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kernel/linux-rt-4.4.41/arch/unicore32/lib/delay.S 1.06 KB
5113f6f70   김현기   kernel add
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  /*
   * linux/arch/unicore32/lib/delay.S
   *
   * Code specific to PKUnity SoC and UniCore ISA
   *
   * Copyright (C) 2001-2010 GUAN Xue-tao
   *
   * 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.
   */
  #include <linux/linkage.h>
  #include <asm/assembler.h>
  #include <asm/param.h>
  		.text
  
  .LC0:		.word	loops_per_jiffy
  .LC1:		.word	(2199023*HZ)>>11
  
  /*
   * r0  <= 2000
   * lpj <= 0x01ffffff (max. 3355 bogomips)
   * HZ  <= 1000
   */
  
  ENTRY(__udelay)
  		ldw	r2, .LC1
  		mul	r0, r2, r0
  ENTRY(__const_udelay)				@ 0 <= r0 <= 0x7fffff06
  		ldw	r2, .LC0
  		ldw	r2, [r2]		@ max = 0x01ffffff
  		mov	r0, r0 >> #14		@ max = 0x0001ffff
  		mov	r2, r2 >> #10		@ max = 0x00007fff
  		mul	r0, r2, r0		@ max = 2^32-1
  		mov.a	r0, r0 >> #6
  		cmoveq	pc, lr
  
  /*
   * loops = r0 * HZ * loops_per_jiffy / 1000000
   *
   * Oh, if only we had a cycle counter...
   */
  
  @ Delay routine
  ENTRY(__delay)
  		sub.a	r0, r0, #2
  		bua	__delay
  		mov	pc, lr
  ENDPROC(__udelay)
  ENDPROC(__const_udelay)
  ENDPROC(__delay)