LXR linux/arch/openrisc/lib/delay.c

   1/*
   2 * OpenRISC Linux
   3 *
   4 * Linux architectural port borrowing liberally from similar works of
   5 * others.  All original copyrights apply as per the original source
   6 * declaration.
   7 *
   8 * Modifications for the OpenRISC architecture:
   9 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  10 *
  11 *      This program is free software; you can redistribute it and/or
  12 *      modify it under the terms of the GNU General Public License
  13 *      version 2 as published by the Free Software Foundation
  14 *
  15 * Precise Delay Loops
  16 */
  17
  18#include <linux/kernel.h>
  19#include <linux/export.h>
  20#include <linux/init.h>
  21#include <asm/param.h>
  22#include <asm/delay.h>
  23#include <asm/timex.h>
  24#include <asm/processor.h>
  25
  26int read_current_timer(unsigned long *timer_value)
  27{
  28        *timer_value = get_cycles();
  29        return 0;
  30}
  31
  32void __delay(unsigned long cycles)
  33{
  34        cycles_t start = get_cycles();
  35
  36        while ((get_cycles() - start) < cycles)
  37                cpu_relax();
  38}
  39EXPORT_SYMBOL(__delay);
  40
  41inline void __const_udelay(unsigned long xloops)
  42{
  43        unsigned long long loops;
  44
  45        loops = (unsigned long long)xloops * loops_per_jiffy * HZ;
  46
  47        __delay(loops >> 32);
  48}
  49EXPORT_SYMBOL(__const_udelay);
  50
  51void __udelay(unsigned long usecs)
  52{
  53        __const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */
  54}
  55EXPORT_SYMBOL(__udelay);
  56
  57void __ndelay(unsigned long nsecs)
  58{
  59        __const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */
  60}
  61EXPORT_SYMBOL(__ndelay);
  62