arch/x86/um/delay.c

   1 /*
   2  * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
   3  * Mostly copied from arch/x86/lib/delay.c
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/export.h>
  11 #include <linux/kernel.h>
  12 #include <linux/delay.h>
  13 #include <asm/param.h>
  14
  15 void __delay(unsigned long loops)
  16 {
  17         asm volatile(
  18                 "test %0,%0\n"
  19                 "jz 3f\n"
  20                 "jmp 1f\n"
  21
  22                 ".align 16\n"
  23                 "1: jmp 2f\n"
  24
  25                 ".align 16\n"
  26                 "2: dec %0\n"
  27                 " jnz 2b\n"
  28                 "3: dec %0\n"
  29
  30                 : /* we don't need output */
  31                 : "a" (loops)
  32         );
  33 }
  34 EXPORT_SYMBOL(__delay);
  35
  36 inline void __const_udelay(unsigned long xloops)
  37 {
  38         int d0;
  39
  40         xloops *= 4;
  41         asm("mull %%edx"
  42                 : "=d" (xloops), "=&a" (d0)
  43                 : "1" (xloops), "0"
  44                 (loops_per_jiffy * (HZ/4)));
  45
  46         __delay(++xloops);
  47 }
  48 EXPORT_SYMBOL(__const_udelay);
  49
  50 void __udelay(unsigned long usecs)
  51 {
  52         __const_udelay(usecs * 0x000010c7); /* 2**32 / 1000000 (rounded up) */
  53 }
  54 EXPORT_SYMBOL(__udelay);
  55
  56 void __ndelay(unsigned long nsecs)
  57 {
  58         __const_udelay(nsecs * 0x00005); /* 2**32 / 1000000000 (rounded up) */
  59 }
  60 EXPORT_SYMBOL(__ndelay);