LXR linux/arch/s390/lib/delay.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *    Precise Delay Loops for S390
   4 *
   5 *    Copyright IBM Corp. 1999, 2008
   6 *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
   7 *               Heiko Carstens <heiko.carstens@de.ibm.com>,
   8 */
   9
  10#include <linux/sched.h>
  11#include <linux/delay.h>
  12#include <linux/timex.h>
  13#include <linux/export.h>
  14#include <linux/irqflags.h>
  15#include <linux/interrupt.h>
  16#include <linux/jump_label.h>
  17#include <linux/irq.h>
  18#include <asm/vtimer.h>
  19#include <asm/div64.h>
  20#include <asm/idle.h>
  21
  22void __delay(unsigned long loops)
  23{
  24        /*
  25         * To end the bloody studid and useless discussion about the
  26         * BogoMips number I took the liberty to define the __delay
  27         * function in a way that that resulting BogoMips number will
  28         * yield the megahertz number of the cpu. The important function
  29         * is udelay and that is done using the tod clock. -- martin.
  30         */
  31        asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1));
  32}
  33EXPORT_SYMBOL(__delay);
  34
  35static void delay_loop(unsigned long delta)
  36{
  37        unsigned long end;
  38
  39        end = get_tod_clock_monotonic() + delta;
  40        while (!tod_after(get_tod_clock_monotonic(), end))
  41                cpu_relax();
  42}
  43
  44void __udelay(unsigned long usecs)
  45{
  46        delay_loop(usecs << 12);
  47}
  48EXPORT_SYMBOL(__udelay);
  49
  50void __ndelay(unsigned long nsecs)
  51{
  52        nsecs <<= 9;
  53        do_div(nsecs, 125);
  54        delay_loop(nsecs);
  55}
  56EXPORT_SYMBOL(__ndelay);
  57