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/*

 *  arch/s390/lib/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/sched.h>

#include <linux/delay.h>

#include <linux/timex.h>

#include <linux/irqflags.h>

#include <linux/interrupt.h>

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" : : "d" ((loops/2) + 1));

}

/*

 * Waits for 'usecs' microseconds using the TOD clock comparator.

 */

void __udelay(unsigned long usecs)

{

        u64 end, time, jiffy_timer = 0;

        unsigned long flags, cr0, mask, dummy;

        int irq_context;

        irq_context = in_interrupt();

        if (!irq_context)

                local_bh_disable();

        local_irq_save(flags);

        if (raw_irqs_disabled_flags(flags)) {

                jiffy_timer = S390_lowcore.jiffy_timer;

                S390_lowcore.jiffy_timer = -1ULL - (4096 << 12);

                __ctl_store(cr0, 0, 0);

                dummy = (cr0 & 0xffff00e0) | 0x00000800;

                __ctl_load(dummy , 0, 0);

                mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT;

        } else

                mask = psw_kernel_bits | PSW_MASK_WAIT |

                        PSW_MASK_EXT | PSW_MASK_IO;

        end = get_clock() + ((u64) usecs << 12);

        do {

                time = end < S390_lowcore.jiffy_timer ?

                        end : S390_lowcore.jiffy_timer;

                set_clock_comparator(time);

                trace_hardirqs_on();

                __load_psw_mask(mask);

                local_irq_disable();

        } while (get_clock() < end);

        if (raw_irqs_disabled_flags(flags)) {

                __ctl_load(cr0, 0, 0);

                S390_lowcore.jiffy_timer = jiffy_timer;

        }

        if (!irq_context)

                _local_bh_enable();

        set_clock_comparator(S390_lowcore.jiffy_timer);

        local_irq_restore(flags);

}