arch/arm/lib/delay-loop.S

   1 /*
   2  *  linux/arch/arm/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 #include <asm/delay.h>
  13
  14                 .text
  15
  16 .LC0:           .word   loops_per_jiffy
  17 .LC1:           .word   UDELAY_MULT
  18
  19 /*
  20  * r0  <= 2000
  21  * HZ  <= 1000
  22  */
  23
  24 ENTRY(__loop_udelay)
  25                 ldr     r2, .LC1
  26                 mul     r0, r2, r0
  27 ENTRY(__loop_const_udelay)                      @ 0 <= r0 <= 0x7fffff06
  28                 ldr     r2, .LC0
  29                 ldr     r2, [r2]
  30                 umull   r1, r0, r2, r0
  31                 adds    r1, r1, #0xffffffff
  32                 adcs    r0, r0, r0
  33                 reteq   lr
  34
  35 /*
  36  * loops = r0 * HZ * loops_per_jiffy / 1000000
  37  */
  38                 .align 3
  39
  40 @ Delay routine
  41 ENTRY(__loop_delay)
  42                 subs    r0, r0, #1
  43 #if 0
  44                 retls   lr
  45                 subs    r0, r0, #1
  46                 retls   lr
  47                 subs    r0, r0, #1
  48                 retls   lr
  49                 subs    r0, r0, #1
  50                 retls   lr
  51                 subs    r0, r0, #1
  52                 retls   lr
  53                 subs    r0, r0, #1
  54                 retls   lr
  55                 subs    r0, r0, #1
  56                 retls   lr
  57                 subs    r0, r0, #1
  58 #endif
  59                 bhi     __loop_delay
  60                 ret     lr
  61 ENDPROC(__loop_udelay)
  62 ENDPROC(__loop_const_udelay)
  63 ENDPROC(__loop_delay)