arch/mips/lib/delay.c

   1 /*
   2  * This file is subject to the terms and conditions of the GNU General Public
   3  * License.  See the file "COPYING" in the main directory of this archive
   4  * for more details.
   5  *
   6  * Copyright (C) 1994 by Waldorf Electronics
   7  * Copyright (C) 1995 - 2000, 01, 03 by Ralf Baechle
   8  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
   9  * Copyright (C) 2007  Maciej W. Rozycki
  10  */
  11 #include <linux/module.h>
  12 #include <linux/param.h>
  13 #include <linux/smp.h>
  14
  15 #include <asm/compiler.h>
  16 #include <asm/war.h>
  17
  18 void __delay(unsigned long loops)
  19 {
  20         __asm__ __volatile__ (
  21         "       .set    noreorder                               \n"
  22         "       .align  3                                       \n"
  23         "1:     bnez    %0, 1b                                  \n"
  24 #if BITS_PER_LONG == 32
  25         "       subu    %0, 1                                   \n"
  26 #else
  27         "       dsubu   %0, 1                                   \n"
  28 #endif
  29         "       .set    reorder                                 \n"
  30         : "=r" (loops)
  31         : "0" (loops));
  32 }
  33 EXPORT_SYMBOL(__delay);
  34
  35 /*
  36  * Division by multiplication: you don't have to worry about
  37  * loss of precision.
  38  *
  39  * Use only for very small delays ( < 1 msec).  Should probably use a
  40  * lookup table, really, as the multiplications take much too long with
  41  * short delays.  This is a "reasonable" implementation, though (and the
  42  * first constant multiplications gets optimized away if the delay is
  43  * a constant)
  44  */
  45
  46 void __udelay(unsigned long us)
  47 {
  48         unsigned int lpj = raw_current_cpu_data.udelay_val;
  49
  50         __delay((us * 0x000010c7ull * HZ * lpj) >> 32);
  51 }
  52 EXPORT_SYMBOL(__udelay);
  53
  54 void __ndelay(unsigned long ns)
  55 {
  56         unsigned int lpj = raw_current_cpu_data.udelay_val;
  57
  58         __delay((ns * 0x00000005ull * HZ * lpj) >> 32);
  59 }
  60 EXPORT_SYMBOL(__ndelay);