include/asm-v850/delay.h

   1 /*
   2  * include/asm-v850/delay.h -- Delay routines, using a pre-computed
   3  *      "loops_per_second" value
   4  *
   5  *  Copyright (C) 2001,03  NEC Corporation
   6  *  Copyright (C) 2001,03  Miles Bader <miles@gnu.org>
   7  *  Copyright (C) 1994 Hamish Macdonald
   8  *
   9  * This file is subject to the terms and conditions of the GNU General
  10  * Public License.  See the file COPYING in the main directory of this
  11  * archive for more details.
  12  */
  13
  14 #ifndef __V850_DELAY_H__
  15 #define __V850_DELAY_H__
  16
  17 #include <asm/param.h>
  18
  19 extern __inline__ void __delay(unsigned long loops)
  20 {
  21         if (loops)
  22                 __asm__ __volatile__ ("1: add -1, %0; bnz 1b"
  23                                       : "=r" (loops) : "0" (loops));
  24 }
  25
  26 /*
  27  * Use only for very small delays ( < 1 msec).  Should probably use a
  28  * lookup table, really, as the multiplications take much too long with
  29  * short delays.  This is a "reasonable" implementation, though (and the
  30  * first constant multiplications gets optimized away if the delay is
  31  * a constant)
  32  */
  33
  34 extern unsigned long loops_per_jiffy;
  35
  36 extern __inline__ void udelay(unsigned long usecs)
  37 {
  38         register unsigned long full_loops, part_loops;
  39
  40         full_loops = ((usecs * HZ) / 1000000) * loops_per_jiffy;
  41         usecs %= (1000000 / HZ);
  42         part_loops = (usecs * HZ * loops_per_jiffy) / 1000000;
  43
  44         __delay(full_loops + part_loops);
  45 }
  46
  47 #endif /* __V850_DELAY_H__ */