LXR linux/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, 2014 Maciej W. Rozycki
  10 */
  11#include <linux/delay.h>
  12#include <linux/export.h>
  13#include <linux/param.h>
  14#include <linux/smp.h>
  15#include <linux/stringify.h>
  16
  17#include <asm/asm.h>
  18#include <asm/compiler.h>
  19#include <asm/war.h>
  20
  21#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
  22#define GCC_DADDI_IMM_ASM() "I"
  23#else
  24#define GCC_DADDI_IMM_ASM() "r"
  25#endif
  26
  27void __delay(unsigned long loops)
  28{
  29        __asm__ __volatile__ (
  30        "       .set    noreorder                               \n"
  31        "       .align  3                                       \n"
  32        "1:     bnez    %0, 1b                                  \n"
  33        "        " __stringify(LONG_SUBU) "     %0, %1          \n"
  34        "       .set    reorder                                 \n"
  35        : "=r" (loops)
  36        : GCC_DADDI_IMM_ASM() (1), "0" (loops));
  37}
  38EXPORT_SYMBOL(__delay);
  39
  40/*
  41 * Division by multiplication: you don't have to worry about
  42 * loss of precision.
  43 *
  44 * Use only for very small delays ( < 1 msec).  Should probably use a
  45 * lookup table, really, as the multiplications take much too long with
  46 * short delays.  This is a "reasonable" implementation, though (and the
  47 * first constant multiplications gets optimized away if the delay is
  48 * a constant)
  49 */
  50
  51void __udelay(unsigned long us)
  52{
  53        unsigned int lpj = raw_current_cpu_data.udelay_val;
  54
  55        __delay((us * 0x000010c7ull * HZ * lpj) >> 32);
  56}
  57EXPORT_SYMBOL(__udelay);
  58
  59void __ndelay(unsigned long ns)
  60{
  61        unsigned int lpj = raw_current_cpu_data.udelay_val;
  62
  63        __delay((ns * 0x00000005ull * HZ * lpj) >> 32);
  64}
  65EXPORT_SYMBOL(__ndelay);
  66