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
  12 void __delay(unsigned long cycles)
  13 {
  14         u64 t0 = get_cycles();
  15
  16         while ((unsigned long)(get_cycles() - t0) < cycles)
  17                 cpu_relax();
  18 }
  19 EXPORT_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
  32 void __udelay(unsigned long us)
  33 {
  34         __delay((us * 0x000010c7ull * HZ * lpj_fine) >> 32);
  35 }
  36 EXPORT_SYMBOL(__udelay);
  37
  38 void __ndelay(unsigned long ns)
  39 {
  40         __delay((ns * 0x00000005ull * HZ * lpj_fine) >> 32);
  41 }
  42 EXPORT_SYMBOL(__ndelay);