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

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
   4 */
   5#include <linux/delay.h>
   6#include <linux/export.h>
   7#include <linux/smp.h>
   8#include <linux/timex.h>
   9
  10#include <asm/processor.h>
  11
  12void __delay(unsigned long cycles)
  13{
  14        u64 t0 = get_cycles();
  15
  16        while ((unsigned long)(get_cycles() - t0) < cycles)
  17                cpu_relax();
  18}
  19EXPORT_SYMBOL(__delay);
  20
  21/*
  22 * Division by multiplication: you don't have to worry about
  23 * loss of precision.
  24 *
  25 * Use only for very small delays ( < 1 msec).  Should probably use a
  26 * lookup table, really, as the multiplications take much too long with
  27 * short delays.  This is a "reasonable" implementation, though (and the
  28 * first constant multiplications gets optimized away if the delay is
  29 * a constant)
  30 */
  31
  32void __udelay(unsigned long us)
  33{
  34        __delay((us * 0x000010c7ull * HZ * lpj_fine) >> 32);
  35}
  36EXPORT_SYMBOL(__udelay);
  37
  38void __ndelay(unsigned long ns)
  39{
  40        __delay((ns * 0x00000005ull * HZ * lpj_fine) >> 32);
  41}
  42EXPORT_SYMBOL(__ndelay);
  43