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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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27f6b41662
The current virtual timer interface is inherently per-cpu and hard to use. The sole user of the interface is appldata which uses it to execute a function after a specific amount of cputime has been used over all cpus. Rework the virtual timer interface to hook into the cputime accounting. This makes the interface independent from the CPU timer interrupts, and makes the virtual timers global as opposed to per-cpu. Overall the code is greatly simplified. The downside is that the accuracy is not as good as the original implementation, but it is still good enough for appldata. Reviewed-by: Jan Glauber <jang@linux.vnet.ibm.com> Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
132 lines
2.8 KiB
C
132 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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#include <asm/vtimer.h>
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#include <asm/div64.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 cr0, cr6, new;
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u64 clock_saved, end;
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end = get_clock() + (usecs << 12);
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clock_saved = local_tick_disable();
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__ctl_store(cr0, 0, 0);
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__ctl_store(cr6, 6, 6);
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new = (cr0 & 0xffff00e0) | 0x00000800;
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__ctl_load(new , 0, 0);
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new = 0;
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__ctl_load(new, 6, 6);
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lockdep_off();
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do {
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set_clock_comparator(end);
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vtime_stop_cpu();
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local_irq_disable();
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} while (get_clock() < end);
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lockdep_on();
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__ctl_load(cr0, 0, 0);
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__ctl_load(cr6, 6, 6);
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local_tick_enable(clock_saved);
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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_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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vtime_stop_cpu();
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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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}
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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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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_clock() + nsecs;
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if (nsecs & ~0xfffUL)
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__udelay(nsecs >> 12);
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while (get_clock() < end)
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barrier();
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}
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EXPORT_SYMBOL(__ndelay);
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