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

   1/*
   2 *      Precise Delay Loops for SuperH
   3 *
   4 *      Copyright (C) 1999 Niibe Yutaka & Kaz Kojima
   5 */
   6
   7#include <linux/sched.h>
   8#include <linux/delay.h>
   9
  10void __delay(unsigned long loops)
  11{
  12        __asm__ __volatile__(
  13                /*
  14                 * ST40-300 appears to have an issue with this code,
  15                 * normally taking two cycles each loop, as with all
  16                 * other SH variants. If however the branch and the
  17                 * delay slot straddle an 8 byte boundary, this increases
  18                 * to 3 cycles.
  19                 * This align directive ensures this doesn't occur.
  20                 */
  21                ".balign 8\n\t"
  22
  23                "tst    %0, %0\n\t"
  24                "1:\t"
  25                "bf/s   1b\n\t"
  26                " dt    %0"
  27                : "=r" (loops)
  28                : "0" (loops)
  29                : "t");
  30}
  31
  32inline void __const_udelay(unsigned long xloops)
  33{
  34        xloops *= 4;
  35        __asm__("dmulu.l        %0, %2\n\t"
  36                "sts    mach, %0"
  37                : "=r" (xloops)
  38                : "0" (xloops),
  39                  "r" (cpu_data[raw_smp_processor_id()].loops_per_jiffy * (HZ/4))
  40                : "macl", "mach");
  41        __delay(++xloops);
  42}
  43
  44void __udelay(unsigned long usecs)
  45{
  46        __const_udelay(usecs * 0x000010c6);  /* 2**32 / 1000000 */
  47}
  48
  49void __ndelay(unsigned long nsecs)
  50{
  51        __const_udelay(nsecs * 0x00000005);
  52}
  53
  54