/arch/x86_64/lib/delay.c
https://bitbucket.org/evzijst/gittest · C · 48 lines · 31 code · 8 blank · 9 comment · 1 complexity · 39de9276b3adf0121e318e073102a719 MD5 · raw file
- /*
- * Precise Delay Loops for x86-64
- *
- * 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.
- */
- #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 */
- void __delay(unsigned long loops)
- {
- unsigned bclock, now;
-
- rdtscl(bclock);
- do
- {
- rep_nop();
- rdtscl(now);
- }
- while((now-bclock) < loops);
- }
- inline void __const_udelay(unsigned long xloops)
- {
- __delay(((xloops * cpu_data[_smp_processor_id()].loops_per_jiffy) >> 32) * 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) */
- }