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

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * OpenRISC Linux
   4 *
   5 * Linux architectural port borrowing liberally from similar works of
   6 * others.  All original copyrights apply as per the original source
   7 * declaration.
   8 *
   9 * Modifications for the OpenRISC architecture:
  10 * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
  11 *
  12 * Precise Delay Loops
  13 */
  14
  15#include <linux/kernel.h>
  16#include <linux/export.h>
  17#include <linux/init.h>
  18#include <asm/param.h>
  19#include <asm/delay.h>
  20#include <asm/timex.h>
  21#include <asm/processor.h>
  22
  23int read_current_timer(unsigned long *timer_value)
  24{
  25        *timer_value = get_cycles();
  26        return 0;
  27}
  28
  29void __delay(unsigned long cycles)
  30{
  31        cycles_t start = get_cycles();
  32
  33        while ((get_cycles() - start) < cycles)
  34                cpu_relax();
  35}
  36EXPORT_SYMBOL(__delay);
  37
  38inline void __const_udelay(unsigned long xloops)
  39{
  40        unsigned long long loops;
  41
  42        loops = (unsigned long long)xloops * loops_per_jiffy * HZ;
  43
  44        __delay(loops >> 32);
  45}
  46EXPORT_SYMBOL(__const_udelay);
  47
  48void __udelay(unsigned long usecs)
  49{
  50        __const_udelay(usecs * 0x10C7UL); /* 2**32 / 1000000 (rounded up) */
  51}
  52EXPORT_SYMBOL(__udelay);
  53
  54void __ndelay(unsigned long nsecs)
  55{
  56        __const_udelay(nsecs * 0x5UL); /* 2**32 / 1000000000 (rounded up) */
  57}
  58EXPORT_SYMBOL(__ndelay);
  59