LXR linux/arch/mn10300/lib/delay.c

   1/* MN10300 Short delay interpolation routines
   2 *
   3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public Licence
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the Licence, or (at your option) any later version.
  10 */
  11#include <linux/module.h>
  12#include <linux/sched.h>
  13#include <linux/delay.h>
  14#include <asm/div64.h>
  15
  16/*
  17 * basic delay loop
  18 */
  19void __delay(unsigned long loops)
  20{
  21        int d0;
  22
  23        asm volatile(
  24                "       bra     1f      \n"
  25                "       .align  4       \n"
  26                "1:     bra     2f      \n"
  27                "       .align  4       \n"
  28                "2:     add     -1,%0   \n"
  29                "       bne     2b      \n"
  30                : "=&d" (d0)
  31                : "0" (loops)
  32                : "cc");
  33}
  34EXPORT_SYMBOL(__delay);
  35
  36/*
  37 * handle a delay specified in terms of microseconds
  38 */
  39void __udelay(unsigned long usecs)
  40{
  41        unsigned long start, stop, cnt;
  42
  43        /* usecs * CLK / 1E6 */
  44        stop = __muldiv64u(usecs, MN10300_TSCCLK, 1000000);
  45        start = TMTSCBC;
  46
  47        do {
  48                cnt = start - TMTSCBC;
  49        } while (cnt < stop);
  50}
  51EXPORT_SYMBOL(__udelay);
  52