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kernel/linux-rt-4.4.41/arch/arm64/lib/delay.c 1.42 KB
5113f6f70   김현기   kernel add
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  /*
   * Delay loops based on the OpenRISC implementation.
   *
   * Copyright (C) 2012 ARM Limited
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   *
   * Author: Will Deacon <will.deacon@arm.com>
   */
  
  #include <linux/delay.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/timex.h>
  
  void __delay(unsigned long cycles)
  {
  	cycles_t start = get_cycles();
  
  	while ((get_cycles() - start) < cycles)
  		cpu_relax();
  }
  EXPORT_SYMBOL(__delay);
  
  inline void __const_udelay(unsigned long xloops)
  {
  	unsigned long loops;
  
  	loops = xloops * loops_per_jiffy * HZ;
  	__delay(loops >> 32);
  }
  EXPORT_SYMBOL(__const_udelay);
  
  void __udelay(unsigned long usecs)
  {
  	__const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */
  }
  EXPORT_SYMBOL(__udelay);
  
  void __ndelay(unsigned long nsecs)
  {
  	__const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */
  }
  EXPORT_SYMBOL(__ndelay);