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
  27 void __delay(unsigned long cycles)
  28 {
  29         cycles_t start = get_cycles();
  30
  31         while ((get_cycles() - start) < cycles)
  32                 cpu_relax();
  33 }
  34 EXPORT_SYMBOL(__delay);
  35
  36 inline void __const_udelay(unsigned long xloops)
  37 {
  38         unsigned long loops;
  39
  40         loops = xloops * loops_per_jiffy * HZ;
  41         __delay(loops >> 32);
  42 }
  43 EXPORT_SYMBOL(__const_udelay);
  44
  45 void __udelay(unsigned long usecs)
  46 {
  47         __const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */
  48 }
  49 EXPORT_SYMBOL(__udelay);
  50
  51 void __ndelay(unsigned long nsecs)
  52 {
  53         __const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */
  54 }
  55 EXPORT_SYMBOL(__ndelay);