Index: sys/compat/linuxkpi/common/include/linux/delay.h
===================================================================
--- sys/compat/linuxkpi/common/include/linux/delay.h
+++ sys/compat/linuxkpi/common/include/linux/delay.h
@@ -33,6 +33,7 @@
 #define	_LINUX_DELAY_H_
 
 #include <linux/jiffies.h>
+#include <sys/kernel.h>
 #include <sys/systm.h>
 
 static inline void
@@ -76,4 +77,14 @@
 
 extern unsigned int linux_msleep_interruptible(unsigned int ms);
 
+static inline void
+fsleep(unsigned long us)
+{
+
+	if (us < (20 * hz))
+		DELAY(us);
+	else
+		linux_msleep(howmany(us, 1000));
+}
+
 #endif	/* _LINUX_DELAY_H_ */