diff options
Diffstat (limited to 'arch/alpha/lib/udelay.c')
-rw-r--r-- | arch/alpha/lib/udelay.c | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/arch/alpha/lib/udelay.c b/arch/alpha/lib/udelay.c new file mode 100644 index 000000000000..1c879bbce419 --- /dev/null +++ b/arch/alpha/lib/udelay.c @@ -0,0 +1,55 @@ +/* + * Copyright (C) 1993, 2000 Linus Torvalds + * + * Delay routines, using a pre-computed "loops_per_jiffy" value. + */ + +#include <linux/config.h> +#include <linux/module.h> +#include <linux/sched.h> /* for udelay's use of smp_processor_id */ +#include <asm/param.h> +#include <asm/smp.h> +#include <linux/delay.h> + +/* + * Use only for very small delays (< 1 msec). + * + * The active part of our cycle counter is only 32-bits wide, and + * we're treating the difference between two marks as signed. On + * a 1GHz box, that's about 2 seconds. + */ + +void +__delay(int loops) +{ + int tmp; + __asm__ __volatile__( + " rpcc %0\n" + " addl %1,%0,%1\n" + "1: rpcc %0\n" + " subl %1,%0,%0\n" + " bgt %0,1b" + : "=&r" (tmp), "=r" (loops) : "1"(loops)); +} + +#ifdef CONFIG_SMP +#define LPJ cpu_data[smp_processor_id()].loops_per_jiffy +#else +#define LPJ loops_per_jiffy +#endif + +void +udelay(unsigned long usecs) +{ + usecs *= (((unsigned long)HZ << 32) / 1000000) * LPJ; + __delay((long)usecs >> 32); +} +EXPORT_SYMBOL(udelay); + +void +ndelay(unsigned long nsecs) +{ + nsecs *= (((unsigned long)HZ << 32) / 1000000000) * LPJ; + __delay((long)nsecs >> 32); +} +EXPORT_SYMBOL(ndelay); |