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  */
  19 void __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 }
  34 EXPORT_SYMBOL(__delay);
  35
  36 /*
  37  * handle a delay specified in terms of microseconds
  38  */
  39 void __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 }
  51 EXPORT_SYMBOL(__udelay);