arch/openrisc/lib/delay.c

   1 /*
   2  * OpenRISC Linux
   3  *
   4  * Linux architectural port borrowing liberally from similar works of
   5  * others.  All original copyrights apply as per the original source
   6  * declaration.
   7  *
   8  * Modifications for the OpenRISC architecture:
   9  * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  10  *
  11  *      This program is free software; you can redistribute it and/or
  12  *      modify it under the terms of the GNU General Public License
  13  *      version 2 as published by the Free Software Foundation
  14  *
  15  * Precise Delay Loops
  16  */
  17
  18 #include <linux/kernel.h>
  19 #include <linux/export.h>
  20 #include <linux/init.h>
  21 #include <asm/param.h>
  22 #include <asm/delay.h>
  23 #include <asm/timex.h>
  24 #include <asm/processor.h>
  25
  26 int read_current_timer(unsigned long *timer_value)
  27 {
  28         *timer_value = get_cycles();
  29         return 0;
  30 }
  31
  32 void __delay(unsigned long cycles)
  33 {
  34         cycles_t start = get_cycles();
  35
  36         while ((get_cycles() - start) < cycles)
  37                 cpu_relax();
  38 }
  39 EXPORT_SYMBOL(__delay);
  40
  41 inline void __const_udelay(unsigned long xloops)
  42 {
  43         unsigned long long loops;
  44
  45         loops = (unsigned long long)xloops * loops_per_jiffy * HZ;
  46
  47         __delay(loops >> 32);
  48 }
  49 EXPORT_SYMBOL(__const_udelay);
  50
  51 void __udelay(unsigned long usecs)
  52 {
  53         __const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */
  54 }
  55 EXPORT_SYMBOL(__udelay);
  56
  57 void __ndelay(unsigned long nsecs)
  58 {
  59         __const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */
  60 }
  61 EXPORT_SYMBOL(__ndelay);