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kernel/linux-imx6_3.14.28/arch/openrisc/lib/delay.c 1.36 KB
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  /*
   * OpenRISC Linux
   *
   * Linux architectural port borrowing liberally from similar works of
   * others.  All original copyrights apply as per the original source
   * declaration.
   *
   * Modifications for the OpenRISC architecture:
   * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
   *
   *      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
   *
   * Precise Delay Loops
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <asm/delay.h>
  #include <asm/timex.h>
  #include <asm/processor.h>
  
  int read_current_timer(unsigned long *timer_value)
  {
  	*timer_value = mfspr(SPR_TTCR);
  	return 0;
  }
  
  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 long loops;
  
  	loops = (unsigned long long)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);