arch/arm26/lib/delay.S

   1 /*
   2  *  linux/arch/arm26/lib/delay.S
   3  *
   4  *  Copyright (C) 1995, 1996 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/linkage.h>
  11 #include <asm/assembler.h>
  12                 .text
  13
  14 LC0:            .word   loops_per_jiffy
  15
  16 /*
  17  * 0 <= r0 <= 2000
  18  */
  19 ENTRY(udelay)
  20                 mov     r2,     #0x6800
  21                 orr     r2, r2, #0x00db
  22                 mul     r1, r0, r2
  23                 ldr     r2, LC0
  24                 ldr     r2, [r2]
  25                 mov     r1, r1, lsr #11
  26                 mov     r2, r2, lsr #11
  27                 mul     r0, r1, r2
  28                 movs    r0, r0, lsr #6
  29                 RETINSTR(moveq,pc,lr)
  30
  31 /*
  32  * loops = (r0 * 0x10c6 * 100 * loops_per_jiffy) / 2^32
  33  *
  34  * Oh, if only we had a cycle counter...
  35  */
  36
  37 @ Delay routine
  38 ENTRY(__delay)
  39                 subs    r0, r0, #1
  40 #if 0
  41                 RETINSTR(movls,pc,lr)
  42                 subs    r0, r0, #1
  43                 RETINSTR(movls,pc,lr)
  44                 subs    r0, r0, #1
  45                 RETINSTR(movls,pc,lr)
  46                 subs    r0, r0, #1
  47                 RETINSTR(movls,pc,lr)
  48                 subs    r0, r0, #1
  49                 RETINSTR(movls,pc,lr)
  50                 subs    r0, r0, #1
  51                 RETINSTR(movls,pc,lr)
  52                 subs    r0, r0, #1
  53                 RETINSTR(movls,pc,lr)
  54                 subs    r0, r0, #1
  55 #endif
  56                 bhi     __delay
  57                 RETINSTR(mov,pc,lr)