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

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *      Precise Delay Loops for Meta
   4 *
   5 *      Copyright (C) 1993 Linus Torvalds
   6 *      Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
   7 *      Copyright (C) 2007,2009 Imagination Technologies Ltd.
   8 *
   9 */
  10
  11#include <linux/export.h>
  12#include <linux/sched.h>
  13#include <linux/delay.h>
  14
  15#include <asm/core_reg.h>
  16#include <asm/processor.h>
  17
  18/*
  19 * TXTACTCYC is only 24 bits, so on chips with fast clocks it will wrap
  20 * many times per-second. If it does wrap __delay will return prematurely,
  21 * but this is only likely with large delay values.
  22 *
  23 * We also can't implement read_current_timer() with TXTACTCYC due to
  24 * this wrapping behaviour.
  25 */
  26#define rdtimer(t) t = __core_reg_get(TXTACTCYC)
  27
  28void __delay(unsigned long loops)
  29{
  30        unsigned long bclock, now;
  31
  32        rdtimer(bclock);
  33        do {
  34                asm("NOP");
  35                rdtimer(now);
  36        } while ((now-bclock) < loops);
  37}
  38EXPORT_SYMBOL(__delay);
  39
  40inline void __const_udelay(unsigned long xloops)
  41{
  42        u64 loops = (u64)xloops * (u64)loops_per_jiffy * HZ;
  43        __delay(loops >> 32);
  44}
  45EXPORT_SYMBOL(__const_udelay);
  46
  47void __udelay(unsigned long usecs)
  48{
  49        __const_udelay(usecs * 0x000010c7); /* 2**32 / 1000000 (rounded up) */
  50}
  51EXPORT_SYMBOL(__udelay);
  52
  53void __ndelay(unsigned long nsecs)
  54{
  55        __const_udelay(nsecs * 0x00005); /* 2**32 / 1000000000 (rounded up) */
  56}
  57EXPORT_SYMBOL(__ndelay);
  58