include/asm-mips64/delay.h

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 1994 by Waldorf Electronics
   7  * Copyright (C) 1995 - 2000 by Ralf Baechle
   8  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
   9  */
  10 #ifndef _ASM_DELAY_H
  11 #define _ASM_DELAY_H
  12
  13 #include <linux/config.h>
  14 #include <linux/param.h>
  15
  16 extern unsigned long loops_per_jiffy;
  17
  18 static __inline__ void
  19 __delay(unsigned long loops)
  20 {
  21         __asm__ __volatile__ (
  22                 ".set\tnoreorder\n"
  23                 "1:\tbnez\t%0,1b\n\t"
  24                 "dsubu\t%0,1\n\t"
  25                 ".set\treorder"
  26                 :"=r" (loops)
  27                 :"0" (loops));
  28 }
  29
  30 /*
  31  * Division by multiplication: you don't have to worry about
  32  * loss of precision.
  33  *
  34  * Use only for very small delays ( < 1 msec).  Should probably use a
  35  * lookup table, really, as the multiplications take much too long with
  36  * short delays.  This is a "reasonable" implementation, though (and the
  37  * first constant multiplications gets optimized away if the delay is
  38  * a constant)
  39  */
  40 static __inline__ void __udelay(unsigned long usecs, unsigned long lpj)
  41 {
  42         unsigned long lo;
  43
  44         /*
  45          * The common rates of 1000 and 128 are rounded wrongly by the
  46          * catchall case.  Excessive precission?  Probably ...
  47          */
  48 #if (HZ == 128)
  49         usecs *= 0x0008637bd05af6c7UL;          /* 2**64 / (1000000 / HZ) */
  50 #elif (HZ == 1000)
  51         usecs *= 0x004189374BC6A7f0UL;          /* 2**64 / (1000000 / HZ) */
  52 #else
  53         usecs *= (0x8000000000000000UL / (500000 / HZ));
  54 #endif
  55         __asm__("dmultu\t%2,%3"
  56                 :"=h" (usecs), "=l" (lo)
  57                 :"r" (usecs),"r" (lpj));
  58         __delay(usecs);
  59 }
  60
  61 #ifdef CONFIG_SMP
  62 #define __udelay_val cpu_data[smp_processor_id()].udelay_val
  63 #else
  64 #define __udelay_val loops_per_jiffy
  65 #endif
  66
  67 #define udelay(usecs) __udelay((usecs),__udelay_val)
  68
  69 #endif /* _ASM_DELAY_H */