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/*

 *  arch/s390/kernel/delay.c

 *    Precise Delay Loops for S390

 *

 *  S390 version

 *    Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation

 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),

 *

 *  Derived from "arch/i386/lib/delay.c"

 *    Copyright (C) 1993 Linus Torvalds

 *    Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>

 */

#include <linux/config.h>

#include <linux/sched.h>

#include <linux/delay.h>

#ifdef CONFIG_SMP

#include <asm/smp.h>

#endif

void __delay(unsigned long loops)

{

        /*

         * To end the bloody studid and useless discussion about the

         * BogoMips number I took the liberty to define the __delay

         * function in a way that that resulting BogoMips number will

         * yield the megahertz number of the cpu. The important function

         * is udelay and that is done using the tod clock. -- martin.

         */

        __asm__ __volatile__(

                "0: brct %0,0b"

                : /* no outputs */ : "r" (loops/2) );

}

/*

 * Waits for 'usecs' microseconds using the tod clock

 */

void __udelay(unsigned long usecs)

{

        uint64_t start_cc, end_cc;

        if (usecs == 0)

                return;

        asm volatile ("STCK %0" : "=m" (start_cc));

        do {

                asm volatile ("STCK %0" : "=m" (end_cc));

        } while (((end_cc - start_cc)/4096) < usecs);

}