LXR linux/arch/arm64/lib/delay.c

   1/*
   2 * Delay loops based on the OpenRISC implementation.
   3 *
   4 * Copyright (C) 2012 ARM Limited
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License version 2 as
   8 * published by the Free Software Foundation.
   9 *
  10 * This program is distributed in the hope that it will be useful,
  11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13 * GNU General Public License for more details.
  14 *
  15 * You should have received a copy of the GNU General Public License
  16 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17 *
  18 * Author: Will Deacon <will.deacon@arm.com>
  19 */
  20
  21#include <linux/delay.h>
  22#include <linux/init.h>
  23#include <linux/kernel.h>
  24#include <linux/module.h>
  25#include <linux/timex.h>
  26
  27void __delay(unsigned long cycles)
  28{
  29        cycles_t start = get_cycles();
  30
  31        while ((get_cycles() - start) < cycles)
  32                cpu_relax();
  33}
  34EXPORT_SYMBOL(__delay);
  35
  36inline void __const_udelay(unsigned long xloops)
  37{
  38        unsigned long loops;
  39
  40        loops = xloops * loops_per_jiffy * HZ;
  41        __delay(loops >> 32);
  42}
  43EXPORT_SYMBOL(__const_udelay);
  44
  45void __udelay(unsigned long usecs)
  46{
  47        __const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */
  48}
  49EXPORT_SYMBOL(__udelay);
  50
  51void __ndelay(unsigned long nsecs)
  52{
  53        __const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */
  54}
  55EXPORT_SYMBOL(__ndelay);
  56