@@ -2,8 +2,11 @@
* 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)
+ * 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 */