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kernel/linux-imx6_3.14.28/arch/mips/lib/delay.c 1.48 KB
6b13f685e   김민수   BSP 최초 추가
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  /*
   * This file is subject to the terms and conditions of the GNU General Public
   * License.  See the file "COPYING" in the main directory of this archive
   * for more details.
   *
   * Copyright (C) 1994 by Waldorf Electronics
   * Copyright (C) 1995 - 2000, 01, 03 by Ralf Baechle
   * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
   * Copyright (C) 2007  Maciej W. Rozycki
   */
  #include <linux/module.h>
  #include <linux/param.h>
  #include <linux/smp.h>
  
  #include <asm/compiler.h>
  #include <asm/war.h>
  
  void __delay(unsigned long loops)
  {
  	__asm__ __volatile__ (
  	"	.set	noreorder				
  "
  	"	.align	3					
  "
  	"1:	bnez	%0, 1b					
  "
  #if BITS_PER_LONG == 32
  	"	subu	%0, 1					
  "
  #else
  	"	dsubu	%0, 1					
  "
  #endif
  	"	.set	reorder					
  "
  	: "=r" (loops)
  	: "0" (loops));
  }
  EXPORT_SYMBOL(__delay);
  
  /*
   * Division by multiplication: you don't have to worry about
   * loss of precision.
   *
   * Use only for very small delays ( < 1 msec).	Should probably use a
   * lookup table, really, as the multiplications take much too long with
   * short delays.  This is a "reasonable" implementation, though (and the
   * first constant multiplications gets optimized away if the delay is
   * a constant)
   */
  
  void __udelay(unsigned long us)
  {
  	unsigned int lpj = raw_current_cpu_data.udelay_val;
  
  	__delay((us * 0x000010c7ull * HZ * lpj) >> 32);
  }
  EXPORT_SYMBOL(__udelay);
  
  void __ndelay(unsigned long ns)
  {
  	unsigned int lpj = raw_current_cpu_data.udelay_val;
  
  	__delay((ns * 0x00000005ull * HZ * lpj) >> 32);
  }
  EXPORT_SYMBOL(__ndelay);