/* *  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>#endifvoid __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);}