include/asm-ppc64/delay.h

   1 #ifndef _PPC64_DELAY_H
   2 #define _PPC64_DELAY_H
   3
   4 /*
   5  * Copyright 1996, Paul Mackerras.
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; either version
  10  * 2 of the License, or (at your option) any later version.
  11  *
  12  * PPC64 Support added by Dave Engebretsen, Todd Inglett, Mike Corrigan,
  13  * Anton Blanchard.
  14  */
  15
  16 extern unsigned long tb_ticks_per_usec;
  17
  18 /* define these here to prevent circular dependencies */
  19 #define __HMT_low()     asm volatile("or 1,1,1")
  20 #define __HMT_medium()  asm volatile("or 2,2,2")
  21 #define __barrier()     asm volatile("":::"memory")
  22
  23 static inline unsigned long __get_tb(void)
  24 {
  25         unsigned long rval;
  26
  27         asm volatile("mftb %0" : "=r" (rval));
  28         return rval;
  29 }
  30
  31 static inline void __delay(unsigned long loops)
  32 {
  33         unsigned long start = __get_tb();
  34
  35         while((__get_tb()-start) < loops)
  36                 __HMT_low();
  37         __HMT_medium();
  38         __barrier();
  39 }
  40
  41 static inline void udelay(unsigned long usecs)
  42 {
  43         unsigned long loops = tb_ticks_per_usec * usecs;
  44
  45         __delay(loops);
  46 }
  47
  48 #endif /* _PPC64_DELAY_H */