengine' into async-tx-next
Conflicts: crypto/async_tx/async_xor.c drivers/dma/ioat/dma_v2.h drivers/dma/ioat/pci.c drivers/md/raid5.c
Diffstat (limited to 'arch/powerpc/include/asm/delay.h')
-rw-r--r--arch/powerpc/include/asm/delay.h36
1 files changed, 36 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/delay.h b/arch/powerpc/include/asm/delay.h
index f9200a65c63..1e2eb41fa05 100644
--- a/arch/powerpc/include/asm/delay.h
+++ b/arch/powerpc/include/asm/delay.h
@@ -2,8 +2,11 @@
#define _ASM_POWERPC_DELAY_H
#ifdef __KERNEL__
+#include <asm/time.h>
+
/*
* Copyright 1996, Paul Mackerras.
+ * Copyright (C) 2009 Freescale Semiconductor, Inc. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
@@ -30,5 +33,38 @@ extern void udelay(unsigned long usecs);
#define mdelay(n) udelay((n) * 1000)
#endif
+/**
+ * spin_event_timeout - spin until a condition gets true or a timeout elapses
+ * @condition: a C expression to evalate
+ * @timeout: timeout, in microseconds
+ * @delay: the number of microseconds to delay between each evaluation of
+ * @condition
+ *
+ * The process spins until the condition evaluates to true (non-zero) or the
+ * timeout elapses. The return value of this macro is the value of
+ * @condition when the loop terminates. This allows you to determine the cause
+ * of the loop terminates. If the return value is zero, then you know a
+ * timeout has occurred.
+ *
+ * This primary purpose of this macro is to poll on a hardware register
+ * until a status bit changes. The timeout ensures that the loop still
+ * terminates even if the bit never changes. The delay is for devices that
+ * need a delay in between successive reads.
+ *
+ * gcc will optimize out the if-statement if @delay is a constant.
+ */
+#define spin_event_timeout(condition, timeout, delay) \
+({ \
+ typeof(condition) __ret; \
+ unsigned long __loops = tb_ticks_per_usec * timeout; \
+ unsigned long __start = get_tbl(); \
+ while (!(__ret = (condition)) && (tb_ticks_since(__start) <= __loops)) \
+ if (delay) \
+ udelay(delay); \
+ else \
+ cpu_relax(); \
+ __ret; \
+})
+
#endif /* __KERNEL__ */
#endif /* _ASM_POWERPC_DELAY_H */