117 lines
2.8 KiB
C
117 lines
2.8 KiB
C
/*
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* Precise Delay Loops for S390
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*
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* Copyright IBM Corp. 1999,2008
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* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
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* Heiko Carstens <heiko.carstens@de.ibm.com>,
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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/module.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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static void __udelay_disabled(unsigned long long usecs)
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{
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unsigned long mask, cr0, cr0_saved;
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u64 clock_saved;
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clock_saved = local_tick_disable();
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set_clock_comparator(get_clock() + (usecs << 12));
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__ctl_store(cr0_saved, 0, 0);
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cr0 = (cr0_saved & 0xffff00e0) | 0x00000800;
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__ctl_load(cr0 , 0, 0);
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mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT;
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lockdep_off();
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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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lockdep_on();
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__ctl_load(cr0_saved, 0, 0);
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local_tick_enable(clock_saved);
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set_clock_comparator(S390_lowcore.clock_comparator);
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}
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static void __udelay_enabled(unsigned long long usecs)
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{
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unsigned long mask;
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u64 clock_saved;
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u64 end;
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mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT | PSW_MASK_IO;
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end = get_clock() + (usecs << 12);
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do {
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clock_saved = 0;
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if (end < S390_lowcore.clock_comparator) {
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clock_saved = local_tick_disable();
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set_clock_comparator(end);
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}
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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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if (clock_saved)
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local_tick_enable(clock_saved);
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} while (get_clock() < end);
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set_clock_comparator(S390_lowcore.clock_comparator);
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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 long usecs)
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{
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unsigned long flags;
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preempt_disable();
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local_irq_save(flags);
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if (in_irq()) {
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__udelay_disabled(usecs);
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goto out;
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}
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if (in_softirq()) {
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if (raw_irqs_disabled_flags(flags))
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__udelay_disabled(usecs);
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else
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__udelay_enabled(usecs);
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goto out;
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}
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if (raw_irqs_disabled_flags(flags)) {
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local_bh_disable();
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__udelay_disabled(usecs);
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_local_bh_enable();
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goto out;
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}
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__udelay_enabled(usecs);
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out:
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local_irq_restore(flags);
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preempt_enable();
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}
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EXPORT_SYMBOL(__udelay);
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/*
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* Simple udelay variant. To be used on startup and reboot
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* when the interrupt handler isn't working.
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*/
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void udelay_simple(unsigned long long usecs)
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{
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u64 end;
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end = get_clock() + (usecs << 12);
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while (get_clock() < end)
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cpu_relax();
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}
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