include/asm-ia64/timex.h

   1 #ifndef _ASM_IA64_TIMEX_H
   2 #define _ASM_IA64_TIMEX_H
   3
   4 /*
   5  * Copyright (C) 1998-2001, 2003 Hewlett-Packard Co
   6  *      David Mosberger-Tang <davidm@hpl.hp.com>
   7  */
   8 /*
   9  * 2001/01/18 davidm    Removed CLOCK_TICK_RATE.  It makes no sense on IA-64.
  10  *                      Also removed cacheflush_time as it's entirely unused.
  11  */
  12
  13 #include <asm/intrinsics.h>
  14 #include <asm/processor.h>
  15
  16 typedef unsigned long cycles_t;
  17
  18 /*
  19  * For performance reasons, we don't want to define CLOCK_TICK_TRATE as
  20  * local_cpu_data->itc_rate.  Fortunately, we don't have to, either: according to George
  21  * Anzinger, 1/CLOCK_TICK_RATE is taken as the resolution of the timer clock.  The time
  22  * calculation assumes that you will use enough of these so that your tick size <= 1/HZ.
  23  * If the calculation shows that your CLOCK_TICK_RATE can not supply exactly 1/HZ ticks,
  24  * the actual value is calculated and used to update the wall clock each jiffie.  Setting
  25  * the CLOCK_TICK_RATE to x*HZ insures that the calculation will find no errors.  Hence we
  26  * pick a multiple of HZ which gives us a (totally virtual) CLOCK_TICK_RATE of about
  27  * 100MHz.
  28  */
  29 #define CLOCK_TICK_RATE         (HZ * 100000UL)
  30
  31 static inline cycles_t
  32 get_cycles (void)
  33 {
  34         cycles_t ret;
  35
  36         ret = ia64_getreg(_IA64_REG_AR_ITC);
  37         return ret;
  38 }
  39
  40 #endif /* _ASM_IA64_TIMEX_H */