130 lines
3 KiB
C
130 lines
3 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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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/export.h>
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#include <linux/irqflags.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <asm/vtimer.h>
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#include <asm/div64.h>
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#include <asm/idle.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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EXPORT_SYMBOL(__delay);
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static void __udelay_disabled(unsigned long long usecs)
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{
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unsigned long cr0, cr0_new, psw_mask;
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struct s390_idle_data idle;
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u64 end;
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end = get_tod_clock() + (usecs << 12);
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__ctl_store(cr0, 0, 0);
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cr0_new = cr0 & ~CR0_IRQ_SUBCLASS_MASK;
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cr0_new |= (1UL << (63 - 52)); /* enable clock comparator irq */
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__ctl_load(cr0_new, 0, 0);
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psw_mask = __extract_psw() | PSW_MASK_EXT | PSW_MASK_WAIT;
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set_clock_comparator(end);
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set_cpu_flag(CIF_IGNORE_IRQ);
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psw_idle(&idle, psw_mask);
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clear_cpu_flag(CIF_IGNORE_IRQ);
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set_clock_comparator(S390_lowcore.clock_comparator);
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__ctl_load(cr0, 0, 0);
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}
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static void __udelay_enabled(unsigned long long usecs)
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{
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u64 clock_saved, end;
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end = get_tod_clock_fast() + (usecs << 12);
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do {
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clock_saved = 0;
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if (tod_after(S390_lowcore.clock_comparator, end)) {
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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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enabled_wait();
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if (clock_saved)
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local_tick_enable(clock_saved);
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} while (get_tod_clock_fast() < end);
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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_tod_clock_fast() + (usecs << 12);
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while (get_tod_clock_fast() < end)
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cpu_relax();
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}
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void __ndelay(unsigned long long nsecs)
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{
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u64 end;
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nsecs <<= 9;
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do_div(nsecs, 125);
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end = get_tod_clock_fast() + nsecs;
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if (nsecs & ~0xfffUL)
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__udelay(nsecs >> 12);
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while (get_tod_clock_fast() < end)
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barrier();
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}
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EXPORT_SYMBOL(__ndelay);
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