@@ -52,4 +52,44 @@ static inline void ssleep(unsigned int seconds)
msleep(seconds * 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.
+ * This is copied from PowerPC based spin_event_timeout() implementation
+ * and modified for generic usecase.
+#define spin_event_timeout(condition, timeout, delay) \
+ typeof(condition) __ret; \
+ unsigned long __loops = usecs_to_jiffies(timeout); \
+ unsigned long __start = jiffies; \
+ while (!(__ret = (condition)) && \
+ time_before(jiffies, __start + __loops + 1)) \
+ if (delay) \
+ udelay(delay); \
+ else \
+ schedule(); \
+ if (!__ret) \
+ __ret = (condition); \
+ __ret; \
#endif /* defined(_LINUX_DELAY_H) */