5a62b19219
This way we get rid of s390's NO_IDLE_HZ and use the generic dynticks variant instead. In addition we get high resolution timers for free. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
75 lines
2.1 KiB
C
75 lines
2.1 KiB
C
/*
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* arch/s390/lib/delay.c
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* Precise Delay Loops for S390
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*
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* S390 version
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* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
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* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com),
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*
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* Derived from "arch/i386/lib/delay.c"
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* Copyright (C) 1993 Linus Torvalds
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* Copyright (C) 1997 Martin Mares <mj@atrey.karlin.mff.cuni.cz>
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*/
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#include <linux/sched.h>
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#include <linux/delay.h>
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#include <linux/timex.h>
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#include <linux/irqflags.h>
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#include <linux/interrupt.h>
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void __delay(unsigned long loops)
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{
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/*
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* To end the bloody studid and useless discussion about the
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* BogoMips number I took the liberty to define the __delay
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* function in a way that that resulting BogoMips number will
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* yield the megahertz number of the cpu. The important function
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* is udelay and that is done using the tod clock. -- martin.
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*/
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asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1));
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}
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/*
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* Waits for 'usecs' microseconds using the TOD clock comparator.
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*/
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void __udelay(unsigned long usecs)
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{
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u64 end, time, old_cc = 0;
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unsigned long flags, cr0, mask, dummy;
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int irq_context;
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irq_context = in_interrupt();
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if (!irq_context)
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local_bh_disable();
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local_irq_save(flags);
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if (raw_irqs_disabled_flags(flags)) {
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old_cc = S390_lowcore.clock_comparator;
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S390_lowcore.clock_comparator = -1ULL;
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__ctl_store(cr0, 0, 0);
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dummy = (cr0 & 0xffff00e0) | 0x00000800;
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__ctl_load(dummy , 0, 0);
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mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT;
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} else
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mask = psw_kernel_bits | PSW_MASK_WAIT |
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PSW_MASK_EXT | PSW_MASK_IO;
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end = get_clock() + ((u64) usecs << 12);
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do {
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time = end < S390_lowcore.clock_comparator ?
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end : S390_lowcore.clock_comparator;
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set_clock_comparator(time);
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trace_hardirqs_on();
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__load_psw_mask(mask);
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local_irq_disable();
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} while (get_clock() < end);
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if (raw_irqs_disabled_flags(flags)) {
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__ctl_load(cr0, 0, 0);
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S390_lowcore.clock_comparator = old_cc;
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}
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if (!irq_context)
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_local_bh_enable();
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set_clock_comparator(S390_lowcore.clock_comparator);
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local_irq_restore(flags);
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}
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