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[/] [or1k/] [trunk/] [linux/] [linux-2.4/] [arch/] [i386/] [lib/] [delay.c] - Rev 1765
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/* * 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/processor.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. */ static void __rdtsc_delay(unsigned long loops) { unsigned long bclock, now; rdtscl(bclock); do { rep_nop(); rdtscl(now); } while ((now-bclock) < loops); } /* * Non TSC based delay loop for 386, 486, MediaGX */ 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)); } extern void __cyclone_delay(unsigned long loops); extern int use_cyclone; void __delay(unsigned long loops) { if (use_cyclone) __cyclone_delay(loops); else if (x86_udelay_tsc) __rdtsc_delay(loops); else __loop_delay(loops); } 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); } void __udelay(unsigned long usecs) { __const_udelay(usecs * 0x000010c6); /* 2**32 / 1000000 */ } void __ndelay(unsigned long nsecs) { __const_udelay(nsecs * 0x00005); /* 2**32 / 1000000000 (rounded up) */ }