include/linux/jiffies.h

   1 #ifndef _LINUX_JIFFIES_H
   2 #define _LINUX_JIFFIES_H
   3
   4 #include <linux/kernel.h>
   5 #include <linux/types.h>
   6 #include <linux/spinlock.h>
   7 #include <linux/seqlock.h>
   8 #include <asm/system.h>
   9 #include <asm/param.h>                  /* for HZ */
  10
  11 /*
  12  * The 64-bit value is not volatile - you MUST NOT read it
  13  * without sampling the sequence number in xtime_lock.
  14  * get_jiffies_64() will do this for you as appropriate.
  15  */
  16 extern u64 jiffies_64;
  17 extern unsigned long volatile jiffies;
  18
  19 #if (BITS_PER_LONG < 64)
  20 u64 get_jiffies_64(void);
  21 #else
  22 static inline u64 get_jiffies_64(void)
  23 {
  24         return (u64)jiffies;
  25 }
  26 #endif
  27
  28 /*
  29  *      These inlines deal with timer wrapping correctly. You are
  30  *      strongly encouraged to use them
  31  *      1. Because people otherwise forget
  32  *      2. Because if the timer wrap changes in future you won't have to
  33  *         alter your driver code.
  34  *
  35  * time_after(a,b) returns true if the time a is after time b.
  36  *
  37  * Do this with "<0" and ">=0" to only test the sign of the result. A
  38  * good compiler would generate better code (and a really good compiler
  39  * wouldn't care). Gcc is currently neither.
  40  */
  41 #define time_after(a,b)         \
  42         (typecheck(unsigned long, a) && \
  43          typecheck(unsigned long, b) && \
  44          ((long)(b) - (long)(a) < 0))
  45 #define time_before(a,b)        time_after(b,a)
  46
  47 #define time_after_eq(a,b)      \
  48         (typecheck(unsigned long, a) && \
  49          typecheck(unsigned long, b) && \
  50          ((long)(a) - (long)(b) >= 0))
  51 #define time_before_eq(a,b)     time_after_eq(b,a)
  52
  53 #endif