[PATCH 2/2] Convert PowerPC macro spin_event_timeout() to architecture independent macro

 
+#ifndef spin_event_timeout
+/**
+ * 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 = timeout/USECS_PER_JIFFY;	\
+	unsigned long __start = jiffies;			\
+	while (!(__ret = (condition)) &&			\
+		time_before(jiffies, __start + __loops + 1))	\
+		if (delay)					\
+			udelay(delay);				\
+		else						\
+			schedule();				\
+	if (!__ret)						\
+		__ret = (condition);				\
+	__ret;							\
+})