delay.c

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/*
 *  Precise Delay Loops for SuperH
 *
 *  Copyright (C) 1999 Niibe Yutaka & Kaz Kojima
 */

#include <linux/sched.h>
#include <linux/delay.h>

void __delay(unsigned long loops)
{
    __asm__ __volatile__(
        /*
         * ST40-300 appears to have an issue with this code,
         * normally taking two cycles each loop, as with all
         * other SH variants. If however the branch and the
         * delay slot straddle an 8 byte boundary, this increases
         * to 3 cycles.
         * This align directive ensures this doesn't occur.
         */
        ".balign 8\n\t"

        "tst    %0, %0\n\t"
        "1:\t"
        "bf/s   1b\n\t"
        " dt    %0"
        : "=r" (loops)
        : "0" (loops)
        : "t");
}

inline void __const_udelay(unsigned long xloops)
{
    xloops *= 4;
    __asm__("dmulu.l    %0, %2\n\t"
        "sts    mach, %0"
        : "=r" (xloops)
        : "0" (xloops),
          "r" (cpu_data[raw_smp_processor_id()].loops_per_jiffy * (HZ/4))
        : "macl", "mach");
    __delay(++xloops);
}

void __udelay(unsigned long usecs)
{
    __const_udelay(usecs * 0x000010c6);  /* 2**32 / 1000000 */
}

void __ndelay(unsigned long nsecs)
{
    __const_udelay(nsecs * 0x00000005);
}