arch/unicore32/lib/delay.S

   1 /*
   2  * linux/arch/unicore32/lib/delay.S
   3  *
   4  * Code specific to PKUnity SoC and UniCore ISA
   5  *
   6  * Copyright (C) 2001-2010 GUAN Xue-tao
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12 #include <linux/linkage.h>
  13 #include <asm/assembler.h>
  14 #include <asm/param.h>
  15                 .text
  16
  17 .LC0:           .word   loops_per_jiffy
  18 .LC1:           .word   (2199023*HZ)>>11
  19
  20 /*
  21  * r0  <= 2000
  22  * lpj <= 0x01ffffff (max. 3355 bogomips)
  23  * HZ  <= 1000
  24  */
  25
  26 ENTRY(__udelay)
  27                 ldw     r2, .LC1
  28                 mul     r0, r2, r0
  29 ENTRY(__const_udelay)                           @ 0 <= r0 <= 0x7fffff06
  30                 ldw     r2, .LC0
  31                 ldw     r2, [r2]                @ max = 0x01ffffff
  32                 mov     r0, r0 >> #14           @ max = 0x0001ffff
  33                 mov     r2, r2 >> #10           @ max = 0x00007fff
  34                 mul     r0, r2, r0              @ max = 2^32-1
  35                 mov.a   r0, r0 >> #6
  36                 cmoveq  pc, lr
  37
  38 /*
  39  * loops = r0 * HZ * loops_per_jiffy / 1000000
  40  *
  41  * Oh, if only we had a cycle counter...
  42  */
  43
  44 @ Delay routine
  45 ENTRY(__delay)
  46                 sub.a   r0, r0, #2
  47                 bua     __delay
  48                 mov     pc, lr
  49 ENDPROC(__udelay)
  50 ENDPROC(__const_udelay)
  51 ENDPROC(__delay)