/*
       *	Precise Delay Loops for i386
       *
       *	Copyright (C) 1993 Linus Torvalds
       *	Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
       *
       *	The __delay function must _NOT_ be inlined as its execution time
       *	depends wildly on alignment on many x86 processors. The additional
       *	jump magic is needed to get the timing stable on all the CPU's
       *	we have to worry about.
       */
      
      #include <linux/config.h>
      #include <linux/sched.h>
      #include <linux/delay.h>
      #include <asm/delay.h>
      
      #ifdef CONFIG_SMP
      #include <asm/smp.h>
      #endif
      
      int x86_udelay_tsc = 0;		/* Delay via TSC */
      
      	
      /*
       *	Do a udelay using the TSC for any CPU that happens
       *	to have one that we trust.
       */
      
  30  static void __rdtsc_delay(unsigned long loops)
      {
      	unsigned long bclock, now;
      	
      	rdtscl(bclock);
  35  	do
      	{
      		rdtscl(now);
      	}
  39  	while((now-bclock) < loops);
      }
      
      /*
       *	Non TSC based delay loop for 386, 486, MediaGX
       */
       
  46  static void __loop_delay(unsigned long loops)
      {
      	int d0;
      	__asm__ __volatile__(
      		"\tjmp 1f\n"
      		".align 16\n"
      		"1:\tjmp 2f\n"
      		".align 16\n"
      		"2:\tdecl %0\n\tjns 2b"
      		:"=&a" (d0)
      		:"0" (loops));
      }
      
  59  void __delay(unsigned long loops)
      {
  61  	if(x86_udelay_tsc)
      		__rdtsc_delay(loops);
  63  	else
      		__loop_delay(loops);
      }
      
  67  inline void __const_udelay(unsigned long xloops)
      {
      	int d0;
      	__asm__("mull %0"
      		:"=d" (xloops), "=&a" (d0)
      		:"1" (xloops),"0" (current_cpu_data.loops_per_jiffy));
              __delay(xloops * HZ);
      }
      
  76  void __udelay(unsigned long usecs)
      {
      	__const_udelay(usecs * 0x000010c6);  /* 2**32 / 1000000 */
      }