root/arch/x86/um/delay.c

DEFINITIONS

1. __delay
2. __const_udelay
3. __udelay
4. __ndelay

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
   4  * Mostly copied from arch/x86/lib/delay.c
   5  */
   6 
   7 #include <linux/export.h>
   8 #include <linux/kernel.h>
   9 #include <linux/delay.h>
  10 #include <asm/param.h>
  11 
  12 void __delay(unsigned long loops)
  13 {
  14         asm volatile(
  15                 "test %0,%0\n"
  16                 "jz 3f\n"
  17                 "jmp 1f\n"
  18 
  19                 ".align 16\n"
  20                 "1: jmp 2f\n"
  21 
  22                 ".align 16\n"
  23                 "2: dec %0\n"
  24                 " jnz 2b\n"
  25                 "3: dec %0\n"
  26 
  27                 : /* we don't need output */
  28                 : "a" (loops)
  29         );
  30 }
  31 EXPORT_SYMBOL(__delay);
  32 
  33 inline void __const_udelay(unsigned long xloops)
  34 {
  35         int d0;
  36 
  37         xloops *= 4;
  38         asm("mull %%edx"
  39                 : "=d" (xloops), "=&a" (d0)
  40                 : "1" (xloops), "0"
  41                 (loops_per_jiffy * (HZ/4)));
  42 
  43         __delay(++xloops);
  44 }
  45 EXPORT_SYMBOL(__const_udelay);
  46 
  47 void __udelay(unsigned long usecs)
  48 {
  49         __const_udelay(usecs * 0x000010c7); /* 2**32 / 1000000 (rounded up) */
  50 }
  51 EXPORT_SYMBOL(__udelay);
  52 
  53 void __ndelay(unsigned long nsecs)
  54 {
  55         __const_udelay(nsecs * 0x00005); /* 2**32 / 1000000000 (rounded up) */
  56 }
  57 EXPORT_SYMBOL(__ndelay);