arch/i386/lib/delay.c

   1 /*
   2  *      Precise Delay Loops for i386
   3  *
   4  *      Copyright (C) 1993 Linus Torvalds
   5  *      Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
   6  *
   7  *      The __delay function must _NOT_ be inlined as its execution time
   8  *      depends wildly on alignment on many x86 processors. The additional
   9  *      jump magic is needed to get the timing stable on all the CPU's
  10  *      we have to worry about.
  11  */
  12
  13 #include <linux/config.h>
  14 #include <linux/sched.h>
  15 #include <linux/delay.h>
  16 #include <linux/module.h>
  17 #include <asm/processor.h>
  18 #include <asm/delay.h>
  19 #include <asm/timer.h>
  20
  21 #ifdef CONFIG_SMP
  22 #include <asm/smp.h>
  23 #endif
  24
  25 extern struct timer_opts* timer;
  26
  27 void __delay(unsigned long loops)
  28 {
  29         cur_timer->delay(loops);
  30 }
  31
  32 inline void __const_udelay(unsigned long xloops)
  33 {
  34         int d0;
  35         xloops *= 4;
  36         __asm__("mull %0"
  37                 :"=d" (xloops), "=&a" (d0)
  38                 :"1" (xloops),"0" (cpu_data[raw_smp_processor_id()].loops_per_jiffy * (HZ/4)));
  39         __delay(++xloops);
  40 }
  41
  42 void __udelay(unsigned long usecs)
  43 {
  44         __const_udelay(usecs * 0x000010c7);  /* 2**32 / 1000000 (rounded up) */
  45 }
  46
  47 void __ndelay(unsigned long nsecs)
  48 {
  49         __const_udelay(nsecs * 0x00005);  /* 2**32 / 1000000000 (rounded up) */
  50 }
  51
  52 EXPORT_SYMBOL(__delay);
  53 EXPORT_SYMBOL(__const_udelay);
  54 EXPORT_SYMBOL(__udelay);
  55 EXPORT_SYMBOL(__ndelay);