arch/blackfin/include/asm/delay.h

   1 /*
   2  * delay.h - delay functions
   3  *
   4  * Copyright (c) 2004-2007 Analog Devices Inc.
   5  *
   6  * Licensed under the GPL-2 or later.
   7  */
   8
   9 #ifndef __ASM_DELAY_H__
  10 #define __ASM_DELAY_H__
  11
  12 #include <mach/anomaly.h>
  13
  14 static inline void __delay(unsigned long loops)
  15 {
  16         if (ANOMALY_05000312) {
  17                 /* Interrupted loads to loop registers -> bad */
  18                 unsigned long tmp;
  19                 __asm__ __volatile__(
  20                         "[--SP] = LC0;"
  21                         "[--SP] = LT0;"
  22                         "[--SP] = LB0;"
  23                         "LSETUP (1f,1f) LC0 = %1;"
  24                         "1: NOP;"
  25                         /* We take advantage of the fact that LC0 is 0 at
  26                          * the end of the loop.  Otherwise we'd need some
  27                          * NOPs after the CLI here.
  28                          */
  29                         "CLI %0;"
  30                         "LB0 = [SP++];"
  31                         "LT0 = [SP++];"
  32                         "LC0 = [SP++];"
  33                         "STI %0;"
  34                         : "=d" (tmp)
  35                         : "a" (loops)
  36                 );
  37         } else
  38                 __asm__ __volatile__ (
  39                         "LSETUP(1f, 1f) LC0 = %0;"
  40                         "1: NOP;"
  41                         :
  42                         : "a" (loops)
  43                         : "LT0", "LB0", "LC0"
  44                 );
  45 }
  46
  47 #include <linux/param.h>        /* needed for HZ */
  48
  49 /*
  50  * Use only for very small delays ( < 1 msec).  Should probably use a
  51  * lookup table, really, as the multiplications take much too long with
  52  * short delays.  This is a "reasonable" implementation, though (and the
  53  * first constant multiplications gets optimized away if the delay is
  54  * a constant)
  55  */
  56 static inline void udelay(unsigned long usecs)
  57 {
  58         extern unsigned long loops_per_jiffy;
  59         __delay(usecs * loops_per_jiffy / (1000000 / HZ));
  60 }
  61
  62 #endif